Everyone is already accustomed to the fact that in a modern car there is a lot of incomprehensible and difficult things from the point of view of understanding of the common man in the street. Motorists are divided into two camps: those who are trying to understand the structure of “all this” and those who are indifferent to all this, since there are specialists who “know what’s what”...
I rather belong to the first type of people and try to at least superficially delve into the structure and principle of operation of this or that unit, so that in case of an unforeseen situation I have an idea of what is happening with my car or at least understand when they try to help me at the service station to deceive, "selling me some kind of game" veiled under Clever words and terms... :)
In my article today I want to talk about a rain sensor, which is also sometimes called a rain sensor, how it works, what it is, how it works, and the myths that surround this device. Interesting? Then let's go!
As the name suggests, the rain sensor has something to do with precipitation, namely rain. That’s right, this sensor, unlike other sensors that a modern car is stuffed with, is responsible for timely automatic switching on wipers. That is, as soon as this sensor detects that there are drops on the windshield, the wiper blades immediately turn on and the glass is cleaned.
But how does this magic happen, you ask? I, and you, probably, have puzzled over this more than once and tried to explain the principle of operation of a rain sensor by the presence of some sensors that are triggered when interacting with moisture or something like that... But in reality, everything is not so The rain sensor works on a completely different principle.
Rain sensor device
Typically, such a sensor consists of several photosensitive elements (photodiodes) and LEDs that work in tandem. The sensor itself is a small circuit board enclosed in a plastic case. All this equipment is attached in the area of the interior rearview mirror, or rather in front of it. The sensor is located in the passenger compartment and is attached to the windshield using sealant or an alternative adhesive.
How does a rain sensor work?
The operating principle of this sensor is based on the law of light refraction. Built-in LEDs emit infrared light that passes through the windshield and is reflected from the outside of it. The reflected signal is then captured by a photosensitive element or photodiode, which analyzes the quality of the received signal. If the signal received by the photodetector is clear and strong, the wipers do not turn on, since a special controller “understands” that the glass is clean and there is no need for “cleaning”. If the glass is covered with raindrops, the signal sent by the LEDs will begin to refract and return with delays and a completely different content. In this case, the controller concludes that the glass is covered with raindrops and, guided by certain algorithms, turns on the wipers at a certain frequency. The heavier the rain, the more the signal will be scattered and the less signal the photoreceiver can receive, therefore, the more intense the wiper blades will work. Thus, regardless of the intensity of rain, the glass will be cleaned effectively.
This is the simple principle that the rain sensor works on. More advanced sensors are capable of analyzing not only precipitation, but also the degree of illumination, and turning on the headlights if necessary.
And now, as I promised about the myths that surround the rain sensor, also known as a rain sensor.
Myth one : “The rain sensor doesn’t work at night!” This is not true, since infrared sensors do not need light to operate, and they do not depend in any way on the degree of illumination environment. For example, let's take any control panel that works using the same technology. As we know, he doesn’t care when to change channels, day or night he works properly!
Myth two : “If you replace the windshield, you’ll have to say goodbye to the rain sensor!” As a rule, most car manufacturers, if not all, when producing glass, take into account the likelihood that you will want to install a rain sensor or you already have one installed. Therefore, special “windows” are provided on the glass for this type of device.
Myth three : “The rain sensor is useless in winter!” Perhaps this is partly true, the sensor really does not respond to snow. But as we all know, snow, falling on the warm glass of a heated car, will certainly melt and turn into water, which the sensor can easily detect and take measures to eliminate. If the windshield is cold, then most likely there is no one in the cabin, which means there is no need for wipers. In all other cases, the temperature in the cabin during snow will be higher than outside and the windshield will somehow be warmer than the environment, which means the snow will melt and the rain sensor will work, and with it the wipers.
I will end here. Thanks to everyone who read to the end! I look forward to your feedback on this invention, as well as comments on the topic: “What is a rain sensor for you: a fashionable feature or a useful and necessary thing?” All the best and see you at .
In this article we will look at the main task and operating principle of a rain sensor. Based on the name, it becomes clear what kind of device this is and its main purpose. The rain sensor is designed to detect the presence of precipitation and automatically turn on the windshield wipers. After all, dirt and rain on the glass cause serious difficulties when driving, and constantly turning the wipers on and off once again distracts the driver from the road.
