JP2015066661A - Screwdriver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a cordless screwdriver capable of realizing a hammering operation and a driving-screw operation with one motor by reversely rotating the motor simultaneously with hammering after a piston is pushed up.SOLUTION: A screwdriver 1 includes: a battery-driven motor 11; a piston 6 movable by a striking spring 9; and a driver bit 7 for driving a screw 50, and drives the screws 50 by compressing the striking spring 9 using a torque of the motor 11 and releasing the compressed striking spring 9 to move the piston 6. The screwdriver 1 is configured to perform a moving operation for compressing the striking spring 9 to move the piston 6, and a rotational operation for rotating the driver bit 7 fixed to the piston 6 via bevel gears 29 and 33 during hammering. The moving operation and the rotational operation are actuated by driving one motor 11 and the actuation is switched by switching a rotational direction of the motor 11.

Description

  The present invention relates to a screw driving machine capable of sequentially driving screws using an electric motor, and more particularly to a screw driving machine capable of performing screw driving and screwing operations with a single tool.

  Compressed air system that uses compressed air by supplying compressed air from the air compressor to the main body of the driving machine, or a gas combustion type driving source (power that mounts a small gas cylinder on the main body of the driving machine and burns the gas stored in the cylinder 2. Description of the Related Art A portable driving machine that uses a power source to sequentially drive connecting stoppers loaded in a magazine from the tip of a driver guide is well known. Among the driving machines disclosed in these prior arts, there is a gas type driving machine that can be used cordlessly. A technique disclosed in Patent Document 1 is known as a screwdriver using a screw as a stopper to be driven here. In this technology, a gas combustion mechanism is provided in the power unit, two power sources of a motor driven by electric power are further provided, and a piston is driven out by gas combustion energy as a power mechanism, and a separately provided motor is used. By rotating the driver shaft, screw driving and screwing operations are performed.

JP 2011-073109 A

  In the driving machine of Patent Document 1, since it is necessary to provide a motor and its power supply in addition to the gas combustion mechanism, there is a problem that the main body becomes large and heavy and the manufacturing cost increases. Further, each time the screw is driven, there is a problem that the cost of the fuel for the gas is increased, the running cost is increased, and the smell of gas combustion is generated.

The present invention has been made in view of the above background, and an object of the present invention is to realize an electric screwdriver using an electric motor, and to perform a tightening operation in addition to a screw driving operation using the electric motor. This is to realize the screwing machine.
Another object of the present invention is to realize a screw driving machine that realizes a tightening operation in addition to a screw driving operation with one electric motor.
Still another object of the present invention is to provide a screw driving machine that can easily switch power transmission to a piston pulling operation and a screw tightening operation by switching the rotation direction of a motor.

Of the inventions disclosed in the present application, typical features will be described as follows.
According to one aspect of the present invention, a battery, a motor driven by the battery, a housing that houses the motor, a piston that is movable within the housing, a striking spring that biases the piston, and a piston are attached. In a screw driving machine which has a driver bit for driving a screw, compresses the hitting spring using the rotational force of the motor, and moves the driver bit by releasing the compressed hitting spring to drive the screw The driver bit is rotated by a motor when the compressed impact spring is released. The number of motors used is preferably one, and both the movement control for compressing the impact spring and the rotation control for rotating the driver bit are realized by switching the output destination of the motor.

  According to another aspect of the present invention, the output of the motor is output via a one-way clutch to a drive system that compresses the impact spring and a drive system that rotates the driver bit, and the direction of rotation of the motor for rotating the driver bit. However, when the motor is rotated in the reverse direction, the power is not transmitted to the drive system that compresses the striking spring by the action of the one-way clutch. did. By switching the rotation direction and the action of the one-way clutch, the output destination of the motor can be practically switched, and both power transmissions can be performed by one motor. Further, the injection timing at which the compressed impact spring is released is detected, and when the release timing is detected, the rotation direction of the motor is reversed. Thus, since the injection timing is accurately detected and the rotation direction of the motor is reversed, accurate motor control can be performed. Furthermore, a weight that is movable in the direction opposite to the piston moving direction and is urged in the direction opposite to the piston by the urging member is provided, and the weight is changed to the piston moving direction by using a drive system that compresses the striking spring. It was configured to move in the opposite direction. By using this weight, the recoil at the time of driving could be suppressed.

  According to another feature of the present invention, the motor output shaft has a pulley for rotating the belt and a bevel gear that rotates in one direction via a one-way clutch, and the piston is rotated about the injection direction by the bevel gear. The piston and the spindle are held so as not to rotate relative to each other, and the spindle is rotated so that the driver bit attached to the piston can be rotated. With this configuration, a mechanism for rotating the driver bit can be realized by rotating the spindle itself. In addition, a sensor for detecting the position of the driver bit is provided, and the rotation of the driver bit is stopped when the sensor confirms that the driver bit is lowered to a predetermined position. With this configuration, the screws can be properly tightened without excess or deficiency. A motor for compressing the impact spring and a motor for rotating the driver bit may be provided independently.

In the screw driving machine of the present invention, the screw is driven by rotating the driver bit instead of driving the screw to the end only by the driving force, so that the life of the screw driving machine can be extended without reducing the driving force. In addition, by moving the driver bit 7 in the injection direction and simultaneously rotating it in the screw tightening direction, it is possible to perform the striking operation and the screwing operation with one motor 11.
The above and other objects and novel features of the present invention will become apparent from the following description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS It is the figure which shows the whole screwdriver 1 which concerns on the Example of this invention, and is the figure which showed the principal part in the cross section. It is a fragmentary sectional view of screwdriver 1 concerning an example of the present invention, and is a figure showing the state at the time of pulling up of piston 6. It is a fragmentary sectional view of screwdriver 1 concerning the example of the present invention, and is a figure showing the state in the middle of driving of screw 50. It is a fragmentary sectional view of screwdriver 1 concerning the example of the present invention, and is a figure showing the state at the time of the completion of the driving of screw 50. It is a perspective view which shows the shape of the weight 16 of FIG. It is a figure for demonstrating operation | movement of the push-down mechanism of the weight 16 of FIG. 1 (the 1). FIG. 8 is a diagram for explaining the operation of a push-down mechanism for the weight 16 in FIG. 1 (No. 2). FIG. 5 is a cross-sectional view taken along a line AA in FIG. It is a figure which shows the structure of the screw feeding part 42 of FIG. It is a simplified block diagram of the control circuit of the screwdriver 1 which concerns on the Example of this invention. It is a figure for demonstrating rotation control of the motor 11 of the screwdriver 1 which concerns on the Example of this invention. It is sectional drawing which shows the state at the time of performing continuous driving | running | working using the screwdriver 1 which concerns on the Example of this invention. It is sectional drawing of the screwdriver 101 which concerns on the 2nd Example of this invention. It is a fragmentary sectional view of screwdriver 101 concerning the 2nd example of the present invention, and is a figure showing the state at the time of pulling up of piston 6. It is a figure for demonstrating operation | movement of the raising mechanism of the piston 106 of FIG. 14, and the pushing down mechanism of the weight 116 (the 1). It is a figure for demonstrating operation | movement of the raising mechanism of the piston 106 of FIG. 14, and the pushing down mechanism of the weight 116 (the 2). It is sectional drawing of CC part of FIG. 14, and is a figure which shows the cross section of the weight 116 part. It is a fragmentary sectional view of screwdriver 101 concerning the 2nd example of the present invention, and is a figure showing the state in the middle of driving in screw 50. It is a fragmentary sectional view of the screw driving machine 101 which concerns on the 2nd Example of this invention, and is a figure which shows the state at the time of the completion of the driving | operation of the screw 50. FIG.

  Hereinafter, a cordless electric screwdriver according to an embodiment of the present invention will be described. Further, in the following drawings, the same portions are denoted by the same reference numerals, and repeated description is omitted. In this specification, description will be made assuming that the front, rear, left, right, and up and down directions are directions shown in the drawing.

