JP2003266325A - Torque transmission mechanism and electric tool using it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that a conventional impact-type screwdriver which obtains instantaneous large tightening torque by hitting an anvil with a hammer generates a large hitting noise at hitting with a hammer, and to improve a torque transmission mechanism which can obtain the instantaneous tightening torque extremely quietly. <P>SOLUTION: An output shaft 87 and a reversal shaft 92 are arranged on both sides in the axial direction of a driving shaft 84, a coil spring 90 is attached over the shafts, the driving shaft 84 is made to run idly by unwinding through displacement of ends 90a and 90b of the coil spring 90 in the unwinding direction, and the coil spring 90 is made to wind around this idly running driving shaft 84 so that inertial torque by idle running is added to output torque of an electric motor 2 to be outputted from the output shaft 87. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a torque transmission mechanism which can be suitably used for an electric tool such as a screw tightening machine for strongly tightening screws and nuts by giving a strong rotating torque in the tool rotating direction. And an electric tool using the same.

[0002]

2. Description of the Related Art Conventionally, as the screw tightener, generally referred to as an impact driver or impact wrench, for example, an impact type screw tightener 150 having a rotary impact mechanism 160 as shown in FIG. 3 is provided. Was there.
This screw tightener 150 has an electric motor 1 as a drive source.
51, a planetary gear mechanism 152 connected to the electric motor 151 via a pinion gear 157 (sun gear) attached to the output shaft 151a of the electric motor 151, and a rotation by the electric motor 151 via the planetary gear mechanism 152. The spindle 159 and the rotary impact mechanism 160 attached to the tip end side of the spindle 159. The rotary striking mechanism 160 includes an anvil 161 that is rotatably supported coaxially with the spindle 159, and a substantially cylindrical hammer 162 that is rotatably and axially movably supported on the outer peripheral side of the spindle 159. Anvil 16
1 is rotatably supported by an impact case 154 attached to the tip of the main body case 153 via a bearing 155. The tip side of the anvil 161 is projected from the impact case 154, and a driver bit (not shown) for screw tightening is attached to the tip of this projected portion. Steel balls 164 and 164 are sandwiched between the spindle 159 and the hammer 162. Steel balls 164,1
Reference numeral 64 denotes a cam groove 159a formed in the outer peripheral surface of the spindle 159, which is inclined with respect to the rotation axis and has a V-shape in a side view and a semicircular cross section, and a cam groove 159a formed in the inner peripheral surface of the hammer 162, which faces in the opposite direction Side view of V-shaped guide groove 16
It is sandwiched between 2a. Therefore, hammer 1
The shaft 62 moves forward or backward in the axial direction while rotating relatively to the spindle 159.

The hammer 162 is urged by a compression spring 163 in the forward direction (rightward in the drawing). Therefore, the backward movement of the hammer 162 is performed against the biasing force of the compression spring 163. On the front end surface of the hammer 162,
Two striking projections 162b, 162b are provided so as to project toward the anvil 161 side. Correspondingly, two striking arms 161a, 161a are provided at the rear end of the anvil 161.
Are provided so as to project in the radial direction. When the hammer 162 moves forward by the urging force of the compression spring 163, the hammer 162 rotates while moving forward as described above. As a result, the anvil 161 is hit in the rotational direction. This impact causes the anvil 161 to rotate in the screw tightening direction, thereby tightening the screw. When a certain amount of external torque (screw tightening resistance) is applied to the anvil 161 via the driver bit during screw tightening work, the hammer 162 relatively rotates with respect to the spindle 159 and retracts in the axial direction to strike the projecting portion. 162b, 1
62b is a striking arm 161a, 161 of the anvil 161.
a, which results in hammer 162 and anvil 16
The engagement state with 1 is released. When the engagement state between the hammer 162 and the anvil 161 is released, the external torque is not transmitted to the hammer 162, and the hammer 162 rotates while advancing by the spring biasing force of the compression spring 163, and after rotating about 180 °, The striking protrusion 162b collides with the striking arm 161a and strikes the anvil 161 in the rotational direction, whereby the anvil 161 rotates and the screw is tightened.

[0004]

As described above, in the conventional impact type screw tightening machine 150, the striking projections 162b, 162b of the hammer 162 are caused to collide with the striking arms 161a, 161a of the anvil 161 in the rotational direction. Since the anvil 161 is configured to give a large rotation torque (screw tightening torque), the impact projection 162 is provided.
When b hits the striking arm 161a, a striking sound (impact sound) is generated, which becomes a noise when the screw tightener 150 is used. Therefore, the present invention is
A torque transmission mechanism that is a mechanism completely different from the above-described conventional rotary striking mechanism, and can be used, for example, in a screw tightening machine to output a large screw tightening torque without generating a striking sound as in the conventional case. An object is to provide an electric tool using this.

