JP2585727Y2 - Electric screwdriver clutch mechanism - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a clutch mechanism for turning on and off the rotation output of an electric motor with respect to a driver bit in an electric screw driver.

[0002]

2. Description of the Related Art A pusher in which a screw head is engaged with the tip of a driver bit and pressed against a workpiece to mesh the teeth of the movable clutch with the teeth of the fixed clutch to rotate the driver bit. This type of tool has a spring interposed between the fixed clutch and the movable clutch that biases them away from each other. The movable clutch side is pressed against the fixed clutch together with the driver bit against this spring force. To engage the clutch to rotate the driver bit.
By the way, in this screw tightening machine, as the driver bit rotates and the screw is tightened, the nose member arranged on the outer peripheral side of the driver bit approaches the surface of the workpiece and eventually comes into contact. However, it is impossible to move any more (the same applies to the fixed clutch). On the other hand, since the driver bit, which is still being rotationally driven, moves closer to the workpiece while tightening the screw together with the movable clutch, The engagement state of the movable clutch and the movable clutch gradually becomes shallow, and finally the engagement is disengaged, the rotation of the driver bit stops, and the screw can be screwed to a predetermined screwing depth.

However, according to the above-mentioned clutch mechanism, there is a problem in that the clutch is repeatedly switched on and off just before the meshing teeth of the clutch are disengaged, so that an abnormal noise is generated and the meshing teeth of the clutch are damaged. .

To solve the above phenomenon, Japanese Patent Application Laid-Open No.
A clutch mechanism disclosed in Japanese Patent Application Laid-Open No. 3-267171 is already known. In brief, the mechanism is such that the movable clutch and the driver bit are connected to each other by an inclined groove formed between them and a steel ball housed in the inclined groove so as to be movable in a predetermined angular range in the rotational direction and in the axial direction. At the moment when the driving clutch is engaged with the fixed clutch and the driving force is transmitted, a relative movement is caused between the movable clutch and the driver bit in the rotational direction and the axial direction, so that the engagement of both clutches is ensured and the driving is performed via the steel ball. The force is transmitted to the driver bit, and at the moment when the movable clutch gradually separates from the fixed clutch at the end of screw tightening and the meshing teeth separate, the rotational driving force to the movable clutch is cut off, and When the axial driving force between the clutch and the driver bit is lost, the movable clutch is moved by the action of the clutch spring and , In which intermittent repetitive phenomenon of meshing teeth so as not to cause.

[0005]

However, in the above-mentioned clutch mechanism, at the moment when the movable clutch gradually separates from the fixed clutch and the teeth are separated, the driver bit to which the driving force is transmitted via the movable clutch has the head of the screw. As a result, the load torque remains between the movable clutch and the movable clutch rotating by inertia. During this time, the axial biasing force between the movable clutch and the driver bit remains, and the movable clutch further separates from the fixed clutch. Movement is stopped. For this reason, the disengagement of the clutch becomes slightly slow, and abnormal noise occurs.

[0006]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a clutch mechanism of an electric screwdriver capable of solving the above-mentioned drawbacks, making the disengagement of the clutch quick and eliminating the occurrence of abnormal noise, and at the same time, preventing damage to the meshing teeth of the clutch. Aim.

[0007]

In order to achieve the above object, a clutch mechanism of an electric screwdriver according to the present invention has a fixed clutch formed with meshing teeth on one surface and connected to an electric motor via a speed reduction mechanism. together with teeth meshing faces the meshing teeth of the fixed clutch, a movable clutch spring biased to movably disposed and always leaving direction axially relative to the fixed clutch, engaging
A driver bit provided so as to be movable in a predetermined range in the axial direction with respect to the movable clutch by being engaged with the movable clutch through the coupling means and to be rotatable in the rotation direction by a predetermined range. The movable class
As well as spring-loaded in the backward direction with a small spring force than the spring force against pitch, the opposing surfaces of the movable clutch and the driver bit, wherein in the axial direction have a inclined surface facing the respective rotational direction Within the specified range
When the driver bit is rotated in the rotational direction by the predetermined range with respect to the movable clutch, the inclined surfaces of the two convex portions slide to move the driver bit into the predetermined position with respect to the movable clutch. When the driver bit receives a predetermined load on the movable clutch and rotates integrally with the movable clutch, the inclined surface of the two convex portions
Is slid so that the driver bit separates from the movable clutch.