  FIG. 1 is a sectional view of a screwdriver according to an embodiment of the present invention. The screwdriver 1 is an electric tool that uses an electric motor 11 as a drive source and drives a screw 50 as a fastener into a material to be tightened such as a gypsum board or wood as a material to be tightened. The screwdriver 1 includes a housing 2 (2a, 2b, 2c, 2d), a motor 11, a drive mechanism 8 for pulling up the piston 6, a winch portion 14, a striking portion (piston 6 and the like), and an injection portion 5. And a magazine section 43. The piston 6 is urged by a striking spring 9 and functions as a striking element that strikes the screw 50 in the injection direction (downward) by the driver bit 7 and tightening that tightens the screw by rotating the driver bit 7. Acts as a child.

  The housing 2 is made of a resin such as polyamide synthetic fiber or polycarbonate, and a body portion 2a that forms a space in which the piston 6 moves in the vertical direction, a handle portion 2b that is held by an operator, and an electric motor 11 inside. Is comprised of four parts: a motor holding part 2c containing a battery and a battery holding part 2d holding a secondary battery. The housing 2 is divided into right and left in a plane passing through the moving direction of the piston 6, and the housings on both sides are combined and fixed with a plurality of screws (not shown). The handle portion 2b is provided so as to extend in a substantially vertical direction from the upper portion of the body portion 2a, and a trigger 3 that performs on / off control of the motor 11 is provided in the vicinity of the connection portion of the handle portion 2b to the body portion 2a. . The motor holding portion 2c of the housing 2 is provided near the lower end of the body portion 2a so as to extend in a direction perpendicular to the substantially cylindrical body portion 2a and substantially parallel to the handle portion 2b. A battery holding part 2d is formed on the handle part 2b and the motor holding part 2c opposite to the body part 2a so as to connect them, and a detachable battery 12 is mounted on the battery holding part 2d. The battery 12 is a secondary battery such as a nickel-cadmium battery or a lithium ion battery.

  The motor 11 is disposed inside the motor holding portion 2c so that the rotating shaft 11a is orthogonal to the screw 50 driving direction (injection direction, downward in FIG. 1) (in the horizontal direction in FIG. 1). A first pulley 20 is provided on the rotation shaft 11a, and the rotational force of the first pulley 20 is transmitted to the second pulley 21 by a belt 19 extending upward. The second pulley 21 is supported on the housing 2 by a bearing so that the first pulley 20 and the rotation axis are parallel to each other above the body portion 2a. The belt 19 is, for example, a V-belt, and is arranged so that the long axis direction of the ellipse is substantially parallel to the central axis direction of the body portion 2a (moving direction of the piston 6).

  The rotational force transmitted to the second pulley 21 is transmitted to the drive mechanism 8 through a speed reduction mechanism including gears 22 and 23. The rotational force of the gear 23 is transmitted to the rotating body 24, and it is controlled whether the rotational force is transmitted to the winch portion 14 via the cam portion 25 or blocked. The number of rotations of the motor 11 is reduced by the drive mechanism 8 from the first pulley 20 to the rotator 24 and transmitted to the rotator 24. However, the configurations of these transmission mechanisms and speed reduction mechanisms are limited to these. Instead, any speed reduction mechanism or transmission mechanism may be used as long as the winch portion 14 can be rotated with a desired torque and a desired number of rotations. Here, the cam portion 25 is connected to the output side winch portion 14 and the rotating body 24 until the rotating body 24 rotates by a predetermined angle (= an angle necessary for the piston 6 to reach the top dead center). Although it rotates in synchronization, in the state rotated only by the predetermined angle, the connection state of the winch part 14 and the rotary body 24 is interrupted | blocked, and the winch part 14 connected to an output side is made into the state which can rotate freely.

  The lifting portion (winding portion) of the piston 6 includes a winch portion 14, a wire 15 wound around the outer periphery of the winch portion 14 and pulled upward, and a piston 6 connected to the tip (lower end) of the wire 15. Configured. The winch portion 14 is a substantially disc-shaped pulley member in which a groove for guiding the wire 15 is formed on the outer peripheral portion, and the tangent line of the circular winch portion 14 coincides with the axis of the driver bit 7 into which the screw is driven. To be arranged. A round metal sphere that functions as a retainer is fixed to both ends of the wire 15. One metal ball is locked in a mounting hole formed in the inner peripheral portion of the drum, and the wire 15 extending from the metal ball is guided into a groove formed in the outer peripheral portion of the winch portion 14, so that the wire 15 is By fixing the penetrated cap 30 to the piston 6, the wire 15 is attached so as to extend downward from the winch portion 14. The piston 6 is configured to be able to slide up and down with the spindle 32 via the rotation guide 31 and not to rotate relative to the rotation direction. In this embodiment, the spindle 32 is configured to be rotatable, and the rotational force of the motor 11 is converted into the rotational force of the spindle 32 through the bevel gear 29 and the bevel gear 33 provided on the output shaft of the motor 11. The bevel gear 33 and the spindle 32 are fixed by a joint portion 33a. In this manner, the piston 6 is rotated by rotating the spindle 32, and the driver bit 7 fixed to the piston 6 so as not to be relatively rotatable is also rotated in synchronization. A one-way clutch 35 is provided between the bevel gear 33 and the rotating shaft 11 a of the motor 11 to prevent the drive mechanism 8 from rotating when the motor 11 rotates in the reverse direction. When the motor 11 is rotated in the reverse direction, the spindle 32 is rotated and screwed by the driver bit 7, but the power transmission to the drive mechanism 8 side is interrupted by the action of the one-way clutch 35 (that is, the belt 19 rotates). The driver bit 7 connected to the piston 6 is screwed and rotated when driven.

  A weight 16 is held between the housing 32 and the outer periphery of the spindle 32 so as to be movable in the vertical direction. The weight 16 is a cylindrical mass having a certain weight, and acts in a direction to cancel the impact force at the time of impact by moving in a direction opposite to the piston 6. The weight 16 is held below the body portion 2a of the housing 2 via a biasing member 17 such as a spring. The piston 6 holds a driver bit 7 for driving a screw into the material to be tightened, and performs an action of transmitting the elastic force generated by the impact spring 9 to the driver bit 7. The piston 6 is fixed to the piston 6 by a cap 30 so that a metal ball on the lower end side of the wire 15 is located in the inner space, and a lower side of the impact spring 9 is formed. Arranged at the end. The piston 6 is manufactured mainly by integral molding of synthetic resin, a rotation guide 31 to be described later is cast therein, and a mounting portion 6a (see FIG. 2) for mounting the driver bit 7 is formed on the lower side. Is done. It is arbitrary whether the piston 6 and the driver bit 7 are configured to be detachable or non-detachable in the mounting portion 6a.

  A power transmission mechanism 37 that abuts against the impact spring 9 is attached to the upper side of the piston 6. The power transmission mechanism 37 is an annular bearing member having an upper surface and a lower surface, and is configured such that when the spindle 32 is rotated, the piston 6 can be rotated smoothly in synchronization with the piston 6 and the impact spring. 9 can be realized by a thrust bearing that makes the relative rotation with 9 smooth. A rotation guide 31 protrudes from the outer periphery of the piston 6. The rotation guide 31 is in contact with a guide groove 32a (described later in FIG. 8) formed on the inner wall or the inner wall of the spindle 32 and parallel to the injection direction, and prevents wear due to the piston 6 coming into direct contact with the inner wall of the spindle 32. . In addition, the guide groove formed on the inner peripheral side of the spindle 32 and having a concave cross section is configured to be able to rotate in synchronization with the spindle 32 while moving in the axial direction (injection direction). Here, the spindle 32 and the piston 6 rotate relative to the housing 2, and the spindle 32 and the piston 6 do not rotate relative to each other. When the piston 6 reaches the lowest position (bottom dead center), the impact force is absorbed by contacting the piston bumper 10 made of resin such as soft rubber or urethane.