[0005]

Therefore, the present invention is
The torque transmission mechanism having the structure described in each claim of the claims and the power tool using the same are provided. According to the torque transmission mechanism of claim 1, when the torque transmission mechanism is applied to, for example, a screw tightener, even when the electric motor is used by rotating the electric motor in the normal direction or the reverse direction such as the screw tightening work and the screw loosening work. It is possible to output a large instantaneous torque without generating a large impact sound in the conventional impact type screw tightener. That is, when the spiral spring is left-handed, if the electric motor is normally rotated,
The drive shaft rotates in the forward direction (clockwise rotation), and the output shaft rotates in the forward direction through the forward rotation path (drive shaft → winding spring → output shaft), whereby the screw can be tightened. If you reverse the electric motor,
The drive shaft reverses (rotates left), and the output shaft reverses through the reverse path (drive shaft → winding spring → reverse shaft → intermediate shaft → output shaft).
This makes it possible, for example, to loosen the tightened screw. In the configuration in which the output shaft and the reverse rotation shaft are arranged coaxially on opposite sides to the drive shaft, for example, a large diameter portion is provided on the drive shaft, and the output shaft is provided on one end side in the axial direction with respect to the large diameter portion. Can be rotatably supported coaxially, and the reverse rotation shaft can be rotatably supported coaxially on the other end side. The above effect can be obtained by setting the large diameter portion of the drive shaft, the output shaft, and the reverse rotation shaft to have substantially the same outer diameter, and by mounting the winding spring over the outer peripheral side thereof.

In this structure, for example, when the spiral spring is left-handed, when the electric motor is started in the forward rotation direction and the drive shaft rotates right (forward rotation), the friction between the drive shaft and the spiral spring is increased. Thereby, the coil spring is twisted and wound around the drive shaft, so that the coil spring rotates right together with the drive shaft. Since the right rotation of the spiral spring is the rotation in the winding direction with respect to the output shaft, when the spiral spring starts rotating right, the spiral spring also winds around the output shaft, whereby the output shaft rotates right together with the drive shaft. . On the other hand, the clockwise rotation of the winding spring is the rotation in the unwinding direction with respect to the reverse rotation shaft, so the winding spring does not wind around the reverse rotation shaft. Therefore, the rotational torque of the drive shaft is not transmitted to the reverse rotation shaft. Therefore, the output shaft smoothly rotates rightward without receiving the rotational torque from the reverse rotation shaft via the intermediate shaft, while the reverse rotation shaft idles clockwise together with the output shaft via the intermediate shaft. On the other hand, when the electric motor starts to rotate in the reverse direction and the drive shaft rotates counterclockwise (reverse rotation), the coil spring is twisted by the friction between the drive shaft and the coil spring and wound around the drive shaft. The coil spring rotates counterclockwise with the shaft. In the case of the structure according to claim 1, since the drive shaft is located at the center of the coil spring, when the drive shaft rotates, the coil spring is always wound around the drive shaft regardless of the rotation direction thereof.

Since the left rotation of the winding spring is the rotation in the winding direction with respect to the reverse rotation shaft, the winding spring also winds around the reverse rotation shaft, whereby the reverse rotation shaft rotates counterclockwise integrally with the drive shaft.
The left rotation of the reverse rotation shaft is transmitted to the output shaft via the intermediate shaft, whereby the output shaft rotates left together with the drive shaft. On the other hand, the counterclockwise rotation of the coil spring causes the coil shaft to rotate in the unwinding direction with respect to the output shaft, so the coil spring does not coil around the output shaft. Therefore, the torque of the drive shaft is transmitted to the output shaft only through the reverse rotation path, and the torque of the drive shaft is not transmitted through the normal rotation path, so that the output shaft rotates smoothly to the left. As described above, according to the torque transmission mechanism of the first aspect, when the electric motor is normally rotated, the output shaft is normally rotated, and when the electric motor is reversely rotated, the output shaft is reversely rotated. Inertia torque due to idling of the drive shaft in addition to the output torque of the electric motor is achieved by switching between the state in which the drive shaft idles by displacing the end in the unwinding direction and the winding direction, and the torque transmission state in which the winding spring is wound. Can be added to output from the output shaft. Therefore, by applying this torque transmission mechanism to a screw tightener, for example, a large torque can be generated extremely quietly without generating a large impact noise as in the case of the conventional impact type tool, and the screw can be regulated. Can be tightened with torque,
Also, the tightly tightened screw can be easily loosened.

According to the torque transmission mechanism of the second aspect,
The locking device locks the end portion of the winding spring in the unwinding direction to regulate the winding of the winding spring around the drive shaft, whereby the drive shaft is held in the idling state. When this locking device is manually released, the end of the coil spring is displaced in the coiling direction and the coil spring winds around the drive shaft, which causes the total torque of the inertia torque due to the drive shaft idling and the output torque of the electric motor. Is output. Therefore, unless the locked state of the lock device is released by a manual operation, the drive shaft idles and the output shaft is held in a standby state where it does not rotate.On the other hand, when the lock device is released by a manual operation, the winding spring winds around the drive shaft. A large torque is output from the output shaft. In this way, it is possible to arbitrarily control the state in which the output shaft rotates and the state in which the output shaft does not rotate by manual operation, so that the usability of the power tool is improved. That is, in a standby state where the electric motor is activated, the winding of the winding spring is regulated by the lock device to idle the drive shaft, and the lock device is released as required by the work to release a large amount from the output shaft. It is possible to use it to obtain a rotating torque. The locking device includes
For example, by providing a lock release lever and disposing this lever in the vicinity of the switch lever for starting the electric motor, the operator can start and stop the electric motor and operate the drive shaft while holding the electric tool. It is possible to switch between an idle state (standby state of the electric tool) and an output state from the output shaft (use state of the electric tool). According to the power tool of claim 3, for example, in a power tool such as a rotary impact tool, without causing a large impact as in the conventional case,
A large torque can be output.

