JP2002066960A - Power tool - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power tool having a built-in continuously variable transmission which continuously performs the variable transmission by solving problems that only the transmission of about two stages of the high speed and the low speed is variable by the engagement of gears in a reduction gear for reducing the rotation of an electric motor in the power tool such as a power driver drill. SOLUTION: The built-in continuously variable transmission 10 comprises a drive V-pulley 11 on the electric motor 4 side and a driven V-pulley 12 on a spindle 7 side, and a V-belt 13 stretched between the V-pulleys 11 and 12, the V-pulleys 11 and 12 comprise a pair of pulley plates 11a, 11b, 12a and 12b which are displaced to each other in the axial direction with the V-belt 13 held therebetween, and either or each of the pulley plates facing each other in the V-pulleys 11 and 12 are advanced/retracted to/from each other by the rotational resistance added via the V-belt 13 to change the diameter of the pulleys.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric tool such as an electric drill, an electric driver or a reciprocating saw for reciprocating a spindle.

[0002]

2. Description of the Related Art Conventionally, this type of power tool has been provided with a built-in transmission such as an electric screwdriver for switching the output speed of a spindle between high speed and low speed. The conventional transmission has a configuration in which the gear ratio is changed stepwise by switching the meshing of gears by a user's manual switching operation. Further, there has been provided an electric tool having a built-in automatic transmission that automatically switches the meshing of gears according to the torque required for the output shaft (rotational resistance or the like added to the output shaft) to change the gear ratio. According to the electric tool incorporating the above-mentioned manual switching type transmission, the transmission ratio can be appropriately switched according to the user's switching operation, for example, according to the diameter or length of the screw to be screwed, and thereby the electric motor , And the battery consumption can be suppressed. Also, according to the electric screwdriver with the built-in automatic transmission, in the initial stage of screw tightening, the transmission can be switched to a high speed side to quickly perform screw tightening at a low torque and high rotation speed, while the final stage of screw tightening. In the stage (when the screw tightening resistance increased), the transmission was switched to a low speed side, and the screw could be firmly tightened at a high torque and a low rotational speed.

[0003]

As described above, the conventional transmission has a structure in which the output of the drive motor is shifted through meshing of the gears, and the gear ratio is changed by switching the meshing gear. . For this reason, conventional transmissions are generally capable of shifting only in two stages of low speed and high speed, and cannot perform a gear shift in a more multi-stage gear ratio in accordance with the required torque, and much less a stepless speed change. Could not do. The present invention provides an electric tool having a built-in continuously variable transmission that can continuously change the output rotational speed to a wider range of gear ratios, thereby enabling a more fine-grained shift according to the required torque. The purpose is to provide.

[0004]

SUMMARY OF THE INVENTION Accordingly, the present invention provides an electric power tool having the structure described in each of the above claims. Claim 1
According to the power tool described above, since the continuously variable transmission is built in, the conventional high-speed or low-speed 2
A finer gearshift is performed in accordance with the required torque than in a stage-only transmission, so that the load on the motor can be further reduced than before, and power consumption of a battery or the like can be suppressed.