  The driver bit 7 moves in the axial direction from the injection portion 5 to hit the screw and rotates around the axis to fasten the screw 50, and is an intermediate portion in the axial direction (vertical direction as viewed in FIG. 1). Is formed with a recess 7a having a reduced diameter for acting on the motor stop switch 36. The concave portion 7a is a groove portion or a small diameter portion formed continuously in the circumferential direction, and a motor stop switch 36 is provided at a position corresponding to the concave portion 7a of the driver bit 7. The motor stop switch 36 is a push switch. When the plunger portion is pushed, the switch is turned on to energize the motor 11, and when the plunger portion is released and the plunger returns to the original position, the motor stop switch 36 is turned on. In this embodiment, it functions as an operation completion detection switch when the driving operation is completed. The position of the driver bit 7 in FIG. 1 is the position after the completion of the impact, and the recess 7a is at a position facing the motor stop switch 36, and the screw portion 7b at the tip of the driver bit 7 is fitted to the screw head after the completion of tightening. Is in a position to do.

  Below the housing is an injection part 5 having an injection hole for projecting a screw 50, and a screw supply connected to the injection part 5 for receiving a plurality of screws 50 and feeding them one by one downward in the axial direction of the driver bit 7. A sending unit 42 is provided. The screw feeding section 42 feeds the screws 50 driven one by one under the tip of the driver bit 7 one by one in conjunction with the lifting operation of the driver bit 7. Although the detailed structure of the screw feeding portion 42 is not shown in FIG. 1, the feeding piston is moved against the feeding spring by an urging means by a spring provided in the magazine portion 43 or electromagnetic force by a solenoid or the like. By moving and engaging the shaft part of the screw 50 or the connecting body 51 with the feed claw, one by one is sequentially loaded into the injection port of the injection part 5 every time the screw is tightened.

  The driving operation by the screw driving machine 1 is as follows. When the push lever 13 is pressed against the material to be tightened and the trigger 3 is pulled and the trigger switch 4 is activated, the motor 11 starts rotating and winding of the wire 15 connected to the piston 6 is started at the winch portion 14. At this time, the piston 6 compresses the striking spring 9 and, when reaching the predetermined striking start position, the cam portion 25 of the winch portion 14 releases the connection between the winch portion 14 and the rotating body. Is released, the piston 6 is urged by the striking spring 9 and suddenly descends to start striking the screw 50. Simultaneously with the release of the rotation of the winch portion 14, the control circuit for controlling the rotation of the motor 11 switches the motor 11 from the normal rotation to the reverse rotation and transmits the rotational force of the motor 11 to the interlocking bevel gear 29 via the one-way clutch 35. Then, the spindle 32 rotates by rotating the bevel gear 33 engaged with the bevel gear 29. Note that when the motor 11 rotates in the reverse direction, the bevel gear 29 rotates, but the power transmission to the belt 19 side is interrupted by the one-way clutch 35, so the drive mechanism 8 does not operate. When the spindle 32 rotates, the piston 6 connected to the driver bit 7 through the rotation guide 31 is rotated, so that the driver bit 7 also rotates. As described above, since the screwing operation is also performed at the time of driving, the user-friendly screwing machine 1 can be realized. In addition, by performing the driving operation and the tightening operation with one motor 11, a screw tightening machine capable of screwing and hitting only with the power of the battery 12 can be realized.

  FIG. 2 is a partial longitudinal sectional view showing a situation when the piston 6 is moved upward while compressing the striking spring 9 by pulling the wire 15 upward. In this specification, the position at which the lower end of the piston 6 is compressed by contacting the piston bumper 10 and reaches the lowest position is referred to as the bottom dead center of the piston 6, and the position at which the piston 6 has moved upward is referred to as the top dead center. I will call it. When the operator holds the screwdriver 1 and presses the push lever 13 against the material 60 to be tightened and the push lever switch 27 is activated, the operator pulls the trigger 3 to start the winding operation of the piston 6 by the motor 11. The When the drive mechanism 8 is rotated to a predetermined position by the rotation of the motor 11, the engagement state between the cam portion 25 and the winch portion 14 is released. FIG. 2 shows a state immediately before the engagement state is released. In the state of FIG. 2, since the wire 15 is wound around the winch portion 14, the piston 6 moves upward against the urging force of the impact spring 9 and reaches the top dead center. When the piston 6 is located at the top dead center, the driver bit 7 connected to the piston 6 is also moved upward, so that the screw portion 7b as the tip of the driver bit 7 is located above the next screw 50 to be driven. Will do. Therefore, the screw 50 to be driven next is fed coaxially with the driver bit 7 by the screw feeding portion 42. In this way, preparation for driving is completed. In this embodiment, the weight 16 is moved downward while resisting the urging force of the urging member 17 by using the rotational force of the second pulley 21 simultaneously with the pulling-up operation of the piston 6. 6 and FIG.

  FIG. 3 is a partial longitudinal sectional view showing a state in the middle of driving of the screw 50. When the second pulley 21 is further rotated by the rotation of the motor 11 from the state of FIG. The engaged state of the winch portion 14 is released, and the piston 6 is suddenly pushed downward by the compression energy stored in the impact spring 9. At the same time, since the engaged state between the weight 16 pushed downward and the second pulley 21 is released, the weight 16 moves upward by the compression energy of the urging member 17. That is, the movement for striking the piston 6 and the movement of the weight 16 in the opposite direction to the piston 6 occur simultaneously. Thus, since the downward movement (= injection direction) of the piston 6 and the upward movement (= reflection direction) of the weight 16 are opposite directions, the repulsive force generated in the main body of the screwdriver 1 at the time of driving is generated. It is possible to effectively reduce, and it is possible to effectively prevent problems such as the fact that the main body floats due to the reaction and the cam-out occurs, and the finish of screw driving can be improved.

  Further, in this embodiment, when the piston moves downward from the top dead center as indicated by the arrow 40a, the motor 11 rotates the piston 6 as indicated by the arrow 40b. In this rotation, the bevel gear 29 is rotated by rotating the motor 11 in the reverse direction to when the motor 11 is pulled up, and the bevel gear 33 meshing with the bevel gear 29 is rotated. Since the bevel gear 33 is fixed to the spindle 32, the spindle 32 rotates as indicated by an arrow 40b. On the other hand, the piston 6 can move relative to the spindle 32 in the injection direction and is fixed so as not to move relative to the rotation direction (the direction indicated by the arrow 40b). And the driver bit 7 fixed to the piston 6 also rotates in the direction of the arrow 40b. Thus, in the operation at the time of injection after the engagement state of the cam portion 25 and the winch portion 14 is released, the tightening direction (arrow) of the screw 50 while moving the driver bit 7 in the injection direction (direction of arrow 40a). In order to rotate in the direction 40b), the screw 50 can be driven into the material 60 to be fastened by the screw portion 7b at the tip of the driver bit 7, and at the same time, the tightening operation can be performed.

  In a typical use situation assumed in the screw driving machine 1 according to the present embodiment, a gypsum board 61 is stretched on a wood 62 as a material to be tightened 60. Although the wood 62 penetrates easily, the wood 62 may not penetrate completely only by striking. Therefore, the screw 50 can be completely fastened to the material 60 to be tightened by striking while rotating the driver bit 7.

