JP2001277156A - Transmission torque adjusting device of power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool with good assembling ability allowing a torque adjusting plate to be easily mounted into a gear case at a normal position during assembling. SOLUTION: Of multiple-strip screw parts 12a, 12b, 15a, 15b of the gear case 12 and the torque adjusting plate 15, at least a pair of screw parts 12b, 15b are molded in a different shape from the other screw parts 12a, 15a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission torque adjusting device for a power tool for adjusting a slip torque of an output shaft such as a driver drill.

[0002]

2. Description of the Related Art FIG. 2 shows an example of a conventional power tool.

[0003] A conventional transmission torque adjusting device for a power tool includes:
A pinion 2 fixed and driven by a motor shaft 1 meshes with a planet gear 4 supported on a support shaft of a carrier 3,
The planet gear 4 meshes with an internal gear 6 fixed to a gear case 5. Further, a sun gear 3a at the next stage is formed on the carrier 3, and the power of the motor shaft 1 is sequentially transmitted to the next stage at a reduced speed, and then transmitted to the sun gear 7a formed at the final stage carrier 7 at a reduced speed. . The sun gear 7a meshes with a planet gear 9 supported on a support shaft of the output shaft 8, and the planet gear 9 is
Meshes with A plurality of axial claws 10a are provided on the end face of the ring gear 10, and the balls 11 engaged with the claws 10a are arranged in holes penetrating through the gear case 12 so that movement is limited to only axial movement. It is elastically urged toward the ring gear 10 by a coil spring 14 via a clutch plate 13 that can move in the axial direction. The coil spring 14 is connected to the clutch plate 1.
3 and the torque adjusting plate 15. An internal thread portion 15a is provided on an inner wall of the torque adjusting plate 15, while an external thread portion 12a screwed with the internal thread portion 15a is provided on an outer wall of the gear case 12. Is screwed in conjunction with the rotation of the cap 16,
The amount of compression of the coil spring 14, that is, the urging force of the coil spring 14 is adjusted. When using a power tool, the biasing force of the coil spring 14 is adjusted to select the slip torque appropriately. However, when a load greater than the selected slip torque is applied to the output shaft 8, the claw 10 a of the ring gear 10 , The ball 11 moves in the axial direction against the urging force, and the ring gear 10 starts to rotate, so that power is not transmitted to the output shaft 8.
That is, if this mechanism is used, the torque transmitted to the output shaft 8 can be adjusted by adjusting the amount of compression of the coil spring 14. When transmitting a larger power to the output shaft 8, the torque adjusting plate 15 is
Rotate the cap 16 until it comes into contact with
May be suppressed in the axial direction. When set to _
Even if the claw 10a of the ring gear 10 attempts to move the ball 11 in the axial direction against the urging force of the coil spring 14, the ball 11 is prevented from moving in the axial direction because the torque adjustment plate 15 prevents the movement of the clutch plate 13 in the axial direction. The ring gear 10 cannot be moved and the ring gear 10 is fixed. That is, the direct connection mode is set.

[0004] By the way, in recent years, the torque of the power tool has been increased, and the rotational force of the ring gear 10 has increased.
In the direct connection mode, the ball 1
1, that is, the force pressing the torque adjustment plate 15 in the axial direction via the clutch plate 13 and the coil spring 14 is increasing. Therefore, the external thread 12a of the gear case 12 and the internal thread 1 of the torque adjusting plate 15
5a is formed as a multi-threaded screw for the purpose of reducing the surface pressure applied to the screw portion and receiving the load as evenly as possible.

[0005]

The conventional transmission torque adjusting mechanism of the electric tool is provided on the inner wall of the torque adjusting plate as described above, so that the cap portion is rotated by the screw portion and the male screw portion provided outside the gear case. In conjunction with, the amount of screwing of the torque adjustment plate is adjusted, the compression amount of the coil spring is adjusted, the slip torque is selected appropriately, and the torque adjustment plate is brought into contact with the clutch plate to set the direct connection mode. However, the screw portion is formed as a multi-threaded screw in order to alleviate the noodle pressure applied to the screw portion and to receive the load as evenly as possible. Therefore, when assembling the mechanism,
For example, in the case of a double-start screw, the torque adjustment plate may be rotated 180 degrees from the normal position at an incorrect position.
The structure is such that it can be easily assembled into the gear case even at the wrong position rotated by an angle, and the assembling operator must assemble while checking the screwing start position of the torque adjustment plate with respect to the gear case, and the assemblability is poor. .

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned drawbacks and to provide a power tool having a good assembling property in which a torque adjusting plate can be easily assembled into a gear case at a proper position at the time of assembling.

[0007]

The above object is achieved by forming at least one pair of the threaded portions of the multi-threaded portion of the gear case and the torque adjusting plate into a shape different from the other threaded portions.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the power tool of the present invention will be described with reference to FIG. Note that the same reference numerals are given to portions having the same configuration as the above-described conventional example, and thus description thereof will be omitted.

As shown in the drawing, an internal thread 15a and an internal thread 15b having a different shape from the internal thread 15a are provided on the inner wall of the torque adjusting plate 15, while the internal thread is provided on the outer wall of the gear case 12. Male thread portions 12a and 12b respectively screwed with 15a and 15b are provided. Since these double-start screws are constituted by two screw portions having different shapes, when assembling the mechanism, for example, the torque adjusting plate 15 is assembled into the gear case 12 at an incorrect position where the torque adjusting plate 15 is rotated by 180 degrees from a normal position. The female thread 15a and the male thread 1
2b cannot be incorporated because it cannot be screwed. In other words, the torque adjustment plate 15 is provided only at the proper position in the gear case 1.
2 can be assembled.

[0010] In the above embodiment, the case of the double-start thread has been described, but the effect is not changed even with a thread portion having three or more start threads.

[0011]

According to the present invention, at least one pair of the threaded portions of the multi-threaded portion of the gear case and the torque adjusting plate is formed into a shape different from the other threaded portions. Since the power tool can be assembled into the gear case only at the position, it is possible to provide a power tool with good assemblability.

[Brief description of the drawings]

FIG. 1 is an enlarged sectional view of a main part showing one embodiment of a power tool of the present invention.

FIG. 2 is an enlarged sectional view of a main part showing an example of a conventional power tool.

[Explanation of symbols]

10 is a ring gear, 10a is a claw, 11 is a ball, 12 is a gear case, 12a and 12b are female threads, 13 is a clutch plate, 14 is a coil spring, 15 is a torque adjusting plate, 15a and 15b are male threads, and 16 is a cap. is there.

Claims (1)

[Claims] 1. A gear case accommodating a planetary gear reduction mechanism and an output shaft, a ring gear provided in the planetary gear reduction mechanism, a ball engaged with an end face of the ring gear, and a coil for urging the ball toward the ring gear. A spring, a multi-threaded portion provided on the gear case, and a multi-threaded portion screwed with the multi-threaded portion. The multi-threaded portion is movable in the axial direction of the output shaft. An electric tool having a torque adjusting member capable of adjusting an amount of compression, wherein at least one pair of threaded portions of the multi-threaded portion of the gear case and the torque adjusting plate is formed in a shape different from other threaded portions. An electric tool characterized by the above-mentioned.