JP4291179B2 - Impact driver - Google Patents

Description

  The present invention relates to an impact driver capable of imparting rotation and intermittent striking operation to an anvil protruding forward of a housing.

  In the impact driver, a hammer is connected to a spindle that is rotated by a motor via a cam groove and a ball, and an anvil that is locked in the rotation direction is pivotally supported in front of the hammer so that the spindle is rotated. A structure for transmitting to the anvil via the wing is known. This is because when the load on the anvil exceeds a certain value, the hammer moves backward along the cam groove and temporarily leaves the anvil, and the hammer moves forward again along the cam groove by a coil spring that is biased forward. By repeating the action of locking, it is possible to intermittently apply an impact operation to the anvil in the direction of rotation.

Such an impact driver is used exclusively for fastening work with screws, bolts, etc. For example, in the case where a work piece is tightened by drilling a pilot hole in a workpiece, Since the two tools, ie, the electric drill and the impact driver, are used separately, there is a trouble in changing the tool and the workability is not good.
Therefore, in Patent Document 1, a connecting member that can move in the axial direction is provided at the shaft center of the drive shaft (spindle) in the housing, and the spindle and the anvil are engaged at a predetermined position of the connecting member. An invention is described in which a drill mode in which a spindle and an anvil are directly connected is obtained by providing a joint and operating a connecting member from the outside of the housing.

JP 2000-317854 A

  However, in the invention of Patent Document 1, since the connecting member is provided on the shaft center of the spindle and the engaging portion and the engaged portion are provided on the shaft center of the spindle and the anvil, the connecting member and the engaging / disengaging mechanism are provided. It is easy to be limited by space, and the degree of freedom in design is low, making it difficult to respond to torque changes. Further, when replacing or repairing the connecting member, it is necessary to remove all the hammering operation parts such as the hammer and the spindle, which is inconvenient to handle.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an impact driver that can easily select a drill mode and can easily change a design, repair, and the like.

In order to achieve the above object, according to a first aspect of the present invention, a spindle that rotates by driving a motor is provided in a housing, and the spindle is engaged with an anvil that is pivotally supported by the housing and protrudes forward. And an impact driver in which a hammer for transmitting the rotation of the spindle to the anvil is provided, and the hammer engages and disengages the anvil according to a load on the anvil, thereby giving the anvil a striking operation in the rotation direction. A first gear that rotates by driving the motor, a second gear that is coaxial with the anvil, and is pivotally supported between the first gear and the second gear; It consists of a intermediate shaft for transmitting the rotation of the first gear to the second gear, rotating heat transfer to transmit to the anvil rotation of the motor to bypass the spindle and the hammer Provided with a means and is characterized in that a switching means capable of interrupting the rotation transmission arbitrarily from the housing exterior to the anvil by the rotation transmitting means.

The invention according to claim 2, in addition to the purpose of claim 1, between said motor and said spindle, planetary gears are rotatably attached to revolve within the internal gear and the output shaft and meshing of the motor, In the case where a carrier for transmitting rotation to the spindle is provided, a second planetary gear meshing with the output shaft is attached to the rear of the carrier in order to easily form the switching means using this planetary gear reduction mechanism. The second carrier is arranged side by side, and teeth are formed on the outer periphery of the second carrier to form the first gear, while the switching means has a forward position that meshes only with the front planetary gear, and a rear first gear. In this configuration, the internal gear is moved to a retracted position that meshes with only the second planetary gear.

