How to measure the cylinder pressure of automobile engine?
2. Start the engine, observe and remember the value indicated by the first jump of the pointer. Release the starter and return the pointer to zero. Repeat the measurement through the same procedure, but each measurement should be based on the highest value that both hands can reach at the first jump. The value that the hand can jump out for the first time is the real pressure of the cylinder.
3. If the height before and after the measurement is uneven, a low value indicates that the piston did not start when it was completely air-filled and compressed. It is worth emphasizing that each cylinder must be measured many times to determine the accurate value of the cylinder. ?
4. Other understandings of different measurement methods and values.
Another way to measure cylinder pressure is to contact the meter head with the spark plug seat hole of the cylinder, and then turn on the starter. Under the action of piston pressure, the gas pressure pushes the meter pointer to rise from zero to a certain value, and then the starter does not stop running immediately, but continues to rotate. The piston repeatedly compresses and pushes the hands to jump intermittently until the hands no longer rise. The highest value reached by the instrument pointer is the pressure of the cylinder. It is problematic to take the highest accumulated value of both hands as the cylinder pressure value.
Extended data:
cylinder block
The cylinder block and upper crankcase of water-cooled engine are usually cast as a whole.
Known as the cylinder block-crankcase, it can also be called the cylinder block. The cylinder block is usually made of gray cast iron. The cylindrical cavity in the upper part of the cylinder block is called the cylinder, the lower part is the crankcase supporting the crankshaft, and its inner cavity is the space for the crankshaft to move. Many reinforcing ribs, cooling water jackets and lubricating oil passages are cast in the cylinder block.
The cylinder block should have sufficient strength and rigidity. According to the different installation plane positions of the cylinder block and the oil pan, the cylinder block is usually divided into the following three forms.
1. General cylinder block: characterized in that the installation plane of oil pan is at the same height as the rotation center of crankshaft. The advantages of this cylinder block are small height, light weight, compact structure, convenient processing and convenient disassembly and assembly of crankshaft; But its disadvantages are poor rigidity and strength.
2. Gantry cylinder block: characterized in that the installation plane of oil pan is lower than the rotation center of crankshaft.
Its advantages are good strength and rigidity, and it can bear large mechanical load. But its disadvantages are poor manufacturability, heavy structure and difficult processing.
3. Tunnel cylinder block: The main bearing hole of the crankshaft of this type of cylinder block is integral with rolling bearings, and the main bearing hole is larger, and the crankshaft is loaded from the back of the cylinder block. Its advantages are compact structure, good rigidity and strength, but its disadvantages are high machining accuracy, poor manufacturability and inconvenient disassembly and assembly of crankshaft.
In order to make the inner surface of the cylinder work normally at high temperature, it is necessary to properly cool the cylinder and cylinder head. There are two cooling methods, one is water cooling and the other is air cooling. Cooling water jackets are processed around the cylinder and cylinder head of water-cooled engine, and the cylinder block and cylinder head are communicated with each other. The cooling water continuously circulates in the water jacket, taking away some heat and cooling the cylinder and cylinder head.
Reference source: Baidu Encyclopedia-Engine