CN1657235A - Electric driver - Google Patents

Abstract

The rotational force transmission device of the electric screwdriver can exert a greater rotational driving force on the screwdriver head when the screw is loosened than when the screw is tightened, and has a simple structure, less wear and tear on the parts, and can transmit a specified rotational force. The screwdriver of the present invention has: the rotary input member 106 that is rotated by the driving motor, the driving roller 108 that is engaged on the rotary input member and can transmit the rotational driving force, and the rotating rotary device that is drivingly connected to the above-mentioned bit holder and can rotate. The output member 110 is held on the rotation output shaft and engaged with the drive roller 108, and transmits the rotation driving force to the driven ball 112 on the rotation output shaft. The drive roller 108 is displaced relative to the rotation input member 106 when the rotation drive input member rotates in the forward direction and in the reverse direction around the rotation center axis, and engages with the driven ball 112 at different points, thereby Therefore, the rotational driving force transmitted to the above-mentioned rotary output member 110 through the driving roller and driven balls is different from the above-mentioned rotary input member 106 .

Description

electric screw driver

technical field

The present invention relates to an electric screwdriver, and more particularly to such an electric screwdriver, that is, a rotary transmission device that transmits a rotational driving force from a drive motor to a bit holder, when the screw is loosened (reversed), the When the electric screwdriver tightens the screw (forward rotation), it can transmit a large rotational driving force to the bit holder.

Background technique

When an electric screwdriver initially loosens a tightened screw, it must apply a greater rotational driving force than when tightening the screw. On the other hand, when tightening a screw, if an excessive rotational driving force is applied, an excessive force is generated on the screw itself and the parts fastened by the screw, and the electric screwdriver itself, thereby causing damage to them. danger.

Therefore, in an electric screwdriver, the rotation transmission device that transmits the rotational driving force from the drive motor to the driver bit generally has a torque limiting device that limits the rotational driving force transmitted to the driver bit to a predetermined value or less.

Figure 1 shows an example of such a torque limiting device. The torque limiting device 10 has: a cylindrical part 12 connected to the rotary drive of the screwdriver bit, a drive shaft 14 that receives the rotational drive force from the drive motor and rotates, and a pair of rollers 16 that are arranged on the opposite side of the drive shaft in the diametrical direction. A pair of balls 20 arranged in a radial through hole on the opposite side of the cylindrical part 12 in the radial direction and a spring device (not shown) that pushes the balls in the radial direction by means of a predetermined elastic force. When tightening the screw, the drive shaft 14 rotates in the counterclockwise direction to engage the above-mentioned roller 16 with the above-mentioned ball 20 (there is a positional relationship with the roller shown by the solid line), and when the screw is loosened, the drive shaft 14 rotates along the Rotating clockwise, the roller 16 is engaged with the above-mentioned ball 20 (there is a positional relationship shown by the dotted line with respect to the same roller), so that the rotational driving force is transmitted to the above-mentioned screwdriver bit through the same ball 20 and the cylindrical part 12 superior. If the rotational drive force transmitted from the drive shaft 14 to the cylindrical part 12 exceeds a specified value, the balls 20 move radially outward against the elastic force F applied radially inward, whereby the drive shaft performs idle rotation. , to cut off the transmission of the rotational driving force (for example, refer to Patent Document 1). Although this torque limiting device can limit the torque in this way, when the screw is tightened or loosened, since the radial position of the roller engaged with the ball (from the rotation center axis of the drive shaft) is the same, the rotational driving force that can be transmitted The maximum value is also the same, so the above-mentioned requirement for generating a large driving force when loosening the screw cannot be satisfied.

In view of this, there is the following form: the rotary drive shaft 14 forms the shape shown in Figure 2, whereby, when the drive shaft 14 rotates clockwise for loosening the screw, it is counterclockwise with the drive shaft 14 for tightening the screw. As shown in the figure, the engaging position of the rotating drive shaft relative to the ball 20 can be engaged at a radial position separated from the central axis of rotation of the same rotating drive shaft 14, thereby A larger rotational driving force is transmitted to the ball 20 (for example, Patent Document 2).

In this structure, if the drill bit is used for a period of time, wear and tear will occur on the engaging part of the rotating drive shaft 14 and the ball 20, and their engaging positions will be displaced radially inward, so that the ball 20 from the rotating drive shaft will The applied rotational drive force is then reduced.

