Since the invention of windshield wipers in 1903, many different wiper mechanism designs have been tried by various manufacturers. Some of them did not go through “natural selection”. In modern cars, various options for installing windshield wiper blades are possible, but in most cases the “tandem” scheme is used.
, as the golden mean between the cost (complexity) of the design and efficiency.
There are two main technologies used in the design of windshield wipers:
- The combination of an electric motor and a gearbox with a worm mechanism ensures that the windshield wipers move with great force;
- A trapezoid with a system of levers converts rotational motion into reciprocating motion.
It takes a lot of force to move the wiper blades quickly. To create this force, an electric motor is used, connected to a gearbox with a worm drive. This mechanism reduces the engine speed by 50 times and increases the applied force.
A short lever is mounted on the output shaft of the gearbox and, rotating, transmits, through another lever, a reciprocating force to the windshield wiper trapezoid. The trapezoid serves to ensure synchronous movement of both windshield wiper blades.
Intermittent operation is provided by the wiper relay, which controls the operation of the electric motor. It is controlled by a relay with a steering column switch or an on-board computer. If the vehicle is equipped with a rain sensor, fully automatic control of the windshield wipers is possible.
With any design option, the only thing that remains unchanged is the presence of a replaceable wiper blade. The brush is attached to the lever (lead) using an adapter (latch). The adapter can be an integral part of the frame or separately included in the brush set. You can read more about the different types of adapters in the article Types of windshield wiper blade mounts
A dirty car windshield significantly impairs visibility on the road, which negatively affects the quality and safety of driving. Therefore, Motorpage experts remind you of the need to keep your windshield clean.
Windshield wipers are installed in cars specifically for this purpose. On some cars they are present not only on the windshield, but also on the rear window.
Windshield wiper device
- Wipers are oblong elements that move along the glass. At rest they are located at the bottom of the windshield. Both wipers are connected by a rod, due to which they move synchronously. The main cleaning function is performed by brushes with a rubber or silicone blade or tape, located on the wipers using a special leash (brush holder). They are a consumable item, since over time the tape wears out and the quality of the cleaning procedure deteriorates. If this happens, the consumable (brush or tape) must be replaced.
- Windshield wiper drive with gearbox Provides movement of the wipers. There are different types: mechanical, pneumatic, etc. Electric drives are installed in modern passenger cars. If this unit fails, then when the windshield wiper is turned on, the wipers do not move.
- Trapezium - the element is located between the drive and the wipers. It consists of rods and levers, the task of which is to convert the rotational motion created by the electric drive into reciprocating motion and transmit it to the leashes.
- The tank is a plastic container (volume from 2.5 to 5 liters) located under the hood or fender of the car. Water is poured into the tank, which is subsequently supplied to the glass when the corresponding wiper function is activated.
- The nozzles are located on the hood and connected to the tank via rubber hoses, through which liquid is sprayed onto the glass.
- The washer motor is a pump in the reservoir that supplies water. At the moment when the car owner turns on the spraying mode, the device creates pressure in the system, which squeezes the liquid through the nozzles onto the glass.
- The switch is located under the steering wheel to control the windshield wiper system. Using it, the driver adjusts the movement of the wipers (single sweep, or at a specified interval, or constant movement at low/high speed), and also activates the fluid supply, if necessary.
- Control unit - the device is not installed in all cars; its main function is to automatically start and turn off the windshield wiper. A rain sensor helps determine when to activate the cleaning system, which analyzes current weather conditions and the cleanliness of the glass.
- Interrupter - the device allows you to adjust the interval between wiper strokes when selecting the intermittent operating mode. This function is useful in light rain to prevent the wipers from rubbing the dry glass.
Windshield wiper system
Standard windshield wipers are designed to remove dirt, dust, and excess sediment from its surface. This allows you to increase visibility of the road at any time, including bad weather conditions: heavy rain or snow. For greater efficiency, the device is combined with a windshield washer, which sprays a special washer fluid under high pressure onto the glass surface. Thus, the glass is cleaned from adhering dirt and insects.
Automotive windshield wipers
Some cars have a rear windshield wiper, as well as special devices for cleaning the headlights (washers). This allows you to ensure traffic safety in all weather conditions. The frequency and duration of operation of the windshield wipers is regulated by the driver from the passenger compartment.
