Washing machine

From Wikipedia, the free encyclopedia

A washing machine is a machine designed to clean laundry, such as clothing, towels and sheets. The term is generally applied only to machines that use water as the primary cleaning solution, as opposed to dry cleaning (which uses alternative cleaning fluids, and is generally performed by specialist businesses) or even ultrasonic cleaners.

Contents 1 History 2 Modern machines 2.1 Top Loading versus Front Loading 2.2 European Standards 3 References 4 See also 5 External links

[edit] History

The first British patent under the category of Washing and Wringing Machines was issued in 1691. A drawing of an early washing machine appeared in the January 1752 issue of "The Gentlemen's Magazine," an English publication. In 1782 Henry Sidgier was issued a British patent for a rotating drum washer.

The first United States Patent titled "Clothes Washing" was granted to Nathaniel Briggs of New Hampshire in 1797. Fire destroyed the patent office and no description of the device exists so it is not known what kind of washing device Briggs "invented."

The electric washing machine was first mass produced in 1906. It is not known who first invented the electric washer. Alva.J. Fisher has been incorrectly credited with the invention of the electric washer. The US patent office shows at least one patent issued before Mr. Fisher's US patent number 966677 (e.g. Woodrow's US patent number 921195).

The first laundromat opened in Fort Worth, Texas in 1934. It was run by a man under the name Andrew Clein. Patrons used coin-in-the-slot facilities to rent washing machines. Since then, laundromats have become common.

By 1940 60% of the 25,000,000 wired homes in the United States had an electric washing machine. Many of these machines featured a power wringer, although built-in spin dryers were not uncommon.

Bendix introduced the first automatic washing machine in 1937,^[1] having applied for a patent in the same year.^[2] In appearance and mechanical detail, this first machine is not unlike the front loading automatic washers produced today. Although it included many of the today's basic features, the machine lacked any drum suspension and therefore had to be anchored to the floor to prevent "walking".

Many of these early automatic machines had coin-in-the-slot facilities and were installed in the basement laundry rooms of apartment houses. Naturally, after Pearl Harbor, US domestic washer production had to be suspended for the duration of WW2.

An improved front loading automatic model, the Bendix Deluxe (which retailed at $249.50) was introduced in 1947.^[3]

General Electric introduced the first top loading automatic also in 1947. This machine had many of the features that are incorporated into modern machines.

A large number of US manufacturers introduced competing automatic machines (mainly of the top loading type) in the late 40s/early 50s. Several manufacturers even produced semi-automatic machines, where the user had to intervene at one or two points in the wash cycle.

Despite the high cost of automatic washers, manufacturers had difficulty in meeting the pent-up demand. Although there were material shortages during the Korean War, by 1953 automatic washing machine sales in the US exceeded those of wringer-type electric machines.

In the UK, electric washing machines did not become popular until the 50s. The early electric washers were single tub, wringer-type machines, automatic washing machines being extremely expensive. During the 60s, twin tub machines briefly became very popular, helped by the low price of the Rolls Razor washers. Automatic washing machines did not really become common in the UK until well into the 1970s.

[edit] Modern machines

Washing machines are available in two main configurations: top loading and front loading. The top loading design, most popular in the United States, Canada, Australia and some parts of Europe, places the clothes in a vertically-mounted cylinder, with a propeller-like agitator in the center of the bottom of the cylinder. However, some top loading washers are more akin to front loading machines and feature a drum with a horizontal axis, access being facilitated by a trapdoor in the drum sidewall. Top loading machines in Asia use impellers instead of agitators. Impellers are similar to agitators except that they do not have the center post extending up in the middle of the wash tub basket. Clothes are loaded through the top of the machine, which is covered with a hinged door. Because they usually incorporate a gearbox, clutch, crank, etc, top loading washers are mechanically more complex than front loading machines. Nevertheless in the US, probably because of the far greater demand, top loading washers are far cheaper than front loading machines. In most top loading washers, if the motor spins in one direction, the gearbox drives the agitator; if the motor spins the other way, the gearbox spins the drum. Similarly if the pump motor rotates one way it recirculates the sudsy water; in the other direction it pumps water from the machine during the spin cycle.

