JP2003260672A - Electric screw driver and method of using electric screw driver - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electric screw driver capable of securely inhibiting noise and vibration when a clutch is released in response to the screw fastening torque. <P>SOLUTION: The electric screw driver comprises first and second spindles 120, 130, first and second clutch means 140, 150 engaged with each other for transmitting the torque between the first and second spindles, a clutch engagement regulating means 160, and a second clutch position regulating means 170. The second clutch position regulating means 170 has a first position regulating means 171 for regulating the second clutch means 150 to be located in a torque transmission permitting position when the reaction torque applied from a processed material side is in a prescribed range, and a second position regulating means 181 for regulating the second clutch means 150 having moved to a torque transmission prohibiting position to return to the torque transmission permitting position when the reaction torque exceeds the prescribed range. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric screwdriver provided with a silent clutch, and more particularly, to an electric screwdriver provided with a silent clutch that is preferably used for screw tightening work while controlling tightening torque. Regarding

[0002]

2. Description of the Related Art As disclosed in, for example, Japanese Patent Application Laid-Open No. 61-219581, as a conventional electric screwdriver, a tool bit and a motor for applying a rotational driving torque to the tool bit are connected by a silent clutch. Therefore, a technique for reducing noise and vibration during screw tightening work is known. According to this silent clutch,
When the screw to be tightened reaches a certain amount of tightening depth with respect to the work material, the rotational torque transmission by the clutch is quickly released based on the tightening depth to rotate the clutch teeth. By avoiding contact, noise is suppressed.

By the way, as one of the forms of the screw to be tightened, there is a screw fixed to a metal material such as an iron plate to fix the material. When performing such screw tightening work, the tightening work is completed according to the screw tightening torque amount, not according to the screw tightening depth. There is a need to do. If the clutch is not quickly and reliably released with the screw tightened on the metal material and the tightening torque is excessive, the tool bit side clutch member that can no longer rotate and the rotating motor side clutch member This is because they come into contact with each other, resulting in abnormal noise and vibration.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and it is possible to reliably suppress abnormal noise and vibration when the clutch is released according to the screw tightening torque. The purpose of the present invention is to provide a simple electric screwdriver.

[0005]

In order to achieve the above object, the invention described in each claim is constituted. According to the first aspect of the present invention, there are provided a machine housing the motor, a first spindle, a second spindle, a first clutch means, a second clutch means, a clutch engagement restricting means, and a position restricting means for the second clutch means. An electric clew driver having is configured.

The first spindle is movable relative to the machine body, the first clutch means is arranged on the end side facing the machine body, and the tool bit for screw tightening is connected to the other end side. . The airframe typically corresponds to a motor housing containing a motor. The second spindle is connected to a motor and rotates. Typically, a configuration in which a motor is connected through a speed reduction mechanism using a planetary gear and rotates is preferable.

The first clutch means rotates together with the first spindle while being relatively movable in the axial direction of the first spindle. The second clutch means rotates relative to the second spindle while being relatively movable in the axial direction of the second spindle, and engages with the first clutch means when the first spindle relatively moves toward the machine body. The drive torque of the motor is transmitted to the tool bit. The first spindle typically moves relative to the machine body due to a reaction force of a pushing load generated by an operator pressing the machine body together with the tool bit toward the workpiece during screw tightening work. Note that various motors such as an AC motor and a DC brushless motor can be adopted as the motor that applies the rotation torque to the tool bit.

The clutch engagement restricting means applies an urging force in a direction in which the first clutch means and the second clutch means separate from each other. The function as the silent clutch of the present invention is ensured by the biasing force that separates the first clutch means and the second clutch means. A typical example of applying the urging force corresponds to an urging spring interposed between the first clutch means and the second clutch means. To ensure the function as a silent clutch,
It is preferable that the urging force by the clutch engagement restricting means is appropriately set so that the engagement between the first clutch means and the second clutch means is released instantaneously and reliably when the screw tightening work is completed.

The position restricting means of the second clutch means is the first
And a second position regulating means. The first position restricting means sets the second clutch means to the first clutch means side when the reaction torque applied to the tool bit from the work piece side when transmitting the driving torque of the motor to the tool bit is within a predetermined range. The rotation torque of the motor is transmitted to the tool bit by restricting it to be placed in the adjacent torque transmission allowable position.
As a typical example of "the reaction torque is within a predetermined range",
In the screw tightening work, the tightening work has not been completed yet,
This corresponds to a state in which the reaction torque applied from the work material to the tool bit is not excessive.

On the other hand, when the reaction torque exceeds the predetermined range, the second position regulating means causes the second clutch means to move to the torque transmission inhibiting position on the machine body side from the torque transmission allowing position via the clutch engagement regulating means. When placed, it restricts the second clutch means from moving to the torque transmission allowable position. As a typical example of "reaction torque exceeds a predetermined range", typically, tightening is completed in the screw tightening work, and further tightening torque is applied to the screw that cannot be tightened any more. Due to this, a state in which the reaction torque applied to the tool bit from the work material becomes excessive is equivalent to this. That is, when the tightening of the screw is substantially completed and the reaction torque from the workpiece to the tool bit exceeds a predetermined range, in other words, when the reaction torque to the tool bit becomes large, The second placed in the torque transmission prohibited position
A first clutch means on the screw side that prevents the clutch means from returning to the torque transmission allowable position and can no longer rotate;
The second clutch means on the motor side is prevented from being inadvertently engaged to generate noise or vibration. It is preferable that the switching of the second clutch means from the torque transmission allowance position to the torque transmission prohibition position is performed promptly according to the urging force of the clutch engagement restricting means. The first position restricting means and the second position restricting means can be installed completely separately or with the same or overlapping members.

As described above, according to the first aspect of the invention, typically, the screw tightening work is substantially completed, and the reaction torque received by the tool bit from the side of the workpiece including the screw becomes large. In this case, the second clutch means, which is disengaged from the first clutch means and placed in the torque transmission prohibited position, is restricted from moving to the torque transmission allowable position. As a result, in an electric screwdriver that performs work while managing the screw tightening torque, the clutch engagement is quickly and reliably released, and the released clutch is inadvertently engaged to cause vibration or noise. An electric screwdriver capable of reliably suppressing the occurrence of the above is provided.

(Invention of Claim 2) In the above invention, it is preferable that the first clutch means and the second clutch means have clutch teeth which mesh with each other at opposite positions. With this configuration, it is possible to reliably transmit the torque through the meshing engagement of the clutch teeth.

(Invention of Claim 3) Further, the second position regulating means in the above electric screwdriver has the second clutch means through the clutch engagement regulating means when the reaction torque exceeds a predetermined range. It is preferable to have a stopper means for locking the second clutch means at the torque transmission prohibiting position in conjunction with the movement of the second clutch means to the torque transmission prohibiting position. With this configuration, the second clutch means placed at the torque transmission prohibiting position when the screw tightening work is substantially completed is reliably locked by the stopper means and is not moved to the torque transmission allowing position. It becomes possible to

(Invention of Claim 4) The first position restricting means in the invention of claim 3 is configured so as to have a spring for urging the second clutch means toward the first clutch means. preferable. The stopper means interlocks with the movement of the second clutch means to the torque transmission prohibiting position via the clutch engagement restricting means when the reaction torque from the work material side exceeds a predetermined range. It is preferable that the second clutch means is configured to project from the peripheral surface of the second spindle so that the second clutch means can be locked in the torque transmission prohibited position. By thus forming the stopper means so as to be retractable from the peripheral surface of the second spindle, the stopper means for locking the second clutch means can be compactly arranged.

(Invention of Claim 5) According to the invention of Claim 5, there is provided a technique for using an electric screwdriver which has substantially the same operation as the electric screwdriver having the above-mentioned structure. It will be.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an electric screwdriver according to an embodiment of the present invention and a method of using the same will be described in detail with reference to the drawings. The main part of the electric screwdriver 100 according to the present embodiment is shown in FIG. It should be noted that FIG. 1 shows only a cross section of a main part of the motor housing 110 and the handgrip forming the main body of the electric screwdriver 100, mainly the former.

The electric screwdriver 100 is generally viewed as a motor housing 110 and a first spindle 12.
0, the second spindle 130, the first clutch cam 140,
The second clutch cam 150, the clutch engagement restricting spring 160, and the second clutch cam position restricting means 170 are main components.

