A driving section generates rotational driving force and has an output shaft that outputs the rotational driving force. An end-bit mounting section holds an end bit and is rotatable about a rotational axis. A friction clutch is provided between the end-bit mounting section and the driving section. T
A driving section generates rotational driving force and has an output shaft that outputs the rotational driving force. An end-bit mounting section holds an end bit and is rotatable about a rotational axis. A friction clutch is provided between the end-bit mounting section and the driving section. The friction clutch includes a drive member and a follow member. The drive member rotates together with the driving section and has a drive-side contact surface. The follow member rotates together with the end-bit mounting section and has a follow-side contact surface contactable with the drive-side contact surface. The friction clutch is movable between a transmission position where frictional force is produced between the drive-side contact surface and the follow-side contact surface so that the output shaft and the end-bit mounting section can rotate together, and a cutoff position where the output shaft and the end-bit mounting section are non-rotatable together.
대표청구항▼
1. A power tool comprising: a handle configured to be gripped by a user;a driving section configured to generate rotational driving force selectively in a forward direction and in a reverse direction and including an output shaft that outputs the rotational driving force;an end-bit mounting section
1. A power tool comprising: a handle configured to be gripped by a user;a driving section configured to generate rotational driving force selectively in a forward direction and in a reverse direction and including an output shaft that outputs the rotational driving force;an end-bit mounting section configured to hold an end bit and to be rotatable about a rotational axis extending in an axial direction; anda friction clutch provided between the end-bit mounting section and the driving section and serving as a first clutch movable between a transmission position and a cutoff position, the friction clutch comprising: a drive member driven by the driving section and including a drive-side contact surface; anda follow member including a follow-side contact surface that is capable of contacting the drive-side contact surface and slidingly movable relative to the drive-side contact surface to generate a frictional force therebeween when the end-bit mounting section moves toward the driving section in the axial direction; anda second clutch provided between the end-bit mounting section and the driving section,wherein the user gripping the handle and pressing the end bit against a workpiece moves the end-bit mounting section toward the driving section in the axial direction and generates a torque transmitted to the end bit mounting section by the friction clutch,wherein the torque transmitted to the end bit mounting section by the frictional clutch is generated only by frictional force,wherein, when the first clutch is at the transmission position, the rotational driving force of the driving section at least in the forward direction can be transmitted to the end-bit mounting section,wherein, when the first clutch is at the cutoff position, the rotational driving force of the driving section through the first clutch is cut off before the end-bit mounting section, andwherein the second clutch is configured to transmit the rotational driving force of the driving section only in the reverse direction to the end-bit mounting section via a different route from the first clutch. 2. The power tool as claimed in claim 1, further comprising: an accommodating section having an inner space and accommodating the drive member and the follow member in the inner space; anda seal member that isolates the inner space of the accommodating section from outside of the accommodating section. 3. The power tool as claimed in claim 1, wherein the first clutch is configured to transmit the rotational driving force of the driving section both in the forward direction and in the reverse direction to the end-bit mounting section when the first clutch is at the transmission position. 4. The power tool as claimed in claim 1, wherein the first clutch comprises a multiple-plate friction clutch. 5. The power tool as claimed in claim 4, wherein the multiple-plate friction clutch comprises: a plurality of drive members that rotates together with the driving section, each of the plurality of drive members having a plate shape; anda plurality of follow members that rotates together with the end-bit mounting section, each of the plurality of follow members having a plate shape; andwherein the plurality of drive members and the plurality of follow members are arranged alternately from the end-bit mounting section side toward the driving section side, one of the plurality of follow members being the closest to the end-bit mounting section. 6. The power tool as claimed in claim 4, further comprising: a gear reduction mechanism rotatably driven by the output shaft; anda shaft connected to the end-bit mounting section and configured to rotate coaxially with the end bit,wherein the multiple-plate friction clutch is arranged between the gear reduction mechanism and the shaft. 7. The power tool as claimed in claim 6, wherein the end-bit mounting section is fitted to the shaft. 8. The power tool as claimed in claim 4, wherein the rotational driving force of the driving section in the forward direction is transmitted to the end-bit mounting section only via the multiple-plate friction clutch; and wherein transmission efficiency of the rotational driving force in the forward direction changes in response to movement of the multiple-plate friction clutch in the axial direction. 9. The power tool as claimed in claim 4, wherein the multiple-plate friction clutch is arranged coaxially with the rotational axis of the end-bit mounting section. 