(19)
(11)EP 1 834 735 B1

(12)EUROPEAN PATENT SPECIFICATION

(45)Mention of the grant of the patent:
11.05.2011 Bulletin 2011/19

(21)Application number: 07004451.6

(22)Date of filing:  05.03.2007
(51)International Patent Classification (IPC): 
B25B 23/14(2006.01)
B25F 5/00(2006.01)
B25B 21/00(2006.01)

(54)

Electric power tool with a torque limiter

Elektrisch angetriebenes Werkzeug mit Drehmomentbegrenzung

Outil électrique à limitation de couple


(84)Designated Contracting States:
AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IS IT LI LT LU LV MC MT NL PL PT RO SE SI SK TR

(30)Priority: 07.03.2006 JP 2006061787

(43)Date of publication of application:
19.09.2007 Bulletin 2007/38

(73)Proprietor: Makita Corporation
Anjo-shi, Aichi-ken 446-8502 (JP)

(72)Inventor:
  • Tokunaga, Manabu c/o Makita Corporation
    Anjo-shi, Aichi-ken 446-8502 (JP)

(74)Representative: Kramer - Barske - Schmidtchen 
European Patent Attorneys Landsberger Strasse 300
80687 München
80687 München (DE)


(56)References cited: : 
EP-A1- 0 761 350
US-A1- 2004 231 952
EP-A1- 0 909 614
  
      
    Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention).


    Description

    BACKGROUND OF THE INVENTION


    Field of the Invention



    [0001] The present invention relates to a rotary fastening tool and typically to a rotary fastening tool with a torque limiter that interrupts torque transmission from the input side to the output side when torque acting on a tool bit reaches a set value.

    Description of the Related Art



    [0002] EP 0 761 350 A1 relates to a locking device for an output shaft of a power tool.

    [0003] US 2004/0231952 A1 relates to a spindle lock system for a power tool.

    [0004] EP 0 909 614 A1 relates to a lock device of an output shaft of a power tool.

    [0005] Japanese utility model publication No. 50-33759 discloses an electric screwdriver having a torque limiter that transmits torque from the input side to the output side. In the known art, a pair of clutches for torque limiter is provided between the input side and the output side. The clutches have clutch teeth formed in the respective clutch surfaces facing with each other and engage with each other in the direction of rotation. One of the clutches is biased toward the other by a spring member. During screw-tightening operation, when the screw head is seated on the workpiece, torque acting upon the output side clutch increases. When the torque reaches a set value, power is interrupted.

    [0006] In screw-tightening operation, a reaction force acts upon a housing that forms a driver body, in a direction opposite to the screw-tightening direction with respect to rotation on the axis of the tool bit Therefore, the user holds the driver body (the handgrip) while applying a force in the screw-tightening direction in such a manner as to prevent the driver body from rotating by the reaction force. However, in this state, when the torque limiter is actuated and the reaction force acting upon the driver body is instantaneously eliminated, as its reaction, the user's hand holding the driver body is caused to move in the screw-tightening direction. Thus, in the known electric screwdriver having a torque limiter, the driver body unexpectedly rotates just after actuation of the torque limiter. Therefore, further improvement in ease of use is desired.

    SUMMARY OF THE INVENTION



    [0007] Accordingly, it is an object of the invention to provide an effective technique for avoiding the influence of reaction during tightening operation in the rotary fastening tool.

    [0008] Above-described problem can be solved by a rotary fastening tool according claim 1.

    [0009] The rotation control mechanism allows the tip-end side rotating member to rotate in the tightening direction during the tightening operation of the tool bit. The rotation control mechanism may preferably be disposed between the tool body and the tip-end side rotating member. When the tip-end side rotating member is fixed to a workpiece with the tool bit during the tightening operation and when torque transmission from the driving-side rotating member to the driven-side rotating member is interrupted, the rotation control mechanism locks the tip-end side rotating member and the tool body together against rotation with respect to each other. As a result, the tool body is prevented from being rotated in the tightening direction, typically at the end of a tightening operation.

    [0010] During the operation of tightening such as screws or bolts, a reaction force acts upon a tool body in a direction opposite to the tightening direction. Therefore, the user of the rotary fastening tool tends to hold the tool body in such a manner as to prevent the tool body from rotating by the reaction force. However, in this state, reaction force acting upon the tool body is instantaneously eliminated for example as a result of a torque limiter, the user's hands holding the tool body is caused to move in the tightening direction as a result of a reaction. According to the invention, the rotation control mechanism prevents the tool body from rotating in the tightening direction by locking the tool body to the tip-end side rotating member which is trapped and fixed to the workpiece with the tool bit at an end of the tightening operation. Thus, the force applied by the user in the tightening direction can be supported by the tip-end side rotating member fixed on the workpiece side. Therefore, the user's hand holding the tool body can be prevented from being caused to move in the tightening direction for example just after actuation of the torque limiter.

    [0011] During the operation of loosening screws or bolts, by rotation of the driven-side rotating member in the loosening direction, the rotation control mechanism is disabled from performing the function of locking the tip-end side rotating member and the tool body together against rotation with respect to each other. Specifically, solely by driving the motor in the reverse direction, the rotation control mechanism can be disabled from performing the function of locking the tip-end side rotating member and the tool body. Therefore, there is no need to perform an additional operation for disabling the locking function of the rotation control mechanism, so that ease of operation in switching between tightening operation mode and loosening operation mode can be enhanced.

    [0012] Further, according to the representative rotary fastening tool, the motor may preferably be selectively driven both in a normal direction to perform a tightening operation and a reverse direction of rotation to perform a loosening operation by mode-selecting operation. During the loosening operation of the tool bit, the rotation control mechanism may be disabled from locking the tip-end side rotating member and the tool body by utilizing a rotation of the driven-side rotating member in the loosening direction. As a result, the tip-end side rotating member is allowed to rotate in the loosening direction to perform a loosening operation of the tool bit.

    [0013] As another aspect of the invention, the rotation control mechanism may include a rotation control member and a retainer. The rotation control member may be disposed between the tool body and the tip-end side rotating member. When the tip-end side rotating member is rotated in the tightening direction, the rotation control member allows said rotation. On the other hand, when the tip-end side rotating member is rotated in the loosening direction, the rotation control member engages with both the tool body and the tip-end side rotating member and is moved between an actuated position and a released position. In the actuated position, the tip-end side rotating member is locked to the tool body. In the released position, the engagement with the tool body and the tip-end side rotating member is released and the tip-end side rotating member can be freely rotate with respect to the tool body.

    [0014] The retainer may be disposed between the tool body and the tip-end side rotating member such that the retainer is allowed to rotate with respect to the tool body and the tip-end side rotating member. The retainer moves the rotation control member between the actuated position and the released position and retains the rotation control member in that position. Typically, the rotation control member may wedge in the tool body and the tip-end side rotating member to lock both members.

    [0015] When the motor is driven in the normal direction and the driven-side rotating member is rotated in the tightening direction, the driven-side rotating member may rotate the retainer in the tightening direction before rotationally driving the tip-end side rotating member to cause the retainer to move the rotation control member to the actuated position. As a result, when the tip-end side rotating member is rotated with respect to the tool body in the loosening direction, the retainer allows the rotation control member to lock the tip-end side rotating member and the tool body together. On the other hand, when the motor is driven in the reverse direction and the driven-side rotating member is rotated in the loosening direction, the driven-side rotating member rotates the retainer in the loosening direction before rotationally driving the tip-end side rotating member, which causes the retainer to move the rotation control member to the released position. As a result, the retainer disables the rotation control member from performing the function of locking the tip-end side rotating member and the tool body together and allows the loosening operation of the tool bit.

    [0016] According to the preferred aspect of the invention, when the driven-side rotating member rotates in the tightening direction or the loosening direction, the retainer is rotated in the tightening direction or the loosening direction before the tip-end side rotating member is rotated. Therefore, during tightening operation, the rotation control member is moved to the actuated position by the retainer and can ensure the function of locking the tool body to the tip-end side rotating member when the torque limiter is actuated. During loosening operation, the rotation control member is moved to the released position by the retainer and can be disabled from performing the function of locking the tool body to the tip-end side rotating member. Thus, the operation of tightening or loosening screws or bolts can be smoothly performed.

