Windscreen wiper
Encyclopedia
Motor vehicle
A motor vehicle or road vehicle is a self-propelled wheeled vehicle that does not operate on rails, such as trains or trolleys. The vehicle propulsion is provided by an engine or motor, usually by an internal combustion engine, or an electric motor, or some combination of the two, such as hybrid...
s, including train
Train
A train is a connected series of vehicles for rail transport that move along a track to transport cargo or passengers from one place to another place. The track usually consists of two rails, but might also be a monorail or maglev guideway.Propulsion for the train is provided by a separate...
s, aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
and watercraft
Watercraft
A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...
, are equipped with such wipers, which are usually a legal requirement.
A wiper generally consists of an arm, pivoting at one end and with a long rubber blade attached to the other. The blade is swung back and forth over the glass, pushing water from its surface. The speed is normally adjustable, with several continuous speeds and often one or more "intermittent" settings. Most automobiles use two synchronized radial type arms, while many commercial vehicles use one or more pantograph
Pantograph
A pantograph is a mechanical linkage connected in a special manner based on parallelograms so that the movement of one pen, in tracing an image, produces identical movements in a second pen...
arms.
History
Early versions
The inventor Mary AndersonMary Anderson (inventor)
Mary Anderson was a real estate developer, rancher, viticulturist and inventor of the windshield wiper blade. In November 1903 Anderson was granted her first patent for an automatic car window cleaning device controlled inside the car, called the windshield wiper.-Early life:Mary Anderson was born...
is credited with devising the first operational windshield wiper in 1903. In Anderson's patent, she called her invention a "window cleaning device" for electric cars and other vehicles. Operated via a lever from inside a vehicle, her version of windshield wipers closely resembles the windshield wiper found on many early car models. Anderson had a model of her design manufactured, then filed a patent (US 743,801) on June 18, 1903 that was issued to her by the US Patent Office on November 10, 1903.
Irish born inventor James Henry Apjohn (1845–1914) devised a method of moving two brushes up and down on a vertical plate glass windscreen in 1903. This was patented in the UK.
In April 1911, a patent for windscreen wipers was registered by Sloan & Lloyd Barnes, patent agents of Liverpool, England, for Gladstone Adams
Gladstone Adams
Captain Gladstone Adams was, at one time, the Chairman of Whitley Bay Urban District Council.In April 1908, he drove down to Crystal Palace Park in a 1904 Daracq-Caron motorcar to see Newcastle United play against Wolverhampton Wanderers in the FA Cup final...
of Whitley Bay
Whitley Bay
Whitley Bay is a town in North Tyneside, in Tyne and Wear, England. It is on the North Sea coast and has a fine stretch of golden sandy beach forming a bay stretching from St. Mary's Island in the north to Cullercoats in the south...
. The first designs for the windscreen wiper are also credited to concert pianist
Pianist
A pianist is a musician who plays the piano. A professional pianist can perform solo pieces, play with an ensemble or orchestra, or accompany one or more singers, solo instrumentalists, or other performers.-Choice of genres:...
Józef Hofmann
Józef Hofmann
Josef Casimir Hofmann was a Polish-American virtuoso pianist, composer, music teacher, and inventor.-Biography:...
, and Mills Munitions, Birmingham
Birmingham
Birmingham is a city and metropolitan borough in the West Midlands of England. It is the most populous British city outside the capital London, with a population of 1,036,900 , and lies at the heart of the West Midlands conurbation, the second most populous urban area in the United Kingdom with a...
who also claimed to have been the first to patent windscreen wipers in England.
The company Oishei formed, the Tri-Continental Corporation, introduced the first windshield wiper, Rain Rubber, for the slotted, two-piece windshields found on many of the automobiles of the time. Today Trico
Trico
Trico is an American company that specializes in windshield wipers. Trico, then Tri-Continental Corporation, invented the windshield wiper blade in 1917. Its original Trico Plant No. 1 is listed on the National Register of Historic Places....
Products is one of the world's leading manufacturers of windshield wiping systems, windshield wiper blades and refills, with wiper plants on five continents. Bosch
Robert Bosch GmbH
Robert Bosch GmbH is a multinational engineering and electronics company headquartered in Gerlingen, near Stuttgart, Germany. It is the world's largest supplier of automotive components...
has the world's biggest windscreen wiper factory in Tienen, Belgium, which produces 350,000 wiper blades every day.