  FIG. 4 is a partial longitudinal sectional view showing a state when the piston 6 moves to the bottom dead center, and shows a state where the driver bit 7 is further moved in the injection direction from the state shown in FIG. Here, the screw portion 7b, which is the tip of the driver bit 7, shows a state where the screw 50 has been tightened, that is, the screw head 50a has reached the position where it matches the surface of the material 60 to be fastened. 7 reaches the position facing the motor stop switch 36. When the recess 7a faces the motor stop switch 36, the plunger that has been pushed into the motor stop switch 36 pops out. As a result, the motor stop switch 36 is turned on, and the reverse rotation of the motor 11 is stopped by the output. To do. As described above, since only the electricity of the battery 12 and one power source (motor 11) can be used for driving and screwing simultaneously, the main body of the screwdriver can be configured to be small and light, It has become possible to perform screwing work without a cord. In addition, since it is driven by the battery 12, it is not necessary to prepare a gas cell as fuel or high-pressure air, and it is possible to realize a driving machine which is very inexpensive and easy to handle.

  Next, the shape of the weight 16 and the moving method thereof will be described with reference to FIGS. FIG. 5 is a perspective view showing the shape of the weight 16. The weight 16 is an integrally molded product of metal that moves up and down on the outer peripheral side of the cylindrical spindle 32 and on the inner peripheral side of the body portion 2a of the housing 2, has a substantially cylindrical shape, and protrudes radially outward 2. A stepped engagement portion is formed. Further, when viewed in the axial direction, a notch portion 16c is formed from the first engagement portion 16a to the second engagement portion 16b. A first engagement portion 16a that protrudes in the radial direction is formed on one side of the first-stage cutout portion 16c. A second engagement portion 16b is formed at the second stage. The second stage is formed along the lower side of the cutout portion 16c, and the second engagement portion 16b is formed long so as to be continuous in the tangential direction. The cutout portion 16 c is disposed so as to open to the rear side as viewed in FIG. 1 and to face the second pulley 21. The first engaging portion 16a and the second engaging portion 16b are moved in the injection direction by two roller cams provided on the second pulley 21 that rotates in the vicinity thereof.

  6-7 is a figure for demonstrating operation | movement of the push-down mechanism of the weight 16. FIG. FIG. 6 is a side view when viewed from the front to the rear in FIG. 1, and the second pulley 21 rotates on the rear side of the weight 16. As for the rotation direction, since the piston 6 is pulled up to the top dead center, the second pulley 21 rotates in the direction of the arrow. A first roller cam 18 a and a second roller cam 18 b are provided at two locations in the circumferential direction of the second pulley 21. The first roller cam 18a and the second roller cam 18b are provided with a fixed shaft on the center side, and the roller is rotatably held around the fixed shaft. Since the first roller cam 18a and the second roller cam 18b rotate and come into contact with the first engagement portion 16a and the second engagement portion 16b of the weight 16, the rotational force resists the biasing force of the biasing member 17. The weight 16 is moved downward. FIG. 6 (1) shows a state when the piston 6 is at the bottom dead center, and is also an initial position of the second pulley 21. When the motor 11 is rotated in the forward rotation direction from this state, the belt 19 rotates and the second pulley 21 also starts to rotate in the direction of the arrow. Then, the second pulley 21 rotates from the position shown in FIG. 6 (1) to the state shown in (2), and the first roller cam 18a rotated accordingly comes into contact with the second engaging portion 16b first. When the second pulley 21 is further rotated as in the state of FIGS. 6 (2) to 6 (3), the weight roller 16 is further moved downward so that the second roller cam 18b is then brought into contact with the first engaging portion 16a. . FIG. 7A shows the state after this. FIG. 7 (1) is a diagram showing a state in which the weight 16 is located at the lowest position. At this time, the piston 6 is located near the top dead center. When the second pulley 21 is further rotated in the direction of the arrow as shown in (2), the contact state between the second roller cam 18b and the first engaging portion 16a is released, so that the force for pushing the weight 16 downward is lost. The weight 16 is suddenly moved upward by the repulsive force of the urging member 17. If the movement timing is configured so as to coincide with the lowering timing of the piston 6, both movement directions are reversed, so that the weight 16 acts as a balancer and the reaction of screw driving by the piston 6. Can be reduced. The axial lengths of the first roller cam 18a and the second roller cam 18b are different from each other, and the first roller cam 18a is longer in the axial direction and is closer to the weight 16. On the other hand, the second roller cam 18b is short in the axial direction and has a distance from the weight 16, and contacts the first engagement portion 16a but does not contact the second engagement portion 16b. The axial length of the first roller cam 18a and the second roller cam 18b and the positional relationship with the weight 16 can be understood from FIG.

  FIG. 8 is a cross-sectional view taken along line AA in FIG. 4, and shows a cross-section of the weight 16 and the second pulley 21. As can be understood from FIG. 8, the piston 6 is disposed inside the rotatable spindle 32, and two guide grooves 32 a formed in parallel in the axial direction are formed. A striking spring 9 is disposed on the upper side of the piston 6 at a position indicated by a two-dot chain line. On the other hand, the piston 6 is provided with a rotation guide 31 arranged in a cross shape. The end portions of the four rotation guides 31 protrude outward in the radial direction from the piston 6, and two end portions thereof are configured to be located inside the guide groove 32 a. The spindle 32 has a cylindrical shape whose outer shape is substantially equal to the inner diameter of the weight 16, and the inner diameter is formed so that the cross section substantially perpendicular to the axial direction is close to a square so that the piston 6 moves without resistance in the axial direction. The gap 34 is formed at four locations on the outer peripheral side.

  The weight 16 is disposed so that the notch portion 16c faces the second pulley 21, and the first roller cam 18a and the second roller cam 18b in which the first engagement portion 16a and the second engagement portion 16b are attached to the second pulley 21. The positional relationship is such that it acts on Here, the length of the first roller cam 18a protruding forward from the second pulley 21 is configured to be longer than the length of the second roller cam 18b protruding forward from the second pulley 21. As a result, the first roller cam 18a contacts both the first engagement portion 16a and the second engagement portion 16b, but the second roller cam 18b engages with the first engagement portion 16a but the second engagement portion 16b. And does not contact because it has a predetermined gap. The weight 16 is moved in the opposite direction in synchronization with the movement of the piston 6 by using the second pulley 21 for rotating the belt 19 by configuring the position and length of the roller cam and the shape of the weight 16 in this way. Can do.

  FIG. 9 is a view showing the structure of the screw feeding section 42 of FIG. The feeding mechanism of the screw 50 can be realized by a known configuration, but since the power source is the battery 12 in this embodiment, it is preferable that the screw 50 is operated by an electric driving means. In this embodiment, the solenoid 45 operated by the electric power of the battery 12 is moved against the compression spring 46 to reciprocate the feed piston 47 in the feeding direction (back to front) and slide on the rail guide 49. The feeder 48 that can be held is driven to feed the screw 50 (see FIG. 1). Thus, since electric power is used as a power source of the screw feeding unit, all the power of the screwdriver 1 can be operated by one battery 12. In this embodiment, the example of the feeding mechanism using the solenoid 45 has been described. However, the present invention is not limited to this configuration, and other feeding mechanisms using the battery 12 as a power source or a power source other than the battery 12 may be used. You may implement | achieve using the feeding mechanism which uses driving reaction force without using.

  FIG. 10 is a simplified block diagram of the control circuit of the screw driving machine according to the embodiment of the present invention. These control circuits 53a are mounted on a control circuit board 53 (see FIG. 1) in the battery holding part 2d of the housing 2. In this embodiment, rotation and stop control of the motor 11 is performed by the microcomputer 54. When an operator attaches the battery 12 to the screwdriver 1 and presses the power switch 58, the power switch (switch) detection circuit 59 detects the state and supplies power to various devices mounted on the control circuit 53a. As a result, the microcomputer 54 is activated and the operation is completed (main switch is turned on). When the operator finishes the work and presses the power switch 58 again, the power switch detection circuit 59 turns off the power switch 58, whereby the power to the various devices mounted on the control circuit 53a is cut off. In this embodiment, a 15-minute timer 79 is further provided. The 15-minute timer 79 counts the non-operation time. When 15 minutes have elapsed without performing work, the 15-minute timer 79 sends an OFF signal to the power switch detection circuit 59. By sending the power, the power switch detection circuit 59 turns off the controller power switch 55, thereby turning off the power of the control circuit 53a. Counting by the 15-minute timer 79 outputs a count reset signal when the microcomputer 54 performs the driving operation. Therefore, if the operation is performed within 15 minutes after the power is turned on or the previous operation is performed, the count is reset and the counting starts again from zero. Is started.