10. The power tool as claimed in claim 4, further comprising a plurality of springs arranged adjacent to the multiple-plate friction clutch at either one of the end bit side and the driving section side or at both of the end bit side and the driving section side, the plurality of springs being configured to urge the multiple-plate friction clutch toward at least one of the end bit side and the driving section side, wherein at least one of the plurality of springs is prevented from being compressed by an amount greater than a predetermined amount, allowing the plurality of springs to have a combined spring constant that changes at the predetermined amount. 11. The power tool as claimed in claim 10, wherein the plurality of springs is arranged in series adjacent to the multiple-plate friction clutch at either one of the end bit side and the driving section side or at both of the end bit side and the driving section side. 12. The power tool as claimed in claim 1, wherein the friction clutch comprises a multiple-plate friction clutch configured to be movable in the axial direction; and wherein the multiple-plate friction clutch is configured to move in the axial direction to transmit the rotational driving force of the output shaft to the end bit in a state where the end bit is pressed against a workpiece. 13. The power tool as claimed in claim 12, wherein the multiple-plate friction clutch comprises: a plurality of drive members that rotates together with the driving section, each of the plurality of drive members having a plate shape; anda plurality of follow members that rotates together with the end-bit mounting section, each of the plurality of follow members having a plate shape; andwherein the plurality of drive members and the plurality of follow members are arranged alternately from the end-bit mounting section side toward the driving section side, one of the plurality of follow members being the closest to the end-bit mounting section. 14. The power tool as claimed in claim 12, further comprising: a gear reduction mechanism rotatably driven by the output shaft; anda shaft connected to the end-bit mounting section and configured to rotate coaxially with the end bit,wherein the multiple-plate friction clutch is arranged between the gear reduction mechanism and the shaft. 15. The power tool as claimed in claim 14, wherein the end-bit mounting section is fitted to the shaft. 16. The power tool as claimed in claim 12, wherein the driving section is configured to generate the rotational driving force selectively in a forward direction and in a reverse direction; wherein the rotational driving force of the driving section in the forward direction is transmitted to the end-bit mounting section only via the multiple-plate friction clutch; andwherein transmission efficiency of the rotational driving force in the forward direction changes in response to movement of the multiple-plate friction clutch in the axial direction. 17. The power tool as claimed in claim 12, wherein the multiple-plate friction clutch is arranged coaxially with the rotational axis of the end-bit mounting section. 18. The power tool as claimed in claim 12, further comprising a plurality of springs arranged adjacent to the multiple-plate friction clutch at either one of the end bit side and the driving section side or at both of the end bit side and the driving section side, the plurality of springs being configured to urge the multiple-plate friction clutch toward at least one of the end bit side and the driving section side, wherein at least one of the plurality of springs is prevented from being compressed by an amount greater than a predetermined amount, allowing the plurality of springs to have a combined spring constant that changes at the predetermined amount. 19. The power tool as claimed in claim 18, wherein the plurality of springs is arranged in series adjacent to the multiple-plate friction clutch at either one of the end bit side and the driving section side or at both of the end bit side and the driving section side. 20. The power tool as claimed in claim 18, wherein the plurality of springs is arranged in parallel adjacent to the multiple-plate friction clutch at either one of the end bit side and the driving section side. 21. The power tool as claimed in claim 1, wherein the end-bit mounting section is configured to be movable in the axial direction between a first position and a second position; wherein the drive member has a first engaging section serving as the drive-side contact surface;wherein the follow member has a second engaging section capable of engaging the first engaging section and serving as the follow-side contact surface;wherein the first engaging section and the second engaging section are configured to be in non-engagement with each other when the end-bit mounting section is at the first position and to be in engagement with each other when the end-bit mounting section is at the second position; andwherein one of the first engaging section and the second engaging section has a conical convex section, and another one of the first engaging section and the second engaging section has a conical concave section. 22. A power tool comprising: a handle configured to be gripped by a user;a driving section configured to generate rotational driving force selectively in a forward direction and in a reverse direction, the driving section including an output shaft that outputs the rotational driving force;an end-bit mounting section configured to hold an end bit and to be rotatable about a rotational axis; anda first clutch and a second clutch both provided between the end-bit mounting section and the driving section,the first clutch being a friction clutch and being movable between a transmission position where the rotational driving force of the driving section at least in the forward direction can be transmitted to the end-bit mounting section, and a cutoff position where the rotational driving force of the driving section through the first clutch is cut off before the end-bit mounting section,the second clutch being configured to transmit the rotational driving force of the driving section only in the reverse direction to the end-bit mounting section via a different route from the first clutch,wherein the user gripping the handle and pressing the end bit against a workpiece moves the first clutch to the transmission position and generates a torque transmitted to the end-bit mounting section to rotate the end bit, andwherein the torque transmitted to the end-bit mounting section by the first clutch is generated only by frictional force. 