Furthermore, there is a form in which the rotational drive shaft does not run idle only when the screw is loosened during the use of the one-way clutch, and the required rotational drive force is transmitted from the rotational drive shaft to the balls, but in this case, the If the loosened screw is tightened too much, the drive motor will be burned out, and the operator will be injured if he does not keep turning the screwdriver, which will cause danger.

[Patent Document 1] Tokyo 2-42631

【Patent Document 2】Shi fair 2-12053

Contents of the invention

The object of the present invention is to provide an electric screwdriver equipped with a rotary transmission device capable of solving the above-mentioned problems.

That is, the present invention provides an electric screwdriver, which includes: a bit holder for fixing and holding the screwdriver bit;

A rotary transmission device for transmitting the rotary driving force of the drive motor to the bit holder, characterized in that,

The rotary transmission has:

A rotary input member that receives the rotary driving force of the drive motor and rotates;

a drive roller that engages with the rotary input and transmits a rotational driving force from the rotary input around the central axis of rotation of the rotary input;

a rotary output member that is drivingly connected to the above-mentioned cutter head holder and can rotate around the above-mentioned rotation central axis of the above-mentioned rotary input member;

a driven ball that is held on the rotary output member and engaged with the above-mentioned driving roller, and transmits a rotational driving force from the driving roller, and transmits the rotational driving force to the rotary output member,

The drive roller is displaced relative to the rotation input member when the rotation drive input member rotates forwardly and reversely about the rotation center axis, and engages with the driven ball in directions different from the rotation center axis. Positionally, thereby, the rotational driving force transmitted from the above-mentioned rotary input member to the above-mentioned rotary output member through the driving roller and the driven ball is different.

According to this electric screwdriver, since the rotational driving force transmitted from the driving roller to the driven ball can be changed during forward rotation and reverse rotation, appropriate rotational driving can be generated when the screw is tightened and when the screw is loosened. force. In addition, since the rotational driving force is transmitted through the engagement between the driving roller and the balls, the reduction in the rotational driving force due to wear can be reduced.

Specifically, the rotation output member has a cylindrical portion concentric with the periphery of the rotation input member, and the driven ball is held by means of the cylindrical portion. , can be engaged with the driven ball at different radial positions centered on the rotation center axis.

In addition, more specifically, the rotary input member includes a ball retaining portion having: a first retaining portion for retaining the driving roller when the rotary input member rotates forward and the driving roller and the driven ball are engaged; a second holding portion that holds the driving roller when the rotary input member is reversely rotated and the driving roller and the driven ball are engaged; and a displacement portion that allows the driving roller to be displaced between the first holding portion and the second holding portion.

As another embodiment, the rotation input member has a first surface that forms a right angle with the rotation center axis and faces the rotation output member;

The above-mentioned rotary output member is a disk-shaped member having a second surface facing and parallel to the above-mentioned first surface;

The rotary output member has a through hole extending from the second surface to an opposite surface, holds the driven ball in the through hole, and partially protrudes from the second surface toward the first surface;

The above-mentioned first surface holds the above-mentioned drive roller and sets the axis of the drive roller along the radial direction of the above-mentioned rotation center axis, and when the drive roller rotates forward and reverse, it can be at a position different from the second surface and The above-mentioned driven balls are engaged.

More specifically, the rotary input includes a ball retaining portion having:

a first holding portion for holding the driving roller when the rotary input member is rotating forward and the driving roller and the driven ball are engaged;

a second retaining portion that holds the drive roller when the rotary input member rotates in reverse and the drive roller engages with the driven ball;

and a displacement portion that allows the driving roller to be displaced between the first holding portion and the second holding portion,

The driving roller held by the first holding portion is located closer to the second surface than the driving roller held by the second holding portion, and is engaged with the driven ball.

More specifically, the driven balls have a size protruding from the second surface and the surface on the opposite side of the output rotating member, and can be adjusted in a predetermined amount by means of a ball pressing portion provided adjacent to the surface on the opposite side. The elastic force pushes the driven ball toward the above-mentioned drive roller.

Brief description of the drawings

FIG. 1 is a partial view showing a main part of a rotational force transmission device in a conventional electric screwdriver.

Fig. 2 is a cross-sectional view showing main parts of another type of rotational force transmission device in a conventional electric screwdriver.