According to the power tool of the present invention, the pulley plates of the drive V pulley and the driven V pulley approach or separate from each other in accordance with the external torque (required torque) input via the spindle. The pulley diameters of the driving V-pulley and the driven V-pulley change steplessly and automatically, whereby the gear ratio changes steplessly and automatically. In the present specification, the pulley diameter refers to a radius of a portion (a contact portion) of the driving V pulley and the driven V pulley where the V belt 13 is stretched. Accordingly, the pulley diameters of the driving V-pulley and the driven V-pulley increase as the distance between the opposing pulley plates decreases, and decrease as the distance between the pulley plates increases.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of the present invention will be described with reference to FIGS.
A description will be given based on FIG. In the present embodiment, a rechargeable electric driver drill (hereinafter, simply referred to as an electric tool 1) will be described as an example of the electric tool. The power tool 1 has a main body 2 and a handle portion 3 extending laterally from the middle of the main body 2 in the machine length direction. A battery pack (not shown) for supplying power to the power tool 1 is attached to a lower end of the handle portion 3. An electric motor 4 as a drive source of the electric tool 1 is built in a rear part (left part in the figure) of the main body 2. The electric motor 4 is started and stopped by turning on and off a switch 5 arranged at the base of the handle portion 3. The switch 5 can be turned on and off by pulling a trigger 6 similarly arranged at the base of the handle 3. The output rotation of the electric motor 4 is controlled by the continuously variable transmission 10 according to the present invention and the conventionally known planetary gear train 50.
And the power is transmitted to the spindle 7. The tip of the spindle 7 protrudes from the front end face (right end face in the figure) of the main body housing 2a, and a chuck 8 for attaching a tip tool (not shown) such as a drill or a driver bit is attached to the protruding portion. I have.

The continuously variable transmission 10 comprises a drive V pulley 11 on the electric motor 4 side, a driven V pulley 12 on the spindle 7 side, and a V-shaped belt 13 having a V-shaped cross section which is bridged between the V pulleys 11 and 12. It has. The drive V pulley 11 is a pair of pulley plates 11a and 11b facing each other.
The driven V pulley 12 also has a pair of pulley plates 12a and 12b facing each other. Pulley plates 11a and 11b and pulley plates 12a and 12b
Are formed in a conical shape in accordance with the cross-sectional shape of the V-belt 13, respectively. Double pulley plate 11
The V-belt 13 is stretched between the driving V-pulley 11 and the driven V-pulley 12 while the V-belt 13 is sandwiched in V-shaped grooves formed between the a and 11b and between the two pulley plates 12a and 12b. ing. In the present embodiment, the pulley plates 11a, 11b, 12a, and 12b all have the same shape and size. Drive V
The pulley plates 11a and 11b of the pulley 11 are mounted on a spline shaft 4b formed on the output shaft 4a of the electric motor 4. For this reason, both pulley plates 11a and 11b rotate integrally when the electric motor 4 is started, while moving in the axial direction of the output shaft 4a and supported so as to be able to approach or separate from each other.

The distal end of the output shaft 4a of the electric motor 4 is rotatably supported by a bearing 2b attached to the main body housing 2a. A retaining ring 4c is attached to the base side of the output shaft 4a of the electric motor 4 so as not to move in the axial direction. A compression spring 14 is interposed between the retaining ring 4c and a pulley plate 11a on the output shaft base side (left side in the figure) of the drive V pulley 11. By the compression spring 14, the pulley plate 11a on the output shaft base side is urged in a direction approaching the pulley plate 11b on the output shaft tip side, whereby a V is applied between the pulley plates 11a and 11b.
The belt 13 is pinched with an appropriate force.

[0009] The driven V pulley 12 is
a through a bearing 2c attached to the output shaft 4a and a bearing 2d attached to a gear case 26. This intermediate shaft 15 includes a spline shaft portion 15a and a gear portion 15b as shown in FIG. The spline shaft portion 15a and the gear portion 15b are connected to each other coaxially and rotatably via a connection shaft portion 15c formed on the spline shaft portion 15a side. The two pulley plates 12a and 12b of the driven V pulley 12 are supported by the spline shaft portion 15a on the left side in the drawing so as to rotate integrally with each other and to be movable in the axial direction (to be able to approach or separate from each other). I have. The other end of the V-belt 13 extends between the pulley plates 12a and 12b. A movable cam portion 16 is integrally formed on the rear surface of the pulley plate 12b on the right side of the driven V pulley 12 in the drawing. The movable cam portion 16 is engaged with a fixed cam portion 17 formed integrally with the gear portion 15b of the intermediate shaft 15. As shown, the movable cam portion 16 and the fixed cam portion 17 have chevron teeth 16a to 16a,
a to 17a, which are alternately meshed. The movable cam portion 16 is displaced in the axial direction integrally with the pulley plate 12b, and is always maintained in a state of being engaged with the fixed cam portion 17. By the engagement between the fixed cam portion 17 and the movable cam portion 16, the rotation of the driven V pulley 12 is transmitted to the gear portion 15b.

