JPH0818263B2 - Electric screwdriver - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an electric screwdriver.

(Prior Art) Generally, in this type of electric screwdriver, an adjusting sleeve for adjusting a tightening amount (length) of a screw is provided at a tip portion of a housing and is rotated by a drive device. Clutch means is interposed between the gear and a spindle provided with a driver bit projecting from the tip of the adjusting sleeve and movably supported in the axial direction. Is configured to cut off power transmission between the main gear of the main gear and the main shaft on the side of the driver bit, and the clutch means engages both clutch pawls between the fixed side clutch pawl and the movable side clutch pawl. It has been devised to provide a central disc to be disengaged so that its engagement is completely disengaged when the tightening is completed. (See, for example, JP-A-61-219581.) (Problems to be Solved by the Invention) However, in the above-mentioned conventional configuration, when the screw tightening reaches a predetermined amount (length), Although the disc can completely disengage the fixed-side clutch claw and the movable-side clutch claw in the clutch means to reduce the noise such as a metallic sound generated when the claws hit each other as much as possible, the clutch means is used as a central disc. Since it is configured to positively dissociate positively by the movement of the screw, the screw that should be tightened for some reason, such as the adjustment sleeve hitting the member to be tightened at an angle, or the main body is not pressed firmly against the member to be tightened Is not tightened slightly to the initially set tightening amount (length), further tightening is not possible, so-called additional tightening is not possible. That was a problem.

Therefore, in view of the above-mentioned conventional drawbacks, the present invention can minimize the noise such as metallic noise generated when the transmission of the clutch means is interrupted, and tighten the screw to the initially set tightening amount (length). The purpose of the present invention is to provide an electric screwdriver that can be tightened even if it is not possible.

(Means for Solving the Problems) In order to achieve the above-mentioned object, the present invention provides an adjusting sleeve mounted at the tip of a housing so that the position of the housing can be adjusted in the axial direction, and rotating and rotating within the housing. A main gear that is movably supported in the axial direction and is rotated from the drive device; and a main gear that is positioned coaxially with the main gear in the housing and is rotatably and axially movably supported in the adjusting sleeve. So as to cooperate with the axial movement of the main shaft provided with a driver bit located at, the fixed clutch portion provided between the main gear and the main gear and provided on the main gear side, and the main shaft. An electric screwdriver provided with a clutch means, which is provided on the main shaft side and is always biased by a first biasing means in a direction away from the fixed clutch section, and a clutch means. A groove portion is formed in a portion of the clutch means that opposes the movable clutch portion and the main shaft, and engaging means that engages with each other in the groove portion to engage and disengage rotation transmission between the movable clutch portion and the main shaft. A non-engaging position at which at least one groove portion of the groove portion is disengaged from the engaging means in response to the engaging / disengaging movement of the clutch means, and the engaging means is in the non-engaging position. From the non-engaging position, a slanted portion for axially displacing and moving from the It has a slanted portion that is displaced in the axial direction, and a second engagement position when there is no load, which has an obstruction portion that is continuous with the slanted portion and temporarily holds the engagement with the engagement means. There is no control groove, and the gap between the main shaft and the movable clutch is weaker than the urging force of the first urging means. A second urging means that urges the main shaft or the movable clutch portion in a direction to return and rotate the main shaft or the movable clutch portion so that the engaging means engages with the second engaging position when there is no load. The point is that the equipment has been installed.

(Operation) The movable clutch is fixed to the fixed clutch through the engagement means located at the engagement position of the control groove having the axial displacement of the main shaft and the axial displacement of the main shaft or the movable clutch. When the movable clutch pawl is engaged with the fixed clutch by being pushed to the side against the elastic force of the first biasing means, the rotation from the drive device is transmitted to the main shaft and the engagement in the control groove is performed. The means is moved to the engagement position under load, and screw tightening is performed by the driver bit. Then, when the adjusting sleeve mounted on the main body is brought into contact with the surface of the member to be screwed, the main shaft and the movable clutch portion are pushed by the clutch tooth height of the clutch means in the opposite direction to the pushing in the axial direction. When the movable clutch and the fixed clutch are disengaged from each other, the rotation transmission is interrupted, and at the same time, the elastic force of the first biasing means causes the movable clutch to move along the control groove and to the disengaged position of the clutch. The escape operation of the engaging means positioned disengages the fixed clutch portion to complete screw tightening. Then, when the main body is separated from the member to be screwed, the movable clutch portion is positively rotationally biased by the second biasing means, and the engaging means is brought to the engaging position when there is no load in the control groove portion. Is located. As a result, the engagement operation between the movable clutch portion and the fixed clutch portion at the time of additional tightening is allowed, and the rotation from the drive device can be transmitted to the main shaft.Therefore, in the above tightening, the initially set tightening amount ( Even if it is not tightened with respect to (length), it can be tightened again.