Of these, the motor housing 110 is an element constituting the "machine" in the present invention. Further, the first clutch cam 140 corresponds to the "first clutch means" in the present invention, the second clutch cam 150 corresponds to the "second clutch means" in the present invention, and the clutch engagement regulating spring 160 is the "clutch" in the present invention. The second clutch cam position restricting means 170 corresponds to the "engagement restricting means", and corresponds to the "position restricting means of the second clutch means" in the present invention.

A motor 113 is housed in the motor housing 110 of the electric screwdriver 100. As the motor 113, a DC motor having a brush or a DC brushless motor is used in this embodiment. The output shaft 113a of the motor 113 is connected to the reduction mechanism 1
It is connected to the second spindle 130 via 15. Since the deceleration mechanism 115 is a well-known mechanism mainly composed of a deceleration gear, its detailed description is omitted for convenience.

On the other hand, the first spindle 120 is coaxial with the second spindle 130 and the motor housing 110.
Is rotatably provided on the front end side (the left end side in FIG. 1). The first spindle 120 has a motor housing 110.
While being supported by the tip sleeve 110a of the first spindle 120, it is configured to be relatively movable in the longitudinal direction of the first spindle 120 in relation to the second spindle 130. A chuck 121 for mounting a tool bit is provided on the tip side of the first spindle 120.
Is provided, and the first clutch cam 140 is provided on the other end side (the right end side in FIG. 1).

The first clutch cam 140 is disposed at the end of the first spindle 120 facing the second spindle 130 with the first steel ball 143 interposed. The first clutch balls 140 are allowed to move relative to the first spindle 120 in the axial direction of the first spindle 120 by the first steel balls 143, and also rotate integrally with the first spindle 120. Is configured. Clutch teeth 141 are provided on the end of the first clutch cam 140 facing the second spindle 130 (on the right end side in FIG. 1).

The first steel ball 143 has an end on the side toward the second spindle 130 in the lead groove 120a formed on the first spindle 120, and a second end.
It is configured to be movable between the ends on the side away from the spindle 130. The first clutch ball 1 is moved by the first steel ball 143 which is movable between the both ends.
40 is allowed to move relative to the first spindle 120 in the axial direction of the first spindle 120.

The first clutch cam 140, together with the first spindle 120, allows the operator to apply a pushing load to the electric screwdriver 100 equipped with a tool bit (not shown) at the time of screw tightening work. The reaction force from the screw and the work material side with respect to the pushing load moves in the direction of the second spindle 130 (rightward in the drawing). Details of these operations will be described later.

The second clutch cam 150 is arranged at the end of the second spindle 130 facing the first spindle 120 (the left end in FIG. 1) with a second steel ball 153 interposed. The second clutch cam 150 causes the second steel ball 153 to cause the second spindle 130 to move.
On the other hand, relative movement in the axial direction of the second spindle 130 is permitted, and the second spindle 130 is configured to rotate integrally with the second spindle 130.

The second steel ball 153 has, in the cam groove 130a provided on the second spindle 130, an end directed toward the first spindle 120 and an end directed away from the first spindle 120. By moving between the two, the second clutch cam 150 also serves as a position defining member. The second clutch cam 1
Clutch teeth 151 are provided at an end of the side of 50 facing the first spindle 120. It is to be noted that, although a structure that allows the second steel ball 153 to move in the axial direction between the both ends is not necessarily functionally required, from the viewpoint of ensuring a smooth sliding operation of the second clutch cam 153 with respect to the second spindle 130. In the present embodiment, the two end portions are configured to be movable as described above.

A clutch engagement regulating spring 16 is provided between the first clutch cam 140 and the second clutch cam 150.
0 is placed. Clutch engagement regulation spring 160
Is the first clutch cam 140 and the second clutch cam 150.
An urging force is generated in a direction in which and are separated from each other. In other words, the clutch engagement restriction spring 160 applies a biasing force so that the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side are disengaged.

Next, the second clutch cam position regulating means 170.
The detailed structure of will be described. The second clutch cam position restricting means 170 mainly includes a biasing spring 171, a stopper 181, a stopper operating pin 183, a stopper engaging groove 185, a ring spring 187, and a stopper operating spring 189.

Of these, the bias spring 171 includes the second clutch cam 150 and the bias spring support washer 179.
The second clutch cam 150 is attached between the first clutch cam 140 and the second clutch cam 150 and applies a biasing force to the second clutch cam 150 toward the first clutch cam 140. The biasing spring 171 is a feature that corresponds to the "first position restricting means" according to this invention.

The stopper 181 is made of a steel ball. The stopper operating pin 183 is provided on the first spindle 120 via a ring spring 187, and the stopper operating spring 189 is also provided.
Is urged in the direction toward the second spindle 130. A stopper engaging groove 185 is formed on the way of the stopper operating pin 183, and the stopper engaging groove 185 is formed.
A stopper 181 is fitted and arranged on the.

Stopper 18 of stopper engaging groove 185
The contact surface to 1 is a taper surface, and the stopper 181 can be retracted from the peripheral surface of the second spindle 130 by the stopper activating pin 183 moving axially by the urging force of the stopper activating spring 189. It is configured to be able to project to.

However, in the state shown in FIG. 1, the leg portion of the second clutch cam 150 is located above the stopper 181 and the stopper 181 is the second clutch cam 15
The second spindle 1
The protrusion from the peripheral surface of 30 is restricted. The stopper 181, the stopper actuating pin 183, the stopper engaging groove 185, the ring spring 187, and the stopper actuating spring 189 form elements corresponding to the "second position restricting means" in the present invention.

The urging force of the urging spring 171 against the second clutch cam 150 is the set torque adjusting ring 17
3, setting torque adjusting pin 175, setting torque adjusting sleeve 177, and bias spring support washer 179
By cooperating with the above, it is possible to appropriately change and adjust in accordance with the screw tightening torque described later. Specifically, by rotating the set torque adjusting ring 173 around the major axis of the motor housing 110, the set torque adjusting ring 17 is rotated.
3, the motor housing 110 is relatively moved in the long axis direction (left and right direction in FIG. 1) by a minute distance. The set torque adjusting ring 173 is connected to the sleeve 177 via a set torque adjusting pin 175, and
7 and the set torque adjusting ring 173 relatively move in the long axis direction of the motor housing 110.

An urging spring support washer 179 is attached to the end of the sleeve 177, and as a result, the arranging position of the urging spring support washer 179 on the second spindle 130 is in the longitudinal direction of the second spindle 130. Changes to. As a result, the length of the biasing spring 171 between the biasing spring support washer 179 and the second clutch cam 150 is appropriately changed, the biasing force of the biasing spring 171 is changed, and the set torque is adjusted.

Next, the operation and use of the electric screwdriver 100 according to this embodiment will be described. Of the electric screwdriver 100, the first spindle 120, the second spindle 130, the first clutch cam 140, the second clutch cam 150, the clutch engagement regulating spring 160, the second clutch cam position regulating means 170.
2 to FIG. 10 show the configuration of the main part mainly composed of.
Of these, FIG. 2 shows an initial state in which the screw tightening work has not yet started in the electric screwdriver 100 according to the present embodiment. 2 to 10 show only the main part of the electric screwdriver 100,
Regarding the positional relationship of the sleeve 177 7 etc. for adjusting the set torque in each drawing, the state in which it is placed in the initial position is shown for convenience.

In the state shown in FIG. 2, the second spindle 13
0 idles without transmitting the rotational torque of the motor 113 (see FIG. 1) to the first spindle 120 and the first clutch cam 140. In addition, the second clutch cam 150 also idles as the second spindle 130 idles. The second
The spindle 130 rotates clockwise when viewed from the motor 113 side in the first spindle 120 direction. Figure 2
In the state shown in (1), the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side are generated by the urging force of the clutch engagement restriction spring 160.
And are kept apart from each other.

In the state shown in FIG. 2, the second clutch cam 150 is moved to the first position by the urging force of the urging spring 171.
While being urged toward the clutch cam 140, the worker has not yet applied a pushing load for screw tightening to the electric screwdriver 100, so the first spindle 120
And the first clutch cam 140 is the second clutch cam 15
The clutch teeth 141 and 151 do not move in the 0 direction, and the clutch teeth 141 and 151 are separated from each other, that is, the clutch disengaged state is maintained.