When rotational resistance (screw tightening resistance) is added to the fixed cam portion 17 via the spindle 7, the meshing teeth 1
The movable cam portion 16 retreats in the axial direction (to the left in the drawing) due to the pressing force (sliding action) of the slope (cam surface) of the meshing teeth 6a and the slope (cam surface) of the meshing teeth 17a, and meshes with the fixed cam portion 17. Becomes shallower (see FIG. 2). When the movable cam portion 16 retreats in the axial direction and the engagement between the two 16 and 17 becomes shallow, the distance between the two pulley plates 12a and 12b becomes small, and the driven V
The pulley diameter of the pulley 12 increases. Then, since the V-belt 13 is displaced downward in the figure, the pulley plate 11a
Is displaced toward the output shaft base side against the compression spring 14, and the pulley diameter of the drive V pulley 11 is reduced. In this specification, (the pulley diameter of the drive V pulley 11) /
(The pulley diameter of the driven V pulley 12) will be described as the speed ratio R of the continuously variable transmission 10. Therefore, while the pulley diameter of the drive V pulley 11 decreases, the pulley diameter of the driven V pulley 12 increases, so that the speed ratio R of the continuously variable transmission 10 decreases. As the rotational resistance applied to the fixed cam portion 17 via the spindle 7 increases, the retreat amount of the movable cam portion 16 increases, and accordingly, the speed ratio R of the continuously variable transmission 10 decreases. On the other hand, in a no-load state where no rotational resistance is applied to the spindle 7, the pulley plate 11a of the drive V pulley 11 is returned to the right in the drawing by the compression spring 14, so that the pulley diameter of the drive V pulley 11 increases, Along with this, the pulley diameter of the driven V pulley 12 decreases, whereby the speed ratio R of the continuously variable transmission 10 increases.

Next, an intermediate gear 20 is meshed with the gear portion 15b of the intermediate shaft 15. This intermediate gear 20
Is rotatably supported by a bearing 2e attached to the main body housing 2a. In the present embodiment, the gear ratio between the gear portion 15b of the intermediate shaft 15 and the intermediate gear 20 is:
1: 5.5 (speed ratio 5.5). A small gear 21 is formed coaxially and integrally with the intermediate gear 20. The small gear 21 functions as a sun gear of the planetary gear train 50. Therefore, the rotation speed of the intermediate gear 20 is the input rotation speed of the planetary gear train 50. Small gear 2
1 is meshed with three planetary gears 22 to 22. Each of the planetary gears 22 to 22 is rotatably supported by a carrier 24 via a support shaft 23. The planetary gears 22 to 22 are meshed with the internal gear 25. The internal gear 25 includes a gear case 26 fixed to the main housing 2a.
It is supported rotatably.

A total of six lock pins 3 (see FIG. 3) are provided on the distal end surface of the internal gear 25 at six equally spaced positions in the circumferential direction.
0 to 30 tips are engaged. Each lock pin 30 ~
30 is supported by the gear case 26 so as to be movable in the axial direction. Each of the lock pins 30 to 30 is
1 urges in a direction (leftward in the figure) in which it engages with the internal gear 25, thereby restricting the rotation of the internal gear 25. Therefore, when a predetermined torque or more is applied to the internal gear 25, the internal gear 25 rotates (unlocks) while pushing down the lock pins 30 to 30 against the compression spring 31. That is, for example, when the screw tightening is completed and the spindle 7 and thus the carrier 24 become unrotatable (when a certain or more rotation resistance is added), the planetary gear 2
2 to 22 cannot be revolved. For this reason, each planetary gear 22 rotates only around the support shaft 23 by the rotation of the electric motor 4, whereby the internal gear 2
5 rotates while pushing down the lock pins 30 to 30.
Thus, the internal gear 25 rotates while the carrier 24 does not rotate, so that the power transmission path is interrupted by the planetary gear train 50. From this, mainly, the internal gear 25 and the lock pin 3
Reference numerals 0 to 30 constitute a so-called torque limiter (a planetary gear train 50 with a torque adjusting function).