(Example) Hereinafter, one example of the present invention will be described in detail with reference to the drawings.

In the figure, the housing of the electric screwdriver 1
A rear end of a support shaft 2 is rotatably supported in a bearing 1a via a bearing, and the support shaft 2 is meshed with a gear portion 4a of a motor shaft 4 of a drive motor 3 via intermediate gears 5a and 5b. A main shaft 6 having a main gear 6 fitted therein and having a replaceable driver bit 7 inserted and held in the tubular portion of the housing 1a is axially movable and rotatable on the same axis as the support shaft 2. Is supported by. The front end of the support shaft 2 is inserted into the rear end of the main shaft 8 to support the front end of the support shaft 2 via a bearing so that the main shaft 8 can rotate and move in the axial direction. The rear end surface of the main shaft 8 faces the main gear 6 with a predetermined gap.

A pair of meshing clutch means 9 is interposed between the main gear 6 and the rear end surface of the main shaft 8, and the clutch means 9 and a fixed clutch claw portion 10 formed on the main gear 6 are provided. , A movable clutch pawl portion 11 that is meshably opposed to the fixed clutch pawl portion 10 and is located at the rear end portion of the main shaft 8.
It consists of and.

The mounting state of the movable clutch claw portion 11 with respect to the rear end portion of the main shaft 8 will be described in detail. A flange portion 12 is integrally formed at the rear end portion of the main shaft 8 and an end surface of the flange portion 12 is formed. A circular recess 130 is formed. Further, on the inner peripheral surface of the circular recess 13, three control groove portions 14 to 14 having a predetermined length are formed at equal intervals in the circumferential direction from the end surface to the bottom surface, and each control groove portion 14 has its bottom surface. As shown in FIG. 4, a substantially non-engagement position where the central portion is deepest and the engagement with the engagement ball 16 which will be described later is released corresponding to the engagement / disengagement movement of the clutch means 9 (disengagement of the clutch). Position) 14a,
This engaging ball 16 is disengaged position (clutch disengagement position)
An inclined surface 14b that is displaced axially from 14a, and the inclined surface
It is steeper than the inclined surface 14b with the first (loading) engagement position 14c continuous with 14b and engaged with the engagement ball 16 and the non-engagement position (clutch disengagement position) 14a. Sloped surface 1 that is moved at an appropriate inclination angle and that displaces the engagement ball 16 in the axial direction from the disengagement position (clutch disengagement position) 14a.
4f and the slanted surface 14f are formed at substantially the same depth as the first (during load) engagement position 14c across the non-engagement position (clutch disengagement position) 14a. And a second (non-loading) engagement position 14d that is engaged with the engagement ball 16 in correspondence with the (loading) engagement position 14c. The disengagement position) 14a and the second (without load) engagement position 14d are formed slightly higher than the bottom surface of the second (without load) engagement position 14d via the inclined surface 14f. It is formed so as to be continuous via a curved surface (obstacle portion) 14e that temporarily holds the engagement between the engagement ball 16 and the second (non-loaded) engagement position 14d.

The movable clutch pawl portion 11 includes a cylindrical portion 11a and a flange portion 11b.
And the cylindrical portion 11a is integrally formed from
Is fitted into the circular recess 13 in a loose fitting manner, and the outer periphery of the cylindrical portion 11a has a shape point-symmetrical to the control groove portion 14 at a portion opposed to the control groove portions 14 to 14 so as to overlap. Departure position
15a, oblique portion 15b, first engagement position 15c, second engagement position 1
The control groove portions 15 to 15 in which 5d are respectively formed are also formed in three places. And both control groove parts 14-14, 15-1
Engaging balls 16 to 16 are located at the mating positions across five.
The inclination angle of the slanted portions 14b, 15b is determined by the axial reaction force generated by the slanted portions 14b, 15b when a certain torque T acts on the shaft generated when the torque T acts on the clutch means 9. It is set to be larger than the directional reaction force.

