Rain sensor - what it is, how it works, how to install it. How does the rain sensor work? What does the rain sensor look like on the windshield

One of the options that was previously installed only on expensive cars - a rain sensor, has become quite affordable for budget cars. However, sometimes a lot of questions arise on it, so it is quite reasonable to ask - how does it work?

Why is such a device needed?

Before dealing with the operation of such a device, let's try to understand why it is needed, and in fact, what is it? The name itself predetermines the purpose of such a product - to establish the fact of rain. Although the tasks that an automobile rain and light sensor performs are much broader than those described.

Among them it is worth noting:

• establishing the fact of the beginning of rain, as well as snow;
• determination of the degree of contamination of the windshield;
• automatic switching on of the wipers during precipitation and setting their operating modes depending on the intensity of bad weather;
• turning on lights at low light levels (applies to the light sensor).

Its installation is carried out behind the rear-view mirror, for example, as shown in the photo:

Having dealt with what the rain and light sensor does, it is necessary to answer the question - why is all this needed? The answer is quite obvious - to improve traffic safety. Such a device, according to the developers, should save the driver from unnecessary operations (turning on / off the wipers), distracting him from driving, and also automatically provide excellent visibility on the road under any conditions.

How does the rain sensor work?

The principle of operation of the rain sensor is based on a comparison of the optical properties of the windshield under different atmospheric conditions, more precisely, on the differences in the reflection of the infrared beam from a clean and wet or contaminated glass surface.

Everything is quite simple - it consists of emitting and receiving infrared LEDs. The device and operation of such a product will help to understand the photo:

This product is located on the windshield from the inside. From the emitting LED, infrared radiation enters the outer surface, is reflected from it and captured by the photodiode. The level of the reflected signal depends on the state of the outer surface of the glass, from clean glass there will be one signal, from dirty glass - another, from wet glass - the third. By the magnitude of this signal, the control unit determines the need to turn on the wipers.

As can be seen from the above description, such a device is arranged quite simply, which predetermines fairly broad possibilities for its use.

What such a device looks like is shown, for example, in the photo:

As can be seen from the figure, in a separate housing there is a control unit connected by a harness to a relay that controls the operation of the wiper. The control unit must be glued in the overlap area of ​​the wiper brushes.

How this work is done will allow you to understand the video. The data presented confirms that it is easy to glue such a device, and this work can be done by yourself.

Flaws

With all the external attractiveness of such a product, it has certain disadvantages, which cannot be ignored. These should include:

1. Delayed performance. It happens that a single drop in the sensor's coverage area causes it to turn on the wipers, although the rest of the glass is clean and dry. The opposite situation is also possible, when water or dirt from an oncoming car fills the glass on the driver's side, but does not reach the sensor, and the wipers do not turn on.
2. Turning on the wipers without turning on the glass washer. The work of the wipers when dirt gets on the glass leads to the fact that the dirt is simply smeared.
3. Sensitivity to glass quality. The slightest bumps, cracks and chips lead to the fact that it stops working.
4. Response delay. It can be up to two seconds in some cases, which gives the impression that the rain sensor is not working. Therefore, sometimes it’s not enough just to stick it, you need to get used to its presence, overcoming the desire to manually turn on the wipers.

Checking how this wiper control works is simple. It is only necessary to splash water into the area where the sensor is located. For example, the video shows how to check the operation of the wipers.


Automatic control of car windshield wipers is possible through the use of the described device. It allows you to save the driver from the need to manually control the work of the wipers, and serves to increase the comfort of driving the car and the safety of the car. How much this device will be necessary and useful for you is already a matter of personal choice.

Modern cars are becoming more and more automated. The central computer controls almost everything: fuel injection into the combustion chamber of the engine, and the operation of the brake system, and airbags, when it determines the strength of the impact received by the car. The automatic control and operation of the wipers, as well as the hatch door, were affected, which became possible thanks to the installation of a special rain sensor. What kind of sensor is this, how to install it on your own car and do you need to do it at all? Look for answers to all these questions in the article below.

1. Why do I need a rain sensor in a car?

The rain sensor differs from conventional sensors in that it does not only work as an electronic device with sensitive membranes. It also has an optical element capable of responding to the presence of moisture on the car glass. It is needed so that the car can automatically control the wipers and other car mechanisms that are responsible for closing the sunroof and door windows. Since it is the humidity of the atmosphere that is important to the sensor, it is installed on the windshield.

But why do all this automatically if the driver himself, seeing raindrops on the windshield, can turn on the wipers and close the windows? According to the designers, such a system can significantly increase traffic safety in cars, since no atmospheric changes can distract the driver from the road, because he will know that the car will do everything for him.