The front loading design, most popular in Europe and the Middle East, mounts the cylinder horizontally, and loading is through a glass door at the front of the machine. The cylinder is also called the drum. Agitation is supplied by the back-and-forth rotation of the cylinder and by gravity. The clothes are lifted up by paddles in the drum and then dropped. This motion flexes the weave of the fabric and forces water and detergent solution through the clothes load. Although rarer, there is also a variant of the horizontal axis design that is loaded from the top, through a small door in the circumference of the drum. These machines usually have a shorter cylinder and are therefore smaller. Front loading machines are ideal for fitted kitchens, since they can be installed under a worktop. A front loading washing machine, in a fully-fitted kitchen, is often disguised as an ordinary base unit. Front loading washers are mechanically relatively simple, the main motor normally being connected to the drum via a grooved pulley belt and large pulley wheel, without the need for a gearbox, clutch or crank.

All washing machines work by using mechanical energy, thermal energy, and chemical action. Mechanical energy is imparted to the clothes load by the rotation of the agitator in top loaders, or by the tumbling action of the drum in front loaders. Thermal energy is supplied by the temperature of the wash bath. Many front loading machines have electrical heating elements to heat the wash bath to near boiling, if desired. Chemical action is supplied by the detergent and other laundry chemicals. Front loaders use special detergents that are designed to release different chemical ingredients at different temperatures. This is so that different type of stains and soils will be cleaned from the clothes as the wash water is heated up by the electrical heater. Front loaders also need to use low sudsing detergents because the tumbling action of the drum folds air into the clothes load that can cause over sudsing.

Tests comparing front loading and top loading machines have shown that, in general, front-loaders wash clothes more thoroughly, cause less wear, and use less water and energy than top-loaders. As a result of using less water, they require less detergent to be used, or conversely, they can use the same amount of detergent with less water, which increases detergent concentration and increases the amount of chemical action. They also allow a dryer to be more easily mounted directly above the washer.

Top-loaders have the advantage that they complete a washing cycle much faster, tend to cost less for the same capacity machine, and allow clothes to be removed at intermediate stages of the cycle (for instance, if some clothes within a wash are not to be spun). They also tend to be easier to load and unload, since reaching into the tub does not require stooping. The top loader's spin cycle between washing and rinsing allows an extremely simple fabric softener dispenser, which operates passively through centrifugal force and gravity. The same objective must be accomplished by a solenoid-operated valve on a front loader. Another advantage to the top loading design is the reliance on gravity to contain the water, rather than potentially trouble-prone or short-lived front door seals.

In the late 1990s, the British inventor James Dyson launched a type of washing machine with two cylinders rotating in opposite directions; which, it is claimed, reduces the wash time and produces cleaner results, however this machine is not currently in production.

Early washing machines were usually connected to the water supply via temporary slip-on connectors to the sink taps. Later, permanent connections to both the hot and cold water supplies became the norm. Nowadays, most machines only have a cold water connection (i.e. cold fill) and rely completely on electric heaters to raise the water temperature.

Since their introduction in the late 1930s/mid 1940s, automatic washing machines have relied on mechanical timers to sequence the washing and drying process. Mechanical timers consist of a series of cams on a common shaft. Each cam actuates, at the appropriate time in the wash cycle, a micro-switch to engage/disengage a particular part of the machinery (e.g. drain pump motor). The timer shaft is driven by a small electric motor via a reduction gearbox.

On the early mechanical timers the motor ran at a constant speed throughout the wash cycle, although it was possible for the user to truncate parts of the program, by manually advancing the control dial. However, by the 50s demand for greater flexibility in the wash cycle led to the introduction of electronic timers to supplement the basic mechanical timer. These electronic timers enable greater variation in such functions as the wash time. With this arrangement, the electric timer motor is periodically switched-off and only re-energised just prior to a micro-switch being engaged/disengaged.