According to the torque transmission mechanism of the fourth aspect,
When the spiral spring is left-handed, when the drive shaft rotates to the right, the spiral spring is twisted in the winding direction (clockwise direction) by the frictional resistance between the spiral spring and the drive shaft, and the spiral spring winds around the drive shaft. Rotate right together. The right rotation of the coil spring rotates in the winding direction with respect to the output shaft, and the rotation in the coil unwinding direction with respect to the reverse rotation shaft.Therefore, when the coil spring rotates right together with the drive shaft, the coil spring rotates on the output shaft. It wraps around, but does not wrap around the reverse shaft. Therefore, when the drive shaft rotates clockwise, the output shaft rotates right together with the drive shaft via the winding spring. On the other hand, when the drive shaft rotates counterclockwise, the winding spring is twisted in the winding direction (counterclockwise direction) by the frictional resistance between the drive shaft and the drive shaft, so that the winding spring winds around the drive shaft and rotates counterclockwise integrally with the drive shaft. . The left rotation of the spiral spring is the rotation in the unwinding direction with respect to the output shaft,
Since the coil spring rotates in the winding direction with respect to the reverse rotation shaft, when the coil spring rotates counterclockwise with the drive shaft, the coil spring does not wind around the output shaft but wind around the reverse rotation shaft. Therefore, when the drive shaft rotates counterclockwise, the reverse rotation shaft rotates counterclockwise integrally with the drive shaft via the winding spring. When the spiral spring is of the right-handed type, when the drive shaft rotates to the right, this is transmitted to the reverse shaft via the spiral spring, and the reverse shaft rotates right together with the drive shaft, and the drive shaft rotates left. This is transmitted to the output shaft via the winding spring, and the output shaft rotates counterclockwise together with the drive shaft. In this way, the output shaft and the reverse rotation shaft, which are coaxially arranged on the opposite sides to each other in the axial direction with respect to the drive shaft, rotate the output shaft and the reverse rotation shaft by switching the rotation direction of the drive shaft. You can switch to and. In the configuration in which the output shaft and the reverse rotation shaft are arranged coaxially on opposite sides to the drive shaft, for example, a large diameter portion is provided on the drive shaft, and the output shaft is provided on one end side in the axial direction with respect to the large diameter portion. Can be rotatably supported coaxially, and the reverse rotation shaft can be rotatably supported coaxially on the other end side. The above effect can be obtained by setting the large diameter portion of the drive shaft, the output shaft, and the reverse rotation shaft to have substantially the same outer diameter, and by mounting the winding spring over the outer peripheral side thereof.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described in detail with reference to the drawings. In the embodiments described below, a screw tightener is illustrated as an example of an electric tool. Also,
The so-called right-hand screw is exemplified as the screw to be tightened by this screw tightener. Therefore, when viewed from the head side of the screw, the screw is tightened when the screw is rotated rightward, and is loosened when the screw is rotated counterclockwise. Further, the rotation direction of each member described below is the rotation direction viewed from the electric motor 2 side (driving source side) unless otherwise specified. FIG. 1 shows the entire screw tightener 80 using the torque transmission mechanism T of this embodiment. This screw tightener 80 includes an electric motor 2 as a drive source inside a main body housing 10 having a substantially cylindrical shape.
And a handle portion 4 provided so as to project laterally from a side portion of the body portion 3. A switch lever 5 is provided at the base of the handle portion 4. The switch lever 5 is of a seesaw type that can be tilted forward or backward. When the operator grips the handle portion 4 and tilts the switch lever 5 to the forward rotation side with the fingertip, the electric motor 2 incorporated in the main body portion 3 rotates in the forward direction, and the forward rotation torque is output via the forward rotation path. By being transmitted to the shaft 87, the output shaft 87 rotates to the right, whereby screw tightening can be performed. On the other hand, when the switch lever 5 is tilted to the reverse rotation side, the electric motor 2 reversely rotates, and this reverse rotation torque is transmitted to the output shaft 87 via the reverse rotation path, and the output shaft 87 rotates counterclockwise. You can loosen the screws.

The output shaft 2a of the electric motor 2 is meshed with two planetary gears 82, 82 of a planetary gear mechanism 81. A drive shaft 84 is integrally and concentrically provided on the front surface side of a carrier 83 that rotatably supports the two planet gears 82, 82. The two planet gears 82, 82 are meshed with the internal gear 85. The internal gear 85 is rotatably supported with respect to the main body housing 10. However, the internal gear 85 has a brake device 86 attached to the main body housing 10.
Gives a certain rotation resistance. The brake device 86 uses the compression spring 86a to connect the main body housing 10 to the brake device 86.
Is provided with a pressing member 86b biased in the direction of protruding inward. The pressing member 86 is pressed by the urging force of the compression spring 86a.
By pressing b against the peripheral surface of the internal gear 85 to generate frictional resistance, a constant rotational resistance is given to the internal gear 85.