Windshield wiper design elements
Design features depend on the type of device and the type of fastening elements. The standard windshield wiper circuit consists of the following parts:
- lever drive (trapezoid);
- leashes;
- relay for controlling operating modes;
- electronic control unit (if equipped);
- electric motor with gearbox;
- hinged fastenings;
- brushes
Design of windshield wipers
Additionally, control devices are provided. For example, for manual control, a steering column switch for windshield wiper operation modes is used, and for automatic mode, a special electronic control unit and a sensor for analyzing glass contamination (rain sensor) are installed in the vehicle.
Windshield wiper circuit work.
Zero position.
The circuit consists of a fuse F, a three-position switch SA, a permanent magnet motor M and a limit switch SQ. The zero position of the SA switch corresponds to the off state of the vehicle's windshield wiper. If the switch is moved to this position after working, then the electric motor will stop only after the limit switch SQ is opened, which occurs when the wiper blades are in the extreme position.
Closing the electric motor brush with the SQ switch to ground leads to dynamic braking and a sharp stop of the electric motor, which prevents the moment of shutdown and re-supply of power to the electric motor brushes through SQ, which will lead to non-stop operation of the electric motor.
First position.
When switch SA is moved to the first position, power from fuse F through the switch contacts will flow to the motor brush and the drive will operate at low speed.
How the device works
Despite the simple functionality of the cleaning system, it is necessary to understand how windshield wipers work. Key details you need to know:
- The electromagnetic relay receives the control command and sets the operating mode of the brushes. Depending on the vehicle, the wipers may operate intermittently at short intervals of 3-5 seconds, continuously move at a set speed, or enter wash mode with the washer on.
- The windshield wiper motor receives power from the on-board electrical system. The exact connection diagram depends on the car model.
- The windshield wiper arms, and along with them the glass cleaning brushes, are driven by an electric motor with a worm gear and a lever drive (trapezoid). The trapezoid transmits and converts rotational motion from the electric motor to brushes, which, pressing tightly against the working surface, remove dirt and moisture from the glass.
A properly configured system should not leave streaks or mechanical damage on the surface of the glass, or make noise during operation. In case of such problems, it is necessary to promptly eliminate the malfunction.
How does a trapezoid work?
The windshield wiper trapezoid consists of a system of rods and levers that convert the rotational movement from the gearbox into the reciprocating movement of the leads with brushes. A standard device should perform the following functions:
- movement of the brushes when the windshield wiper motor is running;
- ensuring the required amplitude and speed of cleaning;
- Windshield wiper arms with two or more blades must move synchronously.
Windshield wiper trapezium
The trapezoid, like the electric motor, is an important component of the system. In case of any malfunctions (the appearance of backlashes) in its operation, the efficiency and quality of glass cleaning deteriorates. For greater reliability, the trapezoid elements are made of sheet steel, which is resistant to aggressive environments and also has high bending rigidity.
Depending on the design of glass wipers, trapezoids can be one-, two-, or three-brush, and according to the principle of operation, they can be symmetrical or asymmetrical.
Wiper motor
The windshield wiper motor has a basic design regardless of the car model. The main elements include the electric motor itself and the gearbox (usually a worm gear), which increases the force from the electric motor several times. Modern devices can be equipped with additional elements, including fuses for protection against heavy loads, heating elements for operation at low temperatures, and much more.
Windshield wiper motor for VAZ 2110
The windshield wiper gear motor is the most important element of the system, which ensures its performance. The brushes must fit tightly to the glass and move freely along it, otherwise there will be an increased load on the electric motor.
The principle of operation of the drive, engine and other mechanism components
If the circuit and design of the windshield wiper do not raise any questions, let’s move on to the next point - the principle of operation. The windshield wiper holder, together with the blade mounted on it, moves left and right, which allows you to almost completely clean the windshield. As stated above, using the switch, the driver can adjust the speed at which the wiper blade holder will move. Some modern cars are equipped with hidden cleaners. In this case, the windshield wiper mechanism is installed under the windshield, and when the driver needs to turn on the wipers, the device pushes up this mechanism, which, after being turned off, “hides” back.
In general, windshield and rear window cleaners are almost identical products, but there are differences in their operation. For example, the windshield wiper blade holder can only operate in one mode, without the possibility of adjustment. That is, if the front wipers are part of a whole system that includes many elements and a control unit, then the rear wiper has only one function. One of the main components of the washer is a pump designed to activate the system’s electric motor.
Let's briefly consider the principle of operation of the system:
- The driver presses the steering column switch, giving the control unit a signal to turn on the wipers and also supply water.
- Through the operation of the electric motor, the liquid begins to be transmitted through hoses through nozzles to the windshield or rear window.
- The windshield wiper blade holder begins to rotate under the influence of an electric motor, to which the control device has sent a signal - at what speed the holders should move.
