Washing Machine

When you use a washing machine, you generally select the length of wash time based on the amount of clothes you wish to wash and the type and degree of dirt you have. To automate this process, we use sensors to detect these parameters (i.e. volume of clothes, degree and type of dirt). The wash time is then determined from this data. Unfortunately, there is no easy way to formulate a precise mathematical relationship between volume of clothes and dirt and the length of wash time required. Consequently, this problem has remained unsolved until very recently. People simply set wash times by hand and from personal trial and error experience. Washing machines were not as automatic as they could be.

To build a more fully automatic washing machine with self determining wash times, we are going to focus on two subsystems of the machine: (1) the sensor mechanism and (2) the controller unit. The sensor system provides external input signals into the machine from which decisions can be made. It is the controller's responsibility to make the decisions and to signal the outside world by some form of output. Because the input/output relationship is not clear, the design of a washing machine controller has not in the past lent itself to traditional methods of control design. We address this design problem using fuzzy logic and FIDE.

For particularly dirty clothing covered with mud or dirt, it was necessary to constantly rub and flex the cloth to break apart solids and help the soap penetrate through thick, dry, or sticky layers of soil on the cloth. At first this was done by pounding or rubbing the clothing with rocks in a river, and later developed into the corrugated wash board. In Roman times a fuller would whiten clothing by stomping on it in a bucket full of fermented urine.

Washing machine technology was developed as a way to reduce the drudgery of this scrubbing and rubbing process, by providing an open basin or sealed container with paddles or fingers to automatically agitate the clothing. The earliest machines were often hand-operated but were built with the belief that the machine itself was faster and easier to operate than washing the clothing by hand directly. As electricity was not commonly available until at least 1930, these early machines were often operated by a low-speed single-cylinder hit and miss gasoline engine.

Because water usually had to be heated on a fire for washing, the warm soapy water was precious and would be reused over and over, first to wash the least soiled clothing, then to wash progressively dirtier clothing. The load of soaking wet clothing would be removed, and another load of dirty clothes added to the machine. While the earliest machines were constructed entirely from wood, later machines made of metal permitted a fire to burn below the washtub, to keep the water warm throughout the day's washing.

Removal of soap and water from the clothing after washing was originally a separate process. The soaking wet clothing would be formed into a roll and twisted by hand to extract water. To help reduce this labour, the wringer/mangle was developed, which uses two rollers under spring tension to squeeze water out of the clothing. Each piece of clothing would be fed through the wringer separately. The first wringers were hand-operated, but were eventually included as a powered attachment above the washer tub. The wringer would be swung over the wash tub so that extracted wash water would fall back into the tub to be reused for the next wash load.

The modern process of water removal by spinning did not come into use until electric motors were developed. Spinning requires a constant high-speed power source, and was originally done in a separate device known as an extractor. A load of washed clothing would be transferred from the wash tub to the extractor basket, and the water spun out. These early extractors were often dangerous to use since unevenly distributed loads would cause the machine to shake violently. Many efforts have been made to counteract the shaking of unstable loads, first by mounting the spinning basket on a free-floating shock-absorbing frame to absorb minor imbalances, and a bump switch to detect severe movement and stop the machine so that the load can be manually redistributed. Many modern machines are equipped with a sealed ring of liquid that works to counteract any imbalances.

What is now referred to as an automatic washer was at one time referred to as a washer/extractor, which combines the features of these two devices into a single machine, plus also includes the ability to fill and drain water by itself. It is possible to take this a step further, to also merge the automatic washing machine and clothes dryer into a single device, but this is generally uncommon because the drying process tends to use much more energy than using two separate devices; a combined washer/dryer not only must dry the clothing, but also need to dry out the wash chamber itself.

In 2009, L'Osservatore Romano, the semi-official newspaper of the Holy See, pronounced the washing machine an important milestone in the liberation of women, as it freed them from the drudgery of household chores.

Right now the statistics say that this machine could perform the same task by using less than 90 per cent of the water of conventional machines and 30 per cent less energy. This machine can have the environmental impact of taking two million cars off the road.

How could that be possible? Here the work of water is replaced by using thousands of tiny reusable nylon polymer beads. These plastic beads attract and absorb dirt under humid conditions. Stephen Burkinshaw said: “We’ve shown that it can remove all sorts of everyday stains including coffee and lipstick while using a tiny fraction of the water used by conventional machines.”

How does this washing machine function? This technology requires a small amount of water and detergent to dampen the clothes and loosen stains. This device also creates the water vapor that allows the beads to work. Once washing is finished, the beads fall through a mesh in the machine’s drum. These beads are reusable. One can reuse them up to a hundred times. One needs 20kg of the beads along with a cup of water and detergent. The chips can be used up to 100 times, the equivalent of six months’ washing.

A demonstration was held at the Clean Show in New Orleans between June 18th and 21st. The beads are placed inside the smaller of two concentric drums along with the dirty laundry, a spew of detergent and a little water. As the drums spin, the water wets the clothes and the detergent gets to work loosening the dirt. Then the nylon beads mop it up.

The beads have a crystalline structure. This structure makes the surface of beads with an electrical charge that attracts dirt. When the beads are heated in humid conditions to the temperature they lose their crystalline structure and acquire an amorphous structure. Now the dirt is drawn into the core of the bead where it remains locked in place.

The whole process takes about 30 minutes and the outer drum stops rotating. The inner drum has the clothes and the beads. The inner drum also has a small slot. As it keeps on rotating, the beads fall through the slot; some 99.95% of them are collected in the outer drum. The remaining that are trapped in the folds of the clothes normally fall into a collection trough while the laundry is being removed, and a vacuum wand can be used to remove them from pockets etc.

Xeros chief executive Bill Westwater said: “We’ve got an eye on the consumer but it will take time and we hope commercial success could act as a springboard to move into the consumer market. We’ve been very encouraged by the response from people, but the proof is in the pudding and that means putting a machine into someone’s operations and justifying the savings.”

We can draw the conclusion that when so little water is used and the warm beads help dry the laundry, less tumble drying is needed. An environmental consultancy, URS Corp, estimates that this washing machine’s carbon footprint was 40% smaller than the most efficient existing systems for washing and drying laundry.