Next, the tip end side of the drive shaft 84 is connected to the output shaft 87. The output shaft 87 is rotatably supported on the tip end side of the main body housing 10 via a bearing 88. Further, a groove portion 84a having a semicircular cross section is formed on the tip side of the drive shaft 84, and two steel balls 89, 89 held by the output shaft 87 are fitted in the groove portion 84a. As a result, the drive shaft 84 and the output shaft 87 are connected to each other such that they can rotate but cannot move relative to each other in the axial direction. The two steel balls 89, 89 are held in holding holes 87a formed in the output shaft 87, respectively. A winding spring 90, which will be described later, is mounted on the outer peripheral side of the rear portion of the output shaft 87. The spiral spring 90 prevents the steel balls 89, 89 from falling out of the holding holes 87a toward the outer peripheral side. On the outer peripheral side of the drive shaft 84, in addition to the output shaft 87 described above, an auxiliary sleeve 91 and a reverse rotation shaft 92 are attached. A fixing pin 93 is driven between the auxiliary sleeve 91 and the drive shaft 84. Therefore, the auxiliary sleeve 91 is fixed to the drive shaft 84 such that it cannot rotate and cannot move in the axial direction. With this auxiliary sleeve 91, a large diameter portion 84b having a large diameter is provided in a stepped shape approximately in the middle of the drive shaft 84 in the axial direction. In addition, as illustrated above, the auxiliary sleeve 9 is a separate member.
1 may be prepared to provide the large diameter portion 84b, or the large diameter portion may be integrally formed as a part of the drive shaft 84. An output shaft 87 is supported on the left side of the large diameter portion 84b in the drawing, and a reverse rotation shaft 92 is supported on the right side of the large diameter portion 84b so as to be mutually rotatable and rotatable with respect to the drive shaft 84. The reverse rotation shaft 92 has a tubular shape as shown in the drawing, and is rotatably supported around the drive shaft 84 with the drive shaft 84 inserted through the inner peripheral side thereof. Further, this reverse rotation shaft 92 is
As shown in the figure, it is located between the large diameter portion 84b and the carrier 83, and is arranged substantially immovable in the axial direction with respect to the drive shaft 84. Further, as shown in the drawing, the outer diameters of the output shaft 87, the large-diameter portion 84b, and the reverse rotation shaft 92 are set to have substantially the same dimensions, and the winding spring 90 is mounted on the outer peripheral side thereof. As the winding spring 90, a left-handed rectangular spring whose wire rod has a rectangular cross-sectional shape is used.

Here, FIG. 2 schematically shows a drive shaft 84, an output shaft 87, a reverse rotation shaft 92, and a winding spring 90, which are essential parts of the torque transmission mechanism T of the present embodiment. Hereinafter, with reference to FIG. 2 as needed, the output shaft 87, the reverse rotation shaft 92, and the winding spring 90 when the drive shaft 84 rotates in the forward or reverse direction.
The state of will be described. When the drive shaft 84 rotates normally or reversely, frictional resistance between the drive shaft 84 and the winding spring 90 causes the drive shaft portion of the winding spring 90 to be wound around the large diameter portion 84b (not shown in FIG. 2) of the drive shaft 84. Is wrapped around. In the case of the left-handed spiral spring 90, when the drive shaft 84 rotates in the normal direction (right rotation), the drive shaft portion of the spiral spring 90 is twisted in the direction indicated by the arrow (a) in FIG.
Wraps around the drive shaft 84. Further, when the drive shaft 84 rotates in the reverse direction (counterclockwise rotation), the drive shaft portion of the winding spring 90 is twisted in the direction indicated by the arrow (b) in FIG. Wrap around. As described above, the drive shaft 84 (large-diameter portion 84b) is positioned in the middle of the winding spring 90 (displaced from the end portions 90a and 90b), so that the drive shaft 84 does not depend on the rotation direction. Whenever 84 rotates, the coil spring 90 winds around the drive shaft 84, which causes the coil spring 90 to rotate.
Rotate forward and reverse together with 4. This also applies to the case where a right-handed spiral spring is used instead of the left-handed spiral spring 90.

Now, returning to FIG. 1, since the spiral spring 90 is left-handed, when the electric motor 2 rotates in the normal direction (right rotation), the drive shaft portion of the spiral spring 90 winds around the drive shaft 84 and the spiral spring 90. Rotates in the forward direction together with the drive shaft 84. The forward rotation of the winding spring 90 is rotation in the winding direction with respect to the output shaft 87. Therefore, when the winding spring 90 rotates in the normal direction, the winding spring 90 also winds around the output shaft 87, and the output shaft 87 rotates in the normal direction together with the drive shaft 84 (normal rotation path). In this case, since the forward rotation of the winding spring 90 rotates in the unwinding direction with respect to the reverse rotation shaft 92, the winding spring 90 does not wind around the reverse rotation shaft 92. Therefore, the output shaft 87 receives the rotational torque only through the forward rotation path, and the reverse rotation path (the intermediate shaft 95
Since it does not receive the rotational torque through the path (), it rotates smoothly and efficiently. On the other hand, the electric motor 2
When the coil spring 90 is rotated in the reverse direction (counterclockwise) and the coil spring 90 is rotated together with the drive shaft 84, the coil spring 90 is rotated in the winding direction with respect to the coil reverse rotation shaft 92. Wrapping, which causes the reverse shaft 92 to drive the drive shaft 8
Reverse with 4 The reverse rotation of the reverse rotation shaft 92 is transmitted to the output shaft 87 via the intermediate shaft 95, whereby the output shaft 87 reversely rotates integrally with the drive shaft 84 (reverse rotation path). In this case, since the reverse rotation of the winding spring 90 causes the output shaft 87 to rotate in the unwinding direction, the winding spring 90 does not wind around the output shaft 87. Therefore, the output shaft 87 receives the rotation torque only through the reverse rotation path and does not receive the rotation torque through the forward rotation path, so that the output shaft 87 smoothly and efficiently reverses.