The gear case 26 has a screw shaft 26a.
The adjusting plate 28 is engaged with the screw shaft portion 26a. This adjustment plate 28
And the receiving plate 27, the compression spring 31 is interposed. The receiving plate 27 is provided with the lock pins 30 to
30 is in contact with the rear end. Therefore, when the adjustment plate 28 rotates, the urging force of the compression spring 31 is changed, and the set torque for unlocking the internal gear 25 can be arbitrarily set within a certain range. The adjustment plate 28 is provided with an engagement piece 28 a, which is engaged with an engagement wall 29 a of an adapter case 29 rotatably attached to the front end of the gear case 26. For this reason, when the adapter case 29 is rotated, the adjustment plate 28 rotates and moves in the axial direction, whereby the set torque can be adjusted from the outside. Note that a steel ball 33 is attached to the gear case 26 in a state of being biased by a spring. The steel balls 33 are formed on the inner surface of the adapter case 29 along the circumferential direction.
b. The position of the adapter case 29 is fixed by fitting the steel ball 33 into the engagement hole 29b. On the other hand, when a predetermined rotation operation force or more is applied to the adapter case 29, the steel ball 33 is pushed down against the spring urging force, and the adapter case 29 can be rotated in any direction.

Next, the carrier 24 is connected to the spindle 7 via a rotation restricting device 32 attached to the gear case 26. The rotation restricting device 32 is conventionally known and does not require any particular change in the present embodiment.
This will be briefly described below. FIG. 3 shows the configuration of the rotation restricting device 32. The rotation restricting device 32 has an outer ring 32a fixed to the gear case 26, and an inner ring 32b rotatably connected to the spindle 7 via a spline shaft 7a formed at the rear end of the spindle 7.
Between the outer race 32a and the inner race 32b, a total of four legs 24b to 24b formed on the carrier 24 and two engagement pins 35, 35 are interposed. In addition, two engaging projections 32c, 32c and two flat surfaces 32d, 32d are formed on the outer peripheral surface of the inner ring 32b at positions equally divided in the circumferential direction, respectively. The engaging pins 35, 35 are arranged to face the flat surfaces 32d, 32d. Also, the legs 24b, 24b of the carrier 24 are provided on both circumferential sides of each engagement pin 35.
Are located on both sides in the circumferential direction of each engaging projection 32c.
b, 24b are located.

According to the rotation restricting device 32 configured as described above, when the carrier 24 is rotated by the activation of the electric motor 4, the two legs 24b, 24b are engaged with the engaging projections 32c, 32c.
The inner ring 32b and, consequently, the spindle 7 are rotated by contacting the inner ring 32c. That is, the rotation from the electric motor 4 side in either the left or right direction is transmitted to the spindle 7 via the rotation restricting device 32. However, in a state where the electric motor 4 is stopped (a state where the carrier 24 does not rotate),
Even if the user tries to rotate the spindle 7 by hand, the rotation of the spindle 7 is prevented because the engagement pins 35, 35 are caught between the flat surface 32d and the outer ring 32a, thereby preventing the rotation of the inner ring 32b. Will be blocked. According to this, in a state where the electric motor 4 is stopped, the chuck 8 can be rotated to easily perform the clamp unclamping operation of the tip tool.

Next, the spindle 7 includes bearings 7b and 7c.
And is rotatably supported by the gear case 26 via the.
In the present embodiment, the gear ratio of the planetary gear train 50 is 1
/ 4. A support hole 24a is formed at the center of the carrier 24, and a support shaft 21a formed at the center of the small gear 21 is rotatably inserted into the support hole 24a. Thus, the intermediate gear 20 and the small gear 21 are rotatably supported by the bearing 2e and the support hole 24a while both ends are supported.

