Important components of the cooling system of mini excavators
(1) Pump
1. Function and structure: The function of the mini excavator water pump is to pressurize the cooling water and circulate it in the cooling system.
The pump is driven by a gear, and the pump speed is 1.5 times that of the diesel engine.
2 Working principle: When the pump impeller rotates, the coolant pump rotates together through the impeller, and is pushed to the edge of the pump casing through centrifugal force, and then reaches the outlet pipe through the outer tangent line of the impeller. Shell. The engine water jacket is inside. At the same time, the impeller The central pressure drops, and the coolant in the radiator tube is sucked into the pump chamber through the inlet, and the coolant circulates throughout the cooling system.
(2) Thermostat
1 Function and structure: The function of the thermostat is to automatically control the flow and circulation path of the coolant according to the operating temperature of the engine.
2 Working principle: When the temperature is low, the paraffin is solid, and the main valve spring presses the main valve on the valve seat, which is in a closed state. At this time, the auxiliary valve opens and the coolant goes through a small circulation.
When the temperature rises, it gradually melts into liquid paraffin, expands in volume, and generates an upward thrust at the end of the push rod. Because the push rod is fixed on the bracket, the thermostat housing moves downward, and the main valve opens to assist The valve starts and closes. When the temperature exceeds a certain value, the main valve is fully opened and the auxiliary valve also closes the pulmonary circulation channel. At this time, the cooling water of the cylinder water jacket circulates through the radiator. Some paths for water cooling system circulation are proposed.
When the engine coolant temperature is within the large and small cycle temperature ranges, both the main valve and the auxiliary valve part of the thermostat are opened. At the same time, there are large and small adjustments to the engine coolant temperature to make it suitable for temperature stability. Large-scale circulation: When the engine coolant rises to a certain temperature, the main valve of the thermostat is fully opened and the auxiliary valve is closed. The coolant enters the radiator through the thermostat and radiator inlet hose. In the radiator, it cools to the The coolant from the radiator circulates around the air for cooling, and then returns to the pump through the radiator's coolant outlet hose.
Small circulation: When the engine coolant temperature is low, the thermostat of the main valve is closed and the auxiliary valve is opened. After the coolant is pressured by the pump, it flows through the water jacket wall of the cylinder block and from the water jacket wall, small, small excavator The heat is absorbed then moves the cylinder head water jacket up and out of the cylinder head past the thermostat. Heats up the rear jacket wall. Then back into the pump.
Measure the test parameters of the thermostatic valve, record the following data, and determine whether the values are correct.
Measure the initial temperature at which the thermostat valve opens. The standard value for the thermostat valve opening temperature is 74.5 to 78.5 degrees.
Measure the rise of the thermostat valve and small excavator, the temperature of the thermostat internal valve is fully opened, and the test temperature is 95 degrees.
C. Thermostat test specifications.
(3) Radiator
The function of the radiator is to transfer the heat absorbed by the coolant to the outside air, and then reduce the temperature of the coolant.
The structure of the radiator consists of upper water, lower water chamber, radiator core, radiator cover and drain switch.
The function of the radiator cap is to seal the water cooling system and regulate the operating pressure of the system.
(4) Cooling fan
The purpose of a cooling fan is to draw air in and pass it through the radiator as the fan rotates.
