In the excavator construction work, water temperature and oil temperature are too common, which has a great impact on machine performance and life.
First, the water temperature is high The water tank is used for heat dissipation, and this heat dissipation method is air-cooled, that is, the fan driven by the engine.
Therefore, the reasons for the high water temperature are:
1. The thermostat is stuck and cannot be opened. At this time, the water can only go through a small cycle, not through the radiator.
2, the inside of the water tank is dirty, the water is not smooth, this can use the temperature gun to detect the temperature above and below the water tank, blocking the temperature below will be very low.
3. The fan speed is not enough and the clutch is faulty.
4. The rubber strip around the radiator is damaged or not. At this time, eddy current is generated, and the hot air is circulated, which cannot achieve the cooling effect.
5, for the fifth point, everyone is easy to ignore, that is, will not be false alarm, the sensor is broken, it is also possible, the computer is very wood, just look at the data does not look at the truth.
Second, the oil temperature is high Oil temperature is high and the water temperature is high, there are also large and small cycles, but not through the thermostat, he has a return oil check valve, if this valve is stuck, the oil temperature will be high, the other is the same as the water temperature.
Of course, the large excavator is driven by a fan pump to adjust the speed of the fan motor. There is also an overflow device. Generally, the oil temperature is high. Checking these places can be solved.
Let me introduce the views of the next expert. According to his many years of experience, he believes that if the engine oil temperature and water temperature are too high at the same time, if the amount of oil and water is insufficient or lacking, the oil temperature should be lowered first and then the water temperature should be lowered. The reasons are as follows:
1. The oil temperature is too high, which is harmful to the engine. The so-called engine temperature is too high, which means that the engine oil temperature and water temperature exceed 90 Â°C.
When these two temperatures are too high at the same time, it will affect the normal operation of the engine and bring certain harm to the engine: the gap is reduced, resulting in serious wear or "cylinder".
The oil temperature mainly indicates how much heat is generated compared with the heat dissipation.
The crankshaft and the bearing generate heat due to friction, and the oil dissipates most of the heat, and the balance between heat generation and heat dissipation (expressed as stable oil temperature) is relative.
When the amount of heat generated exceeds the amount of heat dissipated, the temperature of the bearing bush rises, the local temperature reaches the melting point of lead, and the lead in the bearing bush melts and precipitates. When a large amount of lead is precipitated, the bearing surface of the bearing bush becomes smaller and unevenr, which causes the wear to be intensified. In severe cases, the local temperature can exceed the melting point of copper (1083 Â° C), and the copper also begins to melt, eventually causing severe ablation or occurrence of the crankshaft and the bearing. The consequences of the tile holding the axis.
According to the test, when the oil temperature reaches 110 Â° C, the oil film temperature in the bearing gap can reach 150 Â° C. If the oil film temperature is as high as 150 Â° C or more, it is easily broken to form a semi-dry friction. Since the crankshaft bearing is a copper-lead alloy, if the reduction measures are improper, the bearing temperature will be too high and the lead will melt and precipitate, and the consequences are unimaginable.
Therefore, when the temperature of the oil and water are too high at the same time, the oil temperature should be lowered first.
2. The oil temperature can slow down the increase of water temperature. The oil drop temperature usually adopts the method of â€œdownload, low speedâ€. At this time, although the coolant exchanges heat at a high temperature part for a long time, the water flow speed is slowed down, and the heat dissipation time is prolonged.
At the same time, due to the reduced load and reduced speed, the heat generated by the friction of each moving part is also reduced accordingly.
Therefore, the oil temperature can not only reduce the heat generated by the engine, but also indirectly reduce the heat absorbed by the coolant, which can also slow down the temperature rise.
3. Oil temperature is one of the main factors affecting oil pressure. When the engine oil temperature is too high, it not only increases the fuel consumption (leakage, evaporation, combustion), but also affects the quality of the oil and makes the oil film on the friction surface of the engine parts. It is not easy to form and maintain, which can cause the oil pressure of the main oil passage to be established, thus aggravating the wear of the machine parts.
The effect of water temperature on oil pressure must be achieved by oil temperature. Therefore, it has a certain indirectness and requires a certain amount of time.
4. The first precipitation temperature has a great influence on the oil pressure of the engine shaft. It is well known that the precipitation temperature is generally a method of â€œdownload, high speedâ€. When the rotation speed is too high, the inertia force and centrifugal force of the piston group will be increased, so that the load of the crankshaft bearing is increased.
At the same time, the relative friction speed of the journal and the bearing bush will also increase, so that the heat generated per unit time will increase, the oil volume of the oil pump will decrease, and a large amount of oil will be thrown out from the main oil passage, resulting in no friction surface of each machine. Sufficient lubricating oil will increase wear and the oil temperature will rise further.
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