According to the electric tool 1 configured as described above, when the trigger 6 is pulled and the switch 5 is turned on, the electric motor 4 starts. When the electric motor 4 starts, the output shaft 4a and its spline shaft 4b rotate, and the drive V pulley 11 rotates. Drive V pulley 1
The rotation of 1 is transmitted to the driven V pulley 12 by the V belt 13. Here, in a state where no rotational resistance is applied to the spindle 7 (no load state), a pulley plate 11a on the output shaft base side of the drive V pulley 11 as shown in FIG.
Is displaced toward the distal end of the output shaft by the compression spring 14, whereby the pulley diameter of the drive V pulley 11 is maximized.
When the pulley diameter of the driving V-pulley 11 is maximized, the distance between the pulley plates 12a and 12b of the driven V-pulley 12 is maximized, and the pulley diameter of the driven V-pulley 12 is minimized. And fixed cam part 1
7 is the deepest. In the present embodiment, in a no-load state where the pulley diameter of the driving V pulley 11 is maximum and the pulley diameter of the driven V pulley 12 is minimum, the ratio of the pulley diameters of both pulleys 11 and 12 is 2.
1: 1 (speed ratio R = 2.1) (high-speed low-torque mode).

The rotation of the driven V pulley 12 is controlled by the movable cam portion 1.
6 is transmitted to the gear portion 15b of the intermediate shaft 15 by the engagement between the fixed cam portion 6 and the fixed cam portion 17. When the gear 15b rotates, the intermediate gear 20 and the small gear 21 rotate. The rotation of the small gear 21 causes the planetary gears 22 to 22 to rotate. Since the planetary gears 22 to 22 are meshed with the non-rotating internal gear 25, as a result, the planetary gears 22 to 22 revolve on the inner peripheral side of the internal gear 25 while rotating, whereby the carrier 24 rotates. .
The rotation of the carrier 24 is transmitted to the spindle 7 via the spline shaft 7a, whereby the driver bit (tip tool) mounted on the chuck 8 rotates.

When the driver bit is set on the screw to be tightened and the screw is tightened, a fixed screw tightening resistance is added to the spindle 7 as a rotation resistance. For this reason, a larger output torque is required of the spindle 7 than in the no-load state. The required torque varies depending on the diameter and length of the screw to be tightened. Further, the required tightening torque changes with the progress of the screw tightening. When rotational resistance is added to the spindle 7 due to the screw tightening, the rotational resistance is changed to the planetary gear train 50, the intermediate gear 20 and the gear portion 15 of the intermediate shaft 15.
It is transmitted to the fixed cam portion 17 through the engagement of b. Then, as described above, the movable cam portion 16 and, consequently, the pulley plate 12b are retracted in the axial direction, so that the engagement between the cam portions 16 and 17 becomes shallow, whereby the pulley diameter of the driven V pulley 12 increases. When the pulley diameter of the driven V pulley 12 increases, the displacement of the V belt 13 causes the pulley plate 1
2a is displaced toward the base of the output shaft (to the left in FIG. 2) against the compression spring 14, whereby the pulley diameter of the drive V pulley 11 is reduced.
And the output torque of the spindle 7 increases. As described above, the pulley diameter of the driven V pulley 12 gradually increases in accordance with the rotational resistance applied to the spindle 7, while the pulley plate 11 a of the drive V pulley 11 outputs in response to this, against the compression spring 14. The gear ratio R of the continuously variable transmission 10 is steplessly reduced by being gradually displaced toward the shaft base and the pulley diameter is gradually reduced. As a result, the rotation speed of the spindle 7 is reduced and the output torque is increased. Then, the spindle 7 rotates with the output torque that is optimal for the required screw tightening torque, and the screw tightening proceeds.

