Pulse torque generator and power tool having the same

A power tool comprising:

• a casing;
• a drive source disposed in the casing;
• an input shaft disposed in the casing and connected to the drive source and having an axis and an inner peripheral surface, the input shaft being rotatable about the axis, the input shaft being provided with a hollow section extending in an axial direction of the input shaft and including at least one magnetic section and at least one non magnetic section, the hollow section providing a hollow space;
• an output shaft rotatably extending through the hollow space and having an outer peripheral surface and a tip end to which an end tool is attachable, an annular gap being defined between the inner peripheral surface and the outer peripheral surface;
• a magnetic fluid encapsulated in the annular gap;
• and
• at least one magnetic field generating unit disposed at a radially outside of the hollow section, the magnetic section and the non-magnetic section being alternately confrontable with the magnetic field generating unit by the rotation of the input shaft, the magnetic fluid providing a magnetic bridge bridging between the input shaft and the output shaft each time the magnetic section is brought into confrontation with the magnetic field generating unit for pulsatingly transmitting rotation of the input shaft to the output shaft through the magnetic fluid bridge.

A pulse torque generator comprising:

• an input shaft having an axis and an inner peripheral surface, the input shaft being connected to a drive source and rotatable about the axis, the input shaft being provided with a hollow section extending in an axial direction of the input shaft, the hollow section providing a hollow space;
• an output shaft rotatably extending through the hollow space and having an outer peripheral surface, an annular gap being defined between the inner peripheral surface and the outer peripheral surface;
• a magnetic fluid encapsulated in the annular gap;
• at least one magnetic field generating unit disposed at one of the inner peripheral surface of the input shaft and the outer peripheral surface of the output shaft;
• and
• at least one pair of magnetic members disposed to interpose the at least one magnetic field generating unit between the pair of magnetic members, the magnetic fluid providing a magnetic bridge bridging between the input shaft and the output shaft each time a distance between the input shaft and the output shaft becomes minimum for pulsatingly transmitting rotation of the input shaft to the output shaft through the magnetic fluid bridge.

A power tool comprising:

• a casing;
• a drive source disposed in the casing;
• an input shaft disposed in the casing and having an axis and an inner peripheral surface, the input shaft being connected to the drive source and rotatable about the axis, the input shaft being provided with a hollow section extending in an axial direction of the input shaft, the hollow section providing a hollow space;
• an output shaft rotatably extending through the hollow space and having an outer peripheral surface and a tip end to which an end tool is attachable, an annular gap being defined between the inner peripheral surface and the outer peripheral surface;
• a magnetic fluid encapsulated in the annular gap;
• at least one magnetic field generating unit disposed at one of the inner peripheral surface of the input shaft and the outer peripheral surface of the output shaft;
• and
• at least one pair of magnetic members disposed to interpose the at least one magnetic field generating unit between the pair of magnetic members, the magnetic fluid providing a magnetic bridge bridging between the input shaft and the output shaft each time a distance between the input shaft and the output shaft becomes minimum for pulsatingly transmitting rotation of the input shaft to the output shaft through the magnetic fluid bridge.