Then, the fixed clutch claw portion 10 of the movable clutch claw portion 11
By the dissociation operation with respect to the axial movement of the engagement ball 16 in the control groove portions 14 to 14 and 15 to 15 having an axial displacement amount, that is, the first (loading) engagement position 14c, By moving from 15c to the disengagement positions 14a, 15a of the clutch, the disengagement operation of the movable clutch pawl portion 11 with respect to the fixed clutch pawl portion 10 is completed, and the control groove portions 14-14, 15-15 of the engaging ball 16 are formed.
The fixed clutch pawl portion 10 of the movable clutch pawl portion 11 at the time of additional tightening due to the movement in the inside, that is, the movement from the clutch disengagement position 14a, 15a to the second (no load) engagement position 14d, 15d.
Are engaged with each other.

Two rubber pins 17, 17 are provided in the housing 1a so as to be able to come into contact with one end surface of the movable clutch claw portion 11, whereby the movable clutch claw portion 11 is disengaged from the fixed clutch claw portion 10. In this state, the unnecessary movement of the movable clutch claw portion 11 and the unnecessary movement of the main shaft 8 are prevented.

A first urging member composed of a compression spring is urged between the main gear 6 and the movable clutch pawl portion 11 so as to always urge the movable clutch pawl portion 11 toward the fixed clutch pawl portion 10. Means 18 is elastically mounted, and a second biasing means 19 composed of a spiral torsion spring is elastically mounted between the main shaft 8 and the movable clutch pawl portion 11, and the second biasing means 19 is mounted on the main shaft. 8 is wound around the outer periphery of the flange portion 12 at a predetermined interval, one end of which is engaged with a part of the outer periphery of the flange portion 12 and the other end is formed on the flange portion 11b of the movable clutch pawl portion 11. The control groove portions 14 to 14, 15 to 15 are always engaged with the main shaft 8 and the movable clutch pawl portion 11 and are engaged with the notch groove 11c.
The rotational force in the axial direction is applied to the second engaging positions 14d and 15d in the above so that the engaging balls 16 return to their original positions. An auxiliary spring 20 is provided between the main gear 6 and the main shaft 8.
Is armed. The second urging means 19 applies its urging pressure (the slanted portion 14 of the control groove portions 14 and 15 via the engagement ball 16).
The axial repulsive force generated at f and 15f is set to be slightly weaker than the urging pressure of the first urging means 18. An auxiliary spring 20 is mounted between the main gear 6 and the main shaft 8.

A lock ring 21 is fitted around the outer periphery of the distal end cylindrical portion of the housing 1a at a predetermined interval.
The desired external thread 21a is formed on the inner peripheral surface of the housing 1a, and the locking piece 22 projecting from the rear end is engaged with the engaging groove 1b of the housing 1a to be fixed to the housing 1a. ing. The lock ring 21 is formed with a single slit in the axial direction so that it can be expanded and contracted in the radial direction, and a screw hole 23 is formed in a bulging portion formed in the radial direction of the outer periphery of the slit portion. The cylinder diameter is expanded and reduced by a tightening bolt 24 screwed into the screw hole 23 to lock and release an adjust sleeve 25 described later.

An adjusting sleeve 25 for adjusting the screwing depth of the screw to be tightened is fitted between the housing 1a and the lock ring 21 on the outer periphery of the distal end cylindrical portion, and the adjusting sleeve 25 is formed in a substantially conical cylindrical shape. And its tip extends from the lock ring 21 and extends in the direction of the central axis.
Rotatably supports a driver bit 7 attached to the. A female screw portion 25a screwed to the male screw portion 21a of the lock ring 21 is screwed on the outer periphery of the rear end portion of the adjusting sleeve 25.

Then, the adjusting sleeve 25 has the lock ring 21.
It is configured such that the protruding length of the driver bit 7 from the tip thereof, that is, the screw-in depth of the screw to be tightened can be adjusted by screwing the screw into or out of the screw.