Further, in the state shown in FIG. 2, the stopper 1
Since the leg portion of the second clutch cam 150 is located above 81, the stopper 181 is provided on the second clutch cam 150.
It is restrained from protruding outward from the peripheral surface of the second spindle 130 by being restrained by the leg portions of the.

In the state shown in FIG. 2, the second steel ball 153 is located at the groove end on the side facing the first spindle 120 (or the first clutch cam 140) in the cam groove 130a, and the second clutch cam 150 is provided. Defines the relative position of the second clutch cam 150 on the second spindle 130 so as to face the first clutch cam 140 side.

When starting the screw tightening work from the initial state shown in FIG. 2, the worker pushes the electric screwdriver 100 in the direction of the work material (left direction in the drawing) in order to cause the screw to enter the work material. Go. It should be noted that the screw and the workpiece are not shown for convenience. By pushing a load on the electric screwdriver 100 by an operator,
First spindle 120 and first clutch cam 140
Is moved in the direction of the second spindle 130 by the reaction force against the pushing load from the tool bit or the work piece side. This state is shown in FIG.

In FIG. 3, the first force is generated by the reaction force of the pushing load.
The spindle 120 and the first clutch cam 140 move to the right in the drawing, and the clutch teeth 141 provided at the end of the first clutch cam 140 resist the urging force of the clutch engagement restricting spring 160 and the second clutch. The clutch teeth 151 on the cam 150 side are approached. At this time, the urging force of the urging spring 171 is applied to the second clutch cam 150, and the second steel ball 153 of the second clutch cam 150 has the first spindle 12 of the cam groove 130a.
The first clutch cam 140 is located at the end on the side toward 0.
It is located close to. Thus, by moving the first clutch cam 140 to the right in the figure, the relative distance between the first clutch cam 140 and the second clutch cam 150 is shortened.

In the state shown in FIG. 3, the stopper 18
1 is restricted from projecting outward by the leg portion of the second clutch cam 150. Therefore, when the first spindle 120 moves to the right in the figure, the stopper operating pin 18
The stopper engaging groove 185 formed in
81, and restricts the movement of the stopper operating pin 183 toward the second spindle 130 (to the right in the drawing).
Therefore, the stopper operating spring 189 interposed between the first spindle 120 moving in the right direction in the figure by the reaction force of the pushing load and the stopper operating pin 183 whose movement is restricted is compressed. I will go.

Now, from the state shown in FIG. 3, the first spindle 120 and the first clutch cam 140 are further moved in the direction of the second clutch cam 150 (to the right in the figure), so that the first clutch cam 140 side is moved. The clutch teeth 141 and the clutch teeth 151 on the side of the second clutch cam 150 mesh with each other. This state is shown in FIG.

The first steel ball 143 is movable in the lead groove 120a between the end on the side toward the second spindle 130 and the end on the side away from the second spindle 130. However, as can be understood from the comparison between FIG. 3 and FIG. 4, when the clutch teeth 141 and 151 are engaged with each other, the end on the side away from the second spindle 130 and the end on the side toward the second spindle 130. By moving the clutch teeth 141 and 151, the mesh engagement of the clutch teeth 141 and 151 is permitted.

FIG. 4 shows a state where the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side have started to mesh with each other, and in FIG. 5, the clutch teeth 141 on the first clutch cam 140 side are shown. The state where the clutch teeth 141 and the clutch teeth 151 on the second clutch cam 150 side are completely meshed with each other is shown. 4 and 5
The position of the second clutch cam 150 in the state shown in is defined as the "torque transmission allowable position".

In this embodiment, both clutch teeth 141,
The rotational torque of the motor 113 is reliably transmitted by the meshing engagement of the 151. Specifically, the rotational torque of the motor 113 (see FIG. 1) is increased by the meshing engagement of both the clutch teeth 141 and 151, so that the second spindle 130, the second steel ball 153, the second clutch cam 150, and the second clutch cam. Clutch teeth 15 on the 150 side
1, clutch teeth 141 on the first clutch cam 140 side, first clutch cam 140, first steel ball 143, first spindle 120, tool bit mounting chuck 121
Will be transmitted to the tool bit via the tool (the tool bit itself is not shown for convenience).

In the state shown in FIG. 5, the first spindle 120 which is about to move to the right in the figure, and the stopper operating pin 183 whose movement is restricted by the stopper engaging groove 185 being held by the stopper 181. The stopper actuating spring 189 interposed between the two is made more compressed than the state shown in FIG.

The screw tightening work proceeds in the state shown in FIG.
Although not shown in the drawing, when the screw head is seated on the workpiece and the screw tightening work reaches the final stage, the screw tightening torque becomes excessive, while the first spindle 120 causes the reaction force against the pushing load of the worker. Thus, the state of being pushed in the second spindle direction is maintained. As a result, the clutch teeth 151 on the second clutch cam 150 side, which try to further transmit the rotation torque, are changed to the clutch teeth 14 on the first clutch cam 140 side.
It will be in the state of riding on 1. As a result, as shown in FIG. 6, the second clutch cam 150 moves from the torque transmission allowable position to the first clutch cam 150 while resisting the urging force of the urging spring 171.
It starts moving in a direction away from the clutch cam 140 (rightward in the figure).

In the state shown in FIG. 6, the second steel ball 153 moves away from the end on the side toward the first spindle 120 (the first clutch cam 140) in the cam groove 130a, so that the second steel ball 153 moves into the second groove. Clutch cam 15
A move operation of 0 will be allowed.

When the second clutch cam 150 starts to move to the right in the drawing from the torque transmission allowable position, the stopper 18
The leg portion of the second clutch cam 150 located above 1 is retracted to the right in the figure. On the other hand, the stopper operating pin 183 is in a state of being pressed rightward in the drawing by the urging force of the compressed stopper operating spring 189. Therefore, the stopper 181 is pushed outward into the stopper engagement groove having a tapered contact surface when the stopper operating pin 183 is trying to move to the right, and extends outward from the peripheral surface of the second spindle 130. It will stick out.

FIG. 7 shows a state at the moment when the meshing engagement between the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side is released. In FIG. 7, the reaction force of the pushing load by the operator is applied to the first spindle 120, and the first spindle 12
0 is in the state closest to the second spindle 130 side. In this state, the second clutch cam 150
Is the first clutch cam 140 and the second clutch cam 150.
Due to the urging force of the clutch engagement regulating spring 160 acting on the first clutch cam 140, the clutch teeth are instantaneously moved in the direction away from the first clutch cam 140, and the mesh engagement of the clutch teeth 141 and 151 is released. The clutch engagement restriction spring 160 is
The function as the clutch engagement releasing means in the silent clutch is achieved.

When the second clutch cam 150 moves to the right in the figure, as described above, the restraint of the leg of the second clutch cam 150 on the stopper 181 is lost, and the stopper 181 moves to the outside of the second spindle 130. . Therefore, the stopper operating pin 183 moves in the direction facing the first spindle (rightward in the drawing) by the urging force of the stopper operating spring 189, and the stopper 181 enters the inner concave portion of the second clutch cam 150. Becomes

In this state, the second clutch cam 150
Despite the biasing force of the biasing spring 171, the stopper 181 causes the first clutch cam 14 to move.
It is restricted to move in the 0 direction. In other words, the screw tightening torque becomes excessive and the clutch engagement regulating spring 1
When the clutch teeth 141 and 151 are disengaged by 60, the second clutch cam 150 is locked and maintained at the position separated from the first clutch cam 140, that is, the torque transmission prohibited position. Then, the first clutch cam 140 is changed to the second clutch cam 1 by the careless application of the pushing load.
Even if it approaches in the 50 direction, the second clutch cam 150
Is locked at the torque transmission prohibited position by the stopper 181 and the return to the torque transmission allowable position is restricted, so that careless engagement of the clutch teeth 141 and 151 with each other is avoided. The stopper 181
Is the first clutch cam 140 of the second clutch cam 150.
It is configured to allow movement in a direction away from (rightward in the figure).

When the tightening torque exceeds a predetermined range and becomes excessive due to the screw being tightened into the workpiece,
As shown in FIG. 7, the meshing of the clutch teeth 141 and 151 is released. When the engagement is released, the clutch engagement restriction spring 160 causes the first clutch cam 14 to move.
0 instantaneously moves to the left in the drawing, and the first clutch cam 14
Since the clutch teeth 141 on the 0 side and the clutch teeth 151 on the second clutch cam 150 side are separated from each other, both clutch teeth 1
The meshing engagement between 41 and 151 is surely released. At this point, the operator loosens the pushing load on the electric screwdriver 100 in the direction of the workpiece. This state is shown in FIG.