Next, the end portion 90a of the spiral spring 90 on the reverse rotation shaft side.
(The right end side in the drawing) is inserted into and engaged with an engagement hole 92a provided in the reverse rotation shaft 92. Therefore, unless the reverse rotation shaft 92 is forcibly displaced counterclockwise relative to the drive shaft 84 by the internal gear 85 rotating in the direction opposite to the drive shaft 84 as described later, the reverse rotation of the winding spring 90 is performed. The shaft-side end 90a is held in a state of being displaced in the winding direction with respect to the reverse rotation shaft 92. On the other hand, the output shaft side end portion 90b (the left end side in the drawing) of the spiral spring 90 is inserted into an engagement hole 95b provided in the intermediate shaft 95. Intermediate shaft 95 as shown
Has a tubular shape, and is arranged such that the drive shaft 84, the output shaft 87, the reverse rotation shaft 92, and the coil spring 90 are coaxially housed on the inner peripheral side thereof. This intermediate shaft 95 and output shaft 8
An engagement portion 97 is provided between the engagement portion 97 and the gear 7. Due to this meshing portion 97, the intermediate shaft 95 is integrated with the output shaft 87 in terms of rotation (always rotates integrally). Further, the stop ring 87b attached to the output shaft 87 restricts the movement and rattling of the intermediate shaft 95 to the left with respect to the output shaft 87. Further, a meshing portion 96 is also provided between the intermediate shaft 95 and the reverse rotation shaft 92. With this meshing portion 96, the intermediate shaft 95 and the reverse shaft 9
2 always rotates together.

An annular clutch plate 98 is mounted on the outer peripheral side of the intermediate shaft 95. A steel ball 101 is interposed between the intermediate shaft 95 and the clutch plate 98. Steel ball 10
Reference numeral 1 fits in a guide groove 95a having a semicircular cross section formed on the outer peripheral surface of the intermediate shaft 95 and a holding groove 98a having a semicircular cross section formed on the inner peripheral surface of the clutch plate 98. For this reason, the clutch plate 98 is axially movable with respect to the intermediate shaft 95 within a certain range, and is integrally rotated. A meshing portion 100 is provided between the clutch plate 98 and the internal gear 85. By this meshing portion 100, the internal gear 85 and the clutch plate 98 are united in rotation.
The clutch plate 98 is biased by a compression spring 99 in a direction of moving toward the meshing side on the right side in the drawing. Compression spring 99
When the clutch plate 98 is moved to the disengagement side on the left side in the drawing against the contact force, the meshing of the meshing portion 100 is released, whereby the clutch plate 98 and the internal gear 85 are released.
Are separated for rotation. FIG. 1 shows a clutch plate 98
And the internal gear 85 are in mesh with each other via the meshing portion 100. An engagement groove 98b is formed on the circumferential surface of the clutch plate 98 over the entire circumference thereof. Two actuating arms 102a, 102a of the switching plate 102 are inserted into the engagement groove 98b from both sides in the radial direction, whereby the switching plate 102 allows the clutch plate 98 to rotate with respect to the clutch plate 98. While being engaged in the axial direction. Therefore, by displacing the switching plate 102 in the axial direction (the lateral direction in the drawing), the clutch plate 98 can be moved to the engagement side or the engagement release side with respect to the internal gear 85.

On the other hand, the main body housing 10 is provided with an operating arm 103 rotatably via a support shaft 103a. One end side (the upper end side in the drawing) of the operating arm 103 is inserted into the engagement hole 102b of the switching plate 102 in the main body housing 10. The other end of the actuating arm 103 is inserted into the engaging hole 104 a of the switching lever 104 outside the main body housing 10. The switching lever 104 is supported so as to be slidable in the front-rear direction (left-right direction in the drawing) via a slide support portion 105 provided on the lower surface side of the main body housing 10. Since the switching lever 104 is connected to the clutch plate 98 which is biased toward the meshing side (right side in the drawing) by the compression spring 99 via the operation arm 103 and the switching plate 102, the switching lever 104 is indirectly connected via the compression spring 99. Is urged to the left side (clutch engagement side) in the figure. Switching lever 104
Is pulled to the right in the drawing (disengagement side) against the urging force of the compression spring 99, the operating arm 103 tilts in the counterclockwise direction in the drawing, whereby the clutch plate 98 moves to the disengagement side to the left in the drawing. Is displaced to. Switching lever 10
When the pulling operation of No. 4 is stopped, the switching lever 104 is returned to the meshing side on the left side in the drawing by the indirect action of the compression spring 99, whereby the clutch plate 98 is displaced to the meshing side meshing with the internal gear 85. The rear side of the switching lever 104 is curved in a U shape as shown in the drawing, and this curved portion serves as a finger hooking portion 104b for the operator to hook his / her finger. This finger hook 1
04b is located near the switch lever 5. Therefore, the operator changes the position of the fingertip while holding the handle portion 4 to change the position of the switch lever 5 and the switching lever 10.
Both of the four can be operated.

