GB947747A - Improved load cell - Google Patents

Abstract

947,747. Weighing material on conveyers; load cells. UNITED TOBACCO CO'S. (SOUTH) Ltd. Jan. 9, 1962 [Jan.26, 1961], No. 818/62. Heading G1W. A load cell suitable for use with weighing carriages for weighing material on a conveyer belt comprises a cylindrical wall and an end wall, at least three spaced diaphragms sealed with the cylindrical wall and defining coaxial compartments, a rigid pillar coaxial with the compartments and fast with the diaphragms having a valve closure member at one end and a load receiving anvil at the other, the first compartment having means for admitting fluid under pressure, fluid outlet means connected to fluid pressure measuring means and a fluid exhaust means which can exhaust fluid at a greater rate than it can be admitted by the inlet means, the middle compartment having a fluid inlet means for connection to a supply of fluid under pressure and the third compartment having an opening for connection to the first compartment, all the diaphrams being adapted to flex under fluid pressure and to be displaced by the pressure against the action of a load applied to the anvil, In the form shown, the cell is built up of a base 80, Fig. 3, having a fluid exhaust 34 and a compartment 20 defined by a diaphragm 14 secured to the base by a ring 86. Successive compartments are formed by diaphragms 52, 16, 54 and 18 secured by successive rings 86 and by a top piece 88. The compartments between diaphragms 14 and 52 and between diaphragms 16 and 54 are vented to atmosphere through openings 56, 58. A central rod 92, the lower end 42 of which forms the closure for the exhaust 34 carries a dished disc 94 at the end adjacent the anvil 44 and a series of members 98 each consisting of two dished discs 100,102 connected by a sleeve, the diaphragms being clamped between discs on successive members. In use, the cell 10, Fig. 6, is supported below an arm 130 carrying a roller 134 and a counterweight 128 arranged on the opposite side of a fulcrum 132. The roller 134 bears against the underside of a conveyer belt 136 carrying loads. Initial deadweight loading and tare adjustment are provided for by regulating the pressure of air supplied to the middle compartment. The upward movement of the rod 92 may be regulated by steps 47a on the top piece 88, with which shims of varying thickness may be associated.