Modern cars continue to grow in complexity, and their parts can no longer be disassembled and assembled on the knee. But there are parts that have not changed. One of them is a thermostat.
Working principle and functions
To understand why a thermostat is needed, we recall the principle of the engine’s operation and what works best for it at operating temperatures in the range of 75-95 ° C. At the same time, “cold”, during start-up, the engine does not work efficiently. Output? We need to help him warm up faster. How? When the engine is running at full capacity, it needs a cooling system (radiator, antifreeze, pump, engine cooling jacket) that prevents the engine from overheating. But what if at the start we just need to temporarily overheat and reach the desired temperature? Maybe turn off the cooling system for a while? This is exactly what the thermostat does.
how the thermostat works
When you first start the engine, the thermostat shuts off the coolant flow from the engine to the radiator and pump (in a “large cooling circle”). Antifreeze only revolves around the cylinders and the block head. The fluid heats up faster, and so does the motor. As soon as the engine begins to lower the operating temperature threshold (usually about 75 ° C), the thermostat valve begins to gradually open the coolant flow in a “big circle”. As a rule, the thermostat is set so that by the upper threshold of operating temperatures (about 95 ° C), it will fully open and the system.
Types of thermostats
Thermostats are divided into several types by design. Single-valve are classic thermostats in which one valve opens / closes the required branch pipes. Two-stage – for systems with a high level of cooling system, where one valve fails. They use two valve discs – first, the pressure in the disc is low, and then a large one is put into operation and allows the thermostat to be fully opened. Two-valve thermostats use different valves for different connections. One opens / closes the small cooling circle, the other the large circle. According to the control principle, thermostats can be divided into traditional and electronic ones. In accordance with the opening of the thermostat, the thermosensitive element responds (most often – with technical wax inside). Everything is built on physics – it expands and pulls the valve along with it.
In electronic thermostats, the opening is controlled by a sensor and an electronic control unit. Such a thermostat is configured to open at higher temperatures – above 100 ° C. First of all, this became necessary to reduce the level of harmful emissions when the engine warms up. And if at first such thermostats were mainly on “charged” motors, like the BMW Alpina, now they are used on completely “civilian” cars.