  When the controller power switch 55 is turned on, the microcomputer 54 inputs the output from various sensor means (or switch means) and controls the rotation of the motor 11. The driving detection switch 57 is a switch for detecting a state in which the connection state between the winch portion 14 and the cam portion 25 in FIG. 1 is released, and is provided in the vicinity of the cam portion 25. The motor stop switch 36 is a sensor that is output when the driver bit 7 reaches a predetermined position, and an ON signal is output to the microcomputer 54 when the recess 7a of the driver bit 7 reaches the position of the motor stop switch 36. The The push lever switch 13 a outputs an ON signal to the microcomputer 54 when the push lever 13 positioned at the tip of the injection unit 5 is appropriately pressed against the material to be tightened. The trigger switch 4 outputs an ON signal when the operator pulls the trigger 3. The mode switch 39 is a switch for switching between a “single-shot mode” and a “sequential mode” to be described later. Here, the outputs of the push lever switch 13 a and the trigger switch 4 are input to the logic circuit 56, and the FET 75 is turned on or off by driving the first FET drive circuit 74 according to the calculation result of the logic circuit 56. . The FET 75 is a semiconductor switching element inserted in series in the circuit from the battery 12 to the inverter circuit 73. If the logic circuit 56 is realized by an AND circuit, the trigger switch 4 is pressed with the push lever switch 13a being pressed. As long as is not pulled, the motor 11 can be configured not to be supplied with power, and functions as a safety circuit.

  Further, the output signal of the battery voltage detection circuit 71 is input to the microcomputer 54. When the battery voltage becomes a predetermined value or less, the microcomputer 54 issues a battery remaining amount warning by the display circuit 78 and performs control so that no further screwing operation is executed. As the motor 11 of the present embodiment, a brushless DC motor can be used, and the microcomputer 54 controls the drive current that is sequentially applied to the coils of the motor 11 using the inverter circuit 73, whereby the rotation direction, the rotation speed, Detailed stop control is performed. The control signal output circuit 72 is a circuit for outputting a gate signal to a semiconductor switching element such as an FET included in the inverter circuit 73 in accordance with an instruction from the microcomputer 54. As the inverter circuit 73, for example, a known inverter circuit can be used as a circuit including six FETs. The second FET drive circuit 76 is for controlling on or off of the second FET 77 and can be used when the motor 11 is stopped under the control of the microcomputer 54. Since the function of the second FET 77 can be realized by controlling the inverter circuit 73, the second FET drive circuit 76 and the second FET 77 may be omitted. The display circuit 78 is an LED for displaying the ON state of the power switch, an LED for displaying the remaining battery level or indicating that the remaining battery level is low, and whether the mode switch 39 is in the single mode or the continuous mode. LED is displayed to display the current operation status to the operator.

FIG. 11 is a diagram for explaining the rotation control of the motor 11 of the screwdriver according to the embodiment of the present invention. In FIGS. 11 (1) to 11 (6), the horizontal axis is time, and the horizontal axes are shown to be the same. 11 (1) is a graph showing the state of on or off the trigger switch 4, the operator and pulled the trigger 3 at time t ₁ after pressing the push lever 13 in the tightening member 60. Then, the motor 11 starts to rotate in the forward direction as indicated by the motor rotational speed 82 in (2), and the piston 6 is lifted by rotating forward at a constant speed as indicated by the arrow 82a. At this time, the current flowing through the motor 11 becomes the motor current 83 of (3), increases after starting as shown by the arrow 83a, and then gradually decreases to the arrow 83b. The rotation of the motor 11 moves the piston position 84 from the initial position (slightly above the bottom dead center) to the top dead center indicated by the arrow 84a as shown in (4). Rotation of the motor 11 is continued, the rotation of the winch 14 (see FIG. 1) reaches the predetermined position, at time t ₂ by the bonding state of the cam portion 25 and the winch 14 is released, (4 ), The piston 6 rapidly descends from the top dead center of the arrow 84a as indicated by the arrow 84b and reaches the bottom dead center of the arrow 84c. Here, as shown in (5), the driving detection switch 57 detects the driving operation, that is, the state where the joining state of the cam portion 25 and the winch portion 14 is released, and outputs an ON signal of the driving detection signal 85. To do. Here, when the winding of the winch part is completed, the driving detection switch 57 is turned on by a collision part (not shown) provided in the cam part 25, and then the collision part is detached, as in (5). A pulse wave appears. That is, the collision portion provided in the cam portion 25 at time t ₂ is the implantation detection switch 57 is turned on. When the microcomputer 54 detects the rising edge of the driving detection signal 85 as indicated by an arrow 85a, the microcomputer 54 controls the motor 11 to rotate in the reverse direction as shown in (2).

When the motor 11 is rotated in the reverse direction, the bevel gear 29 is rotated by the action of the one-way clutch 35, but the first pulley 20 is not rotated. Therefore, only the spindle 32 can be rotated without performing the pulling-up operation by the rotation of the motor 11. . Due to the reverse rotation of the motor 11, the motor current increases as shown by the arrow 83c in (3). Next, as shown in (6), when the driver bit 7 reaches the screw tightening completion position, the output signal 86 of the motor stop switch 36 is turned on, so that the microcomputer 54 stops the reverse rotation of the motor 11. In this way, the driving operation and the rotating operation of the driver bit 7 are performed simultaneously at the times t ₂ to t ₃ . Here, since the driving operation is performed with the compression energy stored in the hitting spring 9, it is not necessary to supply energy for hitting by the motor 11 from time t _{2 to} t ₃ . Therefore, in this embodiment, the screw 11 and the tightening operation are simultaneously performed by using the motor 11 for the rotation operation of the driver bit 7 at the times t _{2 to} t ₃ .

After nailing operation at time t ₃ is completed, the microcomputer 54 is "wound up" After returning the position of the piston 6 to the initial position by rotating in the forward direction as indicated by an arrow 82c of the motor 11 (2) Operation Then, the recess 7a of the driver bit 7 is pulled up to a position where it does not face the motor stop switch 36. A worker after this winding operation is completed, the hammering operation is terminated by releasing the trigger 3 at time t _5. Here, since the time from the time t _{3 to} t ₄ is short, even if the timing at which the worker releases the trigger 3 is before t ₄ , that is, between t _{3 and} t ₄ , the microcomputer 54 is at that time. Without stopping the motor 11, the motor 11 is stopped after completing the post-winding operation.

  As described above, in the present embodiment, the motor 11 is reversely rotated simultaneously with the impact after the piston 6 is lifted to perform the screwing operation, and these are driven by the single motor 11. A small and light screwdriver that can be driven was realized. In particular, since the switching of the control mode of the pulling-up operation control of the piston 6 and the tightening rotation control of the piston 6 is realized in conjunction with the switching of the rotation direction of the motor, it is easy to change only the rotation direction of one motor. Pulling up operation and tightening rotation operation can be performed. In addition, since the weight 16 that can move in the direction opposite to the striking direction of the piston 6 is provided on the outer periphery of the spindle 32 so as to cancel the repulsion at the time of driving, the movement of the weight 16 is performed by one motor 11. As a result, it was possible to realize an easy-to-use screwdriver with little reaction during driving. Note that the switching between the pulling-up operation control and the rotation control of the piston 6 may be performed not by the rotation direction of the motor but by other methods. For example, the power transmission from the motor to the pulling operation unit or the tightening rotation control unit may be switched at an arbitrary timing via a clutch mechanism.

