1. Introduction
Thermostat
The thermostat valve is controlled coolant flow path. An automatic temperature control device, typically comprising a thermo-element, through the expansion or shrink to open, turn off the flow of air, gas or liquid.
2. Function
function
into the radiator automatically adjusted according to the level of cooling water temperature of the water, changing the water cycle range, to adjust the cooling capacity of the cooling system, to ensure that the engine working within a suitable temperature range. The thermostat must be kept in good technical condition, otherwise it will seriously affect the normal operation of the engine. The main thermostat valve opens late, can cause overheating of the engine; a main valve opens too early, the engine preheating time extended so that the engine temperature is too low.
3, the structure and working principle
structure and working principle
thermostat is mainly used for the wax of formula section thermostat, when the cooling temperature is lower than a predetermined value, the thermostat temperature sensing body is solid refined paraffin wax, the thermostat valve closes the passage between the engine and the radiator under the action of the spring, the coolant returned to the engine by the pump, small cycles for the engine. When the coolant temperature reaches a predetermined value, it begins to melt gradually to a liquid paraffin, followed by increasing the volume of the rubber tube and presses the shrunk. While contraction of the rubber tube upward thrust to push rod, the push rod of the valve downward thrust reverser open the valve. In this case the radiator and the coolant through the thermostat valve, and then back into the engine by the pump, a large circulation. Wax-type thermostat works: Most thermostat disposed in the cylinder head discharge pipe passage, this has the advantage of simple structure, easy to remove air bubbles in the cooling system; thermostat disadvantage is frequently opened and closed during operation, is generated oscillation phenomenon.
4, thermostat operating state is determined
When the engine cold start operation, the upper water chamber tank inlet line as well as chilled water, then the main valve of the thermostat can not be closed ; when the engine cooling water temperature over 70 ℃, upper water chamber tank inlet line without cooling water outflow, then the main valve of the thermostat does not open properly, then it needs repair. The thermostat can be checked in the vehicle, as follows:
– start the engine after checking: Open the radiator filler opening lid, when the cooling water within the radiator calm, it indicates that the thermostat is working properly, otherwise, It represents thermostat malfunction. This is because, when the water temperature is below 70 ℃, thermostat expansion cylinder in the collapsed state, the main valve is closed; when the water temperature is higher than 80 ℃, expansion of the expansion cylinder, a main valve gradually opens, the water begins to flow in the radiator circulation. When the water temperature table indicates the following 70 ℃, if the radiator water flowing into the water, warm water, warm season the table main valve closed tightly, the cooling water circulation prematurely large.
· Check the water temperature: the initial operation of the engine, the water temperature rises rapidly; 80 indicates when the water table, rate of temperature increase slows down, it indicates that the thermostat is working properly. Conversely, if the water temperature rises up quickly, when the internal pressure reaches a certain level, boiling water suddenly overflowed, it indicates that the main valves are catching and suddenly opened.
When the indication 70 ℃ -80 ℃ in the water table, and open the radiator cap radiator drain switch, its hand with water, if the thermostat are described hot work; plus low if the heat sink temperature at the outlet, and cooling an upper tank inlet line anhydrous little water or effluent described thermostat main valve can not be opened.
have a catching or closing loose thermostat should be removed for cleaning or repair, it will not be used.
5. Check the thermostat
According to information on safe life wax-type thermostat is generally exercised automobile mileage of 50000km, thus requiring periodic replacement in accordance with its safe life.
The method of checking the temperature of the thermostat opening temperature debug main valve thermostatic heating device check the thermostat fully openTemperature and lift, which has a non-compliant value, should replace the thermostat. For example Santana JV engine thermostat, the main valve opening temperature of 87 deg.] C plus or minus 2 ℃, full temperature of 102 deg.] C plus or minus 3 ℃, full lift gt; 7mm.
6, Troubleshooting
The first opening is not closed, the closed can not be opened, the engine temperature is too high, because of the high temperature flame. And because the thermostat is closed to cut off water tank system, therefore, high temperature and high pressure water can not pass through the tank lid and pushed into the tank opening, it is possible to have a small circulating water jacket system damage, such as pad, heater tank, part of the pipe damage.
The second opening is not closed, opening only when the thermostat is not closed, the water temperature can not be increased, especially in winter in particular. Water temperature is low, the water temperature sensor sensing the water temperature is low, the potential of the sensor provided to the computer is also low, the actual commands from computer is wrong. Computer injector pulse to widen, increasing the amount of fuel injection, the car cost of oil.