HS code-based tariff reconciliation

List of the catalog of this article:

• 1,HS code-based tariff reconciliation Title + Why is the engine crankshaft designed as a curved structure instead of a straight structure?
• 2, Heat treatment process design of automobile engine crankshaft
• 3, Is the engine of a car designed with 2 or more Is the above cylinder made at the same time?

Title + Why is the engine crankshaft designed as a curved structure instead of a straight structure?

1. This is mainly because the vertical engine and gearbox are arranged vertically in the engine compartment, which will extend the gearbox to the cockpit, so that the space in the front row will be occupied by the powertrain;The engine, gearbox and other parts of the horizontal engine are arranged horizontally in front of the front axle, so it will not occupy the space of the cab.

2. A spindle neck, a connecting rod neck and a crank form a crank, and the number of cranks is equal to the number of cylinders (inline engine); the number of cranks of a V-type engine crankshaft is equal to half of the number of cylinders. The spindle neck is the supporting part of the crankshaft, which is supported in the main bearing seat of the crankcase through the main bearing.

3. The force of the crankshaft is extremely complex. It works under the combined action of periodically changing gas pressure, reciprocating inertial force and its moment, and bears huge bending and torsional alternating loads. At the same time, it is also a slender high-speed rotating part, so it requires strict dynamic balance, and bending and distortion are not allowed to exceed a certain value.

4. Except for the advantage of cost, the straight 6 engine is not as structurally as good as the V6 engine. Due to the in-line arrangement, the length of the engine is increased, which is much longer than the length of the V6. The requirements for the strength of the crankshaft and camshaft of the engine are high.

5. There is a connecting flange at the rear end of the crankshaft, and the flywheel is connected to the crankshaft through bolts. In order to lubricate the connecting rod shaft neck, there is a lubricating oil channel drilled from the main shaft neck to the connecting rod shaft neck. The integral crankshaft has a simple structure, light quality and reliable operation. It generally adopts sliding bearings and is widely used in medium and small engines.

6. The piston stroke is equal to the rotation diameter length of the crankshaft connecting rod shaft. Generally represented by s, it corresponds to a piston stroke, and the crankshaft rotates 180°. The large piston stroke not only increases the total height of the engine, but also is not conducive to increasing the speed of the engine.

Heat treatment process design of automobile engine crankshaft

1. Process of crankshaft: forging, return Heat treatment technology of fire, coarse car, conditioning, fine car, soft nitriding, grinding and crankshaft.

2. The following is the process of the 618 crankshaft of heavy-duty vehicle engine: forgingConstruction → annealing → coarse turning → conditioning → fine turning → N and C co-permeation (commonly known as soft nitriding) → grinding. According to the purpose, material and manufacturer of the crankshaft, the heat treatment process is different. I specialize in the design of heat treatment equipment, and I know a little about heat treatment technology.

3. Generally, forged steel and ductile cast iron are used. Forged steel needs to be heat treated and tempered, that is, high-temperature tempering after quenching, so that the material has high comprehensive mechanical properties. The surface of the shaft diameter is then surface quenched to improve the surface hardness and wear resistance. The ductile cast iron crankshaft adopts heat treatment processes such as isothermal tempering, intermediate frequency quenching and laser quenching.

4. Working principle of the crankshaft. The crankshaft is one of the most typical and important parts of the engine. Its function is to convert the gas pressure transmitted by the piston connecting rod into torque, output work as power, drive its working mechanism, and drive the auxiliary equipment of the internal combustion engine.

5. CrMo4 heat treatment specification: quenching 820℃-880℃, oil cooling or water cooling; tempering 540℃-680℃; top quenching experiment 850℃±5℃ 42CrMo4 features and applications: 42CrMo4 German grade special steel.

6. The ductile iron crankshaft adopts heat treatment processes such as isothermal tempering, intermediate frequency quenching and laser quenching. Tempering is to reheat the workpiece to a certain temperature below ac1, keep it warm for a period of time, and then take it out to cool it in a certain way.

Is the engine of a car designed with 2 or more cylinders at the same time?

1. In fact, this is not contradictory. The ignition order is indeed 1342.Because the 1st cylinder and the 4th cylinder are homology, and the 2nd cylinder and the 3rd cylinder are isometric, the difference between the two cylinders is 360 degrees, that is, the crankshaft rotates around.

2. The four cylinders are made separately. The order of workmanship is generally 1342 or 1243, and the engine needs to go through four processes of air intake, compression, work and exhaust. That is to say, there is a cylinder working every moment, and a cylinder is inhaling air. One is exhaust, and one is compressed.

3. The multi-cylinder engine has only one cylinder working at a certain time in a working cycle. But in a working cycle, all cylinders have to work once. Of course, the more cylinders, the more power.

4. Cars have twin cylinders or multiple cylinders. Cylinder refers to a piston cylinder. A single cylinder refers to one piston cylinder, a double cylinder refers to two piston cylinders, and a three-cylinder refers to three piston cylinders... By analogy in turn.

5. Yes, it is simultaneous ignition. One of the cylinders is a non-compressed upper stop point. The high-pressure electricity of the ignition coil is easy to break through the spark plug gap. Through the cylinder block, the spark plug gap jumps in another compressed cylinder, and the ignition coil forms a high-pressure loop to complete the work.