Patent GB-893422-A (GB)
Title: Apparatus for measuring weight loss of meat products in the smoke house
IPC: F02M41/12
Filed: 1959-07-23
Abstract: 893,422. Fluid-pressure servomotor-control systems. HAGAN CHEMICALS & CONTROLS Inc. July 23, 1959 [Dec. 5, 1958], No. 25343/59. Class 135. [Also in Group XVIII] The loss in weight of pickled meat products is continuously metered by a pneumatic weighing apparatus 20, Fig. 1, supporting the products on a " tree " 12 in a smokehouse, the weighing apparatus producing a pneumatic pressure proportional to the weight of the products which pressure and a reference pressure are arranged to actuate devices exerting contra-turning forces on the beam 35 of a ratio totalizer 27 which in turn develops an output pressure that operates an alarm when a predetermined weight loss has been achieved. The weighing apparatus 20 comprises a pivoted beam one end of which carries the support 19 for the meat products and the other end of which acts on a thrust block 105, Fig. 8, to which is secured a diaphragm 100 forming one wall of a pressure chamber 103. When the beam turns and raises the thrust block a valve 104 is closed and a valve 111 opened to admit pressure air into the chamber 103 from a source connected to an inlet tube 117 of the apparatus at 114. The pressure behind diaphragm 100 builds up to the value necessary to rebalance the beam, at which value both valves 104 and 111 become closed and the pressure in line 20a meters the weight of the load. The reference pressure is derived from a device 26, Fig. 1, in which a diaphragm 89 loaded on one side by a screw-adjusted spring 93 causes the pressure in a chamber 87 on the other side of the diaphragm to build up to a steady value applied to the line 26a, the pressure fluid being supplied to the chamber from a line 41, by way of a valve 97 which operates in like manner to the valve 111 of the weighing apparatus 20. In operation, the weight pressure in line 20a and the reference pressure in line 26a are converted into beam-loading forces by devices 37 and 38 respectively and as the product weight falls an increasing force is exerted on a device 40 acted on by the other end of the beam 35 and this force is converted into a pressure transmitted to line 27a, the device 40 being of like construction to the device 26 but having a beam-loaded plunger replacing the screw 94. The pressures in lines 20a and 27a act respectively on bellows 29 and 28, Fig. 2, which in turn operate pens 21, 22 in a recorder M to move towards each other as the product weight falls, contacts 42, 43 carried by the penoperating lever systems being closed to operate the alarm when a predetermined weight loss, whose value depends on the initial weight and the magnitude of the reference signal, has been achieved. In a modified system, Fig. 3, the weight signal is applied by line 20b-3 to device 38-3 and the reference signal by line 26a-3 to device 37-3 and a weight-loss signal thus produced in a device 40-3 is further amplified by a pivoted beam device 49 whose fulcrum 66 is adjustable so that the output signal in a line 57 may be made to be a pressure which increases in known proportion to the decrease in weight. In this system the initial pressure in line 57 is zero and it builds up to a value corresponding to the initial weight of the products when a predetermined percentage weight loss, dependent on the setting of fulcrum 66, has been achieved. In further modifications (Figs. 4 and 5, not shown), the output pressure of a ratio totalizer such as 27 in Fig. 1 either increases from zero to a value proportional to the desired weight loss or decreases from such a value to zero in the course of a smoking operation and the recorder M is omitted, the change of pressure between zero and the value representative of the desired loss or vice versa being made to cause directly the actuation of an alarm switch.