GB1319297A - Mixers - Google Patents

Abstract

1319297 Controlling mixing by viscosity SPILLERS Ltd 30 July 1971 [1 Aug 1970] 37275/70 Heading B1C [Also in Divisions Gl and G4] In a dough mixer the energy consumed by the beater during a predetermined period which is shorter than the total duration of the mixing operation is measured and used to control the amount of liquid added during the rest of the mixing operation. In a digital control system, see Fig. 1, (not shown and Division G4) pulses from a watthour meter are registered in a ratchet counter (1) until it reaches a predetermined number, after which they are passed to a binary counter (49) until the timer (17) reaches the end of the predetermined period. Further pulses are then prevented from reaching the counter (49) by the AND gates (3, 18), while the pump (62) is started to supply additional water into the mixer (at a constant rate). At the same time pulses from the astable multivibrator (9), which has a preset frequency are permitted to enter the binary counter (59), and the addition of water continues until the numbers accumulated in the binary counters (49, 59) are equal and produce an output from each of the equivalence circuits (32-37). If the dough consistency be very wet the timer (17) completes its cycle before the ratchet counter (1) reaches its preset point, water addition is prevented by the AND gate (18) and the counter (1) will be reset after delay. If the dough be so stiff that the counter (49) reaches its maximum capacity before the timer (17) completes, the next pulse will produce a zero output on the binary counter (49); the outputs of counters (49, 59) will be equal zero which will prevent further addition of water and also prevent future energy pulses entering the system. In an analog control system, see Fig. 2 (not shown) and Division G1, the voltage and current of the beater motor are fed to an analog multiplier (110) which produces an output representing the power consumption. The difference between this and the consumption of the empty mixer is fed through a gate (116) for a predetermined time to an integrater (118), and the time integral is compared with the desired dough consistency to produce an error signal which is used to add water.