Fig. 3 is a longitudinal sectional view of the electric screwdriver in the present invention.

Fig. 4 is a sectional view along line A-A in Fig. 3, showing the state when the screws are fastened.

Fig. 5 is a view along line A-A of the above, showing the state when the screw is loosened.

Fig. 6 is a longitudinal sectional view of another embodiment of the electric screwdriver of the present invention.

Fig. 7 is a view along line B-B in Fig. 6 .

Symbol Description

100 electric screwdriver, 102 bit holder, 102-1 center hole, 102-2 locking ball, 102-3 locking ball, 104 rotary transmission, 105 reducer, 106 rotary input, 106-1 roller holding Part, 106-2 first holding part, 106-3 second holding part, 106-4 displacement part, 106-5 first surface, 108 driving roller, 110 rotating output member, 110-1 cylindrical part, 110- 2 radial through hole, 110-3 second surface, 110-4 through hole, 112 driven ball, 120 cylinder shell part, 124 spring adjustment device, 124-1 cylinder part, 124-2 cone surface, 124 -3 ball push piece, 124-4 coil spring, 124-5 front cylinder piece, 124-6 spring push piece, 124-7 spring end snap piece, 124-8 spring adjustment piece, 130 positioning pin, a radial position, b radial position, F elastic force, α angle, β angle

Detailed ways

Below according to accompanying drawing (Fig. 3-7), illustrate the implementation form of electric screwdriver among the present invention.

FIG. 3 is a longitudinal section view of the electric screwdriver 100 in the present invention. Fig. 4 is a sectional view along line A-A in Fig. 3, showing the state when the screws are fastened. And Fig. 5 shows the state when the screw in Fig. 3 is loosened.

As shown in the figure, the electric screwdriver 100 includes a bit holder 102 (inserted from the right end shown in FIG. provided) transmits the rotational driving force from the driving motor (not shown) to the rotational transmission 104 on the bit holder 102 .

The rotary transmission device 104 includes: a rotary input member 106 that is rotationally driven by receiving the rotary drive force from the drive motor through the reducer 105; 106 the driving roller 108 of the rotational driving force of the central axis of rotation; the rotary output member 110 that is drivingly connected with the cutter head holder 102 while being able to rotate around the central axis of rotation of the above-mentioned rotary input member 106; The rotary output member 110 engages with the driving roller 108 , receives the rotational driving force from the driving roller 108 , and transmits the rotational driving force to the driven ball 112 on the rotary output member 110 .

The rotary output member 110 has a cylindrical portion 110-1 forming a concentric cylindrical shape around the rotary input member 106, and the driven ball 112 is held in the radial through hole 110-2 in a radially displaceable manner. A through hole is formed in the cylindrical portion 110-1.

The rotary input member 106 has a groove-shaped roller holding portion 106-1 with a section as shown in FIGS. The drill side of the screwdriver observes the state of the motor side) rotates, and holds the first holding part 106-2 of the driving roller 108 when the driving roller 108 is engaged on the driven ball 112; In turn, when the driving roller 108 is engaged on the driven ball 112, the second holding portion 106-3 of the driving roller 108 is held; The displacement part 106-4 that is displaced between. Specifically, the roller holding portion 106-1 has a displacement portion 106-1 that forms a substantially right angle with respect to the diameter at positions on opposite sides in the diameter direction of the cylindrical rotation input member 106 centered on the rotation center axis as a whole. 4. The first retaining portion 106-2 is curved so that one end of the displacement portion 106-4 is consistent with the curved surface of the driving roller 108; the second retaining portion 106 is also curved radially outward at the other end of the displacement portion. -3. In this roller holding portion 106-1, the radial position b (from the above-mentioned rotation center axis) of the driving roller 108 held by the second holding portion 106-3 is larger than that of the driving roller 108 held by the first holding portion 106-2. Radial position a (from the above-mentioned axis of rotation). The driven ball 112 bears a predetermined elastic force F towards the central axis of rotation as described later, and the radial direction of the force (in the direction along the line connecting the center of the ball 112 and the drive roller 108 ) transmitted from the rotary input member 106 through the drive roller 108 When the outward component force exceeds the elastic force F, the driven ball 112 cannot transmit the rotational driving force due to radially outward displacement; and when the above-mentioned component force is lower than the elastic force, the above-mentioned driven ball 112 is kept at In the illustrated position, the component force in the tangential direction of the force transmitted to the driven ball 112 acts as the rotational driving force of the rotary output member 110 . Therefore, as described above, the second holding portion 106-3 is held at the radial position b (separated from the above-mentioned rotation center axis) compared with the first holding portion 106-2. The angle β in FIG. 5 is larger than the angle α in FIG. 4 , and a larger rotational driving force can be exerted on the rotary output member 110 when the screw is loosened.