The first steel ball 143 is movable in the lead groove 120a on the first spindle 120 between the end on the side toward the second spindle 130 and the end on the separated side. However, as can be understood from the comparison with FIG. 7 and FIG. 8, the axial distance between both ends of the lead groove 120a is the axial direction of the first clutch cam 140 when the meshing of the clutch teeth 141 and 151 is released. In addition to defining the amount of movement, it also defines the amount of clearance between the first clutch cam 140 and the second clutch cam 150 at the time of disengagement. That is, in accordance with the moving distance of the first steel ball 143 in the lead groove 143, as shown in FIG.
The clearance C between the two clutch teeth 141 and 151 shown in FIG.

In the present embodiment, as a specific construction of "when the tightening torque exceeds a predetermined range and becomes excessively large", the tightening torque is set to a predetermined value by screwing the screw into the workpiece. When the set torque is reached, the meshing engagement between the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side is set to be immediately released.

Now, in FIG. 8, when the worker loosens the pushing load to the electric screwdriver 100, the first spindle 120 is moved to the first clutch cam 140.
At the same time, a state in which the second spindle 130 moves away from the second spindle 130 (leftward in the drawing), that is, a state in which the second spindle 130 returns to the initial state is shown. In the present embodiment, the pushing load is the clutch engagement regulating spring 160.
When the force is reduced below the urging force of No. 1, the return of the first spindle 120 is allowed. Then, the stopper operating pin 183 attached to the first spindle 120 via the ring spring 187 causes the stopper operating pin 183 to
At the same time, it moves to the left in the figure. Since the stopper operating pin 183 moves together with the first spindle 120, a compressive load does not act on the stopper operating spring 189 when the first spindle 120 returns.

In the state shown in FIG. 8, when the first spindle 120 further moves in the direction away from the second spindle 130, the stopper operating pin 183 also moves further, and the stopper engaging groove 185 is located below the stopper 181. Will be located in. This state is shown in FIG. Further, the stopper 181 has a biasing spring 17
The urging force of No. 1 acts on the leg portion of the second clutch cam 150, and as a result, the stopper 181 is pushed by the leg portion of the second clutch cam 150 while the second spindle 1
It is accommodated in the stopper engagement groove 185 from the peripheral surface of 30.

The stopper 181 is the second spindle 130.
When the second clutch cam 150 is accommodated in the stopper engagement groove 185 from the peripheral surface of the second clutch cam 150, as shown in FIG.
Are allowed to move on the peripheral surface of the second spindle 130 without obstruction. On the other hand, the urging force of the urging spring 171 is set to be larger than the urging force of the clutch engagement restriction spring 160, and the second clutch cam 150 moves in the direction of the first clutch cam 140 by the urging spring 171. I will go. At this time, the second steel ball 1
53 is the first spindle 1 in the cam groove 130a.
20 (first clutch cam 140) toward the end of the second clutch cam 150 by allowing the moving operation of the second clutch cam 150, and by contacting the end, the second spindle of the second clutch cam 150. The position on 130 is defined. Thus, the electric screwdriver 100
The first clutch cam 140 and the second clutch cam 150 return to the initial state (see FIG. 2) in which they are separated.

In the electric screwdriver 100 according to the present embodiment, when the screw is tightened to the work material and the tightening torque becomes excessive, and the reaction torque received by the tool bit from the work material side becomes large, the clutch Due to the urging force of the engagement restriction spring 160, the first clutch cam 140
The engagement between the side clutch teeth 141 and the clutch teeth 151 on the second clutch cam 150 side is released quickly and reliably. At this time, the second clutch cam 150 is locked and maintained in the torque transmission prohibited position by the stopper 181 and
It is prevented from moving to the torque transmission allowable position on the clutch cam 140 side.

Therefore, the electric screwdriver 100 according to the present embodiment engages the meshing engagement of the clutch teeth 141 and 151 in the torque management type screw tightening work in which the screw tightening torque is managed while the screw tightening torque is managed. The second clutch cam 150 can be released quickly and surely, and the second clutch cam 150 can be locked at the torque transmission prohibited position to reliably prevent the clutch from being inadvertently engaged to cause vibration or noise. .

The stopper engagement groove 185 in the present embodiment has various shapes such as a tapered surface and a curved surface within a range in which the stopper 181 can be projected and retracted from the peripheral surface of the second spindle 130. Can be adopted. Further, the clutch engagement restricting spring 160 is provided between the first clutch cam 140 and the second clutch cam 150, in addition to the clutch cams 140, 150.
Each may be set separately and the biasing force may be applied independently.

[0062]

According to the present invention, there is provided an electric screwdriver capable of reliably suppressing abnormal noise and vibration when the clutch is released according to the screw tightening torque.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of an electric screwdriver according to an embodiment of the present invention.

FIG. 2 shows an initial state of the electric screwdriver according to the present embodiment in which screw tightening work has not yet started.

FIG. 3 shows a state in which the first spindle has started to move in the direction of the second spindle when the worker applies a pushing load for tightening the screw.

FIG. 4 shows a state in which the first spindle further moves and the clutch teeth on the first clutch cam side and the clutch teeth on the second clutch cam side start to engage with each other.

FIG. 5 shows a state in which both clutch teeth are engaged with each other and the torque of the motor is transmitted to the tool bit side to perform a screw tightening operation.

FIG. 6 shows a state in which the second clutch cam has started to move rearward due to the screw tightening work reaching the final stage and the tightening torque becoming excessive.

FIG. 7 is a diagram illustrating a clutch engagement restriction spring that moves a second clutch cam in a direction away from a first clutch cam;
The state where the stopper is projected is shown.

FIG. 8 shows a state in which the worker has stopped pushing the load and the first spindle has started to return to the initial state.

FIG. 9 shows a state in which the stopper has started to return into the second spindle along with the return of the first spindle.

FIG. 10 shows the state of the electric screwdriver when the screw tightening work is completed and the initial state is restored.

[Explanation of symbols]

100 Electric Screwdriver 110 Motor Housing (Machine) 113 Motor 115 Speed Reduction Mechanism 120 First Spindle 121 Tool Bit Mounting Chuck 130 Second Spindle 140 First Clutch Cam (Clutch Means) 141 Clutch Teeth 143 First Steel Ball 120a Lead Groove 150 Second clutch cam 151 Clutch teeth 153 Second steel ball 130a Cam groove 160 Clutch engagement regulation spring (clutch engagement regulation means) 170 Second clutch cam position regulation means 171 Energizing spring 173 Set torque adjustment ring 175 For set torque adjustment Pin 177 Setting torque adjusting sleeve 179 Energizing spring support washer 181 Stopper 183 Stopper operating pin 185 Stopper engaging groove 187 Ring spring 189 Stop Over the actuating spring

[Procedure amendment]

[Submission date] April 10, 2002 (2002.4.1)
0)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Title : Electric screwdriver and electric screw
How to use the clew driver

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric screwdriver provided with a silent clutch, and more particularly, to an electric screwdriver provided with a silent clutch that is preferably used for screw tightening work while controlling tightening torque. Regarding

[0002]

2. Description of the Related Art As disclosed in, for example, Japanese Patent Application Laid-Open No. 61-219581, as a conventional electric screwdriver, a tool bit and a motor for applying a rotational driving torque to the tool bit are connected by a silent clutch. Therefore, a technique for reducing noise and vibration during screw tightening work is known. According to this silent clutch,
When the screw to be tightened reaches a certain amount of tightening depth with respect to the work material, the rotational torque transmission by the clutch is quickly released based on the tightening depth to rotate the clutch teeth. By avoiding contact, noise is suppressed.

By the way, as one of the forms of the screw to be tightened, there is a screw fixed to a metal material such as an iron plate to fix the material. When performing such screw tightening work, the tightening work is completed according to the screw tightening torque amount, not according to the screw tightening depth. There is a need to do. If the clutch is not quickly and reliably released with the screw tightened on the metal material and the tightening torque is excessive, the tool bit side clutch member that can no longer rotate and the rotating motor side clutch member This is because they come into contact with each other, resulting in abnormal noise and vibration.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above point, and it is possible to reliably suppress abnormal noise and vibration when the clutch is released according to the screw tightening torque. The purpose of the present invention is to provide a simple electric screwdriver.

