Electric screwdriver

• US 4,878,404 A
• Filed: 09/14/1988
• Issued: 11/07/1989
• Est. Priority Date: 09/14/1988
• Status: Expired due to Fees

• Current Assignee: Hsieh-Yuan Liao
• Original Assignee: Hsieh-Yuan Liao
• Inventors: Liao, Hsieh-Yuan
• Primary Examiner(s): Smith, James G.
• Application Number:
  US07/245,987
• Time in Patent Office: 419 Days
• Field of Search: 81/52, 81/54, 81/429, 173/13, 173/15
• US Class Current: 81/54
• CPC Class Codes: B25B 21/00 Portable power-driven screw or nut setting or loosening tools; details or components, e.g. casings, bodies, of portable power-driven tools not particularly related to the operation performed B25F5/00; for mounting or dismounting wheels B60B29/006; Attachments for drilling apparatus serving the same purpose machines B23P19/06

Abstract

An electric screwdriver includes a housing, a power output end, and a control cylinder mounting therein an active shaft connecting thereto a following shaft connecting thereto a driver mounting piece axially slidably mounted in a cap cylinder and a torsion-adjusting cylinder wherein the mounting piece has an engaging end attaching thereto a flange attaching thereon a light-shielding piece capable of shielding the light emitted by a photic control switch mounted on the control cylinder to allow the motor in the housing to be energized when the mounting piece mounts thereon a driver urging against a screw.

Claims

1. An electric screwdriver comprising a housing securing therein a motor, a power output end rotatably mounted said housing and driven by said motor, a control hollow cylinder having a first end secured to said housing and a second opposite end, an active shaft connected to said power output end and rotatably mounted in said control cylinder, a cap hollow cylinder, a torsion-adjusting hollow cylinder mounted between said cap cylinder and said second opposite end, a driver mounting piece axially slidably mounted in said cap and torsion-adjusting cylinders, a following shaft mounted between said mounting piece and said active shaft for transmitting a rotating power from said active shaft to said driver mounting piece, and a spiral spring mounted between said cap and torsion-adjusting cylinders for providing a spring force against said following shaft, characterized in that:

said mounting piece has an engaging end, which is the end engaging with said following shaft, attaching thereto a flange;

said control cylinder mounts thereon a photic control switch electrically connected to said motor to emit a light to de-energize said motor; and

said flange attachs thereon a light-shielding piece shielding said light to energize said motor when said mounting piece mounts thereon a driver urging against a screw.