  FIG. 12 is a view for explaining the operation in the “continuous firing mode” in the screwdriver 1 of the present embodiment. The “continuous mode” can be switched by operating the mode switch 39. In the repetitive mode, a plurality of screws 50 are driven successively and sequentially, and the trigger 3 is pulled (arrow 1), and the push lever 13 is pressed against the material to be tightened (arrow 2). Operation starts. The screw driving machine 1 according to the present embodiment is configured such that the motor 11 does not start unless the material to be fastened 60 of the push lever 13 is pressed and the trigger 3 is pulled simultaneously. In the “sequential mode” using this mechanism, pressing the push lever 13 against the material 60 to be tightened can be a trigger for screwing. After the driving operation is finished, once the push lever 13 is released from being pressed against the material to be tightened 60 and then pressed against the next material to be tightened 60, the next driving operation can be performed. The trigger 3 may be kept pulled, and it is not necessary to release the trigger 3 every time it is hit. Therefore, when a large number of screws are continuously driven, work efficiency is improved.

  Next, a second embodiment of the present invention will be described with reference to FIGS. The screw driving machine 101 of the second embodiment uses a motor 11 driven by a battery 12 as a driving source, includes a magazine unit 43, and includes a trigger 3 although the driving mechanism of the piston 106 is different. The push lever 13 is provided in the same manner as the screw driving machine 1 of the first embodiment, except that the piston lifting operation mechanism, the weight moving mechanism, and the driver bit rotating mechanism are different. The housing 102 includes a body portion 102a that forms a space in which the piston 106 moves in the vertical direction, a handle portion 102b that is held by an operator, a motor holding portion 102c that houses the motor 11, and a battery holding portion that holds a secondary battery. It is mainly composed of four parts 102d. The housing 102 is divided into two parts by a plane passing through the moving direction of the piston 106, and the housings on both sides are combined and fixed with screws (not shown). The trigger 3 performs on / off control of the motor 11. When the tip of the push lever 13 is pressed against the material 60 to be tightened, the motor 11 is turned on when the trigger 3 is pulled.

  The motor 11 is arranged so that the rotating shaft 11a extends from the rear side to the front side of the housing 2, and one of the outputs serves as a power source of a moving mechanism for moving the piston 106 and the weight 116, and the other is driven. It becomes a power source of a rotating mechanism for rotating the driver bit 107 in the. Here, after the operation of moving the piston 106 and the weight 116 is completed, the rotation direction of the motor 11 is switched from the normal rotation direction to the reverse rotation direction, and the driver bit 107 is rotated in the screw tightening direction when driven.

  The piston 106 is held so as to reciprocate up and down inside the body portion 2a, and a driver bit 107 is attached to the lower end thereof. The cross-sectional shape perpendicular to the axial direction of the driver bit 107 is a hexagon, and a rotating body 133 for rotating the driver bit 107 for screw tightening is disposed below the piston bumper 110. The rotating body 133 has a bevel gear formed on the outer peripheral side and meshes with the bevel gear 129, and is held by the housing 102 so as to be rotatable via a bearing 137. The state of FIG. 13 is a view showing a state in which the piston 106 is located substantially at the bottom dead center. The lower end surface of the piston 106 is in contact with the piston bumper 110, and the upper end surface of the weight 116 is in contact with the weight damper 128. .

  FIG. 14 is a partial cross-sectional view of the screwdriver 101 that performs the pulling-up operation of the piston 106 and shows a state immediately before injection. The output of the motor 11 transmitted to the first gear 120 side is used for a pulling operation for moving the piston 106 upward and a moving operation for moving the weight 116 downward. The piston 106 is accommodated on the inner peripheral side of the weight 116, and a striking spring 109 is disposed on the piston 106. The upper end of the impact spring 109 is held on the upper inner wall side of the weight 116 via the spring damper 141. The piston 106 is held so as not to rotate relative to the housing 102, and can move only in the vertical direction. A driver bit 107 is pivotally supported on the piston 106 so as to be rotatable relative to the piston 106. A concave portion 107 a is formed in the vicinity of the center of the driver bit 107, and when the concave portion 107 a reaches a position facing the motor stop switch 136, the control circuit stops the reverse rotation of the motor 11.

  The rotation shaft 11a of the motor 11 is provided with a pinion gear 130. After being decelerated by the planetary gear reduction mechanism, one of the outputs is transmitted to the first gear 120 and the other is transmitted to the bevel gear 129. On the upper side of the first gear 120, the second gear 121 is arranged so that the teeth formed on the respective outer peripheral parts mesh. FIG. 14 shows a state in which the weight 116 is moved to the bottom dead center at the same time as the piston 106 is moved to the top dead center using the first gear 120 and the second gear 121. Thus, not only the piston 106 but also the weight 116 is moved in the opposite direction, and the striking spring 109 held between them is greatly compressed. When the piston 106 is located at the top dead center, the screw portion 107b at the tip is pulled up so as to be located above the head of the screw 50 to be driven, and is screwed by the screw feeding portion 42 (see FIG. 13). The screw 50 to be driven below is fed.

  A reduction mechanism using a planetary gear is provided at the tip of the motor 11, and a pinion gear 130 serving as a sun gear is provided on the rotation shaft 11a. A plurality of planetary gears 118 rotate around the pinion gear 130, and the planetary gear 118 is rotated. A ring gear 123 is disposed on the outer periphery of the ring. The rotation shaft of the planetary gear 118 is supported by the planet carrier 117. A rotating shaft 117a is formed on the tip side of the planet carrier 117, and the rotating shaft 117a serves as an output shaft for the reduced speed. The rotating shaft 117a is provided with two rotating gears 135a and 135b having a one-way clutch. The rotating gear 135a meshes with teeth arranged on the outer peripheral side of the first gear 120 on the upper side, and the rotating gear 135b meshes with the flat gear portion 129a of the bevel gear 129 on the lower side. Here, the rotation transmission directions of the rotation gear 135a and the rotation gear 135b are set to be opposite to each other. When the motor 11 is rotating in the forward direction, the rotation gear 135a transmits power to the first gear 120. Thus, power transmission to the bevel gear 129 is interrupted by the rotating gear 135b. On the other hand, when the motor 11 is rotating in the reverse direction, the power is interrupted to the first gear 120 by the rotation gear 135a, and the power is transmitted to the bevel gear 129 by the rotation gear 135b.

  The first gear 120 and the second gear 121 are spur gears having teeth on the outer periphery, and have the same diameter and the same number of gears. A first roller cam 120 a is provided in a part of the first gear 120 in the circumferential direction, and a second roller cam 121 a is provided in a part of the second gear 121 in the circumferential direction. The first roller cam 120a and the second roller cam 121a move so as to draw a locus of a predetermined radius of rotation about the rotation shafts 119 and 122 as the first gear 120 and the second gear 121 rotate, and the piston 106 By abutting against one engaging portion 106a, the second engaging portion 106b, or an engaging portion 116a (described later in FIG. 15) of the weight 116, the rotational force of the first gear 120 and the second gear 121 is increased in the vertical direction. Convert to kinetic energy. In the state of FIG. 14, the second roller cam 121a is in contact with the lower surface of the first engagement portion 106a, and the first roller cam 120a is in contact with the engagement portion 116a (not shown in FIG. 14) of the weight 116. When the first gear 120 and the second gear 121 are slightly rotated from the state of FIG. 14, the contact relationship between the second roller cam 121a and the first engagement portion 106a is released, and at the same time, the relationship between the first roller cam 120a and the weight 116 is released. Since the contact relationship of the joint portion is released, the force that holds the piston 106 and the weight 116 by the action of the impact spring 109 disappears, and the driving operation is started.