[0005]

In order to achieve the above object, the invention described in each claim is constituted. According to the first aspect of the present invention, there are provided a machine housing the motor, a first spindle, a second spindle, a first clutch means, a second clutch means, a clutch engagement restricting means, and a position restricting means for the second clutch means. An electric clew driver having is configured.

The first spindle is movable relative to the machine body, the first clutch means is arranged on the end side facing the machine body, and the tool bit for screw tightening is connected to the other end side. . The airframe typically corresponds to a motor housing containing a motor. The second spindle is connected to a motor and rotates. Typically, a configuration in which a motor is connected through a speed reduction mechanism using a planetary gear and rotates is preferable.

The first clutch means rotates together with the first spindle while being relatively movable in the axial direction of the first spindle. The second clutch means rotates relative to the second spindle while being relatively movable in the axial direction of the second spindle, and engages with the first clutch means when the first spindle relatively moves toward the machine body. The drive torque of the motor is transmitted to the tool bit. The first spindle typically moves relative to the machine body due to a reaction force of a pushing load generated by an operator pressing the machine body together with the tool bit toward the workpiece during screw tightening work. Note that various motors such as an AC motor and a DC brushless motor can be adopted as the motor that applies the rotation torque to the tool bit.

The clutch engagement restricting means applies an urging force in a direction in which the first clutch means and the second clutch means separate from each other. The function as the silent clutch of the present invention is ensured by the biasing force that separates the first clutch means and the second clutch means. A typical example of applying the urging force corresponds to an urging spring interposed between the first clutch means and the second clutch means. To ensure the function as a silent clutch,
It is preferable that the urging force by the clutch engagement restricting means is appropriately set so that the engagement between the first clutch means and the second clutch means is released instantaneously and reliably when the screw tightening work is completed.

The position restricting means of the second clutch means is the first
And a second position regulating means. The first position restricting means sets the second clutch means to the first clutch means side when the reaction torque applied to the tool bit from the work piece side when transmitting the driving torque of the motor to the tool bit is within a predetermined range. The rotation torque of the motor is transmitted to the tool bit by restricting it to be placed in the adjacent torque transmission allowable position.
As a typical example of "the reaction torque is within a predetermined range",
In the screw tightening work, the tightening work has not been completed yet,
This corresponds to a state in which the reaction torque applied from the work material to the tool bit is not excessive.

On the other hand, when the reaction torque exceeds the predetermined range, the second position regulating means causes the second clutch means to move to the torque transmission inhibiting position on the machine body side from the torque transmission allowing position via the clutch engagement regulating means. When placed, it restricts the second clutch means from moving to the torque transmission allowable position. As a typical example of "reaction torque exceeds a predetermined range", typically, tightening is completed in the screw tightening work, and further tightening torque is applied to the screw that cannot be tightened any more. Due to this, a state in which the reaction torque applied to the tool bit from the work material becomes excessive is equivalent to this. That is, when the tightening of the screw is substantially completed and the reaction torque from the workpiece to the tool bit exceeds a predetermined range, in other words, when the reaction torque to the tool bit becomes large, The second placed in the torque transmission prohibited position
A first clutch means on the screw side that prevents the clutch means from returning to the torque transmission allowable position and can no longer rotate;
The second clutch means on the motor side is prevented from being inadvertently engaged to generate noise or vibration. It is preferable that the switching of the second clutch means from the torque transmission allowance position to the torque transmission prohibition position is performed promptly according to the urging force of the clutch engagement restricting means. The first position restricting means and the second position restricting means can be installed completely separately or with the same or overlapping members.

As described above, according to the first aspect of the invention, typically, the screw tightening work is substantially completed, and the reaction torque received by the tool bit from the side of the workpiece including the screw becomes large. In this case, the second clutch means, which is disengaged from the first clutch means and placed in the torque transmission prohibited position, is restricted from moving to the torque transmission allowable position. As a result, in an electric screwdriver that performs work while managing the screw tightening torque, the clutch engagement is quickly and reliably released, and the released clutch is inadvertently engaged to cause vibration or noise. An electric screwdriver capable of reliably suppressing the occurrence of the above is provided.

(Invention of Claim 2) In the above invention, it is preferable that the first clutch means and the second clutch means have clutch teeth which mesh with each other at opposite positions. With this configuration, it is possible to reliably transmit the torque through the meshing engagement of the clutch teeth.

(Invention of Claim 3) Further, the second position regulating means in the above electric screwdriver has the second clutch means through the clutch engagement regulating means when the reaction torque exceeds a predetermined range. It is preferable to have a stopper means for locking the second clutch means at the torque transmission prohibiting position in conjunction with the movement of the second clutch means to the torque transmission prohibiting position. With this configuration, the second clutch means placed at the torque transmission prohibiting position when the screw tightening work is substantially completed is reliably locked by the stopper means and is not moved to the torque transmission allowing position. It becomes possible to

(Invention of Claim 4) The first position restricting means in the invention of claim 3 is configured so as to have a spring for urging the second clutch means toward the first clutch means. preferable. The stopper means interlocks with the movement of the second clutch means to the torque transmission prohibiting position via the clutch engagement restricting means when the reaction torque from the work material side exceeds a predetermined range. It is preferable that the second clutch means is configured to project from the peripheral surface of the second spindle so that the second clutch means can be locked in the torque transmission prohibited position. By thus forming the stopper means so as to be retractable from the peripheral surface of the second spindle, the stopper means for locking the second clutch means can be compactly arranged.

(Invention of Claim 5) According to the invention of Claim 5, there is provided a technique for using an electric screwdriver which has substantially the same operation as the electric screwdriver having the above-mentioned structure. It will be.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an electric screwdriver according to an embodiment of the present invention and a method of using the same will be described in detail with reference to the drawings. The main part of the electric screwdriver 100 according to the present embodiment is shown in FIG. It should be noted that FIG. 1 shows only a cross section of a main part of the motor housing 110 and the handgrip forming the main body of the electric screwdriver 100, mainly the former.

The electric screwdriver 100 is generally viewed as a motor housing 110 and a first spindle 12.
0, the second spindle 130, the first clutch cam 140,
The second clutch cam 150, the clutch engagement restricting spring 160, and the second clutch cam position restricting means 170 are main components.

Of these, the motor housing 110 is an element constituting the "machine" in the present invention. Further, the first clutch cam 140 corresponds to the "first clutch means" in the present invention, the second clutch cam 150 corresponds to the "second clutch means" in the present invention, and the clutch engagement regulating spring 160 is the "clutch" in the present invention. The second clutch cam position restricting means 170 corresponds to the "engagement restricting means", and corresponds to the "position restricting means of the second clutch means" in the present invention.

A motor 113 is housed in the motor housing 110 of the electric screwdriver 100. As the motor 113, a DC motor having a brush or a DC brushless motor is used in this embodiment. The output shaft 113a of the motor 113 is connected to the reduction mechanism 1
It is connected to the second spindle 130 via 15. Since the deceleration mechanism 115 is a well-known mechanism mainly composed of a deceleration gear, its detailed description is omitted for convenience.

On the other hand, the first spindle 120 is coaxial with the second spindle 130 and the motor housing 110.
Is rotatably provided on the front end side (the left end side in FIG. 1). The first spindle 120 has a motor housing 110.
While being supported by the tip sleeve 110a of the first spindle 120, it is configured to be relatively movable in the longitudinal direction of the first spindle 120 in relation to the second spindle 130. A chuck 121 for mounting a tool bit is provided on the tip side of the first spindle 120.
Is provided, and the first clutch cam 140 is provided on the other end side (the right end side in FIG. 1).

The first clutch cam 140 is disposed at the end of the first spindle 120 facing the second spindle 130 with the first steel ball 143 interposed. The first clutch balls 140 are allowed to move relative to the first spindle 120 in the axial direction of the first spindle 120 by the first steel balls 143, and also rotate integrally with the first spindle 120. Is configured. Clutch teeth 141 are provided on the end of the first clutch cam 140 facing the second spindle 130 (on the right end side in FIG. 1).

The first steel ball 143 has an end on the side toward the second spindle 130 in the lead groove 120a formed on the first spindle 120, and a second end.
It is configured to be movable between the ends on the side away from the spindle 130. The first clutch ball 1 is moved by the first steel ball 143 which is movable between the both ends.
40 is allowed to move relative to the first spindle 120 in the axial direction of the first spindle 120.