    [0017] As another aspect of the invention, the tip-end side rotating member may include a plane region in a predetermined extent in the circumferential direction. The rotation control member may include a member that has a circular section. During the tightening operation of the tool bit, when torque transmission is interrupted, the rotation control member moves toward one end of the plane region in the circumferential direction and engages with both the plane region and the inner wall surface of the tool body, thereby locking the tip-end side rotating member and the tool body together. Thus, rotation of the tool body in the tightening direction with respect to the tip-end side rotating member can be prevented. Further, the retainer may include an elastic element that biases the circular member toward the one end of the plane region in the circumferential direction.

    [0018] When the torque transmission is interrupted during the tightening operation, the tip-end side rotating member and the tool body can be locked by the wedging effect of the circular member that engages in (a narrow-angle portion) between the plane region of the tip-end side rotating member and the inner wall surface of the tool body. Further, the circular member is biased in the direction of such engagement by the biasing member so that the circular member can instantaneously and reliably achieve such engagement. The member having a circular section may typically include a rod-like element having a circular section or a spherical element When a rod-like element is used as the circular member, surface pressure exerted between the plane region of the tip-end side rotating member and the inner wall surface of the tool body during engagement can be reduced. As a result, the durability can be increased. When a spherical element is used as the circular member, ease of assembling can be enhanced.

    [0019] The torque limiter may include a plurality of first torque receiving parts and a plurality of first torque transmitting parts in the circumferential direction. The first torque receiving parts may be provided on the driven-side rotating member. The first torque transmitting parts may rotate together with the driving-side rotating member and transmit torque of the driving-side rotating member to the driven-side rotating member while being held in contact with the first torque receiving parts.

    [0020] Further, the rotary fastening tool may include a second torque receiving part that protrudes radially outward from the tip-end side rotating member, and a second torque transmitting part having a predetermined phase difference in the circumferential direction with respect to the second torque receiving part. The second torque transmitting part may rotate together with the driven-side rotating member and transmits torque of the driven-side rotating member to the tip-end side rotating member while being held in contact with the second torque receiving part. The rotary fastening tool may further include a third torque receiving part that protrudes from the retainer in the direction of a rotation axis of the driven-side rotating member, and a third torque transmitting part having a predetermined phase difference in the circumferential direction with respect to the third torque receiving part. The third torque transmitting part rotates together with the driven-side rotating member and transmits torque of the driven-side rotating member to the retainer while being held in contact with the third torque receiving part The terms of phase according to the invention may represent a phase of engagement in the direction of rotation or a phase with respect to the angle of engagement or a phase difference of the engagement angle in the direction of rotation between the torque transmitting part and the torque receiving part. In other words, it may represent a play region in which torque transmission is not effected in the direction of rotation.

    [0021] Further, a phase angle between the third torque receiving part and the third torque transmitting part in the circumferential direction may be larger than a phase angle between the first torque transmitting parts in the circumferential direction. With such configuration, when the torque transmission is interrupted during the tightening operation of the tool bit, the retainer is prevented from being rotated by rotation of the driven-side rotating member in the loosening direction. Thus, the rotation control member is held in the actuated position.

    [0022] Further, a phase angle between the third torque receiving part and the third torque transmitting part in the circumferential direction may be smaller than a phase angle between the second torque receiving part and the second torque transmitting part in the circumferential direction. With such configuration, during the tightening operation of the tool bit, the driven-side rotating member rotates the retainer in the tightening direction before rotationally driving the tip-end side rotating member. Thus, the rotation control member is moved to the actuated position. During the loosening operation of the tool bit, the driven-side rotating member rotates the retainer in the loosening direction before rotationally driving the tip-end side rotating member. Thus, the rotation control member is moved to the released position

    [0023] As described above, the driven-side rotating member and the tip-end side rotating member are connected to each other via a play region in which torque transmission is not effected due to a phase difference provided between the second torque receiving part and the second torque transmitting part in the circumferential direction (the direction of rotation). Further, the driven-side rotating member and the retainer are connected to each other via a play region in which torque transmission is not effected due to a phase difference provided between the third torque receiving part and the third torque transmitting part in the circumferential direction.

    [0024] During the tightening operation, when the torque transmission is interrupted or when the first torque receiving part of the driven-side rotating member is disengaged from the first torque transmitting part of the driving-side rotating member, a force acts upon the driven-side rotating member in a direction that causes the driven-side rotating member to rotate in the loosening direction. According to the invention, with the construction in which the play region between the driven-side rotating member and the retainer is larger than the intervals (the play region) between the plurality of the first torque transmitting parts, even if the driven-side rotating member is caused to rotate in the loosening direction when the torque limiter interrupts the torque transmission, this rotation of the driven-side rotating member can be limited within the play region between the driven-side rotating member and the retainer. Therefore, rotation of the driven-side rotating member does not affect the retainer. Specifically, during the tightening operation, the rotation control member can be held in the actuated position, so that the locking function of the rotation control member can be maintained.

    [0025] Further, according to the invention, the play region between the driven-side rotating member and the retainer is smaller than the play region between the driven-side rotating member and the tip-end side rotating member. With this configuration, when the driven-side rotating member starts to rotate in the tightening direction or the loosening direction, the retainer can be rotated in the tightening direction or the loosening direction before the tip-end side rotating member is rotated. Thus, it can be ensured that rotation of the retainer positively precedes rotation of the tip-end side rotating member at the time of mode change between tightening operation and loosening operation.

    [0026] The retainer may preferably be held by friction by the elastic member in such a manner as to be prevented from rotating with respect to the tip-end side rotating member unless rotated by the driven-side rotating member rotating in the loosening direction. The retainer can be prevented from freely moving so that its proper functioning can be ensured. The elastic member may typically include an O-ring or a torsion spring.

    [0027] Other objects, features and advantages of the present invention will be readily understood after reading the following detailed description together with the accompanying drawings and the claims.

    BRIEF DESCRIPTION OF THE DRAWINGS



    [0028] 

    FIG. 1 is a sectional side view schematically showing an entire electric screwdriver according to an embodiment of the invention.

    FIG. 2 is a sectional view of an essential part of the screwdriver, showing the construction of a torque limiter, a first spindle, a second spindle and a one-way clutch.

    FIG. 3 is a schematic view of the torque limiter in development

    FIG. 4 is a side view of a driven-side clutch member of the torque limiter.

    FIG. 5 is a side view of a driving-side clutch member of the torque limiter.

    FIG. 6 is a sectional view taken along line A-A in FIG. 2.

    FIG. 7 is a sectional view taken along line B-B in FIG. 2.

    FIG. 8 is a sectional view taken along line C-C in FIG. 2.

    FIG. 9 is a graph showing the relationship between the torque and time during tightening operation (normal rotation).

    FIG. 10 is a view illustrating the operations of the torque limiter, the first and second spindles and the one-way clutch during tightening operation (normal rotation).

    FIG. 11 is a view illustrating the operations of the torque limiter, the first and second spindles and the one-way clutch during tightening operation (normal rotation).

    FIG. 12 is a view illustrating the operations of the torque limiter, the first and second spindles and the one-way clutch during tightening operation (normal rotation).

    FIG. 13 is a view illustrating the operations of the torque limiter, the first and second spindles and the one-way clutch during loosening operation (reverse rotation).

    FIG. 14 is a view illustrating the operations of the torque limiter, the first and second spindles and the one-way clutch during loosening operation (reverse rotation).

    FIG. 15 is a view illustrating the operations of the torque limiter, the first and second spindles and the one-way clutch during loosening operation (reverse rotation).


    DETAILED DESCRIPTION OF THE INVENTION



    [0029] A representative embodiment of the invention will now be described with reference to the drawings. FIG. 1 shows an entire electric screwdriver 100 as a representative embodiment of the rotary fastening tool according to the present invention. The screwdriver 100 includes a body 101, a driver bit 119 detachably coupled to the tip end region (on the left side as viewed in FIG. 1) of the body 101 via a tool holder 141, and a handgrip (handle 107 connected to the body 101. In the present embodiment, for the sake of convenience of explanation, the side of the driver bit 119 is taken as the front side and the opposite side as the rear side.