According to the screw tightener 80 of the present embodiment configured as described above, when the switch lever 5 is tilted to the forward rotation side to start the electric motor 2 without pulling the switching lever 104. The drive shaft 84 rotates in the normal direction (clockwise rotation) via the planetary gear mechanism 81. However, since the switching lever 104 is not pulled at this stage, the intermediate shaft 95 and the internal gear 85 are connected via the meshing portion 100. The reverse shaft 92 is connected to the intermediate shaft 95 via a meshing portion 96. At this stage, the carrier 83 of the planetary gear mechanism 81 (the drive shaft 8
4) is rotating, the internal gear 85 is not rotated by the brake device 86. Therefore, since the reverse shaft 92 and the intermediate shaft 95 are connected to the internal gear 85 that does not rotate, they do not rotate with respect to the main body housing 10. Since both ends 90a and 90b of the winding spring 90 are constrained with respect to the reverse rotation shaft 92 and the intermediate shaft 95, they cannot be displaced around the drive shaft 84, respectively. It cannot be rotated as a unit. Therefore, even if the winding spring 90 is wound around by the frictional resistance generated by the rotation of the drive shaft 84 to rotate integrally, either the reverse rotation shaft side end portion 90a or the output shaft side end portion 90b of the winding spring 90 is generated. (In the case of normal rotation, the reverse rotation shaft side end portion 90a) is relatively displaced in the unwinding direction, and as a result, the winding spring 90 does not wind around the drive shaft 84 at this stage, and therefore the drive shaft 84 does not move. No rotation is transmitted to the output shaft 87 merely by idling.

When the drive shaft 84 idles, the drive shaft 84, the planetary gear mechanism 81 and the electric motor 2 instantaneously rotate at the highest speed. When the switching lever 104 is pulled in this maximum speed rotation state, the clutch plate 98 is displaced to the left in FIG. 1, whereby the meshing state of the meshing portion 100 is released, and the clutch plate 98 and thus the intermediate shaft 95 rotate. It is separated from the internal gear 85. When the intermediate shaft 95 is disengaged from the internal gear 85, the intermediate shaft 95 and thus the reverse rotation shaft 92 become rotatable, which causes the spiral spring 90 to rotate.
Both ends 90a and 90b of the shaft are switched to a state in which they can be displaced around the drive shaft 84, and both ends 90a and 90b are displaced in the winding direction by the spring restoring force. When both ends 90a and 90b of the spiral spring 90 are displaced in the winding direction, the spiral spring 90 is wound around the large diameter portion 84b of the drive shaft 84 that rotates in the clockwise direction on the inner peripheral side thereof, and the spiral spring 90 is driven. It rotates right together with the shaft 84. Spiral spring 9
Since the right rotation of 0 is the rotation in the winding direction with respect to the output shaft 87, the winding spring 90 also winds around the output shaft 87,
As a result, the output shaft 87 rotates forward integrally with the drive shaft 84.
As described above, the clockwise rotation of the winding spring 90 is the rotation in the unwinding direction with respect to the reverse rotation shaft 92, so the winding spring 90 does not wind around the reverse rotation shaft 92. As described above, when the winding spring 90 is wound around the idling drive shaft 84 and the rotation is transmitted to the output shaft 87, the drive shaft 84, the planetary gear mechanism 20, the electric motor 2, and the rotating members around the idling shaft are idle. Inertial torque TI generated and electric motor 2
The total torque (TI + TM) with the output torque TM of is output instantaneously from the output shaft 87. In this way, the output shaft 87 is rotated clockwise by the torque (TI + TM), whereby the screw is tightened through the socket (not shown) attached to the tip thereof.

As the screw tightening progresses, a large screw tightening resistance is added to the output shaft 87 as a reaction force, whereby the output shaft 8
When the rotation of 7 is stopped, the winding spring 90 and the drive shaft 8
The rotation of 4 also stops. When the drive shaft 84 stops, the revolution of the planetary gears 82, 82 stops, so that the screw tightening resistance is added to the internal gear 85 as a rotational force. Therefore, the screw tightening resistance is received by the frictional force of the brake device 86 with respect to the internal gear 85. Therefore, when the frictional force exceeds the screw tightening resistance, the operator who grips the handle portion 4 can use this screwing resistance. You will receive tightening resistance. This screw tightening resistance is released when the internal gear 85 rotates against the frictional force of the brake device 86. Therefore, the frictional force of the brake device 86, that is, the biasing force of the compression spring 86a is set to an appropriate value so as not to place an excessive burden on the operator. When the screw tightening resistance becomes larger than the frictional force of the brake device 86,
The internal gear 85 starts rotating to the left. At this stage, since the switching lever 104 is in the pulling operation, the clutch plate 98 and the internal gear 85 are not in mesh with each other, and thus the internal gear 85 continues to rotate counterclockwise. When the pulling operation of the switching lever 104 is stopped in this state, the clutch plate 98 is returned to the right side in the drawing by the urging force of the compression spring 99, whereby the clutch plate 98 and the internal gear 85 rotate via the meshing portion 100. Mesh with each other.