In FIG. 3 , 120 is a cylindrical housing portion of the electric screwdriver, and a spring adjusting device 124 is provided on the front end of the cylindrical housing portion for adjusting the elastic force radially inward toward the driven ball 112 . The spring adjusting device 124 includes: a cylindrical part 124-1 fastened with screws at the front end of the cylindrical housing part 120; The ball pusher 124-3 of the tapered surface 124-2; shown in Figure 3, the coil spring 124-4 applied to the spring pressure of the ball pusher 124-3 to the left; shown in Figure 3, The right end of the cylindrical part 124-1 is fastened with screws to the front end cylindrical member 124-5 coaxially fixed with the cylindrical part, which moves in the axial direction by means of screw rotation, and is pushed by the spring pusher 124-5. 6 and the spring end engaging part 124-7 apply a spring adjustment part 124-8 with a suitable pushing force on the coil spring 124-4. A screwdriver bit (not shown) is inserted into the central hole 102-1 of the bit holder 102 from the right side, and is fixed by a locking ball 102-2. Once the bit holder 102 is inserted, the positioning pin 130 extending along the central axis of the electric screwdriver is pushed to the left, acting on the start switch of the driving motor. As mentioned above, when the screw is tightened, the force resisting the tightening becomes larger, and if the radially outward component of the force transmitted from the rotary input member 106 to the driving roller 108 exceeds the above-mentioned elastic force F, the driven ball 112 will Radially outward movement, with which, the ball pusher 124-3 (shown in FIG. 3 ) moves to the right, and the inclined surface near the right end of the ball pusher pushes the ball inwardly in the radial direction. 102-3. Thus, by pushing the positioning pin 130 to the left, the start switch of the driving motor is closed, thereby stopping the driving of the electric screwdriver.

Fig. 6 and Fig. 7 show other implementation forms of the electric screwdriver in the present invention.

The basic structures of the electric screwdrivers are the same, but the transmission mechanism of the rotating driving force between the rotating input member 106 and the rotating output member 110 is different from the above-mentioned embodiments.

That is, in this embodiment, the rotation input member 106 has a first face (ie, the right-hand face in FIG. 5 on the second side 110-3 of the disk. The rotation output member 110 is formed with a through hole 110-4 extending in the above-mentioned rotation axis direction, and the driven ball 112 is movably held in the through hole 110-4. The first surface 106-5 holds the drive roller 108 such that the axis of the drive roller is in the radial direction centered on the above-mentioned rotation center axis. The drive roller 108 engages with the driven ball 112 in the circumferential direction as the rotation input member 106 rotates.

Specifically, as shown in FIG. 7, on the first surface 106-5 of the rotation input member 106, there is formed a roller holding portion 106-1 extending in the circumferential direction as the above-mentioned rotation axis and opening toward the second surface. The driving roller 108 in the roller holding portion 106-1 is rotatably arranged, and its axis is in a direction (ie, a diameter direction) perpendicular to the above-mentioned circumferential direction. The end portion of the roller holding portion 106-1 (on the lower side in FIG. 7 ) is engaged on the lower side by engaging the driven roller 108 with the driven ball 112 when the rotation input member 106 rotates counterclockwise when the screw is loosened. On the end, there is formed a second retaining portion 106-3 for rotating in counterclockwise contact with the driven ball 112 . In addition, the end portion on the opposite side (on the upper side in FIG. 7 ) of the roller holding portion 106-1 is locked by being engaged with the driven ball 112 when the rotation input member 106 is rotated in the clockwise direction when the screw is fastened. The first retaining portion 106 - 2 is formed on the above-mentioned end portion and is rotationally connected with the driven ball 112 and the rotary input member 110 . In this embodiment, the ball pressing portion 124 - 3 is in the shape of a disk adjacent to the rotary input member 110 , and exerts an axial direction on the rotary output member 110 in such a manner that the driven ball 112 is pressed against the driving roller 108 . on the elastic.