    [0030] The body 101 includes a motor housing 103 that houses a driving motor 111, and a gear housing 105 that houses a speed reducing mechanism 113, a torque limiter 120, a first spindle 130, a second spindle 140 and a one-way clutch 150. The driving motor 111 is driven when a trigger 107a on the handgrip 107 is depressed. The direction of rotation of the motor shaft of the driving motor 111 can be selected between normal rotation (clockwise forward or "screw-tightening direction") and reverse rotation (counterclockwise forward or "screw-loosening direction") by operating a rotation selection switch (not shown).

    [0031] The rotating output of the driving motor 111 is transmitted from a power transmitting mechanism in the form of the speed reducing mechanism 113 to the second spindle 140 as a rotating force via a rotation drive disc 115, the torque limiter 120 and the first spindle 130. The tool holder 141 is disposed in the tip end region of the second spindle 140 and rotates together with the second spindle 140. The driver bit 119 held by the tool holder 141 is rotationally driven together with the tool holder 141. The speed reducing mechanism 113 comprises a planetary gear mechanism, but the construction is a known art and therefore will not be described in detail. Further, the rotation drive disc 115 corresponds to a carrier that supports planetary gears of the planetary gear mechanism for free rotation, and forms an output shaft of the speed reducing mechanism 113. The rotation drive disc 115, the torque limiter 120, the first spindle 130, the second spindle 140 and the one-way clutch 150 are all disposed on the same axis.

    [0032] FIG. 2 shows the construction of the torque limiter 120, the first spindle 130, the second spindle 140 and the one-way clutch 150. The torque limiter 120 includes a driving-side clutch member 121 and a driven-side clutch member 123 which face each other, a plurality of first steel balls 125, and a compression coil spring 127. The first steel balls 125 are disposed between the clutch members 121 and 123 and serve to transmit torque of the driving-side clutch member 121 to the driven-side clutch member 123. The compression coil spring 127 serves as a biasing member for biasing the driven-side clutch member 123 toward the driving-side clutch member 121.

    [0033] The driving-side clutch member 121 is mounted on the rotation drive disc 115 such that it is prevented from moving in the axial direction and from rotating on the axis (in the direction of rotation) with respect to the rotation drive disc 115. The driven-side clutch member 123 is fitted on the rear end portion (on the right side as viewed in FIG. 1) of the first spindle 130 in the axial direction. Elongated grooves 130a and 123a are formed in the outside surface of the first spindle 130 and the inside surface of the driven-side clutch member 123, respectively, and extend to a predetermined length in the axial direction. A second steel ball 128 is disposed in the elongated grooves 130a, 123a. Thus, the driven-side clutch member 123 is allowed to move in the axial direction while being prevented from rotating on the axis with respect to the first spindle 130.

    [0034] FIG. 3 shows the torque limiter 120 in development. As shown in FIG. 3, three spherical recesses 123b are formed in the rear side surface (the lower surface as viewed in FIG. 3) of the driven-side clutch member 123 and arranged equidistantly in the circumferential direction (at intervals of 120 degrees). The recesses 123b receive the first steel balls 125. An annular groove 121a is formed corresponding to the travel path of the first steel balls 125 in the front side surface of the driving-side clutch member 121. Six mountain-like cams 121b are formed in the annular groove 121a and arranged equidistantly in the circumferential direction (at intervals of 60 degrees). FIG. 4 shows the driven-side clutch member 123 in side view, and FIG. 5 shows the driving-side clutch member 121 in side view. Each of the first steel balls 125 held by the driven-side clutch member 123 is movably fitted in the annular groove 121a of the driving-side clutch member 121. The first steel ball 125 transmits the torque of the driving-side clutch member 121 to the driven-side clutch member 123 when the first steel ball 125 engages with the associated cam 121b from the circumferential direction. When the torque (rotational load) acting upon the first steel ball 125 exceeds a set value, the first steel ball 125 climbs over the cam 121b while moving the driven-side clutch member 123 away from the driving-side clutch member 121 against the spring force of the compression coil spring 127. As a result, the first steel ball 125 is disengaged from the cam 121b, so that the torque transmission from the driving-side clutch member 121 to the driven-side clutch member 123 is interrupted. The first steel ball 125 and the cam 121b are features that correspond to the "first torque receiving part" and the "first torque transmitting part", respectively, according to this invention.

    [0035] As shown in FIG. 2, the compression coil spring 127 is disposed between the front surface of the driven-side clutch member 123 and a spring receiving member 129 threadably mounted on the first spindle 130. The compression coil spring 127 can change its position with respect to the first spindle 130 in the axial direction by rotating a nut 129a disposed on the front side of the spring receiving member 129. In this manner, the compression coil spring 127 can change its biasing force in order to adjust the torque setting for interruption of torque transmission.

    [0036] A carrier 131 is disposed on the side of the front end portion of the first spindle 130 in the axial direction and rotates together with the first spindle 130. The first spindle 130 is connected to the second spindle 140 via the carrier 131. The carrier 131 includes a square shank 133 and a cylindrical portion 135. The square shank 133 is inserted into a square hole 130b of the first spindle 130, so that the carrier 131 rotates together with the first spindle 130. As shown in FIGS. 2 and 8, the cylindrical portion 135 of the carrier 131 is disposed in the outside region of the axial rear end portion of the second spindle 140. Two radially outwardly protruding driven-side claws 143 are formed in the rear end portion of the second spindle 140 with a phase difference of 180 degrees in the circumferential direction.

    [0037] In a corresponding manner, two radially inwardly protruding driving-side claws 135a are formed in the inside surface of the cylindrical portion 135 of the carrier 131 with a phase difference of 180 degrees in the circumferential direction. When the carrier 131 is caused to rotate together with the first spindle 130 in the normal direction (tightening direction) or the reverse direction (loosening direction), the driving-side claws 135a contact the driven-side claws 143 and transmit the torque of the first spindle 130 to the second spindle 140. The driven-side claws 143 and the driving-side claws 135a are features that correspond to the "second torque receiving part" and the "second torque transmitting part", respectively, according to this invention. One driven-side claws 143 in contact with one driving-side claw 135a is positioned at a predetermined phase angle α1 in the circumferential direction from the other driving-side claw 135a in contact with the other driven-side claw 143. Thus, the carrier 131 and the second spindle 140 are connected to each other via a play region in which torque transmission is not effected in the circumferential direction (see FIG. 8).

    [0038] As mainly shown in FIGS. 2, 6 and 7, one-way clutch 150 includes a fixed ring 151 fitted in the gear housing 105, a plurality of (four in this embodiment) needle pins 153 and a retainer 155 for holding the needle pins 153. The needle pins 153 are disposed between the fixed ring 151 and the second spindle 140 and serve to allow the second spindle 140 to rotate in the normal direction and prevent it from rotating in the reverse direction. The needle pins 153 correspond to the "rotation control member" and the "member having a circular section" according to this invention.

    [0039] The fixed ring 151 has an annular inner peripheral surface 151a having an inside diameter slightly larger than the outside diameter of the retainer 155. Four planar regions 140a having a predetermined width are formed in the outer peripheral surface of the second spindle 140 and arranged equidistantly (at intervals of 90 degrees) in the circumferential direction. The needle pins 153 are disposed between the planar regions 140a and the inner peripheral surface 151 a of the fixed ring 151. The planar regions 140a correspond to the "plane region" according to this invention. The needle pins 153 are disposed such that its axial direction coincides with the axial direction of the second spindle 140.

    [0040] Space 156 is formed between the planar region 140a of the second spindle 140 and the inner peripheral surface 151a of the fixed ring 151. The radial width of the space 156 is at the maximum in the middle of the planar region 140a in the circumferential direction and at the minimum at the ends of the planar region 140a. Each of the needle pins 153 has the outside diameter smaller than the maximum width of the space 156 and larger than the minimum width of the space 156. The needle pin 153 is thus allowed to move between the minimum width position and the maximum width position in the space 156. In the state in which the needle pin 153 is in the minimum width position, when the second spindle 140 rotates in the normal direction (tightening direction), the needle pin 153 is pushed back toward the maximum width position and allows the second spindle 140 to rotate in the tightening direction.