When the intermediate shaft 95 meshes with the internal gear 85 that rotates counterclockwise through the clutch plate 98, the intermediate shaft 95 and the reverse rotation shaft 92 rotate counterclockwise, whereby the end 90a of the spiral spring 90 on the reverse rotation shaft side. Is displaced in the unwinding direction (counterclockwise direction), and the winding state of the winding spring 90 around the drive shaft 84 is released, whereby the drive shaft 84
Starts spinning again. The output shaft 8 is driven by idling of the drive shaft 84.
Since the transmission of the torque to 7 is cut off, the screw tightening resistance added to the output shaft 87 also disappears, and the rotation of the internal gear 85 is stopped. Further, the idling of the drive shaft 84 generates an inertia torque TI of the drive shaft 84, the planetary gear mechanism 81, the electric motor 2 and the peripheral members thereof, which is then wound around the drive shaft 84 and the output shaft 87. Is added to the output torque TM of the electric motor 2 and is output. If the screw is tightened to a predetermined specified torque, the switching lever 104
If the pulling operation is released, the output of the screw tightening torque from the output shaft 87 is stopped, and the drive shaft 84 is held in a standby state in which it idles.

When the screw cannot be tightened with the specified torque by the one-time tightening operation described above (the rotation of the output shaft 87 to the right), the screw is specified by rotating the output shaft 87 to the right again and retightening. Can be tightened up to torque. For this purpose, the switching lever 104 may be pulled again. In this way, the switching lever 10
4 is stopped, the drive shaft 84 is idled, and then the switching lever 104 is operated to pull the winding spring 90 around the drive shaft 84 to output the screw tightening force from the output shaft 87 to increase the number of screws. By tightening and repeating this operation a proper number of times, the screw can be tightened to the specified torque. When the screw is tightened to the specified torque, the pulling operation of the switching lever 104 is stopped to make the drive shaft 84 idle, or the switch lever 5 is turned off to stop the electric motor 2. As described above, according to the screw fastening machine 80 of the present embodiment, the winding spring 90 is wound around the idling drive shaft 84 to instantaneously obtain the output torque TM from the output shaft 87 from the output shaft 87. Can output a large torque (TI + TM). By winding the winding spring 90 around the idling drive shaft 84, a large impact noise unlike the conventional impact type screw tightener is not generated. Therefore, according to the screw tightener 80 of the present embodiment, it is extremely quiet and instantaneous. A large torque can be output to tighten the screw.

Next, a case where the screw tightener 80 of the present embodiment is used to loosen a screw, contrary to the above, will be described.
In this case, when the switch lever 5 is turned on to the reverse rotation side, the electric motor 2 reversely rotates in the counterclockwise direction, whereby the drive shaft 84 rotates leftward via the planetary gear mechanism 81. At this stage, the switching lever 104 has not been pulled. Therefore, since the intermediate shaft 95 and the reverse rotation shaft 92 cannot rotate, both ends 90a, 90 of the winding spring 90 are not rotated.
By extension, the winding spring 90 cannot rotate together with the drive shaft 84. Therefore, even if the drive shaft 84 rotates counterclockwise, the winding spring 90 does not wind around the drive shaft 84, so that the drive shaft 84 idles. When the drive shaft 84 idles, inertia torque TI of the drive shaft 84, the planetary gear mechanism 81, the electric motor 2, and the like is generated. Up to this point, the procedure is the same as in the case of screw tightening (in the case of normal rotation). Drive shaft 8
4 is rotated counterclockwise, the switching lever 1
When 04 is pulled to release the meshing of the clutch plate 98 with the internal gear 85 (meshing portion 100), the intermediate shaft 95 and the reverse rotation shaft 92 are rotatable in the counterclockwise direction, and both ends of the spiral spring 90 are rotated. Parts 90a, 90
Since b is rotatable in the counterclockwise direction, the winding spring 90 winds around the drive shaft 84 at this stage and integrally rotates counterclockwise. Since the left rotation of the spiral spring 90 rotates in the winding direction with respect to the reverse rotation shaft 92, the spiral spring 90 is rotated by the reverse rotation shaft 92.
Also wraps around. As described above, the left rotation of the winding spring 90 is the rotation in the unwinding direction with respect to the output shaft 87, so the winding spring 90 does not wind around the output shaft 87. When the winding spring 90 is wound around the drive shaft 84 and the reverse rotation shaft 92, the reverse rotation shaft 92 rotates counterclockwise (reverse rotation) together with the drive shaft 84. The left rotation of the reverse rotation shaft 92 is transmitted to the output shaft 87 via the intermediate shaft 95, whereby the screw is loosened. As in the case of the screw tightening described above, the drive shaft 8 that idles
When the winding spring 90 is wound around the output shaft 87, the inertia torque TI generated on the output shaft 87 due to idling of the drive shaft 84 and the like.
And the total torque of the output torque TM of the electric motor 2 (TI
+ TM) is transmitted as a screw loosening torque on the reverse rotation shaft 92 and the intermediate shaft 95, and this screw loosening torque (TI + TM)
The screw is loosened via the socket attached to the output shaft 87.