It is also worth noting that such a device is a fairly new invention, and earlier it could only be found on representative car models. Today, such an innovation is becoming more and more accessible to ordinary car owners, and it can even be installed independently at will (separate installations are sold for this).

2. What is the working principle of the rain and light sensor?

Such a sensor consists of two main elements:

- emitter;

A small photodetector.

In order for the sensor to correctly read the weather conditions behind the windshield of the car, the electronic units of the emitter and photodetector have their own parameters for the dryness and humidity of the glass. Therefore, when a lot of raindrops appear on the glass, or dirt is smeared on it, the sensor reads this as a change in the path of refraction of sunlight rays.

This condition of the windshield surface causes a corresponding reaction of the entire rain sensor system, as a result of which the wipers automatically turn on. At the same time, the intensity of their work is even regulated: if the glass is flooded with intense downpour, the wipers will work very quickly and continuously, but if only small and lonely drops of rain, they will turn on at short intervals. The rain sensor is very sensitive, so even if a few drops of dirt get on the glass, the wipers will react almost instantly.

However, Special requirements are also imposed on the sensor:

- placed on the windshield, it should in no case close the view for the driver, otherwise it will automatically turn from a means that increases safety into a means that interferes with it;

The sensor must be located in the area of ​​action of the brushes, that is, it should analyze exactly the area that the brushes can and should clean.

If you decide to buy a rain sensor for your car, keep in mind that its kit consists of a control unit and a relay. At the same time, it will depend on the control unit whether the wipers will work at the right time or not, since it is he who reads information from the glass and gives a command to other electronic devices of the car.

It is worth noting that Putting a rain sensor on any glass will not work. The fact is that if there is at least one minor crack on the windshield, this can already serve as a reason for the sensor to turn on the washers and wipers, since it can recognize the crack as dirt on the windshield. You will also have to constantly monitor the condition of the wiper blades. The fact is that if they are worn out and clean the glass very poorly, the sensor will make them work for a very long period of time.

As for the relay block, which is also included in the rain sensor kit, this device is considered to be an executive one. It is the relay that controls the washer. But this is not the only function of the relay: thanks to this unit, the driver may not be afraid that due to a power drop, the rain sensor will burn out and fail. The relay can be located in any place convenient for the driver, but it is often mounted in such a way that it is most convenient to connect battery power to the unit.

3. How do I install the rain sensor myself?

It is most acceptable to install a new rain sensor if your car already had such a device, but for one reason or another you decided to replace it. If there is no such sensor on the car, then the possibility of installing it on the car must be discussed with specialists. It should be understood that in some cases the rain sensor can play a very negative role for your safety.

But if you have weighed all the pros and cons, and as a result, you still came to the decision to install such a sensor on your car, then we give you detailed instructions for performing this kind of work for two the most common models of this device – RAINsensoe (RS-22) (American production) and DDA (Russian version).

Installation features of the rain sensor RAINsensoe (RS-22)

This option is almost universal, since it can be installed on any car whose electronics operate on 12 V. In order to install it on the windshield and connect it to the electronic system, you must:

1. Since this sensor model comes with a special holder, only the holder needs to be attached to the windshield. Often, it immediately has a double-sided adhesive tape, therefore, having removed the protective film, the holder will simply need to be pressed to the intended place on the glass.

2. On both working areas of the body of the device, it is necessary to apply a special gel that comes with the device. It is necessary in order to equalize the refractive index of the light rays and ensure the most reliable operation of the sensor.

3. Using self-tapping screws, which should also be included in the kit, attach the sensor housing to its holder.

4. It is very important that after installation in the working area between the sensor itself and the windshield there are no air bubbles that could interfere with its operation.

5. We connect the sensor to the switch of operating modes of the car wipers. You need to do this according to the following scheme:

- a blue wire is connected to the body of the car;

It is necessary to connect the red wire from the sensor to the contact "I" of the switch, having previously disconnected the yellow wire with a green stripe from it;

The wire disconnected from the “I” contact must be connected to the yellow wire of the sensor;

We are looking for contact “53” with a blue wire on the switch block and connect the black wire from the rain sensor to it.

But keep in mind that this sensor model still needs to be adjusted to the parameters of the windshield of your car. How to do this, read the instructions for the device.

Description of the connection procedure for the rain sensor DDA

The Russian version of the rain sensor is slightly different from the one described above. In particular, when creating it, the designers tried to achieve the following goals:

- make the device as easy to manage as possible;

Ease of installation of the sensor, which will allow motorists to do it on their own without special experience;

The ability to connect the device without any interference with the integrity of the electrical wiring of the car;

The ability to manually control the wipers in parallel with the operation of the rain sensor;

Affordable price for the Russian consumer.