Inventor William M. Folberth applied for a patent for an automatic windscreen wiper apparatus in 1919, which was granted in 1922. It was the first automatic mechanism. Trico later settled a patent dispute with Folberth and purchased Folberth's Cleveland company, the Folberth Auto Specialty Co. The new vacuum-powered system quickly became standard equipment on automobiles, and the vacuum principle was in use until about 1960. In the late 1950s, a feature common on modern vehicles first appeared, operating the wipers automatically for two or three passes when the windshield washer button was pressed, making it unnecessary to manually turn the wipers on as well. Today, an electronic timer is used, but originally a small vacuum cylinder mechanically linked to a switch provided the delay as the vacuum leaked off.
Intermittent wipers
In 1963, the first modern intermittent wipers were invented by Robert KearnsRobert Kearns
Robert William Kearns was the inventor of the intermittent windshield wiper systems used on most automobiles from 1969 to the present. His first patent for the invention was filed on December 1, 1964....
, an engineering professor at Wayne State University
Wayne State University
Wayne State University is a public research university located in Detroit, Michigan, United States, in the city's Midtown Cultural Center Historic District. Founded in 1868, WSU consists of 13 schools and colleges offering more than 400 major subject areas to over 32,000 graduate and...
in Detroit, Michigan
Detroit, Michigan
Detroit is the major city among the primary cultural, financial, and transportation centers in the Metro Detroit area, a region of 5.2 million people. As the seat of Wayne County, the city of Detroit is the largest city in the U.S. state of Michigan and serves as a major port on the Detroit River...
. The road to intermittent wipers began earlier, on his wedding night in 1953, when an errant champagne cork shot into Kearn's left eye, which eventually went almost completely blind. Nearly a decade later, Kearns was driving his Ford Galaxie through a light rain, and the constant movement of the wiper blades irritated his already troubled vision. He got to thinking about the human eye, which has its own kind of wiper, the eyelid, that automatically closes and opens every few seconds. Finally in 1963, Kearns put his idea into action, building the first intermittent wiper system using off-the-shelf electronic components. Kearns showed it to the Ford Motor Company
Ford Motor Company
Ford Motor Company is an American multinational automaker based in Dearborn, Michigan, a suburb of Detroit. The automaker was founded by Henry Ford and incorporated on June 16, 1903. In addition to the Ford and Lincoln brands, Ford also owns a small stake in Mazda in Japan and Aston Martin in the UK...
, and proposed manufacturing the design.
In the Kearns design, the interval between wipes was determined by the rate of current flow into a capacitor
RC time constant
In an RC circuit, the value of the time constant is equal to the product of the circuit resistance and the circuit capacitance , i.e. \tau = R × C. It is the time required to charge the capacitor, through the resistor, to 63.2 percent of full charge; or to discharge it to 36.8 percent of its...
. When the charge in the capacitor reached a certain voltage, the capacitor was discharged, activating the wiper motor for one cycle. After extensive testing, Ford executives decided to offer a design similar to Kearns’ intermittent wipers as an option on the company's Mercury line, beginning with the 1969 models. Kearns and Ford became involved in a multi-year patent dispute that eventually had to be resolved in court. A fictionalized version of the Kearns invention and patent lawsuit was used for the 2009 film Flash of Genius
Flash of Genius (film)
Flash of Genius is a 2008 American biographical film directed by Marc Abraham. The screenplay by Philip Railsback, based on a 1993 New Yorker article by John Seabrook, focuses on Robert Kearns and his legal battle against the Ford Motor Company when they developed an intermittent windshield wiper...
, which is billed as "based on the true story", but does not claim to be historically accurate in all respects.
Kearns may not, in fact, have been the original inventor of the intermittent wiper concept. John Amos, an engineer for the UK automative engineering company Lucas Industries, was the first to file a patent for an intermittent wiper (US Patent #3,262,042, issued 1966), two years before Kearns applied (US Patent #3,351,836, issued 1967). One notable difference is that the Amos patent describes an electromechanical device, whereas Kearns proposed a solid-state electronic circuit.
In March 1970, Citroën
Citroën
Citroën is a major French automobile manufacturer, part of the PSA Peugeot Citroën group.Founded in 1919 by French industrialist André-Gustave Citroën , Citroën was the first mass-production car company outside the USA and pioneered the modern concept of creating a sales and services network that...
introduced rain-sensitive intermittent windscreen wipers on their SM model. When the intermittent function was selected, the wiper would make one swipe. If the windscreen was relatively dry, the wiper motor drew high current, which set the control circuit timer to delay the next wipe longest. If the motor drew little current, it indicated that the glass was wet, setting the timer to minimize the delay.
