Torque transmission mechanisms and power tools having such torque transmission mechanisms

A torque transmission mechanism, comprising:

• a drive shaft having an axis and arranged and constructed to rotate about the axis,
• a driven shaft extending along substantially the same axis as the drive shaft,
• a torque accumulator arranged and constructed to accumulate a rotational torque of the drive shaft and to transmit the rotational torque to the driven shaft due to a frictional force, and
• a controller arranged and constructed to control the accumulation of the torque in the torque accumulator,
• wherein the torque accumulator comprises a resilient member that has a resiliency in a substantially rotational direction of the driven shaft, the resilient member comprises a coil spring, the coil spring extends substantially linearly along the same axis as the drive shaft and the driven shaft, the coil spring has a first end and a second end opposite to the first end, the first end is coupled to the controller, and the second end is coupled to the driven shaft,
• wherein the controller is operable rotate the first end in the opposite direction to the rotational direction of the drive shaft in order to release the tightening force of the second portion of the coil spring around the driven shaft, the controller comprises a control member and an actuator that is arranged and constructed to rotate the control member, and the control member is coupled to the first end of the coil spring, wherein:
• the actuator comprises a planetary gear mechanism that includes a sun gear, a plurality of planetary gears engaging the sun gear, an internal gear engaging and enclosing the planetary gears, and a carrier rotatably supporting the planetary gears, and
• the controller comprises a coupling device that is arranged and constructed to couple the integral gear to the control member with regard to rotation.

A torque transmission mechanism, comprising:

• a drive shaft,
• a drive unit arranged and constructed to rotate the drive shaft,
• a driven shaft, and
• a first coil spring having a first portion and a second portion, wherein the drive shaft and the driven shaft are inserted into the first portion and the second portion, respectively, so that the first portion and the second portion of the first coil spring are tightened around the drive shaft and the driven shaft, respectively, as the drive shaft rotates, wherein:
• when one end of the first coil spring rotates in a releasing direction, the tightened first coil spring is released to permit an idle rotation of the drive shaft relative to the first coil spring, and
• the first coil spring is then tightened around the drive shaft that rotates idle, so that an inertia torque produced by the idle rotation of the drive shaft in addition to an output torque of the drive unit is transmitted the driven shaft.

A torque transmission mechanism comprising:

• a drive shaft,
• a drive unit arranged and constructed to rotate the drive shaft in a first direction and a second direction opposite to the first direction,
• a driven shaft and a rotary member disposed on opposite sides with each other with respect to the drive shaft and arranged on the same axis as the drive shaft,
• a coil spring fitted on and extend over the rotary member, the drive shaft and the driven shaft, and
• an intermediate shaft arranged and constructed to transmit rotation of the drive shaft to the driven shaft, wherein:
• when the drive shaft rotates in the first direction, the coil spring is tightened around the drive shaft and the driven shaft, so that the driven shaft rotates with the drive shaft;
• when the drive shaft rotates in the second direction, the coil spring is tightened around the drive shaft and the rotary member, so that the rotary member rotates with the drive shaft;
• the drive shaft rotates idle when one end of the coil spring is rotated in a releasing direction to release the tightening of the coil spring around the drive shaft during the rotation of the drive shaft in either the first direction or the second direction, and
• when the one end of the coil spring is rotated in the opposite direction to the releasing direction, the coil spring is again tightened around the drive shaft that rotates idle, so that an inertia torque produced by the idle rotation of the drive shaft in addition to an output torque of the drive unit is applied to the driven shaft.

A torque transmission mechanism comprising:

• a drive shaft,
• a drive unit arranged and constructed to rotate the drive shaft in a first direction and a second direction opposite to the first direction,
• a driven shaft and a rotary member disposed on opposite sides with each other with respect to the drive shaft and arranged on the same axis as the drive shaft, and
• a coil spring fitted on and extended over the rotary member, die drive shaft and the driven shaft;
• wherein
• when the drive shaft rotates in the first direction, the coil spring is tightened around the drive shaft and the driven shaft, so that the driven shaft rotates with the drive shaft in the first direction, and
• when the drive shaft rotates in the second direction, the coil spring is tightened around the drive shaft and the rotary shaft, so that the rotary shaft rotates with the drive shaft in the second direction.