It, like any innovation, is primarily designed to increase comfort when driving a car. Recently the rain sensor has received wide use, it can be seen in the basic configuration of middle-class and golf-class cars.
Principle of operation
The sensor is located with inside windshield. How does it work then? How is rain detected? The trick is that it reacts not to water, but to light. The design of the device is simple and consists of the following elements:
- photodiode;
- two LEDs;
- light sensor;
- foil;
- electronic control unit (ECU).
The device operates by different angles reflections of infrared rays on wet and clean glass. One diode emits an infrared beam, which, when reflected from smooth surface glass, falls on a photodiode, which recognizes the amount of returned light. Signals reflected from clean and wet (dirty) glass have different ray refractions. Wet glass transmits light much more easily. The computer recognizes these differences and, if necessary, gives a signal to automatically turn on the windshield wipers.
Some sensors are able to accurately recognize the number of drops or the presence of snow on the glass and regulate the operating modes of the windshield wipers. At heavy pollution there is a signal about the need to supply washer fluid. The control unit is connected by a wire to the relay that controls the wipers. The sensor must be positioned in such a way as to fall within the operating area of the windshield wipers. The device usually includes an automatic light sensor.
Sensor Installation
If the car is not equipped with a rain sensor at the factory, you can buy and install it yourself; there is no need to go to a car service center for this. Included with the device is step-by-step instruction for installing and configuring the sensor.
Let's look at an example of installation on a Russian Lada Granta car. First you need to open the fuse box, which is located just below the steering wheel on the left. In place of the standard relay, which is located in the far left corner at the top of the fuse box, a rain sensor relay is installed. The control unit is glued to the windshield using the supplied double-sided tape. Before gluing the block, the glass must be wiped with a special cloth (supplied). The wiring from the control unit is laid under the ceiling, then along the left pillar it goes down to the relay unit, and through a hole on the inside it enters the unit itself.
Also, there are universal rain sensors that can be glued to a special gel; this does not change the operating principle of the device and the installation diagram is similar to that described here.
It is necessary to take into account that the standard relay sits very firmly in the socket. You must try to act extremely carefully and not damage the relay mount. You can use a knife and pry up the relay to speed up the work and reduce the chance of damage. Then the rain sensor relay is installed and connected by wire to the control unit. We close the cover of the fuse box and begin testing the operation of the device.
Video instructions for self-installation:
Configuring the sensor operation
To check the operation of the sensor, you need to switch the windshield wiper switching blade to intermittent mode. Then spray the glass with a small amount of water from a spray bottle or water bottle. After a second, the windshield wipers should operate. Depending on the sensor model, it has various modes, which are easy to set up using the instructions. The mode is selected in accordance with the time of year and weather conditions.
Real and mythical disadvantages
Like any device, the sensor has advantages and disadvantages. The disadvantages include untimely activation of the wipers (a few drops are enough to operate, however, they must fall within the sensor’s coverage area). When the windshield wipers are activated, the windshield washer does not always turn on, and the dirt is only smeared, reducing visibility. Another disadvantage is delayed firing, although this effect can be eliminated with tuning. Misconceptions include the opinion that the sensor is useless in winter time of the year. Having studied the principle of its operation, it becomes clear that its functions are relevant not only in rain, but also in snow.
Having studied the principles of operation and an installation example, we can say that rain sensors have deservedly become widespread in the automotive industry and are important components of safe driving.
For the first time, a rain sensor was used in the middle of the last century by the American automaker General Motors on one of its premium models. But mass production was not mastered due to imperfect technology. And only by the mid-nineties, first Japanese automakers, and then others, began to install rain and light sensors on expensive models.
Nowadays they will no longer surprise even the owners of compact and completely inexpensive cars. Modern rain and light sensors are combined into a single module located at the top of the windshield, but the principles of operation of these sensors are different.
Hella light and rain sensor device:
1 - binding medium; 2 - upper sensor housing with optics; 3 - curtain; 4 - printed circuit board with sensor with connector connector; 5 - lower sensor housing; 6 - clamp.
Rain sensor
A- dry windshield; b- wet windshield.
1
- LED transmitter; 2
- prism; 3
- photodiode receiver; 4
- water drop.
Detects the presence of water droplets on the windshield using an optoelectronic measurement method. The sensor's sensing element consists of one or more LEDs (transmitter), a prism and a photodiode (receiver).