As the screw tightening resistance reaches the final stage and the screw tightening resistance increases, the pulley diameter of the driven V pulley 12 increases while the pulley diameter of the driven V pulley 11 decreases, thereby increasing the speed ratio of the continuously variable transmission 10. R becomes smaller. FIG. 2 shows a stage where the speed ratio R of the continuously variable transmission 10 becomes the smallest. At this stage, the number of revolutions of the spindle 7 is the smallest and the output torque thereof is the largest (low-speed high-torque mode). In this embodiment,
At this stage, the ratio of the pulley diameter of the driving V pulley 11 to the pulley diameter of the driven V pulley 12 is 1: 2.1.
(Speed ratio R = 1 / 2.1). here,
When comparing FIG. 2 (low-speed high-torque mode) and FIG. 1 (high-speed low-torque mode), in the low-speed high-torque mode shown in FIG. 2, both pulley plates 11 a and 11 b of the drive V pulley 11 are used.
Is maximized, the pulley diameter is minimized, and the interval between the two pulley plates 12a, 12b of the driven V pulley 12 is minimized, the pulley diameter is maximized, and therefore the speed ratio R is minimized (speed ratio R). R = 1 / 2.1). On the other hand, in the high-speed low-torque mode shown in FIG. 1, both pulley plates 11a and 11b of the drive V pulley 11 are provided.
, The pulley diameter is maximized, and the interval between the two pulley plates 12a, 12b of the driven V pulley 12 is maximized, and the pulley diameter is minimized, whereby the gear ratio R is maximized (the gear ratio R). R = 2.1).

Thus, the screw is firmly tightened while the output torque of the spindle 7 shifts to the low-speed / high-torque mode without any step. When the screw tightening is completed and the spindle 7 cannot rotate, the power transmission path between the electric motor 4 and the spindle 7 is cut off. That is, when the screw tightening is completed and the spindle 7 cannot rotate, the rotation restricting device 32 and the carrier 24 cannot rotate.
The output rotation of the electric motor 4 is transmitted to the planetary gears 22 to 22 by the continuously variable transmission 10 and the intermediate gear 20. However, since the carrier 24 is in a non-rotatable state as described above, each of the planetary gears 22 does not revolve around the inner peripheral side of the internal gear 25 without rotating around the support shaft 23.
Rotate around. When a large torque equal to or greater than the set value is applied to the internal gear 25 by the rotation of each planetary gear 22, the internal gear 25 pushes down the lock pins 30 to 30 against the compression spring 31 while pressing down the lock pins 30 to 30.
Rotate with respect to 6. Thus, a state is realized in which the internal gear 25 rotates and the carrier 24 and thus the spindle 7 do not rotate, whereby the output of the electric motor 4 is cut off at the planetary gear train 50,
The screw is tightened with the set torque.

After the screw tightening is completed, if the tip tool is removed from the screw, the spindle 7 is in a no-load state.
The internal gear 25 is again fixed to the gear case 26, the output rotation of the electric motor 4 is transmitted to the spindle 7, and the continuously variable transmission 10 changes from the low-speed high-torque mode shown in FIG. Shift to the torque mode at once. That is, when the rotational resistance of the spindle 7 is removed and the load becomes a no-load state, as shown in FIG.
The pulley plate 11a of the pulley 11 is displaced by the compression spring 14 in a direction approaching the pulley plate 11b, thereby increasing the pulley diameter of the drive V pulley 11. Then, since the pulley diameter of the driven V pulley 12 decreases due to the displacement of the V-belt 13, the speed ratio R of the continuously variable transmission 10 increases, and the mode returns to the high-speed low-torque mode.
When the pulley diameter of the driven V pulley 12 decreases, the engagement between the movable cam portion 16 and the fixed cam portion 17 increases.

As described above, according to the electric power tool 1 of the present embodiment, the output shaft 4a of the electric motor 4 and the spindle 7
A continuously variable transmission 10 is interposed between the transmission 7 and the transmission 10. The continuously variable transmission 20 automatically changes the gear ratio R in accordance with the screw tightening resistance (external torque, rotation resistance) added to the spindle 7. Therefore, it is possible to perform a finer gear shift as compared with a conventional two-stage transmission using meshing spur gears, thereby improving the performance of this type of power tool.