  An inner peripheral cylindrical portion 106c and an outer peripheral cylindrical portion 106d are formed above the lower surface of the piston 106, and a lower end portion of the impact spring 109 is fixed in a space between them. The piston 106 and the driver bit 107 are pivotally supported so as to be relatively rotatable. The rotating body 133 is pivotally supported on the housing 2 by the metal 124 on the upper side and the bearing 137 on the lower side, and is configured to be rotatable about the longitudinal direction of the driver bit 107 as a central axis. Near the center of the rotator 133, a disk portion that extends in the radial direction is formed, and the outer periphery of the disk portion is a conical shape and is a bevel gear in which a gear is formed. The rotating body 133 is formed with a through-hole 133a for holding the rotating body 133 so as to be slidable with the driver bit 107 in the axial direction. The cross-sectional shape perpendicular to the axial direction of the through hole 133 a is formed in a hexagonal shape that is substantially the same as the outer diameter of the driver bit 107. The nose 138 is provided with a motor stop switch 136 for stopping the rotation of the motor 11. The outer peripheral portions of the bevel gear 129 and the rotating body 133 are bevel gears, but may be realized by other gear-type transmission mechanisms such as a hypoid gear, a worm gear, a rack and pinion, and a miter gear. Further, a permanent magnet may be incorporated in the rotating body, and a stator coil may be provided on the outer peripheral side thereof to rotate the rotating body as an electric motor or an ultrasonic motor.

  Next, the operation of the drive mechanism that performs the upward movement of the piston 106 and the downward movement of the weight 116 will be described with reference to FIGS. 15 and 16. 15 and 16 are views seen from the cross-sectional position of the BB portion in FIG. 13, and a part of the configuration is omitted for explanation. In this embodiment, the first gear 120 having the same diameter and having teeth on the outer peripheral side and the second gear 121 are arranged so as to mesh with each other, and the first roller cam 120a and the second roller cam 121a provided at one point of these side surfaces. Ascending movement that moves the piston 106 upward by rotating the first gear 120 and the second gear 121 while sequentially contacting the first engagement portion 106a and the second engagement portion 106b formed on the piston 106. Is realized. The rotation direction of the motor 11 at this time is a positive direction. Similarly, by bringing the first roller cam 120a into contact with the engaging portion 116a of the weight 116, the weight 116 is moved downward in the direction opposite to the direction in which the piston 106 moves (in this case, the injection direction). FIG. 15A shows the state of the first gear 120 and the second gear 121 when in the initial position. Here, the first roller cam 120a and the second roller cam 121a are not in contact with any of the engaging portions (106a, 106b, 116a), and the piston 106 is positioned on the lower end side by the urging force of the impact spring 109, and the weight 116 Is located on the upper end side. When the motor 11 is activated from the state of (1) and the first gear 120 rotates in the direction of the arrow, the second gear 121 engaged therewith starts to rotate in the opposite direction. (2) shows a state after the first gear 120 and the second gear 121 have started to rotate. At this time, the first roller cam 120a abuts the first engagement portion 106a from the lower side, and the first engagement is performed. The part 106a is moved upward. Here, the first roller cam 120 a and the second roller cam 121 a are provided with rollers that can rotate around a rotation shaft fixed to the first gear 120 and the second gear 121. Therefore, even if the contact position of the first engagement portion 106a and the first roller cam 120a is shifted in the left-right direction, the first engagement portion 106a can slide well, and the second engagement portion 106b can be smoothly moved upward. When the first gear 120 and the second gear 121 are further rotated from the state (2) to the state (3), the first roller cam 120a further moves the first engagement portion 106a upward. The weight 116 has started to move upward, but the weight 116 has not yet started moving. When the first gear 120 and the second gear 121 are further rotated to the position (4), the contact state between the first roller cam 120a and the first engagement portion 106a is released, but immediately before the release. Since the second roller cam 121a contacts the lower side of the second engaging portion 106b, the piston 106 continues to move upward by the rotation of the second gear 121.

  FIG. 16 is a view showing a state of the piston 106 and the weight 116 when the state is further rotated from the state of FIG. 5 (4). In FIG. 16 (1), the first roller cam 120a abuts against the engaging portion 116a from above, and thus acts to push down the weight 116 downward. At this time, since the second roller cam 121a and the second engaging portion 106b are in contact with each other, the piston 106 continues to move upward as the first gear 120 and the second gear 121 rotate. FIG. 16B shows a state in which the piston 106 has moved to the top dead center and the weight 116 has moved to the bottom dead center in this way. Here, a state immediately before the second roller cam 121a is released from the contact state with the second engaging portion 106b is shown. The piston 106 is provided with a first engagement portion 106a and a second engagement portion 106b. Since there is a non-engagement region a in the horizontal direction (left-right direction), the second roller cam 121a has reached this region. At this time, since the piston 106 cannot be supported, the piston 106 is suddenly pushed out in the injection direction by the action of the impact spring 109. Since the first roller cam 120a reaches the non-engagement region b (see (3)) of the engaging portion 116a as the engagement state between the second roller cam 121a and the first engaging portion 106a is released, the weight 116 is reached. Accordingly, the weight 116 is suddenly moved upward by the action of the impact spring 109. If the movement in the injection direction of the piston 106 and the movement in the reflection direction of the weight 116 are performed at the same time, the weight 116 can be moved in the direction opposite to the piston 106 by providing only one striking spring 109. In order to prevent repulsion when driving, a screwdriver that is easy to use with little recoil has been realized.

  FIG. 17 is a cross-sectional view taken along the line C-C in FIG. 14, and shows a cross-section of the piston 106, the weight 116 and the second gear 121. As can be understood from FIG. 14, the piston 106 is disposed inside the movable weight 116. A striking spring 109 is disposed on the upper side of the piston 106. A metal guide member 132 is provided outside the weight 116 and inside the body portion 102a of the housing 102, and guides the weight 116 so that it can be moved favorably in the axial direction. The second gear 121 is pivotally supported so as to be rotatable about a rotation shaft 122, and a second roller cam 121 a is provided on the circumference of the second gear 121. Two protruding first engaging portions 106a and second engaging portions 106b are formed on the second gear 121 side from the piston 106.

  FIG. 18 is a cross-sectional view of the screw driving machine 101 according to the second embodiment of the present invention, showing a state in the middle of screw driving. In the state of FIG. 16 (3), since the engagement state of the first roller cam 120a and the second roller cam 121a with the engaging portion is released, by stopping the motor 11 at the time of FIG. 16 (3), Transmission of rotational force to the first gear 120 can be blocked. However, in this embodiment, when the state shown in FIG. 16 (3) is reached, the motor 11 is controlled to rotate in the reverse direction immediately, and the reverse rotational force is rotated through the rotating gear 135 b and the bevel gear 129 to rotate the driver bit 107. It was decided to rotate the rotating body 133 to be rotated. At this time, the reverse rotation output of the motor 11 is transmitted to the bevel gear 129 but not to the first gear 120 by the action of the rotation gears 135 a and 135 b having the one-way clutch. As a result, the driver bit 107 rotates to tighten the screw as indicated by an arrow 156 while moving downward as indicated by an arrow 155, so that the screw 50 can be tightened while striking it. The control for switching the motor 11 from the forward rotation to the reverse rotation may be performed in the same manner as in the first embodiment. In this case, the first gear 120 or the second gear is used as the driving detection switch 57 shown in FIG. The rotational position 121 may be detected by some sensor, or the driving state may be detected by other methods.

  FIG. 19 is a cross-sectional view of the screwdriver 101 when driving is completed. When the driving is completed, the screw portion 107b of the driver bit 107 reaches the position shown in the figure, so that the concave portion 107a reaches the motor stop switch 136. Therefore, the output of the motor stop switch 136 is transmitted to the microcomputer 54, so that the microcomputer 54 stops the reverse rotation of the motor 11.