According to the first aspect of the present invention, it is possible to perform drilling work and tightening work such as screws with a single impact driver, and improvement in workability can be expected. In particular, since the drill mode is obtained with a rotation transmission means that bypasses the spindle and hammer, the number of gears to be used and the design freedom such as setting the gear ratio are increased, and any drill mode can be selected. It becomes. In addition, parts can be easily replaced and repaired in the rotation transmission means, which is convenient for handling.
Further, in addition to the effects described above , the rotation transmission means can be easily formed with a minimum number of components.
According to the second aspect of the present invention, in addition to the effect of the first aspect , the switching means can be easily formed using the existing planetary gear reduction mechanism.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a partial longitudinal sectional view showing an example of an impact driver. The impact driver 1 is a hammer case that is a front housing in which a spindle 6, a hammer 7, etc. are built in front of a body housing 2 that houses a motor 3. 5 is assembled, and the anvil 8 protrudes in front of the hammer case 5. 9 is a switch and 10 is a trigger. A gear housing 11 is interposed between the main body housing 2 and the hammer case 5, and the gear housing 11 supports the output shaft 4 of the motor 3 via a ball bearing 12 to project into the hammer case 5. ing. The output shaft 4 is fitted with a pinion 13 at the front end, loosely coaxially inserted into a hollow portion 14 formed at the rear end of the spindle 6, and a plurality of shafts attached to a carrier portion 6 a extending rearward of the spindle 6. Of the planetary gears 15, 15..., And the rotation of the output shaft 4 can be reduced and transmitted to the spindle 6.

  The anvil 8 is rotatably supported by a bearing 16 at the front end of the hammer case 5, and the spindle 6 has a small diameter portion 17 at the front end coaxially inserted into the rear surface of the anvil 8, and a hammer is disposed behind the small diameter portion 17. 7 is packaged. The hammer 7 straddles a pair of cam grooves 18 and 18 formed in an inclined shape on the outer peripheral surface of the spindle 6 and a pair of connecting grooves 19 and 19 formed in the axial direction on the inner peripheral surface of the hammer 7. The two steel balls 20 are inserted into the spindle 6 so as to be integrally rotatable, and are urged forward by a coil spring 21 mounted on the spindle 6 at the rear. A pair of engaging claws 23, 23 that can be engaged with a pair of arms 22, 22 extending radially to the rear end of the anvil 8 are formed on the front surface of the hammer 7. In the forward position, the engaging claws 23 and 23 engage with the arms 22 and 22 to integrate the hammer 7 and the anvil 8 in the rotational direction. Reference numeral 24 denotes a chuck sleeve that is externally mounted on the tip of the anvil 8 and locks a driver bit or the like inserted into the anvil 8.

In the hammer case 5, rotation transmission means for transmitting the rotation of the motor 3 to the anvil 8 bypassing the spindle 6 and the hammer 7, and rotation transmission to the anvil 8 by the rotation transmission means are transmitted to the outside of the hammer case 5. Is provided with switching means that can be arbitrarily interrupted. Hereinafter, the rotation transmission means and the switching means will be described.
First, between the gear housing 11 and the spindle 6, a second carrier 26 having second planetary gears 25, 25... Having the same shape as the planetary gear 15 is passed through the output shaft 4 and is connected to the spindle. 6, the pinion 13 of the output shaft 4 is formed long in the axial direction, and meshes with the second planetary gears 25, 25,. An internal gear 27 is provided so as to be movable in the axial direction within the hammer case 5, and an operation portion 28 is provided at the upper end so as to fit into a guide groove 29 formed in the front-rear direction on the upper portion of the hammer case 5. The rotation of the internal gear 27 is restricted by the fitting of the operation portion 28 and the guide groove 29, while the internal gear 27 is moved from the outside of the hammer case 5 to the front side using the operation portion 28. It is possible to move to a forward position that meshes with the second planetary gear 15 and a reverse position that meshes with the second planetary gear 25 on the rear side.

  In addition, a plurality of teeth 30, 30,... Are provided around the outer periphery of the second carrier 26 to form the first gear of the present invention. On the other hand, in front of the arms 22 and 22 in the anvil 8, a second gear 31 having a plurality of teeth 31a, 31a,. Below the hammer case 5, an intermediate shaft 32 parallel to the spindle 6 is supported, and small gears 33 and 33 fitted respectively to the front and rear of the intermediate shaft 32 are connected to the teeth 30 of the second carrier 26. The teeth mesh with the teeth 31a of the second gear 31, respectively. Therefore, a rotation transmission means for transmitting the rotation of the second carrier 26 to the anvil 8 through the intermediate shaft 32 is formed here, but the front and rear positions of the internal gear 27 serving as the switching means are formed. Thus, rotation transmission to the intermediate shaft 32 can be arbitrarily interrupted.