When the screw is not loosened by one screw loosening operation, the output shaft 87 receives a screw loosening resistance, which overcomes the frictional force of the brake device 86 against the internal gear 85 and the internal gear 85 rotates clockwise. Begin to. When the internal gear 85 starts rotating to the right, the clutch plate 98
The intermediate shaft 95 starts to be displaced clockwise through the
As a result, the output shaft side end portion 90b of the winding spring 90 is displaced in the unwinding direction, and the winding of the winding spring 90 with respect to the drive shaft 84 is released, so that the drive shaft 84 begins to idle again. In this idling state, when the switching lever 104 is pulled again to displace the clutch plate 98 to the disengagement side, the output shaft side end portion 90b of the winding spring 90 is returned in the winding direction by the spring restoring force and is moved to the drive shaft 84. The winding spring 90 is wound, whereby the output shaft 87 is again rotated counterclockwise by the screw loosening torque (TI + TM) to loosen the screw.
By repeating this operation, it is possible to surely loosen the screw with a shocking large torque (TI + TM) without producing a loud hitting sound as in the conventional rotary impact tool. Various modifications can be made to the embodiment illustrated above. For example, the case where the torque transmission mechanism T according to the present invention is applied to the screw tightening machine is illustrated, but the invention can be applied to other rotary tools such as an electric drill for drilling, a circular saw machine for cutting, and a planer. Further, it can be applied to a linear reciprocating tool such as a so-called reciprocating saw or a jigsaw having a mechanism for converting rotational movement into linear movement. Also,
Not only electric tools driven by an electric motor, but also hydraulic / pneumatic tools driven by a hydraulic motor or an air motor, or electric tools, hydraulic / pneumatic tools, and torque of various other machines, instruments, devices, etc. It can be applied as the transmission mechanism T.

[Brief description of drawings]

FIG. 1 is a side view showing the inside of a screw tightener according to an embodiment of the present invention.

FIG. 2 is a view schematically showing a main part of the screw fastening machine according to the embodiment of the present invention, and is a side view of a drive shaft, an output shaft, a reverse rotation shaft, and a winding spring.

FIG. 3 is a side view of the internal structure of a conventional screw tightening machine having a rotary impact mechanism.

[Explanation of symbols]

T ... Torque transmission mechanism TM: Output torque of electric motor (screw tightening torque) TI ... inertia torque due to idling (screw tightening torque) 80 ... Screw tightener 84 ... Drive shaft, 85 ... Internal gear 86 ... Brake device 87 ... Output shaft 90 ... Winding spring 91 ... Auxiliary sleeve (large diameter portion 84b) 92 ... Reverse rotation axis (reverse rotation axis) 95 ... Intermediate shaft 98 ... Clutch plate 104 ... Switching lever 150 ... Impact type screw tightener (conventional) 160 ... Rotating striking mechanism 161 ... Anvil 162 ... hammer

Claims (4)

[Claims] 1. A drive shaft that rotates forward and reverse by a drive source, an output shaft and a reverse shaft that are coaxially arranged on the opposite sides of the drive shaft in the axial direction, and straddle the outer peripheral side of these three shafts. An attached winding spring and an intermediate shaft for transmitting the rotation of the reverse rotation shaft to the output shaft, and when the drive shaft rotates in the normal direction, the winding spring is wound around the drive shaft and the output shaft to output the output shaft. When the drive shaft rotates in the forward direction and the drive shaft rotates in the reverse direction, the winding spring is wound around the drive shaft and the reverse rotation shaft, the reverse rotation shaft reverses integrally with the drive shaft, and the reverse rotation of the reverse rotation shaft occurs. While being transmitted to the output shaft via the intermediate shaft, the end portion of the winding spring is displaced in the unwinding direction during forward rotation and / or reverse rotation of the output shaft to wind the winding spring around the drive shaft. The drive shaft idles by releasing the state. And the end portion of the winding spring is displaced in the winding direction with respect to the drive shaft in the idling state so that the winding spring is wound around the drive shaft. A torque transmission mechanism configured to be added to the output torque of a drive source and output from the output shaft. 2. The torque transmission mechanism according to claim 1, further comprising a lock device for restricting winding of a winding spring around the drive shaft to hold the drive shaft in an idling state.
It is possible to arbitrarily control the timing of releasing the winding restriction state of the winding spring by the lock device by manual operation and adding the inertia torque generated by the idling of the drive shaft to the output torque of the drive source to output from the output shaft. Torque transmission mechanism configured. 3. An electric power tool using the torque transmission mechanism according to claim 1. 4. A drive shaft that rotates forward and reverse by a drive source, an output shaft and a reverse shaft that are coaxially arranged on the opposite sides of the drive shaft in the axial direction, and straddle the outer peripheral side of these three shafts. When the drive shaft rotates in the normal direction, the winding spring is wound around the drive shaft and the output shaft, the output shaft rotates in the normal direction integrally with the drive shaft, and when the drive shaft rotates in the reverse direction. A torque transmission mechanism configured such that the winding spring is wound around a drive shaft and the reverse rotation shaft so that the reverse rotation shaft rotates integrally with the drive shaft.