JP3678041B2 - Electric tool - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a mechanism for adjusting slip torque of an output shaft such as a driver drill.
[0002]
[Prior art]
A conventional torque adjusting mechanism will be described with reference to FIG. In the conventional torque adjusting mechanism, the pinion 2 fixedly driven on the motor shaft 1 meshes with the planet gear A4 supported by the support shaft of the carrier A3, and the planet gear A4 is fixed to the gear case A5. Engage with gear A8. Further, the next-stage sun gear A6 is formed on the carrier A3, and the rotation of the motor shaft 1 is sequentially transmitted to the next stage at a reduced speed, and the rotation is transmitted to the last-stage sun gear B7 at a reduced speed. The sun gear B7 meshes with the planet gear C10 supported on the support shaft of the carrier C9, and the planet gear C10 meshes with the internal gear C12. A claw 13 is provided on the end face of the internal gear C12, and a ball 14 that engages with the claw 13 is disposed in a hole that penetrates the gear case B15, and its movement is restricted only to movement in the axial direction. The coil spring 16 is always urged toward the claw side via the spring holder 17 and the thrust plate 18. The coil spring 16 is sandwiched between the spring holder 17 and the clutch plate 19. The clutch plate 19 has three legs that slide on the step-like slope of the cap 20 having a step-like slope having a height in the axial direction and provided with a plurality of horizontal portions on the inner peripheral side wall. The cap plate 19 is fixed by the positions of a plurality of horizontal portions provided on the stepped slope, or the cap portion is provided by a screw portion provided on the inner wall of the clutch plate and a screw portion provided on the outer wall of the gear case B. The structure is such that the slip torque is appropriately selected by adjusting the screwing amount of the clutch plate 19 in conjunction with the rotation of the clutch 20. Usually, the ball 14 is urged to the claw side of the internal gear C12 by the coil spring 16, so that the claw 13 and the ball 14 are engaged and the internal gear C12 cannot be rotated. The rotation is decelerated and transmitted to the output shaft 21 that is spline-fitted with C9.
[0003]
The case where the electric tool incorporating the above-described torque adjusting mechanism is used will be described. First, when a clutch is necessary so as not to damage the screw head or to perform operations such as mechanical screw tightening, when the cap 20 is first rotated, the cap 20 slides and the compression amount of the coil spring 16 changes. Thus, the urging force of the coil spring 16, that is, the slip torque is set. When a load greater than the slip torque set during the screw tightening operation is applied to the output shaft 21, the ball 14 is connected to the thrust plate 18, the spring holder 17, and the coil spring 16 to the pawl 13 provided on the end face of the internal gear C 12. Since the internal gear C12 is moved over in the compression direction and starts to rotate, power is not transmitted to the output shaft 21.
[0004]
Next, when it is not desired to operate the clutch, that is, when performing drilling or the like using a steel cone in the drill mode, the cap 20 is further rotated to move the clutch plate 19 to the thrust plate 18 side most. That is, it is compressed as much as possible, or the end face of the spring holder 17 is pressed and fixed by the clutch plate 19. With this setting, even if a large load is applied to the output shaft 21 due to the urging force of the coil spring 16 or the clutch plate 19, the ball 14 uses the thrust plate provided on the end surface of the internal gear C12 to move the thrust plate to the coil. Even if it moves in the compression direction of the spring and tries to get over, the coil spring cannot be compressed any more, so the ball cannot get over the claw and the internal gear C is fixed. That is, the drill mode can be set.
[0005]
[Problems to be solved by the invention]
The conventional torque adjustment mechanism is an interface in which a claw that engages with the ball is provided on the end surface by suppressing the movement of the steel ball through several parts such as a cap, a clutch plate, a spring, a spring holder, and a thrust plate. The null gear was fixed and the drill mode was used. However, under the circumstances where the torque has increased in recent years, the steel ball has actually passed over the pawl even in the drill mode due to the accumulated tolerance and deformation of parts, and the clutch has been operated. In some cases, it was necessary to strictly control the accuracy of parts.
[0006]
An object of the present invention is to obtain a torque adjusting mechanism capable of eliminating a factor such as cumulative tolerance and deformation of the parts as much as possible and realizing a reliable drill mode.
[0007]
[Means for Solving the Problems]
The object is to provide a planetary gear speed reduction mechanism housed in a gear case and provided with an internal gear C having a claw portion on an end surface, a ball engaging with the claw portion, and a through hole for holding the ball. In the torque adjustment mechanism having a gear case, a rotating member having a groove portion connected to a through hole provided in the gear case is rotatably provided between the gear case and the internal gear C, and the ball is further provided. Arranged so that it is held in the groove and rotated in conjunction with the rotating member, and whether or not the positional relationship between the through hole provided in the gear case and the groove provided in the rotating member is matched. This is achieved by allowing the range of movement of the ball to be limited by selection.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