Headlight wipers
In 1970, Saab AutomobileSaab Automobile
Saab Automobile AB, better known as Saab , is a Swedish car manufacturer owned by Dutch automobile manufacturer Swedish Automobile NV, formerly Spyker Cars NV. It is the exclusive automobile Royal Warrant holder as appointed by the King of Sweden...
introduced headlight wipers across their product range. These operated on a horizontal reciprocating mechanism, with a single motor. They were later superseded by a radial spindle action wiper mechanism, with individual motors on each headlamp.
Power
Wipers may be powered by a variety of means, although most in use today are powered by an electric motorElectric motor
An electric motor converts electrical energy into mechanical energy.Most electric motors operate through the interaction of magnetic fields and current-carrying conductors to generate force...
through a series of mechanical components, typically two 4-bar linkages in series or parallel.
Vehicles with air operated brakes sometimes use pneumatic wipers, powered by tapping a small amount of pressurized air from the brake system to a small air operated motor mounted on or just above the windscreen. These wipers are activated by opening a valve which allows pressurized air to enter the motor.
Early wipers were often driven by a vacuum motor powered by manifold vacuum
Manifold vacuum
Manifold vacuum, or engine vacuum in an internal combustion engine is the difference in air pressure between the engine's intake manifold and Earth's atmosphere....
. This had the drawback that manifold vacuum varies depending on throttle
Throttle
A throttle is the mechanism by which the flow of a fluid is managed by constriction or obstruction. An engine's power can be increased or decreased by the restriction of inlet gases , but usually decreased. The term throttle has come to refer, informally and incorrectly, to any mechanism by which...
position, and is almost non-existent under wide-open throttle, when the wipers would slow down or even stop. This problem was overcome somewhat by using a combined fuel/vacuum booster pump.
Some cars, mostly from the 1960s and 1970s, had hydraulically driven wipers.
On the earlier Citroën 2CV
Citroën 2CV
The Citroën 2CV |tax horsepower]]”) was an economy car produced by the French automaker Citroën between 1948 and 1990. It was technologically advanced and innovative, but with uncompromisingly utilitarian unconventional looks, and deceptively simple Bauhaus inspired bodywork, that belied the sheer...
, the windscreen wipers were powered by a purely mechanical system, a cable connected to the transmission; to reduce cost, this cable also powered the speedometer. The wipers' speed was therefore variable with car speed. When the car was waiting at an intersection, the wipers were not powered, but a handle under the speedometer allowed the driver to power them by hand.
Geometry
Most wipers are of the pivot (or radial) type: they are attached to a single arm, which in turn is attached to the motor. These are commonly found on many cars, trucks, trains, boats, airplanes, etc.Another type of wiper design is pantograph-based (see Fig. 6, below), which are used on many commercial vehicles, especially buses with large windscreens. Pantograph wipers feature two arms for each blade, with the blade assembly itself supported on a horizontal bar connecting the two arms. One of the arms is attached to the motor, while the other is on an idle pivot. The pantograph mechanism, while being more complex, allows the blade to cover more of the windscreen on each wipe. However, it also usually requires the wiper to be "parked" in the middle of the windscreen, where it may partially obstruct the driver's view when not in use.
Some larger cars in the late '70s and early '80s, especially LH driver American cars, had a pantograph wiper on the driver's side, with a conventional pivot on the passenger side.
Mercedes-Benz
Mercedes-Benz
Mercedes-Benz is a German manufacturer of automobiles, buses, coaches, and trucks. Mercedes-Benz is a division of its parent company, Daimler AG...
pioneered a system called the Monoblade, based on cantilever
Cantilever
A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs.This is in...
s (see Fig. 5, below), in which a single arm extends outward to reach the top corners of the windscreen, and pulls in at the ends and middle of the stroke, sweeping out a somewhat 'M'-shaped path. This way, a single blade is able to cover more of the windscreen, and displace the residual streaks away from the center of the windscreen.
Other features
Windscreen washer
Most windscreen wipers operate together with a windscreen (or windshield) washer; a pumpPump
A pump is a device used to move fluids, such as liquids, gases or slurries.A pump displaces a volume by physical or mechanical action. Pumps fall into three major groups: direct lift, displacement, and gravity pumps...
that supplies a mixture of water, alcohol
Alcohol
In chemistry, an alcohol is an organic compound in which the hydroxy functional group is bound to a carbon atom. In particular, this carbon center should be saturated, having single bonds to three other atoms....
, and detergent
Detergent
A detergent is a surfactant or a mixture of surfactants with "cleaning properties in dilute solutions." In common usage, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water...
(a blend called windshield washer fluid
Windshield washer fluid
Windshield washer fluid is a fluid for motor vehicles that is used in cleaning the windshield with the windshield wiper while the vehicle is being driven.-Delivery system:A control within the car can be operated to squirt fluid onto the windshield, typically using an...