    [0041] On the other hand, when the second spindle 140 rotates in the reverse direction (loosening direction), the needle pin 153 engages in the planar region 140a and the inner peripheral surface 151a, so that the second spindle 140 and the fixed ring 151 are locked together. Thus, the second spindle 140 is prevented from rotating. In the state in which the needle pin 153 is in the maximum width position, the needle pin 153 is disengaged from the planar region 140a and the inner peripheral surface 151a, so that the second spindle 140 is allowed to rotate both in the tightening direction and the loosening direction. The minimum width position and the maximum width position respectively correspond to the "actuated position" and the "released position" according to the invention.

    [0042] The retainer 155 is generally cylindrically shaped and disposed between the fixed ring 151 and the second spindle 140 and can rotate with respect to both the fixed ring 151 and the second spindle 140. An O-ring 158 is disposed between the inner peripheral surface of the retainer 155 and the outer peripheral surface of the second spindle 140. Thus, the retainer 155 is provided with frictional resistance to rotation with respect to the second spindle 140. Therefore, unless forcibly torqued, the retainer 155 is held on the second spindle 140. The O-ring 158 is a feature that corresponds to the "elastic member" according to this invention. Four recesses 155a for retaining the needle pins 153 are formed in the retainer 155 and arranged at intervals of 90 degrees in the circumferential direction. Each of the recesses 155a has a notch-like shape having a predetermined depth extending forward from the axial rear end of the retainer 155. Each of the needle pins 153 is allowed to move between the minimum width position and the maximum width position within the associated recess 155a. Further, the needle pin 153 is normally biased toward one end of the planar region 140a in the circumferential direction or toward the minimum width position by a flat spring 157 mounted on the retainer 155. When the driving motor 111 is not driven, the needle pin 153 is held in the minimum width position.

    [0043] Further, the retainer 155 has two rotation following pins 159 protruding to the carrier 131 side in order to be caused to rotate following the second spindle 140 when the second spindle 140 rotates. The rotation following pins 159 are disposed in the retainer 155 at intervals of 180 degrees in the circumferential direction. Correspondingly, two notch-like recesses 135b (see FIG. 8) are formed in the cylindrical portion 135 of the carrier 131 at intervals of 180 degrees in the circumferential direction. Each of the recesses 135b has a predetermined length in the circumferential direction. The protruding portion of each of the rotation following pins 159 is disposed within the associated recess 135b. When the carrier 131 rotates, the rotation following pin 159 is pushed by the carrier 131 in the circumferential direction in contact with an engagement surface 135c for normal rotation or an engagement surface 135d for reverse rotation which extends in a direction crossing the circumferential direction of the recess 135b. Thus, the retainer 155 is caused to rotate following the carrier 131. The rotation following pin 159 and the normal and reverse rotation engagement surfaces 135c, 135d are features that respectively correspond to the "third torque receiving part" and the "third torque transmitting part" according to the invention.

    [0044] A predetermined phase angle α2 is provided in the circumferential direction between the rotation following pin 159 in contact with one of the engagement surfaces 135c, 135d and the other of the engagement surfaces 135c,135d in the recess 135b (see FIG. 8). Thus, the carrier 131 and the retainer 155 are connected to each other via a play region in which torque transmission is not effected in the circumferential direction. The phase angle α2 between the rotation following pin 159 and the engagement surface 135c or 135d is larger than the intervals (the phase angle of60 degrees) between the cams 121b of the torque limiter 120 and smaller than the phase angle α1 between the driven-side claw 143 and the driving-side claw 135a.

    [0045] Operation and usage of the electric screwdriver 100 according to this embodiment will now be explained. First, an operation of tightening screws (not shown) will be explained with reference mainly to FIGS. 9 to 12. The driving motor 111 is driven in the normal direction of rotation (clockwise) with a screw pressed against the workpiece via the driver bit 119. Then, the second spindle 140 is rotationally driven in the normal direction via the speed reducing mechanism 113, the torque limiter 120, the first spindle 130 and the carrier 131. Thus, the screw-tightening operation is performed via the tool holder 141 that rotates together with the second spindle 140, and the driver bit 119.

    [0046] FIG. 9 is a graph showing the relationship between the torque and time during tightening operation (normal rotation). In the graph, step 1 represents a step just before actuation of the torque limiter 120 (just before interruption of torque transmission), step 2 is a step just after actuation of the torque limiter 120 (just after interruption of torque transmission), and step 3 is a step following step 2 after a lapse of a short period of time. Further, FIGS. 10 to 12 show the states in steps 1 to 3, respectively, with the torque limiter 120 shown at right, the carrier 131 and the second spindle 140 in the middle, and the one-way clutch 150 at left.

    [0047] In step 1 as shown in FIG. 10, the driven-side clutch member 123 is placed in engagement with the cams 121 b of the driving-side clutch member 121 via the first steel balls 125, so that the torque transmission of the torque limiter 120 is maintained. In this torque transmission state, the normal rotation engagement surfaces 135c of the carrier 131 that rotates together with the first spindle 130 are in contact with the rotation following pins 159 of the retainer 155. Therefore, the retainer 155 rotates in the tightening direction (clockwise). Further, the driving-side claws 135a of the carrier 131 are in contact with the driven-side claws 143 of the second spindle 140. Therefore, the second spindle 140 rotates in the tightening direction (clockwise) together with the carrier 131. In this state, in the one-way clutch 150, the needle pins 153 held in the minimum width position are pushed back to the maximum width position, so that the second spindle 140 is allowed to rotate. This state remains unchanged from the start to the final stage of the screw-tightening operation in which the seating surface of the screw head is seated on the workpiece.

    [0048] When a screw is fastened to the workpiece with the seating surface of the screw head seated on the workpiece, the torque (rotational load) acting upon the first spindle 130 via the second spindle 140 and the carrier 131 exceeds a set value. Then, the torque limiter 120 is actuated, which brings about the state of step 2 and then the state of step 3. Specifically, as shown in FIG. 11, the first steel balls 125 climb over the cams 121 b while moving the driven-side clutch member 123 away from the driving-side clutch member 121 against the spring force of the compression coil spring 127. As a result, the torque transmission is interrupted. In the torque limiter 120, immediately after the torque transmission, a force acts upon the driven-side clutch member 123 in a direction that causes the driven-side clutch member 123 to rotate in the loosening direction (counterclockwise) (see the torque limiter 120 shown at right in FIGS. 11 and 12). As a result, the carrier 131 is caused to rotate in the loosening direction.

    [0049] Therefore, in this embodiment, the phase angle α2 between the rotation following pin 159 of the retainer 155 and the engagement surface 135c that transmits the torque of the carrier 131 in contact with the rotation following pin 159 is larger than the intervals (of 60 degrees) between the cams 121b. With this construction, even if the carrier 131 is caused to rotate in the loosening direction when the torque limiter 120 is actuated to interrupt the torque transmission, the rotation of the carrier 131 is avoided from causing the retainer 155 to rotate (see the drawings shown in the middle of FIGS. 11 and 12). Specifically, the retainer 155 stops together with the second spindle 140 and holds the needle pins 153 in the minimum width position. In this state, when a force acts upon the fixed ring 151 in a direction that causes the fixed ring 151 to rotate in the tightening direction (clockwise), each of the needle pins 153 engages in the planar region 140a of the second spindle 140 and the inner peripheral surface 151a of the fixed ring 151, so that the second spindle 140 and the fixed ring 151 are locked together. Thus, the fixed ring 151 is prevented from rotating in the tightening direction by actuation of the one-way clutch 150.

    [0050] When a tightening operation is performed by using the screwdriver 100, a reaction force acts upon the body 101 in a direction opposite to the tightening direction with respect to rotation on the axis of the driver bit 119. Therefore, the user holds the handgrip 107 in such a manner as to prevent the body 101 from being caused to rotate by the reaction force (i.e. the user applies a force in the tightening direction). In this state, when the torque limiter 120 is actuated and the reaction force on the body 101 is instantaneously eliminated, as its reaction, the user's hand holding the handgrip 107 may be caused to move in the tightening direction. At this time, according to this embodiment, as described above, the one-way clutch 150 prevents the body 101 (the fixed ring 151) from rotating in the tightening direction. Thus, the force applied by the user in the tightening direction can be supported by the second spindle 140 fixed on the workpiece side. Therefore, the user's hand holding the handgrip 107 can be prevented from moving in the tightening direction just after actuation of the torque limiter 120.