The first clutch cam 140, together with the first spindle 120, allows the operator to apply a pushing load to the electric screwdriver 100 equipped with a tool bit (not shown) at the time of screw tightening work. The reaction force from the screw and the work material side with respect to the pushing load moves in the direction of the second spindle 130 (rightward in the drawing). Details of these operations will be described later.

The second clutch cam 150 is arranged at the end of the second spindle 130 facing the first spindle 120 (the left end in FIG. 1) with a second steel ball 153 interposed. The second clutch cam 150 causes the second steel ball 153 to cause the second spindle 130 to move.
On the other hand, relative movement in the axial direction of the second spindle 130 is permitted, and the second spindle 130 is configured to rotate integrally with the second spindle 130.

The second steel ball 153 has, in the cam groove 130a provided on the second spindle 130, an end directed toward the first spindle 120 and an end directed away from the first spindle 120. By moving between the two, the second clutch cam 150 also serves as a position defining member. The second clutch cam 1
Clutch teeth 151 are provided at an end of the side of 50 facing the first spindle 120. It is to be noted that, although a structure that allows the second steel ball 153 to move in the axial direction between the both ends is not necessarily functionally required, from the viewpoint of ensuring a smooth sliding operation of the second clutch cam 153 with respect to the second spindle 130. In the present embodiment, the two end portions are configured to be movable as described above.

A clutch engagement regulating spring 16 is provided between the first clutch cam 140 and the second clutch cam 150.
0 is placed. Clutch engagement regulation spring 160
Is the first clutch cam 140 and the second clutch cam 150.
An urging force is generated in a direction in which and are separated from each other. In other words, the clutch engagement restriction spring 160 applies a biasing force so that the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side are disengaged.

Next, the second clutch cam position regulating means 170.
The detailed structure of will be described. The second clutch cam position restricting means 170 mainly includes a biasing spring 171, a stopper 181, a stopper operating pin 183, a stopper engaging groove 185, a ring spring 187, and a stopper operating spring 189.

Of these, the bias spring 171 includes the second clutch cam 150 and the bias spring support washer 179.
The second clutch cam 150 is attached between the first clutch cam 140 and the second clutch cam 150 and applies a biasing force to the second clutch cam 150 toward the first clutch cam 140. The biasing spring 171 is a feature that corresponds to the "first position restricting means" according to this invention.

The stopper 181 is made of a steel ball. The stopper operating pin 183 is provided on the first spindle 120 via a ring spring 187, and the stopper operating spring 189 is also provided.
Is urged in the direction toward the second spindle 130. A stopper engaging groove 185 is formed on the way of the stopper operating pin 183, and the stopper engaging groove 185 is formed.
A stopper 181 is fitted and arranged on the.

Stopper 18 of stopper engaging groove 185
The contact surface with respect to 1 is a tapered surface, and the stopper operating spring 189 biases the stopper operating pin 183 in the axial direction, so that the stopper 181 can be retracted from the peripheral surface of the second spindle 130. It is configured to be able to project to.

However, in the state shown in FIG. 1, the leg portion of the second clutch cam 150 is located above the stopper 181 and the stopper 181 is the second clutch cam 15
The second spindle 1
The protrusion from the peripheral surface of 30 is restricted. The stopper 181, the stopper actuating pin 183, the stopper engaging groove 185, the ring spring 187, and the stopper actuating spring 189 form elements corresponding to the "second position restricting means" in the present invention.

The urging force of the urging spring 171 against the second clutch cam 150 is the set torque adjusting ring 17
3, setting torque adjusting pin 175, setting torque adjusting sleeve 177, and bias spring support washer 179
By cooperating with the above, it is possible to appropriately change and adjust in accordance with the screw tightening torque described later. Specifically, by rotating the set torque adjusting ring 173 around the major axis of the motor housing 110, the set torque adjusting ring 17 is rotated.
3, the motor housing 110 is relatively moved in the long axis direction (left and right direction in FIG. 1) by a minute distance. The set torque adjusting ring 173 is connected to the sleeve 177 via a set torque adjusting pin 175, and
7 and the set torque adjusting ring 173 relatively move in the long axis direction of the motor housing 110.

An urging spring support washer 179 is attached to the end of the sleeve 177, and as a result, the arranging position of the urging spring support washer 179 on the second spindle 130 is in the longitudinal direction of the second spindle 130. Changes to. As a result, the length of the biasing spring 171 between the biasing spring support washer 179 and the second clutch cam 150 is appropriately changed, the biasing force of the biasing spring 171 is changed, and the set torque is adjusted.

Next, the operation and use of the electric screwdriver 100 according to this embodiment will be described. Of the electric screwdriver 100, the first spindle 120, the second spindle 130, the first clutch cam 140, the second clutch cam 150, the clutch engagement regulating spring 160, the second clutch cam position regulating means 170.
2 to FIG. 10 show the configuration of the main part mainly composed of.
Of these, FIG. 2 shows an initial state in which the screw tightening work has not yet started in the electric screwdriver 100 according to the present embodiment. 2 to 10 show only the main part of the electric screwdriver 100,
Regarding the positional relationship of the sleeve 177 7 etc. for adjusting the set torque in each drawing, the state in which it is placed in the initial position is shown for convenience.

In the state shown in FIG. 2, the second spindle 13
0 idles without transmitting the rotational torque of the motor 113 (see FIG. 1) to the first spindle 120 and the first clutch cam 140. In addition, the second clutch cam 150 also idles as the second spindle 130 idles. The second
The spindle 130 rotates clockwise when viewed from the motor 113 side in the first spindle 120 direction. Figure 2
In the state shown in (1), the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side are generated by the urging force of the clutch engagement restriction spring 160.
And are kept apart from each other.

In the state shown in FIG. 2, the second clutch cam 150 is moved to the first position by the urging force of the urging spring 171.
While being urged toward the clutch cam 140, the worker has not yet applied a pushing load for screw tightening to the electric screwdriver 100, so the first spindle 120
And the first clutch cam 140 is the second clutch cam 15
The clutch teeth 141 and 151 do not move in the 0 direction, and the clutch teeth 141 and 151 are separated from each other, that is, the clutch disengaged state is maintained.

Further, in the state shown in FIG. 2, the stopper 1
Since the leg portion of the second clutch cam 150 is located above 81, the stopper 181 is provided on the second clutch cam 150.
It is restrained from protruding outward from the peripheral surface of the second spindle 130 by being restrained by the leg portions of the.

In the state shown in FIG. 2, the second steel ball 153 is located at the groove end on the side facing the first spindle 120 (or the first clutch cam 140) in the cam groove 130a, and the second clutch cam 150 is provided. Defines the relative position of the second clutch cam 150 on the second spindle 130 so as to face the first clutch cam 140 side.

When the screw tightening work is started from the initial state shown in FIG. 2, the worker pushes the electric screwdriver 100 in the direction of the work material (the left direction in the drawing) in order to cause the screw to enter the work material. Go. It should be noted that the screw and the workpiece are not shown for convenience. By pushing a load on the electric screwdriver 100 by an operator,
First spindle 120 and first clutch cam 140
Is moved in the direction of the second spindle 130 by the reaction force against the pushing load from the tool bit or the work piece side. This state is shown in FIG.

In FIG. 3, the first force is generated by the reaction force of the pushing load.
The spindle 120 and the first clutch cam 140 move to the right in the drawing, and the clutch teeth 141 provided at the end of the first clutch cam 140 resist the urging force of the clutch engagement restricting spring 160 and the second clutch. The clutch teeth 151 on the cam 150 side are approached. At this time, the urging force of the urging spring 171 is applied to the second clutch cam 150, and the second steel ball 153 of the second clutch cam 150 has the first spindle 12 of the cam groove 130a.
The first clutch cam 140 is located at the end on the side toward 0.
It is located close to. Thus, by moving the first clutch cam 140 to the right in the figure, the relative distance between the first clutch cam 140 and the second clutch cam 150 is shortened.

In the state shown in FIG. 3, the stopper 18
1 is restricted from projecting outward by the leg portion of the second clutch cam 150. Therefore, when the first spindle 120 moves to the right in the figure, the stopper operating pin 18
The stopper engaging groove 185 formed in
81, and restricts the movement of the stopper operating pin 183 toward the second spindle 130 (to the right in the drawing).
Therefore, the stopper operating spring 189 interposed between the first spindle 120 moving in the right direction in the figure by the reaction force of the pushing load and the stopper operating pin 183 whose movement is restricted is compressed. I will go.

