The rocker arm is fixed on the rocker shaft, and the rocker and rocker shaft are the first to be seen when the top cover is removed. It can swing up and down, adjust the nut on the top to change the swing range, and adjust the level of valve opening to adjust the intake/exhaust volume. Most modern car engines use overhead valves. The valves are pressed by the cam. The position of the shaft can be divided into camshaft-mounted type, camshaft-mounted type, and camshaft-mounted type; the camshaft-mounted type has a long distance between the valve and the camshaft, so there are more parts for the valve transmission, the structure is more complicated, and the height of the engine is also different. Increase. The camshaft-mounted camshaft is located in the middle of the cylinder block, and the rocker arm is directly driven by the camshaft through the tappet, eliminating the need for a push rod. The camshaft is arranged on the cylinder head, and the camshaft has two structures: one is that the camshaft drives the valve directly through the rocker arm, so that there is no tappet and no push rod, and the reciprocating movement quality is greatly reduced. Small, this structure is suitable for high-speed engines. Another structure is that the camshaft directly drives the valve or the valve with a hydraulic tappet. The reciprocating movement of this valve mechanism has a smaller mass, and is especially suitable for high-speed engines. .Pull off the cylinder head, turn the cylinder head upside down, you can clearly see the valve and the combustion chamber, the valve has one big and one small, the big one is for the intake and the small one is for the exhaust. Turn the remaining engine upside down and start Assembling the oil pan There is an oil drain bolt at the lower end of the oil pan. Before disassembling the engine, unscrew the bolt first, so that all the internal oil can flow out. After the vehicle has driven for a certain distance, the engine oil should be replaced regularly to ensure that the engine is in good condition. Lubrication. Remove the oil pan to see the oil filter, remove the oil filter and oil pump, and then unscrew the bolts on the crankshaft bearing cover to remove the bearing cover. The bearing cover and the inner bearing bush should be Make a one-to-one correspondence between the marks and the bearings. After removing the bolts that fix the piston on the crankshaft, you can lift the crankshaft, and then you can remove the pistons. The removed pistons should also be marked so that they correspond to each cylinder. One engine is disassembled
This enabled me to sublimate my theoretical knowledge. This enabled me to roughly understand the overall layout of the engine and the appearance of each part, and passed the 7-day disassembly and assembly practice of the engine. The relative position, as well as the assembly and operation between it.
There are gears meshing with the flywheel; the starter is used to start the engine; the distributor and high-voltage coil are used to increase the voltage and distribute the ignition sequence of each cylinder; the spark plug is used to provide the ignition device; there are intake manifolds and intake branch pipes Some cast it into one, and the exterior of the engine is equipped with a generator. Some are riveted together with rivets. There is an air filter on the top to filter the air entering the engine. There is a sensor for detecting the air volume at the position of the throttle valve; The gas main pipe and the exhaust branch pipe are used to discharge the exhaust gas generated during the combustion process of the engine; the modern engine is generally equipped with a three-way catalytic converter here to detect the content of harmful gases in the exhaust gas, and to feedback and adjust the intake air volume and fuel injection The amount of exhaust gas to ensure that the exhaust gas meets the requirements of environmental regulations; oil inlet pipes and oil return pipes should also be installed; due to the flammable mixture injected into the cylinder by the engine, air and gasoline must be mixed well in the intake pipe, and the way of fuel injection has Two types, one is: single-point injection, the other is: multi-point injection, the single-point injection injector is located at the position of the intake manifold, and then enters the cylinder in the branch pipe assigned to each intake; the fuel injection of multi-point injection The device is located at the branch pipes of each intake pipe, and the intake branch pipes are mixed and directly enter the cylinder; there are water inlet pipes and outlet pipes on the side of the engine, which cool the high-speed engine through the flow of water and provide a good working condition for the engine. Environment; generally there is also a sensor for detecting water temperature here, which is used to feedback the working condition of the engine.
The outer device of the engine has been basically introduced. Let's talk about the assembly relationship of the internal parts of the engine and the operation between them.
