Common knowledge of automotive machinery
2024-05-15
What are the basic components of a car's structure?
Answer: Generally, the basic structure of a commonly used car consists of four parts: the engine, chassis, body, and electrical equipment.
What are the components of a four stroke gasoline engine?
Answer: A four stroke gasoline engine consists of a body, a crank connecting rod mechanism, a valve distribution mechanism, a cooling system, a lubrication system, a fuel system, and an ignition system (diesel engines do not have an ignition system).
How does a four stroke gasoline engine cycle?
Answer: The working process of the engine is divided into four processes: intake, compression, operation, and exhaust. A four stroke engine completes these four processes within four strokes of the piston's up and down movement.
Intake stroke: The intake valve opens and the exhaust valve closes. As the piston moves from top dead center to bottom dead center, the volume above the piston increases, the pressure inside the cylinder decreases, and vacuum suction is generated. Inhale the combustible gas mixture into the cylinder.
Compression stroke: Both the intake and exhaust valves are closed, and the piston moves from bottom dead center to top dead center, compressing the mixed gas into the combustion chamber.
Working stroke: At the end of compression, the intake and exhaust valves are still closed, and the spark plug emits an electric spark, igniting the combustible mixture. After combustion, the gas expands violently, generating huge pressure, forcing the piston to quickly descend and the crankshaft to rotate through the connecting rod to work.
Exhaust stroke: The exhaust valve opens, the intake valve closes, and the piston moves from bottom dead center to top dead center to expel exhaust gas.
What are the functions and main components of the body and crank connecting rod mechanism?
Answer: The function of the engine body and the crank connecting rod mechanism is to apply the pressure of gas on the piston top when fuel is burned in the cylinder, and use the torque of the connecting rod to turn it into the crankshaft, so that the crankshaft drives the working machinery to do work. The main components of the engine body and the crank connecting rod mechanism include the cylinder block, cylinder head, piston, connecting rod, crank, flywheel, etc.
5. Explain the function and composition of the valve distribution mechanism?
Answer: The function of the gas distribution mechanism is to timely open and close the intake and exhaust valves according to work needs, and timely introduce combustible gas into the cylinder and discharge exhaust gas. At the same time, drive the power distributor, gasoline pump and other components to work. The main components of the valve distribution system include: intake valves, exhaust valves, camshaft drive components, etc.
6. Explain the function and composition of the cooling system?
Answer: The function of the cooling system is to dissipate the heat from high-temperature components into the atmosphere, in order to maintain the engine operating at normal temperatures. The water cooling system generally consists of components such as the engine's water jacket, water pump, radiator, fan, thermostat, water temperature gauge, and drain switch.
What is the normal water temperature of the engine? How to control the water temperature?
Answer: The normal operating temperature for water-cooled engines should be 80-90 degrees. Taking the Jiefang CA10B car as an example, the temperature of the engine can be adjusted by pulling out (i.e. opening) or pushing out (i.e. opening and closing) the louver control handle in the driver's cabin, changing the amount of air entering the radiator, and thus adjusting the engine temperature.
What is the function of lubricating oil?
Answer: The function of lubricating oil is to lubricate various friction components, reduce friction resistance, and reduce power consumption.
Cooling effect: The oil circulates and can move the friction zone away. Reduce the temperature of the components.
Cleaning function: to wash away impurities on the surface of the parts and reduce wear.
Sealing effect: Maintaining the oil layer between the piston and cylinder wall can increase sealing performance.
How to check the oil level of the engine?
Answer: When checking the oil level of the oil pan, the car should be parked on a relatively flat surface, the engine should stop running, and wait for a little time. Then, pull out the oil dipstick, wipe off the oil on the surface, and insert it all the way through the oil dipstick tube to determine the amount of oil.
10. What is the normal oil pressure for gasoline and diesel engines?
Answer: Observe the oil pressure gauge on the dashboard in the driver's cab: The normal oil pressure for gasoline engines is 200-500 kPa; Diesel engines operate at 600-1000 kilopascals.