A torque adjusting mechanism according to the present invention will be described with reference to FIGS. 1, 2, 3, and 4. FIG. First, the pinion 2 fixed to the motor shaft 1 meshes with the planet gear A4 supported by the support shaft of the carrier A3, and the planet gear A4 meshes with the internal gear A8 fixed to the gear case A5. Further, the next-stage sun gear A6 is formed on the carrier A3, and the rotation of the motor shaft 1 is sequentially transmitted to the next stage at a reduced speed, and the rotation is transmitted to the last-stage sun gear B7 at a reduced speed. The sun gear B7 meshes with the planet gear C10 supported on the support shaft of the carrier C9, and the planet gear C10 meshes with the internal gear C12. A claw A13 is provided on the end face of the internal gear C12, and the ball A14 that engages with the claw A13 is held in the hole of the rotating member 11. Further, as shown in FIG. 2, the rotating member 11 has a claw B24 protruding in the normal direction on the circumference, and a hole provided in the case B15 is provided in the rotating member 11. The nail | claw part B24 which was made can slide. The rotating member 11 and the case B15 are connected by a spring B23, and the rotating member 11 is normally urged in the circumferential direction by the spring B23, and is provided in the gear case B15 as shown in FIG. The ball B arranged in the through hole and the ball A14 arranged in the hole provided in the rotating member 11 are arranged on the same axis, and the movement is limited only to the movement in the axial direction. The ball B22 is always urged toward the claw side by a coil spring 16 via a thrust plate 18. The coil spring 16 is sandwiched between the thrust plate 18 and the clutch plate 19. The clutch plate 19 has three legs that slide on the step-like slope of the cap 20 having a step-like slope having a height in the axial direction and provided with a plurality of horizontal portions on the inner peripheral side wall. The clutch plate 19 is fixed by the positions of a plurality of horizontal portions provided on the stepped slope, and the position of the clutch plate 19, that is, the compression amount of the spring A is adjusted in conjunction with the rotation of the cap 20. It is structured to select properly.
[0009]
In FIG. 1, a position above the center line indicates a position where the clutch is not operated, that is, a cross section in the drill mode, and a position below the center line indicates a cross section at the clutch operating position. First, when a clutch is required, the cap 20 is rotated to set an arbitrary clutch torque position. Then, since the rotating member 11 is biased in the circumferential direction by the biasing force of the spring B23, the ball B22 held in the through hole of the gear case 5 and the hole of the rotating member 11 as shown in FIG. The balls A14 held in the section are arranged coaxially. When a load greater than a set slip torque is applied to the output shaft 21, the ball A14 causes the ball B14, the thrust plate 18, and the spring holder 17 to pass through the pawl A13 provided on the end surface of the internal gear C12. The coil spring 16 is moved in the compression direction to overcome the internal gear C12, so that the power is not transmitted to the output shaft 21.
[0010]
Next, when it is not desired to operate the clutch, when the cap is further rotated, as shown in FIG. 2, a claw B24 protruding from the rotating member 11 and a claw C25 provided on the cap 20 are provided. When the sliding member 11 is slid, the rotating member 11 rotates against the urging force of the spring B23, and the through hole provided in the gear case B15 and the through hole provided in the rotating member 11 as shown in FIG. Set the positional relationship to be non-coaxial. Then, even if a large load is applied to the output shaft 21, the ball A14 that engages with the claw portion 13 provided on the internal gear C12 abuts on the end surface of the case B15 and cannot move in the axial direction. The internal gear C12 is fixed and the clutch does not operate regardless of the urging force of the spring A16 and the position of the clutch plate 19. That is, the drill mode can be set.
[0011]
【The invention's effect】
When the electric tool having the torque adjusting mechanism configured as described above is set to the drill mode, the internal gear involved in the clutch operation is engaged with the claw portion of the internal gear even when a large load is applied to the output shaft. Since the ball is in contact with the end face of the case and cannot move, the ball is securely fixed and power is transmitted without the clutch operating. That is, since the movement of the ball is suppressed only by the end face of the case, the factors involved in the drill mode are limited to the dimensional tolerance and deformation of the gear case, so that the drill mode can be obtained more reliably than before. Furthermore, since the constraints on the dimensional accuracy, deformation and design of the parts that have been involved in realizing the conventional drill mode are alleviated, the cost of the parts can be reduced.
[Brief description of the drawings]
FIG. 1 is a partially longitudinal side view showing a torque adjustment mechanism according to the present invention.
FIG. 2 is a perspective sectional view showing a torque adjustment mechanism according to the present invention.
FIG. 3 is a state diagram showing the operation of the torque adjustment mechanism according to the present invention.
FIG. 4 is a state diagram showing the operation of the torque adjusting mechanism according to the present invention.
FIG. 5 is a partially longitudinal side view showing a conventional torque adjusting mechanism.
[Explanation of symbols]
1 is a motor shaft, 2 is a pinion, 3 is a carrier A, 4 is a planet gear A, 5 is a gear case A, 6 is a sun gear A, 7 is a sun gear B, 8 is an internal gear A, 9 is a carrier C, 10 Is a planet gear C, 11 is a rotating member, 12 is an internal gear C, 13 is a claw A, 14 is a ball A, 15 is a gear case B, 16 is a coil spring, 17 is a spring holder, 18 is a thrust plate, 19 is The clutch plate, 20 is a cap, 21 is an output shaft, 22 is a ball B, 23 is a spring B, 24 is a claw portion B, and 25 is a claw portion C.

Claims (1)

A motor shaft;
An internal gear to which rotation of the motor shaft is transmitted;
An output shaft through which rotation of the motor shaft is transmitted via the internal gear;
A gear case for rotatably holding the internal gear;
In an electric tool having
A claw portion is provided on the end face of the internal gear,
A rotation member is provided in the gear case so as to be rotatable,
A first hole is provided in the rotating member,
A first ball is provided in the first hole so as to be engageable with the claw,
An end face is provided on the gear case so as to be in contact with the first ball,
A second hole is provided on the end face coaxially with the first hole,
Providing a second ball in the second hole;
A spring for biasing the second ball toward the internal gear;
The rotating member has a first position where the first hole and the second hole coincide with each other, and a second position where the first hole and the end face coincide with each other. An electric tool characterized by

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