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An important part of the cooling system of a small excavator

(1) Pump

1. Function and structure: The function of the small excavator water pump is to pressurize the cooling water and make it circulate in the cooling system. The pump is driven by gears, and the pump speed is 1.5 times that of the diesel engine.

2 Principle of operation: 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. The casing. The engine water jacket is inside. Together, the impeller The central pressure drops, and the coolant in the radiator tube is sucked into the pump cavity through the inlet, and the coolant circulates in the entire cooling system.

(2) Thermostat

1 Function and structure: The function of the thermostat is to automatically control the flow and circulation of the coolant according to the operating temperature of the engine.

2 Principle of operation: When the temperature is low, the white wax is solid, and the main valve spring presses the main valve on the valve seat and is in a closed state. At this moment, the auxiliary valve is opened, and the coolant passes through a small cycle.

When the temperature rises, it gradually melts into liquid white wax, its volume expands, and an upward thrust occurs at the end of the push rod. Because the push rod is fixed on the bracket, the thermostat housing is moved downward, the main valve is opened, and the auxiliary The valve is activated. Closed. When the temperature exceeds a certain value, the main valve is completely opened, and the auxiliary valve also closes the lung circulation channel. At this moment, the cooling water of the cylinder water jacket circulates through the radiator. Some ways of circulating the water cooling system are proposed.

When the engine coolant temperature is within the range of large and small circulation temperatures, the main valve and auxiliary valve of the thermostat are opened, and together, 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 completely opened, and the auxiliary valve is closed. It enters the radiator through the thermostat and the radiator coolant inlet hose. In the radiator, it is cooled to heat dissipation. The coolant of the radiator surrounds the air for cooling, and then returns to the pump through the coolant outlet hose of the radiator.

Small circulation: When the temperature of the engine coolant is low, the thermostat of the main valve is closed and the auxiliary valve is opened. After the pressure of the pump, the coolant flows through the water jacket wall of the cylinder block, from the water jacket wall, small, small excavators Absorb the heat, then move the cylinder head water jacket upward, and then suck from the cylinder head through the thermostat. After heating, the jacket wall. Then return to the pump.

Measure the test parameters of the 3J05E thermostatic valve, record the following data, and determine whether the values are correct.

Measure the initial temperature at which the thermostat valve opens. The specification value for the opening temperature of the thermostat valve is 74.5 to 78.5 degrees.

Measure the rise of the thermostatic valve, small and small excavator, the temperature of the external valve of the thermostat is completely opened, and the test temperature is 95 degrees.

C. Thermostat test specification.

(3) Radiator

The role of the radiator is to transfer the heat absorbed by the coolant to the outside air, and then lower 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 cover is to seal the water cooling system and regulate the operating pressure of the system.

(4) Cooling fan

The role of the cooling fan is to suck in air and pass it through the radiator when the fan rotates.