It is also worth noting that the Russian rain sensor is also able to respond to the speed of the car - the lower the speed, the less the intensity of the wipers will be. However, it is still better to use such a sensor only for cars of the Russian car industry. To install such a sensor, you will need to perform the following steps:

1. The rain sensor itself must be attached to the inside of the windshield. You can attach it both with double-sided tape and with a special fixing gel.

2. In the mounting block of the car, you need to find a relay that is responsible for the operation of the wipers and the washer. This relay must be disconnected and removed from the mounting block, and in its place, install the relay block that comes with the rain sensor. When installing, it is very important to observe the necessary markings and the location of the key.

4. After the sensor is fully connected, it must be adjusted in accordance with the instructions.

4. Pros and cons of using.

Ideally, the presence of a rain sensor on the car gives the driver a lot of benefits. And first of all, the advantage of using it is that the device does not allow even a small amount of moisture to appear on the glass - it immediately activates the wipers, which remove everything superfluous. Thus, the driver always has a clear view of the road, and for this he does not need to press any levers or buttons.

But human intelligence is not inherent in an electronic device, so very often the operation of the wipers occurs arbitrarily, which, on the contrary, can very much annoy the driver while driving. Due to the high sensitivity of the rain sensor, it can work even if air bubbles just appeared on the windshield, or someone left a fingerprint.

Only a thorough washing of the windshield of the car will help to cope with the false activation of the sensor. In addition, you can also try to reduce the sensitivity of the sensor to this kind of "irritants" by adjusting it.

It is also worth mentioning that there are a lot of myths among motorists, because of which a slightly wrong idea has formed about this device. It concerns the following functions:

1. Many motorists do not install a rain sensor on their car for the reason that they believe that supposedly it is not able to function in the dark. Actually, it is not. The sensor receives information about whether there is dirt on the windshield thanks to infrared rays, so the degree of illumination does not affect the operation of the rain sensor in any way.

2. There is a myth that the rain sensor cannot be used on tinted glass. This is also incorrect. The only caveat in installing a rain sensor on tinted glass is that, especially for the device, it is necessary to make a small hole in the tinting film, which will not even be noticeable outwardly.

3. The statement that it is generally better to turn off the sensor in winter is also mythical. In winter, the rain sensor does work a little worse, since such a device, first of all, is configured to remove raindrops from the glass, not snowflakes. However, if an additional glass heating device is installed, the operation of the rain sensor in winter during snowfall will be as effective as in summer during heavy rain.

4. If for one reason or another you need to replace the windshield, this does not mean at all that you will have to buy a new rain sensor and reconnect it to the wipers and to the new glass.

If the old sensor worked properly before the glass was replaced, then it can be easily rearranged to a new one. At the same time, new glass can be purchased with a special window for installing the sensor. It is also worth noting that in the event of a failure of the sensor itself, only the device will need to be changed; this procedure will not affect the windshield in any way.

5. Another myth about rain sensors is that this device breaks down very quickly and for this reason you constantly have to buy a new sensor. Such a statement is again erroneous, although it has some grounds. The reason for the failure of the sensor may be its contamination: if a lot of condensate and dust have accumulated on its surface, they simply need to be removed, and the sensor will resume its work.

Thus, a properly installed sensor makes it possible to significantly increase the safety of driving, since it removes the driver's responsibility for turning on / off the washer and wipers, as well as adjusting the position of the windows in the car's doors and in the hatch opening.

Today we will consider such an interesting question: how does the rain sensor work, why is it needed, how to install it? Previously, such a device was the prerogative of only very expensive cars of cool models. Now the device, designed, like all gadgets, to improve the comfort of driving a car, is available, probably, to every car owner who is hungry for improvements and innovations. However, sometimes a lot of additional questions arise for such tuning: how does it function, in what place should it be located correctly, why is it needed at all?

Principle of operation

How does a rain sensor work in a car? The principle of operation of the device is based on the difference in the reflection of infrared rays with wet (dirty) and clean glass - different atmospheric conditions. The sensor inside looks simple: two LEDs (one receives, the other emits), as well as a photodiode, light sensors and foil. The infrared beam emitted by one diode is displayed from the windshield and caught by a photodiode. The signal from clean glass looks different than from dirty or drippy glass.

By the nature of the incoming data, the ECU gives the go-ahead for the work of the wipers. Usually, the device consists of a remote computer placed on the windshield inside the cabin. The rain sensor control unit is connected via a wiring harness to the wiper relay, and it must be located in an area that overlaps the wiper blades.