[0008]

According to the above construction, when the screw tip held by the driver bit is pressed against the workpiece, the driver bit moves the movable clutch toward the fixed clutch against the bias of the spring. Are engaged with each other, and the rotation of the fixed clutch is transmitted to the movable clutch. After the movable clutch rotates by a predetermined range, the driver bit also starts rotating away from the movable clutch. At this time, the inclined surface of the convex portion of the convex portion and the driver bit of the movable clutch is engaged to each other, sliding with each other by sliding action of the two inclined surfaces, spring driver bit towards the spring force is small at the bracing force Moves away from the movable clutch against the force. Since the rotation of the movable clutch is limited to a predetermined range, the projected state is maintained.

At the end of the screwing, the movable clutch is dry.
Screwing direction to fixed clutch with babbit
When moving away from the fixed clutch by moving to the
Meshing teeth of the movable clutch and fixed clutch that releases solutions.
At that moment, the transmission of the rotational force from the fixed clutch to the movable clutch is released, and the driver bit stops rotating .
The movable clutch always moves away from the fixed clutch.
And the driver bit is retracted.
The spring is biased to engage the driver bit with the screw head.
By positively releasing it, the projection is turned freely.
From the tension between the movable clutch and the convex part of the driver bit
Force instantaneously disappears, the movable clutch and driver bit
Since the inclined surface of the convex portion slides in the opposite direction and approaches, the movable clutch moves in the direction further away from the fixed clutch, and the engagement of the meshing teeth is ensured.

[0010] As described above, according to the present invention, the movable clutch constituting the clutch mechanism is formed separately from the driver bit, and the driver bit is arranged in the axial direction with respect to the movable clutch.
It is possible to move only a predetermined range in the direction
The driver bit and the movable
The projection of the latch does not directly contribute to the transmission of the rotational force. I
As a result, the projections collide with each other during rotation, generating abnormal noise.
Never.

[0011] In addition, the driver bit of another body in the initial stage of rotation
The movable clutch is moved rearward in the axial direction to
Immediately after connecting the fixed clutch and
To the front of the movable clutch.
At the end of the engagement, the meshing teeth of the movable clutch and the fixed clutch
Dissociation was the moment, the movable clutch is fixed click La by the spring-biased
And the driver bit is also biased by the spring.
Since it retracts further and becomes free with the screw head, the movable
And the inclined surface of the convex part of the driver bit slides,
Sometimes close. At this time, is the movable clutch a fixed clutch?
As they move away, their movement is quick. But
Therefore, the disengagement of the clutch becomes agile, no abnormal noise occurs,
Further, damage to the meshing teeth of the clutch can be prevented.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings, an embodiment of the present invention will be described. FIG. 1 shows a vertical cross section of an electric screwdriver. This electric screwdriver includes an electric motor 1, a clutch mechanism 2, and a driver bit 3. A nose member 4 is provided in front of the housing 1 so as to be relatively movable with respect to the housing 1, and the clutch mechanism 2 includes a fixed clutch 6 and a driver bit 3 connected to the electric motor 1 via a speed reduction mechanism 5. The rotational output of the electric motor 1 is turned on and off with respect to the driver bit 3 by providing the connected movable clutch 7 coaxially and engaging and disengaging the meshing teeth of the fixed clutch 6 and the movable clutch 7. .

The fixed clutch 6 is a disc-shaped body integrally formed with the output shaft 9 connected to the electric motor 1 via the speed reduction mechanism 5, and has a meshing tooth 8a on the end face on the driver bit 3 side.
Are formed in the circumferential direction.

The movable clutch 7 is a short cylindrical member with a bottom which is arranged so as to be movable coaxially with the fixed clutch 6 and the output shaft 9. As shown in FIG.
0 is formed, and the meshing teeth 8 of the fixed clutch 6 are formed on the other side.
A meshing tooth 8b is formed on the outer surface facing a. Convex portions 11 are formed on the inner surface of the bottom wall of the central concave portion 10 at intervals in the circumferential direction. Each convex portion 11 has an inclined surface 11a inclined in the rotational direction, and the central portion of the bottom wall. Is formed with a through hole 12 of the output shaft 9.
An engagement groove 13 is formed on the inner peripheral surface of the recess 10 in parallel with the axial direction. Further, a compression spring 16 is interposed between the outer peripheral edge 14 of the movable clutch 7 and the outer peripheral edge 15 of the fixed clutch 6, and the movable spring 7 is always separated from the fixed clutch 6 by the compression spring 16. The spring is biased.