    [0051] Screw-loosening operation is explained with reference mainly to FIGS. 13 to 15. The driving motor 11 is driven in the reverse direction of rotation (counterclockwise) with the driver bit 119 pressed against a screw to be loosened. FIG. 13 shows the state just after the start of rotation in the reverse direction. In the torque limiter 120, the first steel balls 125 held by the driven-side clutch member 123 engage with the cams 121b of the driving-side clutch member 121, so that the carrier 131 is rotated together with the first spindle 130 in the reverse direction. FIG. 14 shows an advanced state of the reverse rotation. When the carrier 131 is rotated, the reverse rotation engagement surface 135d of the carrier 131 contacts the rotation following pin 159 of the retainer 155. Thereafter, the driving-side claw 135a of the carrier 131 contacts the driven-side claw 143 of the second spindle 140. Specifically, with the construction in which the phase angle (engagement angle) α2 for contact (engagement) between the engagement surface 135d and the rotation following pin 159 in the direction of rotation is smaller than the phase angle (engagement angle) α1 for contact (engagement) between the driving-side claw 135a and the driven-side claw 143 in the direction of rotation, contact between the engagement surface 135d and the rotation following pin 159 precedes contact between the driving-side claw 135a and the driven-side claw 143.

    [0052] When the retainer 155 is caused to rotate in the reverse direction by contact between the engagement surface 135d and the rotation following pin 159, the needle pin 153 in the recess 155a of the retainer 155 is pushed by the wall surface 155b of the recess 155a and moved from the minimum width position to the maximum width position of the space 156 formed between the planar region 140a of the second spindle 140 and the inner peripheral surface 151a of the fixed ring 151. As shown at left in FIG. 15, when the needle pin 153 is moved to the maximum width position of the space 156, the needle pin 153 is disengaged from the fixed ring 151 and the second spindle 140. As a result, the function of the one-way clutch 150 is disabled and the second spindle 140 is allowed to rotate. Thereafter, the driving-side claw 135a of the carrier 131 contacts the driven-side claw 143 of the second spindle 140, so that the torque of the carrier 131 is transmitted to the second spindle 140. Thus, the screw-loosening operation is smoothly performed.

    [0053] As described above, during the screw-tightening operation, the one-way clutch 150 disposed between the second spindle 140 and the gear housing 105 can eliminate the problem of reaction which may be caused when the torque limiter 120 is actuated. Further, during the loosening operation, the engaging function of the one-way clutch 150 can be automatically disabled, so that the loosening operation is smoothly performed. Particularly, in this embodiment, when the driving motor 111 is driven in the reverse direction of rotation, the engaging function of the one-way clutch 150 can be automatically disabled by utilizing rotation of the carrier 131 driven in the reverse direction. Therefore, the need to perform an additional operation for disabling the engaging function of the one-way clutch 150 can be eliminated, so that ease of operation in switching between tightening operation mode and loosening operation mode can be enhanced.

    [0054] Further, according to this embodiment, in the tightening operation in which the second spindle 140 is rotationally driven in the tightening direction, the second spindle 140 and the fixed ring 151 can be reliably locked by the wedging effect of the needle pin 153 that engages in (a narrow-angle portion) between the planar region 140a of the second spindle 140 and the inner peripheral surface 151a of the fixed ring 151 when the torque limiter 120 is actuated. Further, the needle pin 153 is biased toward the minimum width position by the flat spring 157, so that the needle pin 153 can be instantaneously and reliably engaged between the planar region 140a and the inner peripheral surface 151a.

    [0055] Further, in this embodiment, with the construction in which the retainer 155 is held on the second spindle 140 via the O-ring 158 by friction, the retainer 155 can be prevented from freely moving, unless forcibly rotated by the carrier 131 rotating in the loosening direction. Thus, the proper functioning of the one-way clutch 150 can be ensured

    [0056] Further, in this embodiment, the electric screwdriver 100 having the torque limiter 120 is described as an example of the rotary fastening tool of the present invention. However, this invention can also be applied to any other rotary fastening tool having the torque limiter 120.

    Description of Numerals



    [0057] 
    100
    electric screwdriver
    101
    body
    103
    motor housing
    105
    gear housing
    107
    handgrip
    107a
    trigger
    111
    driving motor
    113
    speed reducing mechanism
    115
    rotation drive disc
    119
    driver bit
    120
    torque limiter
    121
    driving-side clutch member
    121a
    annular groove
    121b
    cam
    123
    driven-side clutch member
    123a
    elongated groove
    123b
    recess
    125
    first steel ball
    127
    compression coil spring
    128
    second steel ball
    129
    spring receiving member
    129a
    nut
    130
    first spindle
    130a
    elongated groove
    130b
    square hole
    131
    carrier
    133
    square shank
    135
    cylindrical portion
    135a
    driving-side claw
    135b
    recess
    135c, 135d
    engagement surface
    140
    second spindle
    140a
    planar region
    141
    tool holder
    143
    driven-side claw
    150
    one-way clutch
    151
    fixed ring
    151a
    inner peripheral surface
    153
    needle pin
    155
    retainer
    155a
    recess
    155b
    wall surface
    156
    space
    157
    flat spring
    158
    O-ring
    159
    rotation following pin



    Claims

    1. A rotary fastening tool comprising
    a tool body (101),
    a motor (111) housed within the tool body (101),
    a driving-side rotating member (121) that is rotationally driven by The motor (111),
    a driven-side rotating member (123) that is disposed coaxially with the driving-side rotating member (121),
    a tip-end side rotating member (140) that is disposed coaxially with the driven-side rotating member (123) and rotationally driven via the driven-side rotating member (123), the tip-end side rotating member (140) driving a tool bit (119) to perform a tightening operation,
    a rotation control mechanism (150) that allows the tip-end side rotating member (140) to rotate in the tightening direction during the tightening operation of the tool bit (119), and a torque limiter (120) that transmits torque of the driving-side rotating member (121) to the driven-side rotating member (123) when the torque acting upon the driven-side rotating member (123) is lower than a predetermined set value, while interrupting the torque transmission when the torque acting upon the driven-side rotating member (123) exceeds the set value
    characterized in that, when the tip-end side rotating member (140) is fixed to a workpiece with the tool bit (119) during the tightening operation and when torque transmission from the driving-side rotating member (121) to the driven-side rotating member (123) is interrupted by the torque limiter (120), a force acts upon the driven-side rotating member (123) in a direction that causes the driven-side rotating member (123) to rotate in a loosening direction, whereby the rotation control mechanism (150) locks the tip-end side rotating member (140) and the tool body (101) together against rotation with respect to each other to prevent the tool body (101) from rotating in the tightening direction.
     
    2. The rotary fastening tool as defined in Claim 1 wherein the motor (111) is driven either in a normal direction to perform a tightening operation or a reverse direction of rotation to perform a loosening operation by mode-selecting operation, and
    wherein, during the loosening operation of the tool bit (119), the rotation control mechanism (150) is disabled from locking the tip-end side rotating member (140) and the tool body (101) by utilizing a rotation of the driven-side rotating member (123) in the loosening direction to allow the loosening operation of the tool bit (119).
     
    3. The rotary fastening tool as defined in claim 1 or 2, wherein the rotation control mechanism (150) comprises
    a rotation control member (153) disposed between the tool body (101) and the tip-end side rotating member (140), the rotation control member (153) being provided with an actuated position and a released position wherein the rotation control member (153) in the actuated position locks the tip-end side rotating member (140) and the tool body (101) when the tip-end side rotating member (140) is rotated in the loosening direction during the tightening operation, while the rotation control member (153) in the released position releases the locking between the tip-end side rotating member (140) and the tool body (119).
     
    4. The rotary fastening tool as defined in claim 3, wherein the rotation control mechanism (150) comprises a retainer (155) that is disposed between the tool body (101) and the tip-end side rotating member (140) such that the retainer (155) is allowed to rotate with respect to the tool body (101) and the tip-end side rotating member (140) and wherein the retainer (155) moves the rotation control member (153) between the actuated position and the released position and retains the rotation control member (153) in that position,
     
    5. The rotary fastening tool as defined in claim 4, wherein, when the motor (111) is driven in the normal direction and the driven-side rotating member (123) is rotated in the tightening direction, the driven-side rotating member rotates (123) the retainer (155) in the tightening direction before rotationally driving the tip-end side rotating member (140) and the retainer (155) moves the rotation control member (153) to the actuated position.
     