In the 1990s upmarket machines incorporated microcontrollers for the timing process. These proved reliable, so many cheaper machines now incorporate microcontrollers, rather than mechanical timers. Washing machines are a classic application for fuzzy logic.

In early washing machines, any changes in impeller/drum speed were achieved by mechanical means or by a rheostat on the motor power supply. However, since the 1970s electronic control of motor speed has become a common feature.

Traditionally, top loading machines have tended to be more complex mechanically than front loading washers, because the former generally require a gearbox, clutch, crank, etc to perform the wash cycle. However, the recent introduction of direct drive motors has greatly simplified some of the top loading washers on the market. Also, because of the introduction of electronics, modern machines are far less complex than the early automatic washers. Consequently, the price of automatic machines, in real terms, has fallen considerably.

Early front loading machines, especially those manufactured in Mediterranean countries (e.g. Italy), had relatively low spin speeds (e.g. 800rpm or less). Nowadays, a spin speed of 1200rpm is common and a peak spin speed as high as 1600rpm is available on some machines. However, because they were not susceptible to gravitational forces, some early top loading machines had spin speeds in excess of 1000rpm, although some were as low as 360rpm.

[edit] Top Loading versus Front Loading

Feature	Top Loading Washer	Front Loading Washer
US Price	$400USD to $1100USD	Typically twice as much
US Market Share	95%	5%
European Market Share	10%	90%
Loading/Unloading Drum	No body stooping required	Body stooping required *<see note> (may be unable to remove clothing during wash or rinse cycle if power outage or machine malfunction occurs.
Water Consumption	up to 40 gallons per load (Energy Star rated machines comparable to front loaders)	40-60% less
Energy Consumption	Up to 800 kWh per year based on usage (Energy Star rated machines comparable to front loaders)	30-50% less
Detergent Consumption	Based on detergent concentration	50-70% less (Must use more expensive HE detergent)
Spin Speed~rpm	600 - 1200 typical	800-1600
Drying Time	Based on spin cycle efficiency	Significantly lower
Washing Time	Significantly Less	Up to 90 minutes per load (based on cycle)
Washing Thoroughness	Varies with Manufacturer	Comparable to high quality top loaders
Clothes Deterioration	Varies with manufacturer	Comparable to high quality top loaders
Access during wash cycle	Yes	Yes
Mechanical Complexity	Based on manufacturer	Much less with more electronics
Door Seal	None	Leakage, due to wear
Ease of Access for Repair	Usually Better	Complex
Install Under Worktop, Permanently	No	Yes *
Stackable	No	Probably OK
Noise Level	Varies with Manufacturer	Usually lower

• * To prevent stooping, some manufacturers are now selling front loading machines with a base unit to elevate the washer. Such machines, of course, cannot be installed below a normal worktop.

[edit] European Standards

Capacity and cost are the main considerations when purchasing a washing machine. If intended for use by a single person, a capacity of under 5Kg should be sufficient (thus saving energy and running costs).

Washing machines are given Eurobell grades for washing performance, energy efficiency and spin efficiency. Grades run from A to G (best to worst), and provide a simple method for judging running costs and performance. An AAA machine will denote top performance in the three categories.

[edit] References

[edit] See also

• Bleach
• Centrifugation
• Clothes dryer
• Combo washer dryer
• Energetic efficiency
• Home appliance and major appliance
• Laundry symbols
• Tunnel washer
• Hotpoint
• Detergent
• Laundry detergent
• Fabric softener

[edit] External links

• A website devoted to the preservation and exhibition of vintage washing machines
• Washing Machine Diagnostic and Repair Guide
• How Washing Machines Work Article by HowStuffWorks.com
• How to Choose a Washing Machine
• Washing Machine basic repair and troubleshooting - UK site.
• Washing Machine Museum
• Simple Washing Machine Repairs and Faults
• Comprehensive washing machine guide: how do you choose your washing machine?