The infrared rays emitted by the LED enter the windshield through a prism, are reflected from the outer surface and enter a sensitive photodiode. The beam is reflected almost completely from dry and clean glass, and therefore the signal at the photodiode is larger. When water drops hit the glass, the light rays are refracted, and therefore only a small part of them reaches the signal receiver. The heavier the rain, the fewer rays hit the photodiode.
The electronic unit continuously determines the amount of water on the glass and adjusts the frequency of strokes and operating speed. The system even knows how to assess whether the glass is dirty: if after one double stroke of the wipers transparency has not been restored, the windshield washer automatically turns on.
Light sensor
V- front light sensor; G- sensor external lighting.
1
- light guide with lens; 2
- light guide with light filter.
In the first combined light and rain sensors, there was only one element that measured illumination. When it got dark or entered a tunnel, he turned on the headlights and instrument lighting. Then, up to three photosensitive elements were placed in the same assembly, each with its own area of responsibility.
The light intensity in front of the vehicle is measured by a narrow-angle front light sensor. Using the signal from the sensor, the electronics recognize day and night and turn the headlights off or on accordingly.
Light sensor response zones:
Using a wide-angle light guide, the ambient light sensor (also known as sun sensor) detects the level of light above the vehicle. An additionally installed light filter allows you to distinguish between sunlight and artificial light. This is necessary so that, for example, the automation turns on when entering a lighted tunnel during the day; and if the car is under the scorching sun, the climate control should cool the interior more intensively.If the car is equipped with a head-up display, a narrow directional HUD sensor is installed. It measures the illumination of the area where information is projected. And the electronic system adjusts the brightness of the backlight of the elements displayed on the display.
Interaction of light and rain sensors with other vehicle systems
|
On your own
If your car does not have standard sensor rain and light, it's possible. For example, there are rain sensors on sale, both domestic and foreign (usually Chinese) made. They are a small plastic box that is glued to the inside of the windshield and connected to the car's electrical system with a wiring harness. There is even a version for 24-volt electrical equipment. Simple universal rain sensors cost up to a thousand rubles, the most sophisticated ones cost a little more than two thousand.
If you don't want to understand the car's electrical circuits to adapt the sensors, search for a specific model. In addition to the sensor, the kit includes a central light switch with the Auto position, wiring harnesses, and plastic sensor covers that fit onto the rear view mirror bracket. The price of such sets is in the range of 3800–4500 rubles, and complete with a self-dimming rearview mirror they can cost up to 9500 rubles.
Destroying MYTHS
- The rain sensor is triggered by the impact of water drops.
No. The sensor operation is based on optoelectronic measurement. - At night the rain sensor is powerless.
No. External lighting does not affect the operation of the system since it uses its own infrared light sources. - You can say goodbye to the sensor when replacing the windshield.
No. Glass manufacturers provide a window in the tinted or silk-screened layer. Installing an old sensor on new glass is possible, but subject to the technology, and after installation you need to check the correct operation of the sensor. - In winter, the sensor acts up.
No. The sensor may not respond correctly to snow. But the reaction to water droplets from melted snowflakes will be correct. The worst thing is if the sensor installation site is covered with a crust of ice.
In this case, it is better to switch to manual control of the windshield wipers. - Rain sensors work the same on all cars.
No. The car manufacturer is responsible for adapting the rain sensor to the vehicle. At the same time, a full range of finishing work is not always carried out with all possible types of glass (thermal different colors, equipped with electric heating, with a tinted strip in the upper part). With some options, a little less is possible correct work sensor
Cars almost always have manual adjustment of the sensor sensitivity. And only on some cars this function is software disabled.
Photo: manufacturing companies, depositphotos.com
This smart device is located inside the car - how does it sense raindrops? The secret is that the rain sensor reacts not to moisture, but to light. It has two elements: an LED and a photodiode. The LED emits infrared light. We don’t see this light, although we actively use it in everyday life - for example, when switching television channels with a remote control.
Infrared light hits the glass, is partially reflected from its smooth surface and returns to the sensor. Here it is caught by a photodiode. It determines how much light has returned. When the glass is dry, a lot of light returns. When wet it is much less, since light easily penetrates out through drops of water. Having detected that the glass is wet, the sensor activates the windshield wipers. Some sensor models can very accurately determine the amount of moisture and accordingly adjust the speed of the wipers and the supply of washer fluid.