    6. The rotary fastening tool as defined in claim 4 or 5, wherein, when the motor (111) is driven in the reverse direction and the driven-side rotating member (123) is rotated in the loosening direction, the driven-side rotating member (123) rotates the retainer (155) in the loosening direction before rotationally driving the tip-end side rotating member (140) and the retainer (155) moves the rotation control member (153) to the released position.
     
    7. The rotary fastening tool as defined in any one of claims 3 to 6, wherein
    the tip-end side rotating member (140) has a plane region (140a) in a predetermined extent in the circumferential direction,
    the rotation control member (153) comprises a member having a circular section (153), wherein, during the tightening operation of the tool bit (119), when the torque limiter (120) interrupts the torque transmission, the rotation control member (153) moves toward one end of the plane region (140a) in the circumferential direction and engages with both the plane region (140a) and a inner wall surface of the tool body (101), thereby locking the tip-end side rotating member (140) and the tool body (101) together and controlling rotation of the tool body (101) in the tightening direction with respect to the tip-end side rotating member (140), and
    the retainer (155) has an elastic element (157) that biases the circular member (153) toward the one end of the plane region (140a) in the circumferential direction.
     
    8. The rotary fastening tool as defined in any one of claims 1 to 7, wherein:

    the torque limiter (120) includes a plurality of first torque receiving parts (125) and a plurality of first torque transmitting parts (121b) in the circumferential direction, wherein the first torque receiving parts (125) are provided on the driven-side rotating member (123) and the first torque transmitting parts (121b) rotate together with the driving-side rotating member (121) and transmit torque of the driving-side rotating member (121) to the driven-side rotating member (123) while being held in contact with the first torque receiving parts (125), and

    the rotary fastening tool further includes

    a second torque receiving part (143) that protrudes radially outward from the tip-end side rotating member (140),

    a second torque transmitting part (135a) having a predetermined phase difference in the circumferential direction with respect to the second torque receiving part (143), wherein the second torque transmitting part rotates (135a) together with the driven-side rotating member (123) and transmits torque of the driven-side rotating member (123) to the tip-end side rotating member (140) while being held in contact with the second torque receiving part (143),

    a third torque receiving part (159) that protrudes from the retainer (155) in the direction of a rotation axis of the driven-side rotating member (123), and

    a third torque transmitting part (135c, 135d) having a predetermined phase difference in the circumferential direction with respect to the third torque receiving part (159), wherein the third torque transmitting part (135c, 135d) rotates together with the driven-side rotating member (123) and transmits torque of the driven-side rotating member (123) to the retainer (155) while being held in contact with the third torque receiving part (159),

    wherein a phase angle between the third torque receiving part (159) and the third torque transmitting part (135c, 135d) in the circumferential direction is larger than a phase angle between the first torque transmitting parts (121b) in the circumferential direction, and

    a phase angle between the third torque receiving part (159) and the third torque transmitting part (135c, 135d) in the circumferential direction is smaller than a phase angle between the second torque receiving part (143) and the second torque transmitting part (135a) in the circumferential direction.


     
    9. The rotary fastening tool as defined in any one of claims 4 to 8, wherein the retainer (155) is held by friction by the elastic member (158) in such a manner as to be prevented from rotating with respect to the tip-end side rotating member (140) unless rotated by the driven-side rotating member (123) rotating in the loosening direction.
     
    10. The rotary fastening tool as defined in any one of claims 1 to 9, wherein the rotary fastening tool is provided as an electric screw driver to drive a driver bit (119) for tightening and/or loosening a screw.
     


    Ansprüche

    1. Drehendes Befestigungswerkzeug, mit
    einem Werkzeugkörper (101),
    einem Motor (111), der in dem Werkzeugkörper (101) angeordnet ist,
    einem antriebseitigen Drehbauteil (121), das drehend durch den Motor (111) angetrieben wird,
    einem angetriebenenseitigen Drehbauteil (123), das koaxial zu dem antriebseitigen Drehbauteil (121) angeordnet ist,
    einem spitzenendseitigen Drehbauteil (140), das koaxial zu dem angetriebenenseitigen Drehbauteil (123) angeordnet ist und über das angetriebenenseitige Drehbauteil (123) drehend angetrieben wird, wobei das spitzenendseitige Drehbauteil (140) ein Werkzeugbit (119) zum Ausführen eines Festziehvorgangs antreibt,
    einem Drehungssteuerungsmechanismus (150), der es dem spitzenendseitigen Drehbauteil (140) ermöglicht, sich während des Festziehvorgangs des Werkzeugbits (119) in der Festziehrichtung zu drehen, und
    einem Drehmomentbegrenzer (120), der ein Drehmoment des antriebseitigen Drehbauteils (121) an das angetriebenenseitige Drehbauteil (123) überträgt, wenn das Drehmoment, das auf das angetriebenenseitige Drehbauteil (123) wirkt, kleiner als ein vorbestimmter Einstellwert ist, während er die Drehmomentübertragung unterbricht, wenn das Drehmoment, das auf das angetriebenenseitige Drehbauteil (123) wirkt, den Einstellwert übersteigt,
    dadurch gekennzeichnet, dass, wenn das spitzenendseitige Drehbauteil (140) während des Festziehvorgangs an ein Werkstück mit dem Werkzeugbit (119) angebracht ist und wenn die Drehmomentübertragung von dem antriebseitigen Drehbauteil (121) an das angetriebenenseitige Drehbauteil (123) durch den Drehmomentbegrenzer (120) unterbrochen ist, eine Kraft auf das angetriebenenseitige Drehbauteil (123) in einer Richtung wirkt, die verursacht, dass sich das angetriebenenseitige Drehbauteil (123) in einer Löserichtung dreht, wobei der Drehungssteuermechanismus (150) das spitzenendseitige Drehbauteil (140) und den Werkzeugkörper (101) miteinander gegen eine Drehung im Bezug zueinander verriegelt, um den Werkzeugkörper (101) von einer Drehung in der Festziehrichtung abzuhalten.
     
    2. Drehendes Befestigungswerkzeug nach Anspruch 1, bei dem der Motor (111) durch einen Betriebsartauswählvorgang entweder in einer normalen Richtung zum Ausführen eines Festziehvorgangs oder in einer umgekehrten Drehrichtung zum Ausrühren eines Lösevorgangs angetrieben wird, und
    bei dem während des Lösevorgangs des Werkzeugbits (119) der Drehungssteuermechanismus (150) vom Verriegeln des spitzenendseitigen Drehbauteils (140) und des Werkzeugkörpers (101) durch Nutzen einer Drehung des angetriebenenseitigen Drehbauteils (123) in der Löserichtung blockiert ist, um den Lösevorgang des Werkzeugbits (119) zu ermöglichen.
     
    3. Drehendes Befestigungswerkzeug nach Anspruch 1 oder 2, bei dem der Drehungssteuermechanismus (150)
    ein Drehungssteuerbauteil (153) aufweist, das zwischen dem Werkzeugkörper (101) und dem spitzenendseitigen Drehbauteil (140) angeordnet ist, wobei das Drehungssteuerbauteil (153) eine Betätigungsposition und eine gelöste Position einnehmen kann, wobei das Drehungssteuerbauteil (153) in der Betätigungsposition das spitzenendseitige Drehbauteil (140) und den Werkzeugkörper (101) verriegelt, wenn das spitzenendseitige Drehbauteil (140) während des Festziehvorgangs in der Löserichtung gedreht wird, während das Drehungssteuerbauteil (153) in der gelösten Position die Verriegelung zwischen dem spitzenendseitigen Drehbauteil (140) und dem Werkzeugkörper (119) löst.
     
