The radiator is one of the key and most important elements of the liquid cooling system. Dissipating heat into the atmosphere becomes the main task, which was diverted from the engine by the coolant. The radiator of the engine cooling system can be considered the most important part of the power unit itself.
We also recommend reading the article, in which the device of the fuel system of the internal combustion engine is considered. From this article you will be able to learn about the main elements, mixture formation and principles of system operation.
Devices, similar to a modern radiator, were installed on the earliest versions of cars with internal combustion engines, since without the specified cooling element, the operation of the power plant becomes simply impossible. This device is directly responsible for maintaining the normal operating temperature of the engine within strictly defined limits. Such protection protects the motor from overheating, which will inevitably put almost any internal combustion engine out of order.
The history of radiator creation
The water cooling system appeared at the dawn of engine building. For the first time, the radiator concept was applied to the first production car called Benz Velo, which ended up on free sale in 1886 year. This idea of the device was further developed by Wilhelm Maybach, who designed a product with honeycombs. The development found application in the design of the Mercedes 35HP model. Over the following decades and to this day, the radiator device has not undergone global changes, remaining almost in the same form, as in Maybach's time.
The first liquid engine cooling systems did not have a water pump (pumps), which forced the coolant (in the very beginning it was just water) forced to circulate in the system. Early developments of the internal combustion engine cooling system relied on the thermosiphon effect.
Thanks to this effect, the coolant entered the radiator. The thermosiphon effect is based on that, that the density of water decreases when heated. Due to this property, heated water is directed upwards. As a result, heated liquid appeared in the device, entering there through the passage through the upper nozzle.
Water cooling took place inside the radiator, the density of the liquid increased again. This led to, that water was falling into the lower part of the radiator, and from there it penetrated back into the engine jacket through the lower pipe. The main disadvantage of systems with the thermosiphon effect was that, that they could not provide adequate cooling against the background of the ever-increasing power of internal combustion engines. Such systems quickly supplanted solutions, which were based on the use of a centrifugal water pump (pumps).
Liquid cooling system radiator
The main task of the element is to remove heat from the power plant into the atmosphere by cooling the liquid, which passes inside the channels. To ensure better heat dissipation, the device is mounted in such a place, where the best blowing by the oncoming air flow during the movement of the car is noted. A typical place of installation in the underhood space is the area behind the radiator grille at the front of the car. It is worth noting, that even in cars with a rear internal combustion engine, the radiator is most often installed in the front. The difference is the laying of longer lines of the engine cooling system.
There are other places for installing the cooling device, but are less common. Cars with a rear-engine layout can have a radiator, which is installed along the side wall. Such a solution can be found on sports cars, which have two cooling radiators at once, located along both walls of the engine compartment. Effective air blowing is realized by using air intakes. The specified air intake is placed in the rear of the machine on the side walls.
Radiator device
and is a device; b - the steam valve is open; c – the air valve is open.
- The radiator has an upper design (1) and lower (7) tanks. These tanks are connected to each other by tubes (5) from brass or aluminum. Plates are attached to these tubes using soldering (6), which increase the area of surface cooling of the element. Through this surface, heat is transferred from the coolant and released into the environment.
- The upper tank has a filler neck for filling with coolant. The neck is covered with a cork (3). There is steam in this cork (11) and air (12) valves.
- The upper tank also has a spigot (2) for, to connect the radiator to the engine cooling jacket. Such a connection is implemented using a rubber hose. In addition, there is a steam outlet tube (4), as well as an electric thermometer sensor (13).
- Lower tank (7) has a nozzle (8) to connect the device to the pump (pump). There is also an additional tap, which is capable of draining the coolant. The radiator is attached to the car frame with special fasteners (9).
The so-called cores (radiator plates) are the main elements of heat exchange. Depending on the type of core, the following types of radiators are distinguished:
- tubular;
- lamellar;
- tubular-ribbon, etc. d.
Radiator tanks can be made of plastic or metal. If you look at the device in more detail, then the main part of the core, essentially, is a set of seamless aluminum or brass tubes. Tubes, connecting the upper and lower nozzles, having walls up to 0,15 millimeters. Liquid, which passes through the core of the cooling radiator, diverges into a large number of microflows. Each such tube is covered with peculiar ribs, which are thin corrugated copper or aluminum tape.