  That is, when the operation unit 28 is advanced and the internal gear 27 is slid to the advanced position in FIG. 1, the front planetary gear 15 can revolve in the internal gear 27, and the rear second planetary gear 25 is Become free. Therefore, the rotation of the output shaft 4 is transmitted only to the spindle 6 via the planetary gear 15 and the second carrier 26 is not rotated (impact mode). On the other hand, when the operating portion 28 is moved backward to slide the internal gear 27 to the retracted position in FIG. 2, the rear second planetary gear 25 can revolve in the internal gear 27, and the front planetary gear 15 is Become free. Therefore, the rotation of the output shaft 4 is transmitted only to the second carrier 26 via the second planetary gear 25, and the spindle 6 is not rotated (drill mode).

  In the impact driver 1 configured as described above, when the operation unit 28 is advanced to select the impact mode of FIG. 1, when the switch 9 is turned on by pushing the trigger 10 and the motor 3 is driven, the output shaft 4 is decelerated by the speed reduction mechanism on the planetary gear 15 side and transmitted to the spindle 6 to rotate the anvil 8 via the hammer 7. Therefore, the screw can be tightened with a driver bit or the like inserted at the tip of the anvil 8. At this time, the intermediate shaft 32 is rotated by the rotation of the anvil 8 and the second carrier 26 meshing with the intermediate shaft 32 is rotated. However, since the second planetary gear 25 on the rear side is in a rotation free state, the output The rotation of the shaft 4 and the anvil 8 is not affected.

  When the screw tightening progresses and the load on the anvil 8 increases, the hammer 7 moves against the bias of the coil spring 21 while rolling the steel balls 20, 20 backward along the cam grooves 18, 18 of the spindle 6. Retreat and disengage from the anvil 8. However, at the moment when it is detached from the anvil 8, it moves forward with the spindle 6 again by the bias of the coil spring 21, and the engaging claws 23, 23 are reengaged with the arms 22, 22 of the anvil 8. By repeating the separation and engagement of the hammer 7 with respect to the anvil 8, a striking operation (impact) is intermittently generated in the rotational direction on the anvil 8, and retightening is possible.

  On the other hand, when the operation unit 28 is moved backward and the drill mode of FIG. 2 is selected, the internal gear 27 revolves only the second planetary gear 25 on the rear side, so that the rotation of the output shaft 4 is the second planetary gear. The speed is reduced by the speed reduction mechanism on the gear 25 side, and is transmitted from the second carrier 26 to the anvil 8 via the intermediate shaft 32. Therefore, regardless of the load on the anvil 8, the constant speed rotation of the anvil 8 does not change, and no impact is generated on the anvil 8. The hammer 7 follows the rotation of the anvil 8 and the spindle 6 also rotates, but this time the planetary gear 15 is in a rotation free state, which affects the rotation of the output shaft 4 and the anvil 8. There is no.

  Thus, according to the impact driver 1 of the said form, while providing the rotation transmission means which bypasses the spindle 6 and the hammer 7 and transmits to the anvil 8 by rotation, the rotation transmission to the anvil 8 by the rotation transmission means is provided. By providing a switching means that can be cut off from the outside of the hammer case 5, drilling work and tightening work such as screws can be performed with a single impact driver, and improvement in workability can be expected. In particular, since the drill mode is obtained by using a rotation transmission means that bypasses the spindle 6 and the hammer 7, the number of gears to be used and the design freedom such as the setting of the gear ratio are increased. Drill mode can be selected. In addition, parts can be easily replaced and repaired in the rotation transmission means, which is convenient for handling.