The driver bit 3 is integrally connected to the main shaft 3a, and the main shaft 3a is guided by the shaft guide 18 fixed to the housing 1 so as to be able to protrude in the axial direction with respect to the movable clutch 7. The end 17 of the main shaft 3a is small enough to be inserted into the concave portion 10 of the movable clutch 7 and has a larger diameter than the shaft guide 18. Further, an insertion hole 19 for the output shaft 9 is formed at the center of an end surface of the large diameter end portion 17 opposite to the inner surface of the bottom wall of the concave portion 10 of the movable clutch 7, and a peripheral edge of the end surface is formed at the center. A convex portion 20 corresponding to the convex portion 11 of the movable clutch 7 is formed. The projection 20 also has an inclined surface 20a that is inclined in the rotation direction. Therefore, the driver bit 3 is configured such that the large-diameter end portion 17 of the main shaft 3a is inserted into the concave portion 10 of the movable clutch 7 and the two convex portions 11, 2
0 and the tips of the inclined surfaces 11a and 20a of the two convex portions 11 and 20 while being in contact with the shaft guide 18.
A predetermined range between the position where the vicinity of the surface is engaged and the position where the vicinity can be engaged can be moved along the axial direction.

A projection 21 is formed on the outer peripheral surface of the large-diameter end portion 17, and the projection 21 is disposed in the engagement groove 13 in the inner wall of the concave portion 10 of the movable clutch 7 (FIG. a)
reference). Since the width dimension and the axial dimension of the groove of the engagement groove 13 are larger than the protrusion 21, the main shaft 3 a moves within a predetermined range where the protrusion 21 is engaged with both side walls of the engagement groove 13. It can move freely in the rotation direction and the axial direction. When the movable clutch 7 rotates, the rotational force is transmitted to the main shaft 3a through the engagement between the protrusion 21 and the engagement groove 13, whereby the driver bit 3 rotates.

Further, the shaft guide 18 has a fitting hole 2 into which the main shaft 3a of the driver bit 3 is fitted.
2, and the inside diameter of a part of the fitting hole 22 is formed large. A compression spring 23 is disposed inside the large diameter portion, and the driver bit 3 is constantly biased rearward. Note that the spring force of the compression spring 23 is
The spring force of No. 6 is also set small.

Next, a description will be given operation mode of the clutch mechanism 2 of the screwdriver of the configuration. First,
When the electric motor 1 is operated, its rotational force is reduced by the speed reduction mechanism 5.
To the output shaft 9 to rotate the fixed clutch 6. When the nose member 4 at the tip of the housing 1 is pressed against the workpiece P as shown in FIG. 3A, the nose member 4 relatively moves backward with respect to the housing 1, and thus projects relatively forward. The tip of the driver bit 3 is a nose member 4
Engages with the head of the screw N supplied. Then, when the screw tip is further pressed against the workpiece P, the driver bit 3 retreats relatively to the housing 1 as shown in FIG. 4A, and the large-diameter end portion 17 of the main shaft 3a is moved by the movable clutch. 7 is pushed backward to move backward against the compression spring 16, and the meshing teeth 8 a and 8 b of both the movable clutch 7 and the fixed clutch 6 are meshed, and the rotation of the fixed clutch 6 is transmitted to the movable clutch 7.

By the way, when the meshing teeth 8a and 8b of the fixed clutch 6 and the movable clutch 7 mesh with each other to rotate the movable clutch 7, first, the movable clutch 7 rotates around the main shaft 3a which is not rotating. The amount of rotation is such that the protrusion 21 of the main shaft 3a moves from one end of the engagement groove 13 of the movable clutch 7 shown in FIGS. 3 (b) and 4 (b) to the engagement groove 13 shown in FIG. 5 (b). Rotate a predetermined range to the opposite end. By this relative rotation, the convex portion of the movable clutch 7 and the inclined surfaces 11a and 20a of the convex portions 11 and 20 of the large-diameter end portion 17 of the main shaft 3a engage with each other.
a, the main shaft 3 slides by the sliding action of 20a.
a is pushed out against the spring force of the compression spring 23 and separated from the movable clutch 7 (actually, the housing 1 is pushed back in the direction opposite to the pressing side), and as shown in FIG. Stops at the initial position against the rear surface . This and
The movable clutch 7 and the two convex portions 1 of the main shaft 3a.
Near the front ends of the inclined surfaces 11a and 20a of the first and the second 20 are engaged,
The state in which the driver bit 3 protrudes away from the movable clutch 7 by the tension force is maintained. The rotation of the movable clutch 7 also rotates the main shaft 3a integrally under a predetermined load.
The screw held in the workpiece P shown by the dotted line in FIG.
It is screwed against.