23. The power tool as claimed in claim 22, wherein: the end-bit mounting section is configured to be rotatable about the rotational axis extending in an axial direction, the end-bit mounting section being movable in the axial direction in accordance with the user pressing of the end bit against a workpiece;the first clutch is a multiple-plate friction clutch, andthe user gripping the handle and pressing the end bit against a workpiece moves the end-bit mounting section toward the driving section in the axial direction and generates the torque transmitted to the end-bit mounting section by the multiple-plate friction clutch. 24. The power tool as claimed in claim 22, wherein: the end-bit mounting section is configured to be rotatable about the rotational axis extending in an axial direction, the end-bit mounting section being configured to be movable in the axial direction between a first position and a second position; andthe first clutch includes: a drive member that receives the rotational driving force of the driving section and that is rotatable by the rotational driving force, the drive member including a first engaging section; anda follow member including a second engaging section capable of engaging the first engaging section, the follow member being rotatable,the first engaging section and the second engaging section is configured to be in non-engagement with each other when the end-bit mounting section is at the first position and to be in engagement with each other when the end-bit mounting section is at the second position,one of the first engaging section and the second engaging section has a conical convex section, and another one of the first engaging section and the second engaging section has a conical concave section, the conical convex section and the conical concave section being slidingly movable relative to each other to generate a frictional force therebetween when the end-bit mounting section is at the second position, andthe driving force of the driving section is transmitted to the end-bit mounting section by the frictional force generated between the conical convex section and the conical concave section. 25. The power tool as claimed in claim 22, wherein: the end-bit mounting section is configured to hold an end bit and to be movable in an axial direction in accordance with the user pressing of the end bit against a workpiece in the axial direction,the first clutch further comprises: a drive member driven by the driving section; anda follow member provided between the end-bit mounting section and the driving section, the follow member capable of contacting the drive member and slidingly movable relative to the drive member when the end-bit mounting section moves toward the driving section in the axial direction,the user gripping the handle and pressing the end bit against a workpiece moves the end-bit mounting section toward the driving section in the axial direction and generates the torque transmitted to the end-bit mounting section by increase of a frictional force generated between the drive member and the follow member, andthe torque transmitted to the end-bit mounting section is generated only by frictional force between the drive member and the follower member. 26. The power tool as claimed in claim 22, wherein: the end-bit mounting section is configured to be rotatable about the rotational axis extending in an axial direction and configured to move in the axial direction, andthe first clutch further comprises: a drive member driven by the driving section; anda follow member movable in the axial direction relative to the end-bit mounting section and the drive member and configured to transmit the rotational driving force from the drive member to the end-bit mounting section, the movement of the end-bit mounting section toward the driving section in the axial direction moving the follow member toward the drive member to transmit the rotational driving force from the drive member to the end-bit mounting section. 27. The power tool as claimed in claim 26, wherein the movement of the end-bit mounting section toward the driving section in the axial direction causes the follow member to be sandwiched between the drive member and the end-bit mounting section. 28. The power tool as claimed in claim 27, wherein the sandwich of the follow member between the drive member and the end-bit mounting section generates a frictional force between the drive member and the follow member, the fictional force serving as a torque to transmit the rotational driving force of the drive member to the end-bit mounting section. 29. The power tool as claimed in claim 22, wherein: the end-bit mounting section is configured to be rotatable about the rotational axis extending in an axial direction and is configured to move in the axial direction, andthe first clutch comprises: a drive member driven by the driving section; anda follow member disposed between the drive member and the end-bit mounting section in the axial direction, the movement of the end-bit mounting section toward the driving section in the axial direction moving the follow member toward the drive member and causing the follow member to be sandwiched between the drive member and the end-bit mounting section. 30. The power tool as claimed in claim 29, wherein the sandwich of the follow member between the drive member and the end-bit mounting section generates a frictional force between the drive member and the follow member, the fictional force serving as a torque to transmit the rotational driving force of the drive member to the end-bit mounting section.
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이 특허에 인용된 특허 (11)
Gallagher, William F.; Doyle, Michael C.; Hatfield, Eric E.; Tomayko, David C.; Krout, Daniel L.; Malloy, Tanika, Angle grinder.
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