Further, the rotation transmitting means is supported between the second carrier 26 that rotates by driving the motor 3, the second gear 31 that is coaxial with the anvil 8, and the second carrier 26 and the second gear 31. Since the rotation of the second carrier 26 is formed from the intermediate shaft 32 that transmits the rotation of the second carrier 26 to the second gear 31, the rotation transmitting means can be easily formed with a minimum number of components.
Further, a second carrier 26 on which a second planetary gear 25 that meshes with the output shaft 4 is arranged in parallel behind the carrier portion 6 a of the spindle 6, and teeth 30 are arranged on the outer periphery of the second carrier 26. Is formed as a first gear, while the switching means is provided with an internal gear 27 between a forward position that meshes only with the front planetary gear 15 and a reverse position that meshes only with the second planetary gear 25 on the rear side. Since the moving operation is adopted, the switching means can be easily formed by using an existing planetary gear reduction mechanism.

In the above embodiment, the second carrier on which the second planetary gear is mounted is used as the first gear. However, the first gear extends integrally with a single gear meshing with the output shaft or the pinion of the output shaft. A provided gear or the like may be used, and the present invention is not limited to a form that also serves as a carrier.
The switching means is not limited to the use of the internal gear, and one of the small gears before and after the intermediate shaft is provided so as to be movable in the axial direction, and the small gear is moved from the outside of the housing to the meshing position and the non-meshing position. Thus, a structure is conceivable in which switching can be performed, or the intermediate shaft itself can be moved in the axial direction, and switching can be performed by moving the intermediate shaft from the outside of the housing to the meshing position and the non-meshing position.

Further, the second gear is not limited to the structure integrally formed in front of the arm in the anvil as in the above embodiment, and the gear serving as the second gear is coaxially fitted to the outer periphery of the arm and meshed with the intermediate shaft. Alternatively, the arm and the second gear can be formed at a distance in the axial direction.
In addition, the intermediate shaft is not limited to a structure provided with a small gear, but may be a spline shaft, and the rotation transmission means may employ a structure in which a plurality of intermediate shafts and gears are combined in addition to using a single intermediate shaft. Is possible. In this way, even when there is no linear space between the first gear and the second gear, it is possible to easily transmit the rotation between the two gears.

It is a partial longitudinal cross-sectional view of an impact driver (impact mode). It is a partial longitudinal cross-sectional view of an impact driver (drill mode).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Impact driver, 2 ... Body housing, 3 ... Motor, 4 Output shaft, 5 ... Hammer case, 6 ... Spindle, 7 ... Hammer, 8 ... Anvil, 15 ... Planetary gear, 25 ... Second planetary gear, 26 2nd carrier, 27 internal gear, 28 operation section, 30 teeth, 31 second gear, 32 intermediate shaft.

Claims (2)

A spindle that rotates by driving of a motor is provided in the housing, and a hammer that engages with an anvil that is pivotally supported by the housing and projects forward, and that transmits the rotation of the spindle to the anvil is provided. In accordance with a load on the anvil, the hammer is an impact driver that engages and disengages the anvil to give the anvil a striking action in a rotational direction,
A first gear that is rotated by driving of the motor, a second gear that is coaxial with the anvil, and a shaft that is pivotally supported between the first gear and the second gear in the housing. An intermediate shaft that transmits the rotation of the motor to the second gear, and provided with a rotation transmission means for bypassing the spindle and the hammer to transmit the rotation of the motor to the anvil, and to the anvil by the rotation transmission means An impact driver comprising switching means capable of arbitrarily interrupting rotation transmission from the outside of the housing. Between the motor and the spindle, the apparatus having the planetary gear revolves in the internal gear and the output shaft and meshing of the motor has been pivotally provided a carrier that rotates transmitted to the spindle, the A second carrier on which a second planetary gear that meshes with the output shaft is juxtaposed behind the carrier, and teeth are formed on the outer periphery of the second carrier to form a first gear, The switching means is configured to move and operate the internal gear between a forward position that meshes with only the front planetary gear and a reverse position that meshes with only the second planetary gear on the rear side. The impact driver according to 1 .

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