    4. Drehendes Befestigungswerkzeug nach Anspruch 3, bei dem der Drehungssteuermechanismus (150) eine Halterung (155) aufweist, die zwischen dem Werkzeugkörper (101) und dem spitzenendseitigen Drehbauteil (140) so angeordnet ist, dass es der Halterung (155) ermöglicht ist, relativ zu dem Werkzeugkörper (101) und dem spitzenendseitigen Drehbauteil (140) zu drehen, und wobei die Halterung (155) das Drehungssteuerbauteil (153) zwischen der Betätigungsposition und der gelösten Position bewegt und das Drehungssteuerbauteil (153) in dieser Position hält.
     
    5. Drehendes Befestigungswerkzeug nach Anspruch 4, bei dem, wenn der Motor (111) in der normalen Richtung angetrieben wird und das angetriebenenseitige Drehbauteil (123) in der Festziehrichtung gedreht wird, das angetriebenenseitige Drehbauteil (123) die Halterung (155) in der Festziehrichtung dreht, bevor es das spitzenendseitige Drehbauteil (140) drehend antreibt, und die Halterung (155) das Drehungssteuerbauteil (153) in die Betätigungsposition bewegt.
     
    6. Drehendes Befestigungswerkzeug nach Anspruch 4 oder 5, bei dem, wenn der Motor (111) in der umgekehrten Richtung angetrieben wird und das angetriebenenseitige Drehbauteil (123) in der Löserichtung gedreht wird, das angetriebenenseitige Drehbauteil (123) die Halterung (155) in der Löserichtung dreht, bevor es das spitzenendseitige Drehbauteil (140) drehend antreibt, und die Halterung (155) das Drehungssteuerbauteil (153) in die gelöste Position bewegt.
     
    7. Drehendes Befestigungswerkzeug nach einem der Ansprüche 3 bis 6, bei dem
    das spitzenendseitige Drehbauteil (140) einen ebenen Bereich (140a) in einem vorbestimmten Ausmaß in der Umfangsrichtung hat,
    das Drehungssteuerbauteil (153) ein Bauteil aufweist, das einen kreisförmigen Abschnitt (153) hat, wobei während des Festziehvorgangs des Werkzeugbits (119), wenn der Drehmomentbegrenzer (120) die Drehmomentübertragung unterbricht, das Drehungssteuerbauteil (153) sich in Richtung eines Endes des ebenen Bereichs (140a) in der Umfangsrichtung bewegt und sowohl mit dem ebenen Bereich (140a) als auch mit einer Innenwandfläche des Werkzeugkörpers (101) in Eingriff kommt, und dabei das spitzenendseitige Drehbauteil (140) und den Werkzeugkörper (101) miteinander verriegelt und die Drehung des Werkzeugkörpers (101) in der Festziehrichtung in Bezug auf das spitzenendseitige Drehbauteil (140) steuert, und
    die Halterung (155) ein elastisches Element (157) hat, das das kreisförmige Bauteil (153) in Richtung des einen Endes des ebenen Bereiches (140a) in der Umfangsrichtung vorspannt.
     
    8. Drehendes Befestigungswerkzeug nach einem der Ansprüche 1 bis 7, bei dem der Drehmomentbegrenzer (120) eine Mehrzahl von ersten Drehmomentaufnahmeteilen (125) und eine Mehrzahl von ersten Drehmomentübertragungsteilen (121b) in der Umfangsrichtung hat, wobei die ersten Drehmomentaufnahmeteile (125) an dem angetriebenenseitigen Drehbauteil (123) vorgesehen sind, und die ersten Drehmomentübertragungsteile (121b) zusammen mit dem antriebseitigen Drehbauteil (121) drehen und ein Drehmoment des antriebseitigen Drehbauteils (121) an das angetriebenenseitige Drehbauteil (123) übertragen, während sie in Kontakt mit den ersten Drehmomentaufnahmebauteilen (125) gehalten werden, und
    das drehende Befestigungswerkzeug weiter enthält:

    einen zweiten Drehmomentaufnahmeteil (143), der von dem spitzenendseitigen Drehbauteil (140) radial nach außen hervorsteht,

    einen zweiten Drehmomentübertragungsteil (135a), der eine vorbestimmte Phasendifferenz in der Umfangsrichtung in Bezug auf den zweiten Drehmomentaufnahmeteil (143) hat, wobei der zweite Drehmomentübertragungsteil (135a) zusammen mit dem angetriebenenseitigen Drehbauteil (123) dreht und ein Drehmoment des angetriebenenseitigen Drehbauteils (123) an das spitzenendseitige Drehbauteil (140) überträgt, während es in Kontakt mit dem zweiten Drehmomentaufnahmeteil (143) gehalten wird,

    einen dritten Drehmomentaufnahmeteil (159), der von der Halterung (155) in Richtung einer Drehachse des angetriebenenseitigen Drehbauteils (123) hervorsteht, und

    einen dritten Drehmomentübertragungsteil (135c, 135d), der eine vorbestimmte Phasendifferenz in der Umfangsrichtung in Bezug auf den dritten Drehmomentaufnahmeteil (159) hat, wobei der dritte Drehmomentübertragungsteil (135c, 135d) zusammen mit dem angetriebenenseitigen Drehbauteil (123) dreht und ein Drehmoment des angetriebenenseitigen Drehbauteils (123) an die Halterung (155) überträgt, während es in Kontakt mit dem dritten Drehmomentaufnahmeteil (159) gehalten wird,

    wobei ein Phasenwinkel zwischen dem dritten Drehmomentaufnahmeteil (159) und dem dritten Drehmomentübertragungsteil (135c, 135d) in der Umfangsrichtung größer als ein Phasenwinkel zwischen den ersten Drehmomentübertragungsteilen (121b) in der Umfangsrichtung ist, und

    ein Phasenwinkel zwischen dem dritten Drehmomentaufnahmeteil (159) und dem dritten Drehmomentübertragungsteil (135c, 135d) in der Umfangsrichtung kleiner als ein Phasenwinkel zwischen dem zweiten Drehmomentaufnahmeteil (143) und dem zweiten Drehmomentübertragungsteil (135a) in der Umfangsrichtung ist.


     
    9. Drehendes Befestigungswerkzeug nach einem der Ansprüche 4 bis 8, bei dem die Halterung (155) durch Reibung von dem elastischen Bauteil (158) derart gehalten wird, dass es an einer Drehung in Bezug auf das spitzenendseitige Drehbauteil (140) gehindert wird, sofern es nicht durch das angetriebenenseitige Drehbauteil (123), das in der Löserichtung dreht, gedreht wird.
     
    10. Drehendes Befestigungswerkzeug nach einem der Ansprüche 1 bis 9, bei dem das drehende Befestigungswerkzeug als ein elektrischer Schraubendreher zum Antreiben eines Eintreibbits (119) zum Festziehen und/oder Lösen einer Schraube vorgesehen ist.
     


    Revendications

    1. Outil de fixation rotatif comprenant :

    un corps d'outil (101) ;

    un moteur (111) logé à l'intérieur du corps d'outil (101) ;

    un élément rotatif côté menant (121), qui est entraîné en rotation par le moteur (111),

    un élément rotatif côté mené (123), qui est disposé coaxialement avec l'élément rotatif côté menant (121),

    un élément rotatif côté extrémité de pointe (140), qui est disposé coaxialement avec l'élément rotatif côté mené (123) et entraîné en rotation via l'élément rotatif côté mené (123) ; l'élément rotatif côté extrémité de pointe (140) entraînant une mèche d'outil (119) pour effectuer une opération de serrage,

    un mécanisme de commande de rotation (150) qui permet à l'élément rotatif côté extrémité de pointe (140) de tourner dans le sens de serrage pendant l'opération de serrage de la mèche d'outil (119), et un limiteur de couple de torsion (120) qui transmet le couple de torsion de l'élément rotatif côté menant (121) à l'élément rotatif côté mené (123) lorsque le couple de torsion agissant sur l'élément rotatif côté mené (123) est inférieur à une valeur de consigne prédéterminée, tout en interrompant la transmission du couple de torsion lorsque le couple de torsion agissant sur l'élément rotatif côté mené (123) dépasse la valeur de consigne,

    caractérisé en ce que, lorsque l'élément rotatif côté extrémité de pointe (140) est fixé à une pièce avec la mèche d'outil (119) pendant l'opération de serrage et que la transmission du couple de torsion de l'élément rotatif côté menant (121) à l'élément rotatif côté mené (123) est interrompue par le limiteur de couple de torsion (120), une force agit sur l'élément rotatif côté mené (123) dans un sens qui amène l'élément rotatif côté mené (123) à tourner dans un sens de desserrage, dans lequel le mécanisme de commande de rotation (150) verrouille l'élément de rotation côté extrémité de pointe (140) et le corps d'outil (101) ensemble à l'encontre d'une rotation l'un par rapport à l'autre pour empêcher le corps d'outil (101) de tourner dans le sens d'un serrage.


