Control system for a continuous compaction large square baler

Bale density impacts the cost to harvest, aggregate, store and transport hay or biomass. To achieve legal transport weight limits in many countries, the large square bale (LSBe) wet basis density should be approximately 240 kg·m−3. Current large-square balers (LSBers) create density by employing a reciprocating plunger to apply pressures in excess of 700 kPa to the bale face, but densification by a reciprocating plunger is inefficient because of the intermittent manner that the pressure is applied. What is explored here is an alternative bale densification method that uses an auger and conical compaction rollers to compact material in a continuous fashion. Compared to conventional LSBers, this new baler concept has the potential to create high-density bales with a machine that is less complicated and lighter weight. An important component of this baling mechanism was a closed-loop control system developed to achieve a desired bale density, as well as control bale separation and bale length. The control system varied bale chamber compression panel pressure to alter auger force and subsequent bale density. Using this control system enabled the baler to achieve dry basis densities ranging from 166 to 334 kg·m−3 with auger forces less than 44 kN, nearly a fifteen-fold reduction in force compared to a conventional plunger type LSBer.