Products made of aluminum have a lower weight compared to other manufacturing materials, but prone to accelerated destruction. The point is, that a number of significant difficulties arise when trying to weld this metal, and also aluminum is poorly resistant to mechanical damage.
In order for the aluminum product to approach the quality of cooling to the brass structure, it must be made large in size and increase the thickness of the element. At the beginning of the automotive era, cellular radiators were actively used. Such a device was made of small sections of brass tubes, which had a pentagonal section. The liquid inside such tubes did not circulate forcibly, and the entire cooling process was carried out using the contact of metal ribs with the counterflow of air.
Let's return to the device of a modern radiator. Steam valve, shown in the figure, is loaded by a special spring (10). The spring has elasticity 1250-2000 p. This allows you to increase the pressure in the cooling radiator and raise the boiling point of the coolant in the liquid cooling system to 110-119°С. This solution ensures a reduction in the volume of coolant in the entire system, which means a parallel decrease in engine mass. At the same time, the required cooling intensity of the power unit is maintained. Another plus is the reduction of losses, which should be understood as the evaporation of the cooling liquid.
The air valve is also spring-loaded, but weaker in resistance. The elasticity of such a spring is on the mark 50-100 p. The task of the air valve is to let air into the device in that case, if coolant condensation occurred after that, how it boiled and was cooled.
In other words, excessive pressure may occur inside the system due to the phenomenon of vaporization. The boiling point of the coolant rises accordingly, at the same time, there is no dependence on atmospheric pressure, since the reset pressure is set by the valve in the cover. This feature of the cooling system is indispensable when driving in mountainous terrain. Due to the reduced atmospheric pressure in the mountains, the coolant boils faster, than under normal conditions. This solution for installing the air valve thus prevents the destruction of the radiator. which can simply be crushed by atmospheric pressure.
Cork, equipped with valves, ensures the opening of the exhaust valve in the event of boiling of the coolant inside the system and the occurrence of excess pressure, which is approximately on the mark 0,5 kg / cm2. The steam is discharged into the steam outlet tube. The intake valve provides air access then, when the pressure inside is below atmospheric pressure (lower 1 kg / cm2), which occurs on the device when cooling the coolant.
So, the plug device completely isolates the cooling system from the outside atmosphere. For this reason, the described system is called a closed cooling system.
In a closed cooling system, to drain the coolant, you need to open the drain taps and remove the radiator plug. To drain the fluid from the engine water jacket, in the lower part of the unit, a suitable tap for draining is provided separately. There is also an open cooling system. In an open system, the neck of the cooling device is closed with a plug without valves. In such a system, water naturally boils at a temperature of 100°C.
Adjusting the temperature of the coolant
The thermostat is responsible for maintaining a constant temperature in the engine cooling system. This element distributes the movement of the coolant along the contours. These contours are called the small and large circle. The engine jacket can be considered a small circle, the movement of the flow through the radiator is a large circle. Such a situation arises, when cooling with external air during the movement of coolant in a large circle in hot weather or under loads is insufficient. To ensure effective removal of heated air and maintain a constant temperature of the coolant, one or a whole row of fans is additionally installed. Такі вентилятори можуть мати механічний привід (вискомуфту) or electric drive.
Регулювання теплового режиму «шторкою»
Рідинна система охолодження двигуна внутрішнього згорання може бути оснащена подвійним регулюванням теплового режиму. Першим регулятором виступає термостат, про який ми вже говорили. The second heat-regulating element is a curtain-blind.
Devices with double regulation have blinds by design, installed directly in front of the radiator. Thanks to this solution, the radiator can be covered in severe frosts, reducing the intensity of external air blowing. Heat dissipation will decrease, namely heat can be more effectively used to maintain the working temperature of the internal combustion engine and intensive heating of the car interior.