The present embodiment is configured as described above, and the tightening operation will be described with reference to FIGS. 7A to 7G and 8A to 8E.

Now, according to the screwing depth of the screw Y to be tightened, the adjusting sleeve 25 is screwed in or out of the lock ring 21 to adjust and set the protruding length of the driver bit 7 from the tip thereof, and The tip of the screw 7 is aligned with the head of the screw Y to be tightened and the screw Y is brought into contact with the portion W to be tightened.

In this state, as shown in FIG. 2, the main shaft 8 is always in the second position.
Since the rotational force is applied in the axial direction by the urging means 19 of the engaging balls 16 to 16, the engaging balls 16 to 16 are in the second (non-loaded) engaging positions 14d and 15d in the control groove portions 14 and 15, respectively. The movable clutch pawl portion 11 is further urged by the first urging means 18 in the direction in which it disengages from the fixed clutch pawl portion 10, and the main shaft 8 is moved by the auxiliary spring 20 to the movable clutch pawl portion 11 Since the clutch pawls 10 and 11 are biased in the same direction, the engagement between the clutch claws 10 and 11 is disengaged. Therefore, even if the drive motor 3 is driven to rotate the motor shaft 4, only the main gear 6 is rotated and the rotation to the main shaft 8 and the driver bit 7 is not transmitted. (See FIG. 7A) In this case, the second engaging position 1 in each of the control groove portions 14 and 15
The engaging balls 16 to 16 located in 4d and 15d have some play in the axial direction.

Therefore, when the main body of the electric screwdriver 1 is pressed together with the screw Y to be tightened onto the portion W to be tightened (in the lateral direction), the main shaft 8 together with the driver bit 7 resists the biasing force of the auxiliary spring 20 and the main gear. 6 is moved in the axial direction toward the 6 side, and the movable clutch pawl 11 is biased by the first biasing means 18 via the engaging balls 16 at the second engaging positions 14d, 15d in the control grooves 14, 15. It is pushed to the side of the main gear 6 against the force and meshes with the fixed clutch claw portion 10. (7th
(See FIG. B) In this case, the engagement balls 16 to 16 located in the second (non-loaded) engagement positions 14d and 15d in the control groove portions 14 and 15 have no play.

When the drive motor 3 is driven in this state, the rotation of the motor shaft 4 is transmitted to the main shaft 8 via the main gear 6 and the clutch means 9 in the meshed state, and the driver bit 7 starts rotating to tighten the screw Y. Is started. When the screw tightening load is applied to the main shaft 8 side with the start of tightening by the driver bit 7, the clutch means 9 is completely engaged, and the main shaft 8 is maintained in the engaged state. And the movable clutch claw portion 11 are relatively rotated in the direction around the axis, and the engagement balls 16 of the movable clutch pawl portion 11 are in the second (non-loaded) engagement positions 14d and 15d of the control groove portions 14 and 15, respectively.
Is displaced to the first (loading) engagement position 14c, 15c. (See FIG. 7C) At this time, the urging force for the return rotation of the movable clutch pawl portion 11 is accumulated in the second urging means 19.

As described above, the tightening operation for the screw Y proceeds while advancing the entire main body of the electric screwdriver 1. Then, when the tip end of the adjusting sleeve 25 comes into contact with the portion W to be tightened (see FIG. 7D), the advance of the main body of the electric screwdriver 1 to the portion W to be screwed is stopped, so that it is temporarily stopped. The main shaft 8 and the movable clutch claw portion 11 are advanced by the tooth height of the fixed clutch claw portion 10 (pushed in the direction opposite to the initial pushing direction), and the screw bit Y is tightened by the driver bit 7 by that tooth height. After that, the engagement between the movable clutch claw portion 11 and the fixed clutch claw portion 10 is disengaged. (See Fig. 7E)
At this moment, the engaging balls 16 are still in the respective control groove portions 1.
It is located at the first (loaded) engagement position 14c, 15c at 4,15.

