Indesit Co. configured its Moon washing machine to overcome the vibration and noise issues that often stem from an unbalanced load. Daniele Rossi, product technical director, laundry, says engineers put great care into “redistributing the load” to keep unbalance to an absolute minimum.
Indesit engineers started by dividing the load balancing system in two clearly defined stages—the reading of the unbalance and the redistribution of the load. “The first part is done by analyzing two very clear physical quantities: the change in speed of the drum and the change in the current absorbed by the motor in one revolution,” Rossi tells APPLIANCE. “Imagine spinning a bucket of water around at arm’s length. Our capacity to keep it spinning constantly and to keep our effort constant gives us the feel of how much water is in the bucket, or to put it technically, the ‘unbalancing weight.’
“Once we’ve recognized the unbalance, we can decide whether or not to activate the spin function,” Rossi continues. “But we always want the spin, so knowing how to read the unbalance would be useless if didn’t also know how to reduce it.”
That is why the second part of the equation—the load redistribution—is so important, he says. “This procedure uses techniques based on modulating the speed of rotation of the drum in such a way that the load can be redistributed as evenly as possible,” Rossi explains. By alternating reduction of speed, maintenance, and what Rossi calls “sudden accelerations,” engineers caused a relative movement between the masses that distributed the load uniformly in the drum.
“But that isn’t enough,” Rossi notes. “Loads often have cotton items and synthetic items, and even if they are evenly distributed when the spin starts, the speed at which water is ‘released’ varies from fabric to fabric, so we could still find there’s growing unbalance as the speed increases. Here too, we can sense the onset of such unbalance and compensate for it.”