     
    2. Outil de fixation rotatif selon la revendication 1, dans lequel le moteur (111) est entraîné dans un sens normal pour effectuer une opération de serrage ou dans un sens de rotation inverse pour effectuer une opération de desserrage par une opération de sélection de mode, et
    dans lequel, pendant l'opération de desserrage de la mèche d'outil (119), le mécanisme de commande de rotation (150) est désactivé du verrouillage de l'élément rotatif côté extrémité de pointe (140) et du corps d'outil (101) en utilisant une rotation de l'élément rotatif côté mené (123) dans le sens d'un desserrage pour permettre l'opération de desserrage de la mèche d'outil (119).
     
    3. Outil de fixation rotatif selon la revendication 1 ou 2, dans lequel le mécanisme de commande de rotation (150) comprend :

    un élément de commande de rotation (153) disposé entre le corps d'outil (101) et l'élément rotatif côté extrémité de pointe (140), l'élément de commande de rotation (153) présentant une position actionnée et une position libérée, dans lesquelles l'élément de commande de rotation (153), en position actionnée, verrouille l'élément rotatif côté extrémité de pointe (140) et le corps d'outil (101) lorsqu'on fait tourner l'élément rotatif côté extrémité de pointe (140) dans le sens de desserrage pendant l'opération de serrage, tandis que l'élément de commande de rotation (153), en position libérée, libère le verrouillage entre l'élément rotatif côté extrémité de pointe (140) et le corps d'outil (119).


     
    4. Outil de fixation rotatif selon la revendication 3, dans lequel le mécanisme de commande de rotation (150) comprend un élément de retenue (155) qui est disposé entre le corps d'outil (101) et l'élément rotatif côté extrémité de pointe (140) de sorte que l'élément de retenue (155) puisse tourner par rapport au corps d'outil (101) et à l'élément rotatif côté extrémité de pointe (140) et dans lequel l'élément de retenue (155) déplace l'élément de commande de rotation (153) entre la position actionnée et la position libérée et retient l'élément de commande de rotation (153) dans cette position.
     
    5. Outil de fixation rotatif selon la revendication 4, dans lequel, lorsque le moteur (111) est entraîné dans le sens normal et que l'élément rotatif côté mené (123) est mis en rotation dans le sens de serrage, l'élément rotatif côté mené (123) fait tourner l'élément de retenue (155) dans le sens de serrage avant d'entraîner en rotation l'élément rotatif côté extrémité de pointe (140) et l'élément de retenue (155) déplace l'élément de commande de rotation (153) dans la position actionnée.
     
    6. Outil de fixation rotatif selon la revendication 4 ou 5, dans lequel, lorsque le moteur (111) est entraîné en sens inverse et que l'élément rotatif côté mené (123) est mis en rotation dans le sens de desserrage, l'élément rotatif côté mené (123) fait tourner l'élément de retenue (155) dans le sens d'un desserrage avant l'entraînement en rotation de l'élément rotatif côté extrémité de pointe (140) et l'élément de retenue (155) déplace l'élément de commande de rotation (153) dans la position libérée.
     
    7. Outil de fixation rotatif selon l'une quelconque des revendications 3 à 6, dans lequel :

    l'élément rotatif côté extrémité de pointe (140) a une région plane (140a) dans une extension prédéterminée de la direction circonférentielle,

    l'élément de commande rotatif (153) comprend un élément ayant une section circulaire (153), dans lequel, pendant l'opération de serrage de la mèche d'outil (119) ; lorsque le limiteur de couple de torsion (120) interrompt la transmission du couple de torsion, l'élément de commande de rotation (153) se déplace vers une extrémité de la région plane (140a) dans la direction circonférentielle et s'engage à la fois sur la région plane (140a) et sur une surface de paroi interne du corps d'outil (101), verrouillant ainsi l'élément rotatif côté extrémité de pointe (140) et le corps d'outil (101) ensemble et commandant une rotation du corps d'outil dans le sens du serrage par rapport à l'élément de rotation côté extrémité de pointe (140), et

    l'élément de retenue (155) a un élément élastique (157) qui presse l'élément circulaire (153) vers l'extrémité de la région plane (140a) dans la direction circonférentielle.


     
    8. Outil de fixation rotatif selon l'une quelconque des revendications 1 à 7, dans lequel :

    le limiteur de couple de torsion (120) comprend une pluralité de premières parties (125) de réception de couple de torsion et une pluralité de premières parties (121b) de transmission de couple de torsion dans la direction circonférentielle, dans lequel les premières parties (125) de réception de couple de torsion sont aménagées sur l'élément rotatif côté mené (123) et les premières parties (121b) de transmission de couple de torsion tournent ensemble avec l'élément rotatif côté menant (121) et transmettent le couple de torsion de l'élément rotatif côté menant (121) à l'élément rotatif côté mené (123) tout en étant maintenues en contact avec les premières parties (125) de réception de couple de torsion et l'outil de fixation rotatif comprend en outre :

    une deuxième partie (143) de réception de couple de torsion qui fait saillie radialement vers l'extérieur de l'élément rotatif côté extrémité de pointe (140),

    une deuxième partie (135a) de transmission de couple de torsion ayant une différence de phase prédéterminée dans la direction circonférentielle par rapport à la deuxième partie (143) de réception de couple de torsion, dans lequel la deuxième partie (135a) de transmission de couple de torsion tourne conjointement avec l'élément rotatif côté mené (123) et transmet le couple de torsion de l'élément rotatif côté mené (123) à l'élément rotatif côté extrémité de pointe (140) tout en étant maintenue en contact avec la deuxième partie (143) de réception de couple de torsion,

    une troisième partie (159) de réception de couple de torsion qui fait saillie de l'élément de retenue (155) dans la direction de l'axe de rotation de l'élément rotatif côté mené (123) ; et

    une troisième partie (135c, 135d) de transmission de couple de torsion ayant une différence de phase prédéterminée dans la direction circonférentielle par rapport à la troisième partie (159) de réception de couple de torsion, dans laquelle la troisième partie (135c, 135d) de transmission de couple de torsion tourne conjointement avec l'élément de rotation côté mené (123) et transmet le couple de torsion de l'élément rotatif côté mené (123) à l'élément de retenue (155) tout en étant maintenue en contact avec la partie (159) de réception de couple de torsion,

    dans lequel un angle de phase entre la troisième partie (159) de réception de couple de torsion et la troisième partie (135c, 135d) de transmission de couple de torsion dans la direction circonférentielle est supérieur à un angle de phase entre les premières parties (121b) de transmission de couple de torsion dans la direction circonférentielle, et

    un angle de phase entre la troisième partie (159) de réception de couple de torsion et la troisième partie (135c, 135d) de transmission de couple de torsion dans la direction circonférentielle est inférieur à un angle de phase entre la deuxième partie (143) de réception de couple de torsion et la deuxième partie (135a) de transmission de couple de torsion dans la direction circonférentielle.


     
    9. Outil de fixation rotatif selon l'une quelconque des revendications 4 à 8, dans lequel l'élément de retenue (155) est maintenu par frottement par l'élément élastique (158) de manière à l'empêcher de tourner par rapport à l'élément de rotation côté extrémité de pointe (140) à moins qu'il ne soit mis en rotation par l'élément de rotation côté mené (123) tournant dans le sens de desserrage.
     
    10. Outil de fixation rotatif selon l'une quelconque des revendications 1 à 9, dans lequel l'outil de fixation rotatif est mis en oeuvre sous la forme d'un tournevis électrique pour entraîner une mèche visseuse (119) pour serrer ou desserrer une vis.
     




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    Cited references

    REFERENCES CITED IN THE DESCRIPTION



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    Patent documents cited in the description