Then, at the moment when the engagement between the movable clutch pawl portion 11 and the fixed clutch pawl portion 10 is understood, the rotation transmission to the main shaft 8 side is cut off, so that the first biasing force acting on the movable clutch pawl portion 11 is cut off. By the urging force of the means 18, the movable clutch claw portion 11 is pushed back (moved to the left in the drawing) until it abuts on the rubber pins 17, 17, so that the engaging ball 16 in each control groove portion 14, 15 is the first ( Slope 1 from engagement position 14c, 15c (under load)
It is located in the clutch disengagement positions 14a, 15a along the first (loading) engagement position 14c, 15c along with 4b, 15b and the axial displacement. As a result, the disengaged state of the engagement between the movable clutch claw portion 11 and the fixed clutch claw portion 10 is completed, and
That state is maintained. (Refer to FIG. 7F) Therefore, the rotation transmission from the main gear 6 to the main shaft 8 is completely cut off, and the disengagement operation of the engagement between the fixed clutch claw portion 10 and the movable clutch claw portion 11 does not generate a mechanical sound or the like. It should be done smoothly and reliably.

After that, when the main body of the electric screwdriver 1 is separated from the part W to be tightened, the main shaft 8 is pushed back to the initial state (moved to the left in the figure) by the elasticity of the auxiliary spring 20,
A play occurs in the engaging balls 16 to 16 located in the clutch disengagement positions 14a and 15a in the control groove portions 14 and 15 in the axial direction. As a result, the rotational force about the relative axis is applied between the main shaft 8 and the movable clutch claw portion 11 by the second biasing means 19.
The main shaft 8 side is slightly rotated because it is abutted against and is prevented from rotating. By the rotation of the main shaft 8, the main shaft 8
In the control groove portion 14 on the side, the engagement ball 16 crosses over the curved surface 14e slightly higher than the second (no load) engagement position 14d from the clutch disengagement position 14a and the second (when no load is applied). Of the control groove portion 15 on the movable clutch claw portion 11 side.
The clutch disengagement position 15a is
To the second engagement position 15d by surpassing the curved surface 15e which is slightly higher than the second (non-loaded) engagement position 15d, and therefore the engagement ball 16 is located at the second position in each control groove portion 14, 15.
The movable clutch pawl portion is positively positioned in the engagement positions 14d and 15d (when there is no load) in the first state, that is, when the driver bit 7 and the main shaft 8 are moved in the axial direction.
This corresponds to the meshing state of 11 and the fixed clutch claw portion 10. (Refer to FIG. 7G) In this embodiment, the screw Y is tightened as described above. For example, a member W on which an adjusting sleeve is slanted against a member W to be tightened or a main body is tightened. If the screw Y to be tightened does not reach the initially set screw-in length due to some reason such as weak pressing against the screw, it is necessary to correct this and further tighten the screw, so-called additional tightening. The following describes this catch-up operation.

Now, as described above, when the screw tightening work is completed and the head of the screw Y is out of the surface W to be tightened by the length t, additional tightening is required.

In this state, the engagement balls 16 are positively positioned in the second (non-loaded) engagement positions 14d, 15d in the control groove portions 14, 15. (See FIG. 8A) Then, the tip of the driver bit 7 is matched with the head of the screw Y to be tightened, and the electric screwdriver 1
When the main body is pressed against the portion W to be tightened, the movable clutch claw portion 11 is meshed with the fixed clutch claw portion 10 as in the above-described tightening operation. (See FIG. 8B) When the drive motor 3 is driven in this state, the driver bit 7 starts rotating to start tightening the screw Y in the same manner as described above, and the screw tightening load is applied to the main shaft 8 side. When the clutch means 9 is completely engaged, the engagement ball 16 moves from the second (at no load) engagement positions 14d, 15d in both control groove portions 14, 15 to the first (load). It is displaced to the engaging position 14c, 15c (at the time). (See FIG. 8C) When the additional tightening is completed, the meshing of the movable clutch claw portion 11 and the fixed clutch claw portion 10 is disengaged in the same manner as described above. (See FIG. 8D) Then, at the moment when the engagement between the movable clutch claw portion 11 and the fixed clutch claw portion 10 is disengaged, the rotation transmission to the main shaft 8 side is interrupted in the same manner as described above, so that the movable clutch claw portion is disconnected. Part 11
Are pushed back until they come into contact with the rubber pins 17, 17, and the engaging balls 16 in the respective control groove portions 14, 15 move from the first (loading) engaging positions 14c, 15c along the inclined surfaces 14b, 15b to the first position. It is located in the disengagement positions 14a, 15a of the clutch having the axial displacement in the engagement positions 14c, 15c (when loaded). As a result, the disengaged state of the engagement between the movable clutch claw portion 11 and the fixed clutch claw portion 10 is completed and the state is maintained. (See FIG. 8E) In this way, the additional tightening work is performed.
Also in this case, the fixed clutch claw portion 10 and the movable clutch claw portion 11
The disengagement operation of the engagement with and is smoothly and surely performed without producing mechanical noise or the like.