) from a tank to the windscreen. The fluid is dispensed through small nozzle
Nozzle
A nozzle is a device designed to control the direction or characteristics of a fluid flow as it exits an enclosed chamber or pipe via an orifice....
s mounted on the hood
Hood (vehicle)
The hood or bonnet is the hinged cover over the engine of motor vehicles that allows access to the engine compartment for maintenance and repair. In British terminology, hood refers to a fabric cover over the passenger compartment of the car...
. Conventional nozzles are usually used, but some designs use a fluidic oscillator to disperse the fluid more effectively.
In warmer climates, water may also work, but it can freeze in colder climates, damaging the pump. Although automobile antifreeze
Antifreeze
Antifreeze is a freeze preventive used in internal combustion engines and other heat transfer applications, such as HVAC chillers and solar water heaters....
is chemically similar to windscreen wiper fluid, it should not be used because it can damage paint. The earliest documented idea for having a windshield wiper unit hooked up to a windshield washer fluid reservoir was in 1931, Richland Auto Parts Co, Mansfield, Ohio
Hidden wipers
Some larger cars are equipped with hidden wipers (or depressed-park wipers). When wipers are switched off in standard non-hidden designs, a "parking" mechanism or circuit moves the wipers to the lower extreme of the wiped area near the bottom of the windscreen, but still in sight. For designs that hide the wipers, the windscreen extends below the rear edge of the hood, and the wipers park themselves below the wiping range at the bottom of the windscreen, but out of sight.Rain-sensing wipers
Vehicles are now available with driver-programmable intelligent (automatic) windscreen wipers that detect the presence and amount of rain using a rain sensorRain sensor
A rain sensor or rain switch is a switching device actuated by rainfall. There are two main applications for rain sensors. The first is a water conservation device connected to an automatic irrigation system that causes the system to shut down in the event of rainfall...
. The sensor automatically adjusts the speed and frequency of the blades according to the amount of rain detected. These controls usually have a manual override.
Rain-sensing windscreen wipers appeared on various models in the late 20th century, one of the first being Nissan's 200SX
Nissan Silvia
The S12 was produced from 1984 to 1988, with revisions to the exterior trim in 1987 . It was sold in three configurations—a coupe , a hatchback, and a widebody chassis called grandprix .A number of different engines were equipped in the S12 chassis, depending on production year and more...
/Silvia
Nissan Silvia
The S12 was produced from 1984 to 1988, with revisions to the exterior trim in 1987 . It was sold in three configurations—a coupe , a hatchback, and a widebody chassis called grandprix .A number of different engines were equipped in the S12 chassis, depending on production year and more...
. , rain-sensing wipers are optional or standard on all Cadillac
Cadillac
Cadillac is an American luxury vehicle marque owned by General Motors . Cadillac vehicles are sold in over 50 countries and territories, but mostly in North America. Cadillac is currently the second oldest American automobile manufacturer behind fellow GM marque Buick and is among the oldest...
s and most Volkswagen
Volkswagen
Volkswagen is a German automobile manufacturer and is the original and biggest-selling marque of the Volkswagen Group, which now also owns the Audi, Bentley, Bugatti, Lamborghini, SEAT, and Škoda marques and the truck manufacturer Scania.Volkswagen means "people's car" in German, where it is...
s, and are available on many other mainstream manufacturers.
Headlight wipers
Some vehicles have small wipers or washers on the headlights. In some recent vehicles, these have been replaced with a powerful jet spray, without wipers.Rear wipers
Some vehicles are fitted with wipers (with or without washers) on the back window as well. Rear-window wipers are typically found on hatchbackHatchback
A Hatchback is a car body style incorporating a shared passenger and cargo volume, with rearmost accessibility via a rear third or fifth door, typically a top-hinged liftgate—and features such as fold-down rear seats to enable flexibility within the shared passenger/cargo volume. As a two-box...
s, station wagons, sport utility vehicle
Sport utility vehicle
A sport utility vehicle is a generic marketing term for a vehicle similar to a station wagon, but built on a light-truck chassis. It is usually equipped with four-wheel drive for on- or off-road ability, and with some pretension or ability to be used as an off-road vehicle. Not all four-wheel...
s, minivan
Minivan
Minivan is a type of van designed for personal use. Minivans are typically either two-box or one box designs for maximum interior volume – and are taller than a sedan, hatchback, or a station wagon....
s, and some sports car
Sports car
A sports car is a small, usually two seat, two door automobile designed for high speed driving and maneuverability....
s. They were first implemented in the 1970s, but SUVs did not use them until the 1980s.