The illustrated power tool 1 further includes a planetary gear train 50 in addition to the above-described continuously variable transmission 10, and the planetary gear train 50 is provided at the time when a predetermined or more external torque is applied to the spindle 7. Has a function of a torque limiter that rotates the internal gear 25 and thereby cuts off the power transmission path. For this reason, the screw is tightened with the set torque.

Various modifications can be made to the embodiment described above. For example, in the illustrated embodiment, in addition to the first-stage transmission mechanism by the continuously variable transmission 10, the second-stage transmission mechanism by meshing the intermediate gear portion 15 and the intermediate gear 20, and the third-stage transmission by the planetary gear train 50 Although the configuration having the mechanism is exemplified, the second and third speed change mechanisms may be provided as necessary. Also, pulley plates 11a,
11b, 12a, and 12b all have the same shape and size, but the drive V pulley and the driven V pulley have different shapes (mainly with respect to the inclination angle of the conical surface) and sizes of pulley plates. May be used.

In the illustrated embodiment, the gear ratio R is automatically adjusted according to the external torque applied to the spindle 7.
Is illustrated, but a continuously variable transmission having a configuration (manual type) in which the gear ratio R is continuously changed by a manual operation can be used. In this case, for example, a slide lever is provided on the upper surface of the housing 2, and the end of the slide lever on the inner side of the housing 2 is connected to the drive V
The pulley plate 11a on the output shaft base side of the pulley 11 is axially displaceably engaged with the pulley plate 11a so as not to hinder its rotation operation.
What is necessary is just to make it the structure which displaces 1a to an axial direction. further,
Although an electric driver drill has been exemplified as an example of the electric tool, the technology according to the present invention can be similarly applied to not only these rotary tools but also reciprocating cutting tools such as reciprocating saws.

[Brief description of the drawings]

FIG. 1 is a view showing an embodiment of the present invention, and is a side view showing an internal structure of an electric screwdriver drill. This figure shows a state where the continuously variable transmission is switched to a high-speed low-torque mode.

FIG. 2 is a view showing the embodiment of the present invention, and is a side view showing an internal structure of the electric screwdriver drill. This figure shows a state in which the continuously variable transmission is switched to the low-speed high-torque mode.

FIG. 3 is a sectional view taken along line (3)-(3) of FIG. 2;
It is a cross-sectional view of a rotation restricting device.

FIG. 4 is a partially broken side view of the intermediate shaft.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electric tool (electric driver drill) 4 ... Electric motor 7 ... Spindle 10 ... Continuously variable transmission 11 ... Drive V pulley 11a ... Pulley plate (output shaft base side), 11b ... Pulley plate (output shaft tip side) 12 ... Driven V pulley, 12a, 12b Pulley plate 13 V belt 15 Intermediate shaft, 15a Spline shaft portion, 15b Gear portion 16 Movable cam portion 17 Fixed cam portion 20 Intermediate gear 21 Small gear (sun gear) Reference numeral 22: Planetary gear, 24: Carrier, 25: Internal gear 26: Gear case, 26a: Screw shaft 28: Adjustment plate 29: Adapter case, 30: Lock pin, 32: Rotation restricting device 50: Planetary gear train

Claims (2)

[Claims] An electric tool having a continuously variable transmission between an output shaft of an electric motor and a spindle for continuously changing the rotation of the output shaft and transmitting the rotation to the spindle. 2. The electric power tool according to claim 1, wherein the continuously variable transmission includes a drive V pulley on the electric motor side, a driven V pulley on the spindle side, and a V belt stretched between the V pulleys. The two V-pulleys have a pair of pulley plates facing each other, and the distance between the two pulley plates is changed according to the rotational resistance applied to the spindle to change the diameter of each pulley. Power tools.