Now, from the state shown in FIG. 3, the first spindle 120 and the first clutch cam 140 are further moved in the direction of the second clutch cam 150 (to the right in the figure), so that the first clutch cam 140 side is moved. The clutch teeth 141 and the clutch teeth 151 on the side of the second clutch cam 150 mesh with each other. This state is shown in FIG.

The first steel ball 143 is movable in the lead groove 120a between the end on the side toward the second spindle 130 and the end on the side away from the second spindle 130. However, as can be understood from the comparison between FIG. 3 and FIG. 4, when the clutch teeth 141 and 151 are engaged with each other, the end on the side away from the second spindle 130 and the end on the side toward the second spindle 130. By moving the clutch teeth 141 and 151, the mesh engagement of the clutch teeth 141 and 151 is permitted.

FIG. 4 shows a state where the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side have started to mesh with each other, and in FIG. 5, the clutch teeth 141 on the first clutch cam 140 side are shown. The state where the clutch teeth 141 and the clutch teeth 151 on the second clutch cam 150 side are completely meshed with each other is shown. 4 and 5
The position of the second clutch cam 150 in the state shown in is defined as the "torque transmission allowable position".

In this embodiment, both clutch teeth 141,
The rotational torque of the motor 113 is reliably transmitted by the meshing engagement of the 151. Specifically, the rotational torque of the motor 113 (see FIG. 1) is increased by the meshing engagement of both the clutch teeth 141 and 151, so that the second spindle 130, the second steel ball 153, the second clutch cam 150, and the second clutch cam. Clutch teeth 15 on the 150 side
1, clutch teeth 141 on the first clutch cam 140 side, first clutch cam 140, first steel ball 143, first spindle 120, tool bit mounting chuck 121
Will be transmitted to the tool bit via the tool (the tool bit itself is not shown for convenience).

In the state shown in FIG. 5, the first spindle 120 which is about to move to the right in the figure, and the stopper operating pin 183 whose movement is restricted by the stopper engaging groove 185 being held by the stopper 181. The stopper actuating spring 189 interposed between the two is made more compressed than the state shown in FIG.

The screw tightening work proceeds in the state shown in FIG.
Although not shown in the drawing, when the screw head is seated on the workpiece and the screw tightening work reaches the final stage, the screw tightening torque becomes excessive, while the first spindle 120 causes the reaction force against the pushing load of the worker. Thus, the state of being pushed in the second spindle direction is maintained. As a result, the clutch teeth 151 on the second clutch cam 150 side, which try to further transmit the rotation torque, are changed to the clutch teeth 14 on the first clutch cam 140 side.
It will be in the state of riding on 1. As a result, as shown in FIG. 6, the second clutch cam 150 moves from the torque transmission allowable position to the first clutch cam 150 while resisting the urging force of the urging spring 171.
It starts moving in a direction away from the clutch cam 140 (rightward in the figure).

In the state shown in FIG. 6, the second steel ball 153 moves away from the end on the side toward the first spindle 120 (the first clutch cam 140) in the cam groove 130a, so that the second steel ball 153 moves into the second groove. Clutch cam 15
A move operation of 0 will be allowed.

When the second clutch cam 150 starts to move to the right in the drawing from the torque transmission allowable position, the stopper 18
The leg portion of the second clutch cam 150 located above 1 is retracted to the right in the figure. On the other hand, the stopper operating pin 183 is in a state of being pressed rightward in the drawing by the urging force of the compressed stopper operating spring 189. Therefore, the stopper 181 is pushed outward into the stopper engagement groove having a tapered contact surface when the stopper operating pin 183 is trying to move to the right, and extends outward from the peripheral surface of the second spindle 130. It will stick out.

FIG. 7 shows a state at the moment when the meshing engagement between the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side is released. In FIG. 7, the reaction force of the pushing load by the operator is applied to the first spindle 120, and the first spindle 12
0 is in the state closest to the second spindle 130 side. In this state, the second clutch cam 150
Is the first clutch cam 140 and the second clutch cam 150.
Due to the urging force of the clutch engagement regulating spring 160 acting on the first clutch cam 140, the clutch teeth are instantaneously moved in the direction away from the first clutch cam 140, and the mesh engagement of the clutch teeth 141 and 151 is released. The clutch engagement restriction spring 160 is
The function as the clutch engagement releasing means in the silent clutch is achieved.

When the second clutch cam 150 moves to the right in the figure, as described above, the restraint of the leg of the second clutch cam 150 on the stopper 181 is lost, and the stopper 181 moves to the outside of the second spindle 130. . Therefore, the stopper operating pin 183 moves in the direction facing the first spindle (rightward in the drawing) by the urging force of the stopper operating spring 189, and the stopper 181 enters the inner concave portion of the second clutch cam 150. Becomes

In this state, the second clutch cam 150
Despite the biasing force of the biasing spring 171, the stopper 181 causes the first clutch cam 14 to move.
It is restricted to move in the 0 direction. In other words, the screw tightening torque becomes excessive and the clutch engagement regulating spring 1
When the clutch teeth 141 and 151 are disengaged by 60, the second clutch cam 150 is locked and maintained at the position separated from the first clutch cam 140, that is, the torque transmission prohibited position. Then, the first clutch cam 140 is changed to the second clutch cam 1 by the careless application of the pushing load.
Even if it approaches in the 50 direction, the second clutch cam 150
Is locked at the torque transmission prohibited position by the stopper 181 and the return to the torque transmission allowable position is restricted, so that careless engagement of the clutch teeth 141 and 151 with each other is avoided. The stopper 181
Is the first clutch cam 140 of the second clutch cam 150.
It is configured to allow movement in a direction away from (rightward in the figure).

When the tightening torque exceeds a predetermined range and becomes excessive due to the screw being tightened into the workpiece,
As shown in FIG. 7, the meshing of the clutch teeth 141 and 151 is released. When the engagement is released, the clutch engagement restriction spring 160 causes the first clutch cam 14 to move.
0 instantaneously moves to the left in the drawing, and the first clutch cam 14
Since the clutch teeth 141 on the 0 side and the clutch teeth 151 on the second clutch cam 150 side are separated from each other, both clutch teeth 1
The meshing engagement between 41 and 151 is surely released. At this point, the operator loosens the pushing load on the electric screwdriver 100 in the direction of the workpiece. This state is shown in FIG.

The first steel ball 143 is movable in the lead groove 120a on the first spindle 120 between the end on the side toward the second spindle 130 and the end on the separated side. However, as can be understood from the comparison with FIG. 7 and FIG. 8, the axial distance between both ends of the lead groove 120a is the axial direction of the first clutch cam 140 when the meshing of the clutch teeth 141 and 151 is released. In addition to defining the amount of movement, it also defines the amount of clearance between the first clutch cam 140 and the second clutch cam 150 at the time of disengagement. That is, in accordance with the moving distance of the first steel ball 143 in the lead groove 143, as shown in FIG.
The clearance C between the two clutch teeth 141 and 151 shown in FIG.

In the present embodiment, as a specific construction of "when the tightening torque exceeds a predetermined range and becomes excessively large", the tightening torque is set to a predetermined value by screwing the screw into the workpiece. When the set torque is reached, the meshing engagement between the clutch teeth 141 on the first clutch cam 140 side and the clutch teeth 151 on the second clutch cam 150 side is set to be immediately released.

Now, in FIG. 8, when the worker loosens the pushing load to the electric screwdriver 100, the first spindle 120 is moved to the first clutch cam 140.
At the same time, a state in which the second spindle 130 moves away from the second spindle 130 (leftward in the drawing), that is, a state in which the second spindle 130 returns to the initial state is shown. In the present embodiment, the pushing load is the clutch engagement regulating spring 160.
When the force is reduced below the urging force of No. 1, the return of the first spindle 120 is allowed. Then, the stopper operating pin 183 attached to the first spindle 120 via the ring spring 187 causes the stopper operating pin 183 to
At the same time, it moves to the left in the figure. Since the stopper operating pin 183 moves together with the first spindle 120, a compressive load does not act on the stopper operating spring 189 when the first spindle 120 returns.