Why is it so necessary? The name itself speaks for itself. The device is designed to detect the presence of precipitation and automatically turn on the wipers, without the participation of the driver. But, in fact, the tasks of the device are much wider. It establishes the presence of not only rain, but also snow. Determines if the windshield is dirty.

Depending on the nature of the precipitation - strong, weak, heavy rain - the rain sensor can switch the operating modes of the wipers automatically. And in case of insufficient lighting, the device turns on additional light using a light sensor.

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How to install?

As a rule, detailed instructions for installation and setup of work are attached to the device. Everything is done quite simply, so when buying a rain sensor, there is no need to go to the service station to install it. You can do it yourself, with your own hands. Let's talk about an example.

So, first of all, open the mounting block, located behind the wheel of the driver on the left. Remove the cover to access the fuse box. We put the rain sensor instead of the standard relay, which is located on the block in the extreme left corner at the top. We glue the sensor on the windshield, using a double-sided mount (included). We draw the wires under the casing at the top and to the left. We go down to the relay block along the rack. From the inside we start to the block itself.

The device comes with a degreasing cloth. Wipe the glass with it before gluing the sensor to the windshield. Attention: the factory relay can sit very firmly in the socket! We act carefully, trying not to break the leg on the relay. You can pick it up, for example, with a screwdriver, so that things go faster. And in its place we insert a rain sensor relay connected by wires hidden under the casing to the ECU itself. We put the cover of the mounting block in its place and check the sensor.

How to check? In order for the sensor to start functioning, it is necessary to switch the wiper blade to intermittent mode. A good way to check is to spray on the windshield with a spray bottle or drip some water from your hand. The janitors must react immediately. The sensor has several modes of operation (read the instructions). Choose according to weather conditions and time of year, and go!

Flaws

If you have just installed this device and cannot get enough of looking at how the rain sensor works, you still need to know that such a gadget also has its drawbacks.

• Firstly, untimely unproductive operation can be attributed to them (sometimes one droplet accidentally falling is enough, and the wipers start working);
• Secondly, the wipers turn on without washers (and this leads to the fact that the dirt, for example, is simply smeared, reducing visibility);
• Thirdly, sometimes, delayed response and unreasonable sensitivity to defects on the windshield. So, having installed a rain sensor on your car, you also need to get used to its operation.

A car rain sensor is an optoelectronic device that is installed on the windshield of a car and reacts to its moisture. It is necessary in order to automatically turn on the wipers when determining moisture. The first experiments to create a rain sensor were carried out in the 50s of the last century by the General Motors automaker for Cadillac Eldorado. However, the imperfection of the technologies of that time did not allow to bring the idea to life. One of the first production cars with a rain sensor was the '94 Nissan Silvia. At the beginning of the zero sensors began to be installed on cars, BMW, Cadillac and others. Today, automakers are starting to use rain sensors as standard on midsize and golf cars. How rain sensors work - about this in today's issue!

The rain sensor is an infrared emitter and a small photodetector that actually reacts not to moisture, but to light. An optical element is located between the sensor and the windshield. Its task is to focus and align outgoing and incoming light. The sensor itself is attached to the windshield with adhesive foil. The principle of operation of the rain sensor is as follows: outgoing infrared rays are partially reflected on the glass surface, then focused by an optical element and enter the photodiode. The system is designed in such a way that if the glass is dry, all the light is reflected back and hits the photodetector. Since the beam is modulated by pulses, the sensor does not react to extraneous light.

And raindrops or dirt located on the windshield cause a change in the path of refraction of the rays. And thus the amount of light that hits the photodiode changes. The stronger the wetting of the windshield, the less the reflection of the refracted light. The sensor is based on this information. The amount of reflected light is detected by the sensor and the controller calculates the appropriate wiper operation. The sensitivity of the light detectors is very high. They take into account thousandths of a milliliter of water on the windshield and work within a few milliseconds.

Some rain sensors have a sensitivity control. With it, you can set the mode of operation of the wipers: they will start working either when the first drops hit, or when the rain completely breaks out. There are also models of sensors that are able to control the windshield washer.

It should be noted that since the operation of the rain sensor is based on the principle of reflection of infrared rays, it is able to function at any time of the day, including at night. In winter, the operation of the sensor is somewhat complicated, but when the glass heating is turned on and the snow melts, it functions in the same way as in the warm season in rainy conditions.