When the driver bit 3 continues to rotate and the leading end of the nose member 4 comes into contact with the surface of the workpiece P shown by a solid line in FIG. 25 engages the stopper piece 26 of the housing 1 and cannot move any further. Therefore, although the fixed clutch 6 cannot move forward, the screwing of the screw N continues, so that the driver bit 3 moves forward by the remaining screwing amount as shown in FIG. As a result, the meshing teeth 8a, 8b disengage from the fixed clutch 6 as a result. At the moment of disengagement, the transmission of the rotational force from the fixed clutch 6 to the movable clutch 7 is released, whereby the rotation between the movable clutch 7 and the driver bit 3 is stopped, and the movable clutch 7 receives the load from the driver bit 3 By the rotation, the tension generated between the two inclined surfaces 11a and 20a is eliminated, and the protrusion 21 of the main shaft 3a is reversed along the engagement groove 13 of the movable clutch 7 as shown in FIG. The movable clutch 7 moves further away from the fixed clutch 6 by the action of the compression spring 16 to ensure that the meshing teeth are disconnected. At this time,
The driver bit 3 is also separated from the screw head by the action of the spring 23
The driver bit 3 and the screw N
And the load on driver bit 3 is eliminated,
The tension between the moving clutch 7 is instantaneously lost, and
Movement of the dynamic clutch 7 in the direction away from the fixed clutch 6
, And returns to the initial position shown in FIG.

According to the clutch mechanism 2, as described above, the movable clutch 7 constituting the clutch mechanism 2 is configured separately from the driver bit 3, axially aft and driver bit 3 and the movable clutch 7 to the rotation initial fixed class is moved to the movable clutch 7 only fixed clutch 6 and first driver bit 3 immediately after ligated were separated forward with respect to the movable clutch 7, and the movable clutch 7 at the end screwing in
Meshing teeth 8b of pitch 6, 8a collapsed away the moment, the movable click
The latch 7 is separated from the fixed clutch 6 by the bias of the spring.
The driver bit 3 is also retracted by the spring
Since the head of J-N becomes free, the movable clutch 7 and
The inclined surfaces of the convex portions 20 and 11 of the driver bit 3 slide, and both
Come close instantaneously. At this time, the movable clutch 7
The latch six et away, its movement is rapidly performed. Therefore, the disengagement of the clutch becomes quick, no abnormal noise occurs, and damage to the meshing teeth of the clutch can be prevented.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part of a clutch mechanism of an electric screwdriver according to the present invention.

FIG. 2 is an exploded perspective view of the clutch mechanism.

FIG. 3A is an explanatory diagram of an initial state of an operating state of the clutch mechanism, and FIG. 3B is an explanatory diagram of a positional relationship between a movable clutch and a driver bit in the same state.

FIG. 4A is an explanatory view of an operation state at the time of starting engagement of meshing teeth of the clutch mechanism, and FIG. 4B is an explanatory view of a positional relationship between a movable clutch and a driver bit in the same state.

FIG. 5A is an explanatory diagram of an operation state immediately after the engagement of the meshing teeth of the clutch mechanism is started, and FIG. 5B is an explanatory diagram of a relative rotation between a movable clutch and a driver bit in the same state.

6A is an explanatory diagram of an initial state of an operating state immediately after the meshing of the meshing teeth of the clutch mechanism is disengaged, and FIG. 6B is an explanatory diagram of relative rotation between a movable clutch and a driver bit in the same state. It is.

[Explanation of symbols]

 Reference Signs List 3 driver bit 6 fixed clutch 7 movable clutch 8a meshing tooth 8b meshing tooth 11 convex portion 11a inclined surface 16 compression spring 20 convex portion 20a inclined surface

Claims (1)

(57) [Scope of request for utility model registration] A fixed clutch formed with meshing teeth on one surface and connected to an electric motor via a speed reduction mechanism;
Together with teeth meshing faces the meshing teeth of the fixed clutch, a movable clutch spring biased to movably disposed and always leaving direction axially with respect to the fixed clutch, the movable clutch through the engagement means By engaging
Ri and an only rotatably provided driver bit predetermined range and the rotational direction movable in the axial direction by a predetermined range with respect to the movable clutch, the Allowed the driver bit
As well as spring-loaded in the backward direction with a small spring force than the spring force for moving the clutch, the opposing surfaces of the movable clutch and the driver bit, wherein in the axial direction have a inclined surface facing the respective rotational direction Within the specified range
When the driver bit rotates in the rotational direction by the predetermined range with respect to the movable clutch, the inclined surfaces of the two convex portions slide, and the driver bit moves relative to the movable clutch. When the driver bit is separated or approached in the axial direction by the predetermined range , and the driver bit receives the predetermined load and rotates integrally with the movable clutch, the inclined surfaces of the two convex portions slide to slide the driver bit. The clutch mechanism of the electric screwdriver, wherein the clutch is separated from the movable clutch.