After that, when the main body of the electric screwdriver 1 is separated from the portion W to be tightened, the engaging balls 16 are released in the same manner as described above.
Is positively positioned in the second engagement positions 14d and 15d in the control groove portions 14 and 15, and returns to the initial state.

Although the present embodiment has been described with respect to an electric screwdriver, it can be easily applied to a pneumatic screwdriver.

(Effect) As described above, according to the present invention, the control groove portion between the movable clutch pawl portion and the main shaft in the clutch means and the engaging means engaging with the control groove portion can prevent metallic noise and the like generated when transmission of rotation of the clutch means is interrupted. While reducing noise as much as possible,
By positively controlling the positional relationship between the control groove and the engaging means that engages with it, even if the tightening is not tightened to the initially set tightening length, the follow-up tightening operation can be performed with the tightening completed. It can be done easily.

[Brief description of drawings]

FIG. 1 shows an embodiment of the present invention, FIG. 1 is a front sectional view including a partial breakage, FIG. 2 is a plan view of a main part, FIG. 3 is an exploded perspective view of the same part, and FIG. FIG. 5 is an enlarged plan view showing the control groove portion in a developed manner, FIG. 5 is a sectional view taken along line VV of FIG. 1, and FIG.
Sectional drawing which shows the operating state of the engaging means and the 2nd urging | biasing means which are shown, FIG. 7A-G is explanatory drawing which shows an operating state, and FIG. 8A-E shows an operating state at the time of overtightening. FIG. 1 ... Electric screwdriver 1a ... Housing, 6 ... Main gear 7 ... Driver bit, 8 ... Main shaft 9 ... Clutch means, 10 ... Fixed clutch pawl 11 ... Movable clutch pawl 14,15 ... Control groove 14a, 15a Release position 14b, 15b Slope 14c, d, 15c, d Engagement position 16 Engagement ball 18 First urging means 19 Second Biasing means 25 …… Adjusting sleeve

Claims (1)

[Claims] 1. An adjusting sleeve mounted at a front end portion of a housing so as to adjust a position in an axial direction, and a main body rotatably and axially movably supported in the housing and rotated by a driving device. A gear, a main shaft that is supported coaxially with the main gear with respect to the housing, is rotatably and axially movably supported, and has a driver bit that is positioned in the adjusting sleeve; A fixed clutch portion interposed between the main shaft and the main gear side, and provided on the main shaft side so as to cooperate with the axial movement of the main shaft and always fixed by the first biasing means. In an electric screwdriver provided with a clutch means including a movable clutch portion biased in a direction away from the clutch portion, the movable clutch portion of the clutch means and the main shaft are opposed to each other. A groove portion is formed in the portion, and an engaging means that engages with each other in the groove portion to engage and disengage the rotation transmission between the movable clutch portion and the main shaft is provided, and at least one groove portion of the groove portion is the A non-engagement position that disengages from the engagement means in correspondence with the engagement / disengagement movement of the clutch means, a slanted portion that displaces the engagement means axially from the disengaged position, and the slanted portion. A first engagement position under load that is continuous with the engagement portion and engages with the engagement means, a slanted portion that axially displaces the engagement means from the non-engaged position, and the slanted portion. And a control groove portion having a second engagement position when there is no load, which is provided with an obstacle portion that is continuously connected to the engagement means, and between the main shaft and the movable clutch portion. Is set to be weaker than the urging force of the first urging means, and the main shaft or the movable clutch portion is always Electric screw Wu driver Conjunction means characterized by being So設 the second biasing means for biasing in a direction to return rotated to engage the second engagement position when the no-load.