5 myths about the operation of a rain sensor
We have already dispelled myth No. 1: the rain sensor is NOT activated by the impact of drops on the glass, as well as vibration and other mechanical influences. The operation of the rain sensor is based on the action of photocells. If the sensor responded to shocks, the brushes would diligently wipe flies, mosquitoes and small pebbles from the glass.
Myth #2: “The rain sensor does not work at night.” As we have already found out, the operation of the rain sensor is based on the principle of reflecting infrared rays. Their properties do not depend on illumination. Otherwise, for example, remote controls remote control didn't work in the dark.
Myth No. 3: “When replacing glass, you will have to say goodbye to the rain sensor.” You don’t have to: many manufacturers offer car windows with space for a rain sensor. For example, from the Olympia company you can purchase rain sensor glass for most foreign cars: Camry, Passat, A4 and other cars.
Myth #4: “You can’t put a tint strip on a windshield with a rain sensor.” You can: in this case, a hole is cut out in the tint film for the sensor. The main thing is that the glass tinting is done according to.
Myth #5: “A rain sensor is useless in winter.” Since the rain sensor works by reacting to water drops and not snow, it functions less well in winter. However, if the car has heated glass, falling snow will immediately melt into water, and the rain sensor will work normally.
Interesting facts about rain sensors
- General Motors conducted the first experiments on creating rain sensors back in the 1950s. The sensor was created for the iconic Cadillac Eldorado model. But the technology was far from perfect: between how the rain sensor works on a modern car and the first experiments of GM engineers there are decades of design development.
- One of the first production cars with a rain sensor was the Nissan Silvia, a sports coupe. In the 2000s, rain sensors appeared on cars from Volkswagen, Cadillac and other leading manufacturers.
- Rain sensor operation is used not only in the automotive industry, but also in agriculture, to control the irrigation system. “Field” sensors have a different operating principle than automobile ones: they have hygroscopic disks, which increase in size when wet and shrink when dry. This regulates the water supply. Interestingly, some sensors have a built-in temperature indicator that stops water flow if the temperature drops below zero.
Many car owners consider a rain sensor to be an unnecessary device that they can do without. To understand whether it is really necessary, it is worth learning about the features of such devices.
The described device is a device that detects the appearance of precipitation and turns on the wipers. Typically, the sensor also reacts to light levels and is used to automatically turn on the headlights.
Rain sensor
This device is designed to solve several problems:
- determining the presence of rain or snow;
- turning on the wipers when it rains;
- determining the degree of contamination of the windshield;
- turning on the headlights if the sensor is also designed to detect the level of illumination.
The described device is installed between the windshield and rearview mirror. The rain sensor is designed to create more safe conditions while driving in the city or on a busy highway. If it begins to rain or snow during heavy traffic, the driver has to make unnecessary movements to turn the wipers on and off, taking his attention from the road. This contributes to loss of attention and can lead to an accident. In addition, the device allows for excellent visibility in the presence of large amounts of precipitation.
Rain sensors have several disadvantages:
- False or inappropriate positives. In some cases, just one drop causes the wipers to turn on, although the rest of the glass remains dry. At the same time, the sensor often does not work when part of the glass is filled with water and dirt, but the drops do not fall into the coverage area of the device.
- Turning on the wipers without windshield washer. Because of this, dirt is smeared across the surface, causing poor visibility.
- Triggered due to defects in the windshield. The presence of scratches and other defects on the surface may cause the device to malfunction.
- Response delay. In some cases, the rain sensor is activated within 1-2 seconds after rain drops appear on the windshield.
To avoid such problems and configure the sensor in advance to required level sensitivity, just splash water on the place where the sensor is installed. If it works correctly, the wipers will automatically turn on.
The rain sensor is mounted under the windshield on back side rear view mirrors. During installation of the device, the following nuances are taken into account:
- The sensor should be located on the windshield in such a way that it does not interfere with the driver's view of the road. It is important to install it in an area that is cleared by the wipers while they are running. Otherwise, the device may not function correctly.
- There should be no cracks or other defects in the area where the sensor is located, since the efficiency of its operation depends on this.
- Before attaching the device, you need to make sure that the wipers effectively clean the windshield and do not leave dirt.
The sensor can be installed as in service center, and independently. Moreover, it is not at all difficult. None special tools not required for installation.
Below we provide instructions for installing a simple rain sensor DDA-35.
