Structural improvement of electric screwdriver with respect to the torsion adjustment thereof

• US 4,653,359 A
• Filed: 10/11/1985
• Issued: 03/31/1987
• Est. Priority Date: 10/11/1985
• Status: Expired due to Fees

• Current Assignee: Hsieh-Yuan Liao
• Original Assignee: Hsieh-Yuan Liao
• Inventors: Liao, Hsieh-Yuan
• Primary Examiner(s): Meister, James M.
• Assistant Examiner(s): Knoble, John L.
• Application Number:
  US06/786,869
• Time in Patent Office: 536 Days
• Field of Search: 81/467, 81/473, 81/475, 81/57.11, 81/57.14, 81/57.12, 81/57.13, 173/93
• US Class Current: 81/475
• 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
• CPC Class Codes: B25B 23/141 Mechanical overload release couplings
• CPC Class Codes: B25B 23/147 specially adapted for electrically operated wrenches or screwdrivers

Abstract

Structural improvement of electric screwdriver with respect to the torsion adjustment thereof, incorporating a torsion mechanism having outer threads in the anterior shell in coordination with a hollow-set torsion adjustment lid having correspondingly provided inner threads, so that manually imposed rotative feeding of the adjustment lid may force the supporting stem to exert depression on the depression spring through the adjustment disk, resulting in vertical engagement of both the upper and the lower ratchet, also in mortise joint of the torsion stem with the lower ratchet; that activation of a finely-touched switch starts the motor to acquire an increased torque by virtue of the main gear in relation to the vernier gear, eventually setting the torsion stem to rotation while locking the screw or else releasing the same, the torsion adjustment lid permissive of multiple-shifted helic adjustments with precision and convenience. The motor being smooth in running, thereby shortens time and labor in work.

Claims

1. In an electric screwdriver, a torsion adjustment mechanism, comprising:

an outer dual sectioned shell forming a grip for holding;

a motor mechanism installed in a forward section of the outer shell, incorporating;

(a) a motor shell, smaller than said outer shell and fixed to said forward section;

(b) a motor, mounted inside said motor shell and including a motor shaft;

(c) a main gear, fixed to the motor shaft and extending outside the motor shell;

a vernier gear unit, incorporated in the forward section of the casing and engaged with the main gear so as to help increase the torque, said gear unit having a transmission stem at one side;

a torsion rod, comprising an extensible transmission rod, having a clamp provided at a forward end to permit adaption with all kinds of screwdriver heads, the rear end having a mortise slot cut therein;

a torsion mechanism, incorporated in the forward section of the outer shell and seated in front of the motor, said torsion mechanism including;

(a) a torsion body, formed as a hollow tubing an outer threaded cylinder in front, the rear side thereof fitted to the motor casing, the torsion rod penetrated therethrough;

(b) a depression spring carried within the torsion mechanism and associated with the torsion rod, said spring enabling compression and expansion via its body;

(c) two adjustment disks, one provided in front of the depression spring, and the other to the rear side of the depression spring, the one adjustment disk being attached to the torsion rod so that under pressure it will compel the other adjustment disk to move through the depression disk;

(d) a bushing, attached to the torsion rod and in front of the one adjustment disk, driven by the torsion rod to compel the frontal adjustment disk to displace accordingly;

(e) three supporting struts mounted by the outer threaded cylinder in front of the torsion rod, tips of all three struts bearing against the one adjustment disk;

(f) a forward ratchet having a hub and a plurality of sloped shoe members, the hub being provided with a mortise slot for engagement with a complementary boss provided in vernier gear unit;

(g) a rearward ratchet, having a follower shaft and a plurality of slant shoe members, the shoe members being engageable with the counterpart provided on the forward ratchet, the follower shaft being mortise-jointed with the mortise slot on the rear of the torsion rod to achieve transmission;

(h) a bearing, of the ball-bearing type, provided over the hub perimeter of the upper ratchet to facilitate sliding; and

(i) a vernier switch located by the torsion mechanism, controlled by the rearward adjustment disk, which in turn serves to selectively activate motor running;

a torsion adjustment cap, secured to the outer threaded cylinder of the torsion mechanism, the inner threaded cylinder including screwing studs to permit helical progression or recession;

whereby when the torsion adjustment cap is rotated to cause the supports to extend in the torsion mechanism, so that the forward adjustment disk reacts to compress the depression spring and both the forward and rearward ratchets are brought into engagement with each other via the other adjustment disk, the adjustment cap triggers the vernier switch to transmit the motor, so that the torsion rod is transmitted by virtue of the increased torque.

2. The torsion adjustment device according to claim 1, characterised in that the torsion rod is provided with an annular appendage to facilitate the moving of bushings.

3. The torsion adjustment device according to claim 1, characterised in that the outer shell is provided with scales indicative of the torque that prevails or is likely to result as the torsion adjustment cap is rotated in one, or the opposite, direction.