  As described above, in the second embodiment, the moving mechanism (pickup mechanism, push-down mechanism) of the piston 106 is realized without using the belt 19, the winch portion 14, and the wire 15 as in the first embodiment, and the weight is also achieved. A balancer mechanism that reduces the recoil at the time of driving without using a spring is realized, thus realizing a lightweight and highly durable screwing machine. In addition, since the cross-sectional shape of the driver bit 107 is a non-circular shape and the rotational force is applied to the driver bit 107 by the rotating body 133 that can move relative to the driving direction, the tightening operation can be effectively performed simultaneously with the screw driving. Now you can do it. Furthermore, since the force in the direction of twisting in the rotational direction does not act on the piston 106, the life of the piston 106 can be extended.

  As mentioned above, although demonstrated based on the Example which shows this invention, this invention is not limited to the above-mentioned form, A various change is possible within the range which does not deviate from the meaning. For example, in the above-described embodiment, the moving mechanism of the piston and weight and the rotating mechanism of the driver bit are realized by the driving force of one motor, but each of them is configured to be driven separately using two motors. Also good. In this case, control is performed so that the rotational speeds of the two motors are changed in accordance with the position of the driver bit. For example, when the start of driving or the timing before and after it is detected, the rotation of the motor on the piston pulling side is stopped or decelerated and the rotation of the motor on the driver bit rotation side is started. When two motors are used, the rotational speeds of the two motors may be switched at different timings, for example, the driver bit is rotated before the spring is released.

  Further, in this embodiment, the movement mechanism for moving the piston and lowering the weight is performed by the forward rotation of the motor, and the rotation mechanism of the driver bit is performed by the reverse rotation of the motor. This mechanism is selected and driven. However, the motor may be configured to be forward rotated at any operation without rotating the motor in the reverse direction. In this case, the motor is configured to rotate at a low speed when the piston and weight are lifted, and at a high speed when the driver bit rotates, and the transmission of power to the moving mechanism and the rotating mechanism can be switched using a centrifugal clutch or other It may be realized using a power switching mechanism. For example, the piston pulling mechanism is connected to the motor via a centrifugal clutch, and the motor is rotated at a high speed until the spring is released. After the spring is released, the motor is rotated at a low speed to rotate the motor only for the rotation of the driver bit. It can be configured to transmit force. Further, the conversion of the motor driving method (for example, the start of reverse rotation) is not necessarily limited simultaneously with the opening of the spring, but can be performed immediately before or after.

DESCRIPTION OF SYMBOLS 1 Screwdriver 2 Housing 2a Body part 2b Handle part 2c Motor holding part 2d Battery holding part 3 Trigger 4 Trigger switch 5 Injection part 6 Piston 6a Mounting part 7 Driver bit 7a Recessed part 7b Screw part 8 Drive mechanism 9 Impact spring 10 Piston bumper DESCRIPTION OF SYMBOLS 11 Motor 11a Rotating shaft 12 Battery 13 Push lever 13a Push lever switch 14 Winch part 15 Wire 16 Weight 16a First engaging part 16b Second engaging part 16c Notch part 17 Energizing member 18a First roller cam 18b Second roller cam 19 Belt 20 First pulley 21 Second pulley 22, 23 Gear 24 Rotating body 25 Cam part 27 Push lever switch 28 Weight bumper 29 Bevel gear 30 Cap 31 Rotation guide 32 Spindle 32a Guide groove 33 Bebergi 33a Joint part 34 Clearance 35 One-way clutch 36 Motor stop switch 37 Power transmission mechanism 38 Nose 39 Mode switch 42 Screw feed part 43 Magazine part 44 Magazine cover 45 Solenoid 46 Compression spring 47 Feed piston 48 Feeder 49 Rail guide 50 Screw 50a Screw Head 51 Connected body 53 Control circuit board 53a Control circuit 54 Microcomputer 55 Controller power switch 56 Logic circuit 57 Driving detection switch 58 Power switch 59 Power switch detection circuit 60 Tightened material 61 Gypsum board 62 Wood 71 Battery voltage detection circuit 72 Control signal Output circuit 73 Inverter circuit 74 First FET drive circuit 75 FET 76 Second FET drive circuit 77 FET 78 Display circuit 79 15-minute timer 81 Trigger signal 82 Motor speed 8 3 Motor current 84 Piston position 85 Driving detection signal 86 Output signal 101 Screw driving machine 102 Housing 102a Body part 102b Handle part 102c Motor holding part 102d Battery holding part 106 Piston 106a First engaging part 106b Second engaging part 106c Inside Peripheral side cylindrical part 106d Peripheral side cylindrical part 107 Driver bit 107a Recessed part 107b Screw part 109 Strike spring 110 Piston bumper 116 Weight 116a Engaging part 117 Planetary carrier 117a Rotating shaft 118 Planetary gear 119 Rotating shaft 120 First gear 120a First roller cam 121 Second gear 121a Second roller cam 122 Rotating shaft 123 Ring gear 124 Metal 128 Weight damper 129 Bevel gear 129a Flat gear portion 130 Pinion gear 132 Guide portion 133 rotating body 133a through hole 135a, 135b rotate the gear 136 motor stop switch 137 bearing 138 nose 141 spring damper

Claims (10)

A battery, a motor driven by the battery, a housing for housing the motor, a piston movable within the housing, a striking spring for biasing the piston, and driving a screw attached to the piston; A screw driver for driving the screw by moving the driver bit by releasing the compressed hitting spring by compressing the hitting spring using the rotational force of the motor.
The screw driver according to claim 1, wherein the driver bit is rotated by the motor when the compressed impact spring is released.   The screw driving machine according to claim 1, wherein the number of the motors is one, and driving is performed while switching between movement control for compressing the impact spring and rotation control for rotating the driver bit. Output the output of the motor via a one-way clutch to a drive system that compresses the impact spring and a drive system that rotates the driver bit,
The rotation direction of the motor for rotating the driver bit is opposite to the rotation direction of the motor for compressing the impact spring;
3. The screw driving machine according to claim 2, wherein when the motor is reversely rotated, power is not transmitted to a drive system that compresses the impact spring by the action of the one-way clutch. Detecting the injection timing at which the compressed impact spring is released;
4. The screw driving machine according to claim 3, wherein when it is detected that the motor is released, the direction of rotation of the motor is reversed. A weight that is movable in a direction opposite to the moving direction of the piston and is urged by the urging member in the direction opposite to the piston is provided,
4. The screw driving machine according to claim 2, wherein the weight is moved in a direction opposite to a moving direction of the piston by using a drive system for compressing the hitting spring. The output shaft of the motor has a pulley that rotates a belt, and a bevel gear that rotates in one direction via the one-way clutch,
The piston reciprocates in a cylindrical spindle that rotates around the injection direction by the bevel gear,
Holding the piston and the spindle relatively unrotatable,
The screwdriver according to claim 5, wherein the driver bit attached to the piston is rotatable by rotating the spindle. A sensor for detecting the position of the driver bit is provided,
The screw driving machine according to claim 6, wherein when the lowering of the driver bit to a predetermined position is confirmed by the sensor, the rotation of the driver bit is stopped.   The screw driving machine according to any one of claims 1 to 7, wherein a motor for compressing the impact spring and a motor for rotating the driver bit are provided independently. A battery, a motor driven by the battery, a housing for housing the motor, a piston movable within the housing, a striking spring for biasing the piston, and driving a screw attached to the piston; A screw driver for driving the screw by moving the driver bit by releasing the compressed hitting spring by compressing the hitting spring using the rotational force of the motor.
A rotation mechanism that rotates the driver bit when the driver bit is released after completion of the moving operation of compressing the striking spring and moving the piston;
A sensor for detecting the completion of screw tightening by the rotating mechanism is provided,
A screwdriver, wherein when the completion of screw tightening is detected by the sensor, the rotation of the driver bit is stopped. The screw driving machine according to claim 9, wherein the sensor is a switch operated by a recess formed in the driver bit.

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