First you need to “aim” - select a place on the inside of the windshield where the sensor will be glued. As mentioned earlier, it should not interfere with the driver's view. For beauty, it is advisable to check the location and install the sensor at the top in the middle, next to the mirror mount.
Purchased rain sensors most often come with a special cloth for wiping and degreasing the glass. Thanks to this, the sensor is attached better.
If such a napkin is not included in the kit, you can use any glass napkin.
Carefully wipe the area on the windshield where we will glue the rain sensor.
Remove the sensor from the inside protective film, thereby opening the fasteners that will hold the sensor to the glass.
After this, apply the rain sensor to the selected place on the glass and carefully press the device against the glass. We try to make sure everything goes smoothly, since we won’t have a second chance. With each disconnection, the holder will stick to the surface worse and worse.
We push the wire from the sensor under the headliner.
If there is not enough space under the upholstery, then slightly loosen the screws securing the visor.
Remove the cover plate from the rack and lay the wire under it. After this we put the cover back on.
Let's go lower. Carefully push the cable under the rack seal.
Open the fuse box (in different models he is in different places), and install the rain sensor in place of the windshield wiper control relay (be sure to follow the markings and the position of the key). If we don’t know exactly where to install the relay, look in the documentation.
If necessary, the remaining cable can be wound up and left in the mounting block.
This completes the process of installing a rain sensor on a car. All that remains is to check its functionality by splashing water on the windshield (with the car's ignition on, of course).
Checking the functionality of the rain sensor
You can also watch a video about installing a rain sensor:
After connecting the device, the wipers can be controlled manually. This may be necessary when moisture gets onto the glass from under the wheels of a car moving in front and does not reach the sensor’s coverage area. In this case, the driver turns on the wipers manually.
It is necessary to set up the device immediately after installation, so as not to be distracted by such actions while driving. The DDA-35 has 3 operating modes - standard, rain and snow. Modes are switched by pressing a single button one by one.
Built-in factory rain sensors are adjusted using the steering column switch. The power handle standardly has 5 positions (sometimes more and less). In position “0” the device is turned off. Numbers from 1 to 4 indicate the degree of sensitivity of the sensor. When you turn on the device in mode 4, it will operate in maximum sensitivity mode. To turn it off, simply turn the knob to position 0.
The rain sensor is adjusted using the steering column switch
How the rain sensor works
The described device consists of an LED and several photosensitive elements (photodiodes). The light emanating from the LED is reflected from the glass surface and returned to the light-sensitive elements. If there is rain or snow on the surface, the degree of reflection changes and the sensor turns on the wipers.
The more wet the windshield is, the less refracted light will be reflected. Photocells react to the change and after that the wipers turn on. This is why false alarms may occur when insects get on the glass or if there are defects on the surface. To prevent untimely activation of the wipers, it is enough to turn off the sensor in dry weather and install the device only on undamaged glass.
Turning on the factory rain sensor after installation is quite simple - to do this, you need to turn the steering column lever to positions from 1 to 4. It turns off when you switch the lever to position 0. If problems arise in the operation of the sensor, you should not try to turn it off yourself if you don’t know how to do it correctly.
Example of setting up a rain sensor.
To turn it on, you must move the steering column lever to position 1. The dial A must be set in accordance with the desired sensitivity (bottom - minimum, top - maximum).
To turn off the rain sensor, move the steering column lever to position 0.
The main mistake many drivers make is turning off the device as soon as possible. in a simple way– by cutting the wire. Such actions may cause a malfunction of the on-board power supply control unit. If the sensor does not respond to small drops, you should first unscrew the knob to position 4, at which it will operate in maximum sensitivity mode.
To safely disconnect the sensor, simply remove the connector from it. In this case, an error will be displayed in the on-board power supply unit. If you need to completely turn off the device, you should contact a car service.
Many rain sensors are universal and can be installed on any car. They all work on the same principle, so any driver can configure the device independently.
How much does a rain sensor cost?
The cost of many rain sensors is about 2 thousand rubles. The price depends on the sensitivity of the device, as well as on whether the electronic relay is built into the car or is removable. The method of connecting the sensor depends on this.
Many universal models cost no more than 2 thousand rubles. Such sensors are the most common and are installed on a wide variety of machines. If the sensor is installed at a service center, specialists select the most suitable device for the car.
Rain sensor - what is it, how does it work, how to install
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