Patent ID: 7578219
Filing Date: 2009-08-25
Classification: B25B

Abstract:
1. An adjustable spanner with electronic strain gauge function comprising: a head; an fixed jaw extending from the head; and a sliding groove being transversally formed at one upper side of the head; a handle connected to a lower side of the head; at least one strain gauge; a hollow connecting tube having one end connected to the handle; the hollow connecting tube being installed with an output display device having an operation unit and a display; a power source supplying power to the output display device; the output display device being electrically connected to the strain gauges; a moveable jaw being comprised of an engaging surface, a sliding rod, and a reinforcing rib, a fixed positioning portion being extended from the engaging surface to face the opening between the fixed jaw and the moveable jaw so that a working area is formed among the engaging surface of the moveable jaw, the positioning portion and one side of the fixed jaw so as to clamp different-size screw means, a non-working area being located below the working area of the moveable jaw, and the reinforcing rib being extended downward from the positioning portion of the non-working area, so as to locate the positioning portion between the engaging surface of the moveable jaw and the reinforcing rib; a sliding rod being received at the sliding groove of the fixed jaw so that the movable jaw can be adjusted to move toward or far away from the fixed jaw such that the distance between the fixed jaw and movable jaw can be adjusted randomly; wherein the distance from the connection of the positioning portion to the engaging surface of the moveable jaw is L, and the widest opening between the side of the fixed jaw and the engaging surface of the moveable jaw is S, the ratio of L to S is no more than 22%; the height from the connection of the positioning portion and the engaging surface of the moveable jaw to a slidable slot is H, the ratio of H to S is within 35% to 49%; as the position of the positioning portion is limited at clamping the screw means, the different-size screw means can be biased, so that during clamping the largest size of screw means and the smallest size of screw means, the error of the distance from the central point of the largest size of the screw means to the central point of the strain gauge and the distance from the central point of the smallest size of the screw means to the central point of the strain gauge is retained less then 5%.