Tightening tool

Abstract

Tightening tools is provided with a pair of clutch members disposed between a motor and a tool bit. The pair of clutch members is provided with a first engaging portion and a second engaging portion. The first engaging portion is constructed so as to disengage the pair of clutch members when the torque applied to the tool bit is equal to or above a first predetermined value. The second engaging portion does not engage the pair of clutch members while the first engaging portion engages the pair of clutch members and the second engaging portion engages the pair of clutch members after the first engaging portion disengages the pair of clutch members. The second engaging portion is constructed so as to disengage the pair of clutch members when the torque applied to the tool bit is equal to or above a second predetermined value. The second predetermined value may be different from the first predetermined value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the configuration of an electric screwdriver of a first embodiment.

FIG. 2 shows an enlarged view of the internal configuration of the electric screwdriver of the first embodiment.

FIG. 3 shows a first clutch member of the first embodiment seen from a first opposing face side.

FIG. 4 shows a second clutch member of the first embodiment seen from a second opposing face side.

FIG. 5 shows an expanded cross-sectional view along the line V of FIG. 4.

FIG. 6 shows an enlarged view of a set of engaging portions of the first embodiment.

FIG. 7 shows the first clutch member and the second clutch member of the first embodiment in an engaged state.

FIG. 8 shows the first clutch member and the second clutch member of the first embodiment in a disengaged state.

FIG. 9 shows the electrical configuration of the electric screwdriver of the first embodiment.

FIG. 10 shows a timing chart showing the flow of operations of the electric screwdriver of the first embodiment.

FIG. 11 shows the configuration of an electric screwdriver of a second embodiment.

FIG. 12 shows an enlarged view of the internal configuration of the electric screwdriver of the second embodiment.

FIG. 13 shows a second clutch member of the second embodiment seen from a second opposing face side.

FIG. 14 shows an expanded cross-sectional view along the line XIV of FIG. 13.

FIG. 15 shows an enlarged view of a set of engaging portions of the second embodiment.

FIG. 16 schematically shows the electrical configuration of the electric screwdriver of the second embodiment.

FIG. 17 shows a timing chart showing the flow of operations of the electric screwdriver of the second embodiment.

Claims

1. A tightening tool adapted to tighten a fastener, comprising: a motor;a tool bit that can engage with the fastener;a pair of clutch members disposed between the motor and the tool bit; anda spring member that pushes one of the clutch members towards the other; wherein:the pair of clutch members comprises a first engaging portion and a second engaging portion for engaging the pair of clutch members;the first engaging portion is constructed so as to disengage the pair of clutch members when the torque applied to the tool bit is equal to or above a first predetermined value;the second engaging portion does not engage the pair of clutch members while the first engaging portion engages the pair of clutch members and the second engaging portion engages the pair of clutch members after the first engaging portion disengages the pair of clutch members;the second engaging portion is constructed so as to disengage the pair of clutch members when the torque applied to the tool bit is equal to or above a second predetermined value; andthe second predetermined value is different from the first predetermined value.

2. A tightening tool as set forth in claim 1, wherein: the second predetermined value is larger than the first predetermined value.

3. A tightening tool as set forth in claim 1, further comprising: a motor controller constructed so as to keep driving the motor after the first engaging portion disengages the pair of clutch members.

4. A tightening tool as set forth in claim 3, wherein: the motor controller is constructed so as to cease driving the motor when the pair of clutch members has been disengaged a predetermined number of times.

5. A tightening tool as set forth in claim 2, wherein: each of the engaging portions comprises a gradient face that engages with the other of the clutch members; andthe gradient face of the second engaging portion is steeper than the gradient face of the first engaging portion.

6. A tightening tool as set forth in claim 1, further comprising: a motor controller constructed so as to cease driving the motor whenever the pair of clutch members is disengaged.

7. A tightening tool as set forth in claim 1, further comprising: an indicator constructed so as to function in a first manner when the first engaging portion disengages the pair of clutch members, and constructed so as to function in a second manner when the second engaging portion disengages the pair of clutch members.

8. A tightening tool as set forth in claim 1, wherein: the pair of clutch members further comprises a third engaging portion;the third engaging portion does not engage the pair of clutch members while one of the first engaging portion and the second engaging portion engages the pair of clutch members and the third engaging portion engages the pair of clutch members after the second engaging portion disengages the pair of clutch members;the third engaging portion is constructed so as to disengage the pair of clutch members when the torque applied to the tool bit is equal to or above the third predetermined value; andthe third predetermined value is different from the second predetermined value.

9. A tightening tool as set forth in claim 8, wherein: the third predetermined value is larger than the second predetermined value.

10. A tightening tool as set forth in claim 8, further comprising: a motor controller constructed so as to keep driving the motor after the first engaging portion disengages the pair of clutch members, constructed so as to keep driving the motor after the second engaging portion disengages the pair of clutch members, and constructed so as to cease driving the motor when the third engaging portion disengages the pair of clutch members.

11. A tightening tool as set forth in claim 9, wherein: each of the engaging portions comprises a gradient face that engages with the other of the clutch members;the gradient face of the second engaging portion is steeper than the gradient face of the first engaging portion; andthe gradient face of the third engaging portion is steeper than the gradient face of the second engaging portion.

12. A tightening tool as set forth in claim 8, further comprising: a motor controller constructed so as to cease driving the motor whenever the pair of clutch members is disengaged.

13. A tightening tool as set forth in claim 8, further comprising: an indicator constructed so as to function in a first manner when the first engaging portion disengages the pair of clutch members, constructed so as to function in a second manner when the second engaging portion disengages the pair of clutch members, and constructed so as to function in a third manner when the third engaging portion disengages the pair of clutch members.