- With a short-term supply of liquid, a certain volume is applied to the glass. When the water stops flowing, the wipers continue to work for some time, usually 1-3 strokes (the author of the video is the Volkswagen channel RUS-LAN center).
Purifier management
The windshield cleaning system can be controlled in two ways - electronic and electrical. The last option involves manually changing operating modes. Under the steering wheel there is a special control lever that allows you to turn on the device, adjust the pause in the wipers and change the cleaning modes. But this option requires constant driver participation.
Understeering's shifter
The electronic control system is completely autonomous and does not require human intervention. The car is equipped with a special electronic unit and a rain sensor, which analyzes the cleanliness of the glass and weather conditions. Electronic control provides a range of functions:
- automatic switching on and off;
- changing the operating parameters of the purifier;
- blocking the motor in the presence of obstacles on the windshield;
- additional cleaning with windshield washer;
- preventing brushes from freezing when the engine is off.
Types of brushes
Car manufacturers provide car owners with a choice of brush types. Depending on the design and operational characteristics, they can be of the following types:
Frame brushes
- Frame brushes are the best and affordable option. They adapt well to the working surface of the windshield, but deteriorate the quality of cleaning at sub-zero temperatures and high speeds.
- Frameless wipers are a more expensive option that provides high-quality glass cleaning. The device is more resistant to freezing and also lasts longer. Among the disadvantages, it is necessary to note the difficulty of selecting brushes to ensure proper fit to the glass.
- Hybrid windshield wipers - these are often called winter wipers due to their closed design and moisture resistance. Ideal for regions with low temperatures, where it is important to ensure the functionality of the cleaning system.
Frameless wipers
Frameless brush device
Frameless wiper blades are rarely used and this is due to their high cost and narrow applicability. Each brush is produced for a specific narrow range of car models. They are not universal.
Frameless brushes differ from frame ones in that instead of a rocker arm system, a flat, wide, spring-loaded metal plate is used, on which the wiper tape holders are secured with rivets.
The shape of the generating plate is made in accordance with the shape of the windshield of a particular car. Therefore they do not fit any model. This wide tape is covered with a rubber casing glued to it, thereby eliminating cases of disruption of the hinges, like with a frame brush. The design of the rubber band and the principle of its operation when cleaning glass does not differ from work in a frame wiper. In frameless wipers, it is also possible to replace the rubber band when worn, as in a frame wiper.
Methods for attaching brushes
Before 1999, most car manufacturers used a type of mounting for OEM windshield wiper blades called a "hook" or "hook". This is a universal device in the shape of the letter “U”, which allows you to snap the brush into place and not worry about the reliability of its installation. The following types of mounts are currently gaining popularity:
- Side pin - appeared in 2005 on BWM, Volvo and other cars. Allows brushes to be fixed using a special 22 or 17 mm side pin.
- Button or “Push Button” is an adapter for standard 16 mm wide wiper blades. It is enough to snap the device into place for fastening, and to remove it you need to press a special button.
- Pin lock - fixation of brushes using a special built-in lock. Used in Audi cars.
“Push Button” mounting scheme
This is not a complete list of types of fastenings. Each manufacturer can use their own designs for fixing brushes.
Despite the relative simplicity of windshield wipers, it is difficult to imagine a modern car without them. Drivers can control the operation of the wipers directly from the cabin, remove dirt and improve visibility of the road situation. And electronic systems automatically monitor the cleanliness of the glass, increasing the comfort and safety of driving without human intervention.
The working principle of the wiper blade
The wiper blade removes water from the surface of the car windshield thanks to the special shape of the working area of the rubber band. The photograph shows the position of the tape when the wiper blade moves from left to right, in the direction of the blue arrow.
As you can see, the working surface of the rubber band is slightly bent so that its right angle is perpendicular to the plane of the glass. Thus, the wide part of the tape removes a thick layer of water. The remaining thin film of water, pressing it to the glass, is removed by the right angle of the tape.
When changing the direction of movement of the brush, the working part of the rubber band of the wiper blade is shifted and already pushes a thin layer of water through another right corner of the band. Thus, the wiper blade cleans the car's windshield during forward and reverse strokes. The remaining water residues after passing the brush in the form of a micron film due to scratches on the glass and the ingress of small mechanical particles quickly evaporate and the glass becomes transparent.
If, when the wiper is operating, the working part of the tape or part of it takes a position relative to the surface of the glass being cleaned that differs from that shown in the photographs, then the car glass will remain opaque or streaks of water will remain.
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