GB1083260A - Improvements in or relating to lift control systems - Google Patents

Abstract

1,083,260. Measuring weight electrically. SCHWEIZERISCHE WAGONS-UND AUFZUGEFABRIK A. G., SCHLIEREN - ZURICH. Nov.19, 1964 [Nov.21, 1963], No.47135/64. Heading G1N. In measurement of the load in a lift cage eccentric loading is accounted for by supporting the lift floor at each corner, on springs of identical spring rate on the cage bottom, and the average change in height of the springs is detected and converted into an electrical signal representative of the total load. In Fig. 2 two lateral traverses 6 each rest respectively on a pair of springs 4 and a beam 7 joins the centres of the traverses. The displacement of the centre of the beam 7 on load, with respect to a point on a cross member 16 of the lift cage frame, thus represents the average deflection of the four springs. As the beam 7 is deflected it engages a lever 10 pivoted to the frame and the lever amplifies the displacement and operates a pressure switch 11; or alternatively Fig. 4 (not shown) the centre point of beam 7 may carry a plunger armature which is slidable in a coil fixed to the frame, to produce a change in the inductance thereof. Strain gauges may be used instead of the plunger and core. Instead of using the traverses 6 and beam 7 there may be diagonally disposed traverses or, the deflection of each spring may be sensed by a hydraulic cylinder or bellows mounted beside it Fig. 5 (not shown), and the four bellows are connected in a closed hydraulic circuit to a measuring cylinder or bellows. The liquid displaced in the four bellows on load results in a proportional elongation of the measuring bellows which is coupled to a plunger armature movable within a coil. As a further alternative there may be a plunger armature and coil adjacent each spring the displacements of which are summed electrically. There may be two concentric springs at each corner having different rates of compression for identical loads one being more sensitive to light loads.