In the state shown in FIG. 8, when the first spindle 120 further moves in the direction away from the second spindle 130, the stopper operating pin 183 also moves further, and the stopper engaging groove 185 is located below the stopper 181. Will be located in. This state is shown in FIG. Further, the stopper 181 has a biasing spring 17
The urging force of No. 1 acts on the leg portion of the second clutch cam 150, and as a result, the stopper 181 is pushed by the leg portion of the second clutch cam 150 while the second spindle 1
It is accommodated in the stopper engagement groove 185 from the peripheral surface of 30.

The stopper 181 is the second spindle 130.
When the second clutch cam 150 is accommodated in the stopper engagement groove 185 from the peripheral surface of the second clutch cam 150, as shown in FIG.
Are allowed to move on the peripheral surface of the second spindle 130 without obstruction. On the other hand, the urging force of the urging spring 171 is set to be larger than the urging force of the clutch engagement restriction spring 160, and the second clutch cam 150 moves in the direction of the first clutch cam 140 by the urging spring 171. I will go. At this time, the second steel ball 1
53 is the first spindle 1 in the cam groove 130a.
20 (first clutch cam 140) toward the end of the second clutch cam 150 by allowing the moving operation of the second clutch cam 150, and by contacting the end, the second spindle of the second clutch cam 150. The position on 130 is defined. Thus, the electric screwdriver 100
The first clutch cam 140 and the second clutch cam 150 return to the initial state (see FIG. 2) in which they are separated.

In the electric screwdriver 100 according to the present embodiment, when the screw is tightened to the work material and the tightening torque becomes excessive, and the reaction torque received by the tool bit from the work material side becomes large, the clutch Due to the urging force of the engagement restriction spring 160, the first clutch cam 140
The engagement between the side clutch teeth 141 and the clutch teeth 151 on the second clutch cam 150 side is released quickly and reliably. At this time, the second clutch cam 150 is locked and maintained in the torque transmission prohibited position by the stopper 181 and
It is prevented from moving to the torque transmission allowable position on the clutch cam 140 side.

Therefore, the electric screwdriver 100 according to the present embodiment engages the meshing engagement of the clutch teeth 141 and 151 in the torque management type screw tightening work in which the screw tightening torque is managed while the screw tightening torque is managed. The second clutch cam 150 can be released quickly and surely, and the second clutch cam 150 can be locked at the torque transmission prohibited position to reliably prevent the clutch from being inadvertently engaged to cause vibration or noise. .

The stopper engagement groove 185 in the present embodiment has various shapes such as a tapered surface and a curved surface within a range in which the stopper 181 can be projected and retracted from the peripheral surface of the second spindle 130. Can be adopted. Further, the clutch engagement restricting spring 160 is provided between the first clutch cam 140 and the second clutch cam 150, in addition to the clutch cams 140, 150.
Each may be set separately and the biasing force may be applied independently.

[0062]

According to the present invention, there is provided an electric screwdriver capable of reliably suppressing abnormal noise and vibration when the clutch is released according to the screw tightening torque.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a main part of an electric screwdriver according to an embodiment of the present invention.

FIG. 2 shows an initial state of the electric screwdriver according to the present embodiment in which screw tightening work has not yet started.

FIG. 3 shows a state in which the first spindle has started to move in the direction of the second spindle when the worker applies a pushing load for tightening the screw.

FIG. 4 shows a state in which the first spindle further moves and the clutch teeth on the first clutch cam side and the clutch teeth on the second clutch cam side start to engage with each other.

FIG. 5 shows a state in which both clutch teeth are engaged with each other and the torque of the motor is transmitted to the tool bit side to perform a screw tightening operation.

FIG. 6 shows a state in which the second clutch cam has started to move rearward due to the screw tightening work reaching the final stage and the tightening torque becoming excessive.

FIG. 7 is a diagram illustrating a clutch engagement restriction spring that moves a second clutch cam in a direction away from a first clutch cam;
The state where the stopper is projected is shown.

FIG. 8 shows a state in which the worker has stopped pushing the load and the first spindle has started to return to the initial state.

FIG. 9 shows a state in which the stopper has started to return into the second spindle along with the return of the first spindle.

FIG. 10 shows the state of the electric screwdriver when the screw tightening work is completed and the initial state is restored.

[Explanation of reference numerals] 100 electric screwdriver 110 motor housing (machine) 113 motor 115 reduction mechanism 120 first spindle 121 tool bit mounting chuck 130 second spindle 140 first clutch cam (clutch means) 141 clutch teeth 143 first steel Ball 120a Lead groove 150 Second clutch cam 151 Clutch tooth 153 Second steel ball 130a Cam groove 160 Clutch engagement regulating spring (clutch engagement regulating means) 170 Second clutch cam position regulating means 171 Energizing spring 173 Set torque adjusting ring 175 Set torque adjustment pin 177 Set torque adjustment sleeve 179 Energizing spring support washer 181 Stopper 183 Stopper operating pin 185 Stopper engagement groove 187 Ring spring 189 stopper actuating spring

Claims (5)

[Claims] 1. An airframe housing a motor, and first and second airframes.
An electric screwdriver having a spindle, first and second clutch means, clutch engagement restricting means, and position restricting means for the second clutch means, wherein the first spindle is in the machine direction. The first clutch means is arranged on the end side facing the machine body and is relatively movable, the tool bit for screw tightening is connected to the other end side, and the second spindle is connected to the motor. The first clutch means rotates together with the first spindle while being relatively movable in the axial direction of the first spindle, and the second clutch means relatively moves in the axial direction of the second spindle. While being movable, it rotates together with the second spindle, and engages with the first clutch means when the first spindle relatively moves toward the machine body. The drive torque of the motor is transmitted to the tool bit, the clutch engagement restricting means applies a biasing force in a direction in which the first clutch means and the second clutch means are separated from each other, and the second clutch The position regulating means of the means sets the second clutch means to the second clutch means when the reaction torque applied to the tool bit from the workpiece side when transmitting the driving torque of the motor to the tool bit is within a predetermined range. When the reaction torque exceeds a predetermined range, the second clutch means causes the second clutch means to intervene through the clutch engagement restricting means. The second clutch means is moved to the torque transmission permissible position when the torque transmission forbidden position is located closer to the machine than the torque transmission permissible position. Screwdriver, characterized in that it comprises a second position restriction means win. 2. The electric screwdriver according to claim 1, wherein the first clutch means and the second clutch means have clutch teeth meshingly engaged with each other at opposing positions. Screw driver. 3. The electric screwdriver according to claim 1 or 2, wherein the second position restricting means, via the clutch engagement restricting means, when the reaction torque exceeds a predetermined range. An electric screwdriver, comprising: stopper means for locking the second clutch means in the torque transmission prohibiting position in association with movement of the second clutch means to the torque transmission prohibiting position. 4. The electric screwdriver according to claim 3, wherein the first position restricting means includes a spring that biases the second clutch means toward the first clutch means, and the stopper means. Is interlocked with the movement of the second clutch means to the torque transmission inhibition position via the clutch engagement restricting means when the reaction torque exceeds a predetermined range. An electric screwdriver, wherein the electric screwdriver projects from the peripheral surface so that the second clutch means is locked at the torque transmission prohibiting position. 5. The first clutch means is arranged on the end side facing the machine body, and a tool bit for screw tightening is connected to the other end side, and moreover, by a pushing load by an operator at the time of screw tightening. The first movable in the direction of the body
A spindle, the second spindle connected to a motor to rotate, a second spindle, first clutch means rotatable with the first spindle while being relatively movable in the axial direction of the first spindle, and the first spindle. The two spindles rotate together with the second spindle while being relatively movable in the axial direction, and engage with the first clutch means to engage the first clutch means when the first spindle moves toward the machine body due to the pushing load. Electric screwdriver having a second clutch means for transmitting a driving torque to the tool bit, the first clutch means, and a clutch engagement restricting means for applying an urging force in a direction in which the second clutch means separates from each other. Therefore, when transmitting the driving torque of the motor to the tool bit, the tool bit is applied to the tool bit from the work piece side. When the reaction torque exceeds the predetermined range, the second clutch means is regulated so as to be placed in the torque transmission allowable position close to the first clutch means side, and when the reaction torque exceeds the predetermined range. And a method of using the electric screwdriver, wherein the second clutch means is regulated via the clutch engagement regulation means so as to be placed at a torque transmission prohibition position closer to the machine body than the torque transmission allowable position. .