That's what you want to say, but I really did not know how the rain sensor works in the car. If it was immediately clear about light - "some kind of photocell", then about rain it is more difficult. When I recently moved with an old Daewoo Nexia, I certainly went nuts from the presence of all sorts of sensors and amenities. I don’t touch the light at all - it turns on at any time of the day, such as is needed by the light sensor. I don’t touch the wiper brushes either - the rain sensor works very clearly. But how? I casually assumed that maybe somewhere there is a sensor for flowing water from the glass, but the brushes work even with small droplets. How else is moisture measured on glass? Where is the glass interesting?

And it turned out to be much easier ...

1 - rain and light sensors; 2 – rear-view mirrors; 3 – zone of overlapping of action of screen wipers; 4 - windshield

The rain and light sensor is designed to turn on the wiper depending on the amount of precipitation from zero to the maximum cleaning cycle, or turn on the headlights, depending on the lighting conditions, when moisture is detected on the glass. The sensor is activated by certain levers or switches.

The rain and light sensor consists of a combination of photosensitive elements and an LED. All parts are mounted on a board in the sensor housing. The optical element covers the sensor housing and the windshield. The task of the optical element is to focus and align the outgoing and incoming light. The entire sensor is attached to the windshield with adhesive foil. Rain detection uses LED 6 and photodiode 8.

The principle of operation of the rain sensor is that the light coming from the LED is partially reflected on the surface of the glass and, having been focused through the optical element, falls on the photodiode. If it is dry outside, all the light is reflected back and hits the photodetector (this is how the optical system is designed). Since the beam is modulated by pulses, the sensor will not react to extraneous light, like a TV that "does not see" someone else's remote control. The degree of reflection of light from the diode, and thus the amount of light that hits the photodiode, changes if the glass is covered with water droplets or has a water film. The stronger the moisture, the less the reflection of the refracted light. Based on this, the output signal of the photodiode is used to determine the amount of precipitation. This is detected by the sensor and the controller calculates the appropriate wiper operation. Rain detection response time, i.e. the time elapsed between the detection of precipitation and the output signal to the wiper is less than 20 ms.

1 - windshield; 2 – light from a remote source; 3 - penetrating external light; 4 - raindrops; 5 – optical element; 6 - LED; 7 – remote photodiode-sensor; 8 – photodiode; 9 - photodiode-sensor of external illumination

A remote photodiode 7 and an ambient light sensor 9 are used to detect light. Sensor 9 captures the light conditions in the immediate space around the vehicle and serves to automatically turn on the headlights, and remote sensor 7 captures the light conditions at a distance of up to three vehicle lengths in the direction of travel.

The system generally detects a decrease or increase in light levels and switches the headlights on or off. From the signal difference of the two sensors, the system can, for example, determine that a vehicle is entering a tunnel and thus the headlights are switched on at the latest at the entrance to the tunnel. The logic of the system operates in such a way that the light is turned off only when the light sensor detects a sufficient value of illumination. If rain detection is also active in addition to light detection, the system switches on the headlights even in heavy rainfall.

1 - analysis of external illumination; 2 – analysis of illumination difference; 3 – analysis of remote illumination; a - the difference in illumination is less than the value of the turn-on threshold, the light is off; b - the difference in illumination is greater than the value of the turn-on threshold, the light is on

Here are 5 more myths about the operation of the rain sensor

Myth No. 1 we have already dispelled: 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 reacted to shocks, the brushes would diligently erase flies, mosquitoes and small pebbles from the glass.

Myth #2: "The rain sensor doesn't work at night." As we have already found out, the operation of the rain sensor is based on the principle of reflection of infrared rays. Their properties do not depend on illumination. Otherwise, for example, remote controls would not work in the dark.

Myth No. 3: “When replacing glass with a rain sensor, you have to say goodbye.” You don’t have to: many manufacturers offer auto glass with a place for a rain sensor. For example, at Olympia you can purchase glasses for rain sensors for most foreign cars: Toyota Camry, VW Passat, Audi 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 in accordance with GOST.

Myth #5: “The rain sensor is useless in winter.” Since the rain sensor works by reacting to water drops and not snow, it does not function well in winter. However, if the car has a heated glass, the falling snow immediately melts, turning into water, and the operation of the rain sensor will be normal.

Interesting facts about rain sensors

Concern General Motors conducted the first experiments on the creation of rain sensors back in the 1950s. The sensor was created for the iconic model - Cadillac Eldorado. But the technology was far from perfect: between how a rain sensor works on a modern car and the first experiences of GM engineers, there are decades of design development.
- One of the first mass-produced 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.
- The operation of the rain sensor is used not only in the automotive industry, but also in agriculture, to control the irrigation system. - “Field” sensors have a different principle of operation than automobile ones: they have hygroscopic discs, 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 the water supply if the temperature drops below zero.

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