Blinds are metal plates, which are connected by hinges. These curtains can be positioned vertically or horizontally in front of the device. Management of such a solution is carried out by a handle from the interior of the car, and can also be implemented automatically in individual designs. The principle of operation of the mechanical device is as follows, that by pushing or pulling the handle in the cabin, the driver rotates the plates. There is a change in the gap between the blinds and the intensity of blowing the radiator with air currents is adjusted. The result is an effect on the temperature of the coolant.
In conditions of rather low temperatures, a special insulating cover is additionally attached to the hood and radiator grill. Such a cover is made of waterproof fireproof fabric. The specified measures contribute to maintaining the operating thermal regime of the engine within the necessary limits.
Installation of an additional radiator
The appearance of powerful high-pressure atmospheric and turbo engines, which work in different load modes, set the developers the task of installing additional cooling devices. Engineers implemented a parallel installation of an additional radiator. Such a solution received its own separate electric fan. Do not confuse an additional cooling radiator with an intercooler, which is installed to cool compressed air in systems with a turbocharger.
The principle of operation
For proper functioning, modern liquid cooling systems take into account many important parameters during operation. Special sensors record engine temperature readings, coolant and engine oil temperatures, temperature overboard, etc. d.
To briefly describe the principle of operation of the cooling system, then a liquid pump should be taken as a starting point. This element causes the coolant to constantly move and circulate in a circle. At the same time, passage through the engine cooling jacket (small circuit) allows the fluid to wash the hot walls of the cylinder head and. When the temperature of the coolant rises, then, at the specified indicators, the thermostat activates and opens the access of liquid to the large circle (radiator). In this way, it is possible to avoid overheating of the engine and effectively transfer excess heat from heated engine parts to the liquid. When hot liquid enters the cooling device, it dissipates heat into the surrounding atmosphere. The complete cycle ends, and the cooled liquid moves similarly from the new cycle.
Quite obviously, that the radiator is a kind of heat exchanger, which provides effective cooling of not the motor itself, and coolant. Installation of an additional fan or shutter allows you to maintain the temperature of the liquid at the optimal level for the operation of the motor, as in extreme cold, and in intense heat.
Do-it-yourself diagnostics and repair of radiator malfunctions
The main diagnostic procedure is periodic control of the engine cooling system for leaks and a decrease in the volume of coolant in the expansion tank. You can control the amount of liquid visually. Because the liquid is constantly heating and cooling, over time, the water included in any coolant partially evaporates, resulting in an overall decrease in volume.
If we talk about malfunctions of the radiator, then the main one is pollution of its cells and channels, as well as their destruction. Pollution leads to, that the fluid circulation inside the device deteriorates, The coolant does not have time to cool down when moving in a large circle. In such conditions, the power of the fan ceases to be sufficient, because engine overheating is inevitable.
Repairing an engine cooling radiator with dirty honeycombs should begin with the usual washing of the core with running water. It is necessary to disconnect the lower pipe, and then start pouring water through the neck. It is highly desirable to wash the cells of the cooling device with water under pressure. In some cases, when the radiator is heavily clogged, it can be unsoldered and the upper and lower tanks dismantled. After dismantling, it becomes possible to clean the core mechanically.
During the operation of the upper or lower tank, and also the cells themselves begin to flow. This happens due to the use of low-grade coolants, mechanical damage, etc. d. If the leakage is insignificant, then you can try to fall asleep or pour into the radiator a solution specially designed for the temporary elimination of such defects from a car store. Addition of a large portion of mustard powder is included in the "grandfather's" methods, which wets and tightens the crack. As the first, and the second method does not repair the device completely, but only allows you to eliminate the flow for the time of the road to the service station and putting the car in for repair.
Remember, that when the engine is hot, it is dangerous to open the radiator cap! You can get a severe burn from steam and hot coolant. Before opening the cork on the neck, it is necessary to cover the plug itself and the area around it with fabric material as widely as possible, and then turn away.
As for the expansion tank, then the plug on it should be unscrewed with the same care when the engine is warmed up. Twist the cork slightly, but not to the end. You will hear a characteristic sound, that escapes air, similar to that, that occurs when you open the cap on a soda bottle. After such draining, the lid of the tank can be gradually opened completely and control or topping up of the coolant can be carried out.