As shown in the figure, the bottom surface of the roller holding groove is inclined, the second holding portion 106-3 is relatively shallow, and the first holding portion 106-2 is relatively deep. Therefore, the driving roller 108 held in the second holding part 106-3 is located closer to the second surface 110-3 than the driving roller 108 held in the first holding part 106-2, and is engaged with the driven ball 112. Therefore, as in the first embodiment, a larger rotational driving force can be applied to the rotational input member 110 in the first holding portion.

Claims (6)

1. an electric screw driver comprises:

The fixing cutter head clamper that keeps driver bit;

Be used for rotary driving force with drive motors and be delivered to rotary actuator on the cutter head clamper,

It is characterized in that rotary actuator has:

The rotation input component of accepting the rotary driving force of drive motors and rotatablely moving;

Be fastened on the driven roller of rotary driving force on this rotation input component, from this rotation input component transmission around this rotation input component pivot axis;

Be connected, can be simultaneously the rotation output of center rotation with above-mentioned cutter head clamper driving with the above-mentioned pivot axis of above-mentioned rotation input component;

Remain on this rotation output and be fastened on the above-mentioned driven roller, and transmit rotary driving force, this rotary driving force is delivered to driven ball on this rotation output from this driven roller,

When above-mentioned driven roller is central forward rotation and counter-rotating at above-mentioned rotation driving input component with above-mentioned rotary middle spindle line, with respect to the displacement of above-mentioned rotation input component, and above-mentioned relatively driven ball is fastened on the different points, whereby, make from above-mentioned rotation input component the rotary driving force difference of transmitting to above-mentioned rotation output by this driven roller, driven ball around above-mentioned pivot axis.

2. electric screw driver as claimed in claim 1, it is characterized in that, above-mentioned rotation output has the cylindric portion that forms concentric circles with rotation input component periphery, above-mentioned driven ball is by this cylindric maintenance, when driven roller was rotated in the forward with counter-rotating at above-mentioned rotation input component, being fastened on above-mentioned rotary middle spindle line with above-mentioned driven ball was in the different radial position at center.

3. electric screw driver as claimed in claim 2 is characterized in that, the rotation input component comprises the ball maintaining part, and this ball maintaining part has:

Be rotated in the forward and driven roller and driven ball keep first maintaining part of this driven roller when fastening at this rotation input component;

Second maintaining part that when this rotation input component counter-rotating and driven roller and driven ball fasten, keeps this driven roller;

And the displacement portion that allows driven roller displacement between first maintaining part and second maintaining part.

4. electric screw driver as claimed in claim 1 is characterized in that, above-mentioned rotation input component has with above-mentioned pivot axis form right angle and faces first of above-mentioned rotation output;

Above-mentioned rotation output be have towards and be parallel to second above-mentioned first discoid parts;

This rotation output has the through hole that extends to the face of opposition side from above-mentioned second face, keeps above-mentioned driven ball in this through hole, and from above-mentioned second towards above-mentioned first face portion give prominence to;

Above-mentioned first keeps above-mentioned driven roller and makes the radially setting of the axis of driven roller along above-mentioned pivot axis, and this driven roller can engage with above-mentioned driven ball on different positions with above-mentioned second identity distance when being rotated in the forward with counter-rotating.

5. electric screw driver as claimed in claim 4 is characterized in that, the rotation input component comprises the ball maintaining part, and this ball maintaining part has:

Be rotated in the forward and driven roller and driven ball keep first maintaining part of this driven roller when fastening at this rotation input component;

Second maintaining part that when this rotation input component counter-rotating and driven roller and driven ball fasten, keeps this driven roller;

And the displacement portion that allows driven roller displacement between first maintaining part and second maintaining part,

Remain on driven roller in first maintaining part and compare the driven roller that remains in second maintaining part and be in more approaching above-mentioned second position, and be fastened on the driven ball.

6. electric screw driver as claimed in claim 5, it is characterized in that, above-mentioned driven ball have from this output revolving part above-mentioned second with and the outstanding size of the face of opposition side, the ball pushing portion that can be provided with by means of the face in abutting connection with above-mentioned opposition side pushes driven ball with the elastic force of stipulating to above-mentioned driven roller.

Images