新闻详情banner

newsdetailed

CHANGYING MACHINERY

Your current location : home page >> News >> Company News

What are the key assembly points for components such as engine valve clamps?

author:
2020.11.20 09:50:18

What are the key assembly points for the engine valve assembly?

The valve set includes valves, guides, valve springs, spring seats, locks, and snap ring parts. The main purpose of the valve group is to ensure a close fit between the valve cone and the valve seat cone, with sufficient strength and wear resistance at high temperatures. Therefore, the following requirements are proposed for the valve body assembly work: First, the matching between the valve seat and the valve seat should meet the requirements; The second is that the valve body has a good guiding effect on the upward and downward movement of the valve stem, ensuring that the valve does not deflect on the valve seat; The third is to have sufficient stiffness and preload, with one end face perpendicular to the valve centerline.

Key points of valve assembly

The valve is composed of a valve stem and a valve head. The valve is in direct contact with high-temperature gas, resulting in high operating temperature. During operation, the valve opens and closes frequently, impacting the valve seat, and the lubrication condition is poor. Therefore, damage to the intake and exhaust valves is one of the main faults of diesel engines. Check the valve before assembly: ① Use a dial indicator to check the bending of the valve stem. The swing difference of the gauge needle should not exceed 0.05 mm. Or place the valve rod on a flat plate for rolling inspection. If there is any bending, it should be corrected or replaced. ② Measure the wear of the valve stem. Use a screw micrometer to measure the upper, middle, and lower parts of the valve stem. When comparing the measured results with the undamaged portion of the valve stem end, if it exceeds 0.05mm, or if there is a significant stepped feeling when touching with your hand, the valve should be replaced. ③ Check the valve length. The tail end of the valve rod is worn unevenly, and it should be repaired with a grinding wheel. The grinding amount should not exceed 0.50 mm. ④ Check whether there are worn spots and pits on the working surface of the valve such as grooves, wideness, and ablation, and polish if necessary. When assembling the valve, pay attention to the marks that identify the intake and exhaust valves. ① Structural feature markings: For most engines, the head diameter of the intake valve is larger than the exhaust valve; The valve cone angle is sometimes different, the intake valve is sometimes 30 °, and the exhaust valve is often 4500 ② Mark: Some engines have the same intake and exhaust valve diameter as the valve cone angle. To distinguish, a mark is engraved on the top of the exhaust valve when leaving the factory. ② Grinding marks. For the ground valve end, the serial number should be stamped with a steel stamp (for example, 1 on the 12 valve heads in a 1.2... 12, 6-cylinder engine, with the first valve in the first cylinder as 1, and then marked in order) to ensure that each valve and the valve seat that is ground with it will not be misplaced. Therefore, ensure the sealing fit of each valve and valve seat.

The key point of valve stem assembly is that the valve stem is cylindrical, with tapered or annular grooves at the ends. Some are drilled with pin holes, which are used to install lock pieces, snap rings, or pins to secure the spring seat, preventing serious accidents caused by the valve falling into the cylinder when the valve spring is broken or the lock piece falls off. During operation, the valve stem moves in the valve guide. In order to accurately seat the valve on the valve seat and prevent air leakage due to left and right sway, the fit clearance between the valve stem and guide tube is very small. The intake valve is 0.025-0.077 mm, and the wear clearance is 0.15 mm; The exhaust valve is 0.040~0.092mm, and the wear clearance is 0.15mm. When the valve train of the top valve operates, oil in the valve chamber will flow into the cylinder from the fitting gap between the valve stem and valve guide, causing carbon deposition in the cylinder, affecting the normal operation of the engine. An oil baffle made of film is installed on the valve stem to reduce the amount of oil in the valve chamber entering the cylinder. Some engines only install an oil deflector on the intake valve lever. When entering the valve, the vacuum generated in the cylinder sucks oil into the valve chamber through the fitting gap between the valve stem and the valve tube. After the valve spring seat manufacturer installs the oil retainer, excessive oil leakage into the cylinder can be avoided, resulting in adverse consequences. Therefore, when assembling the valve stem assembly, do not omit small components such as valve keys, snap rings, and oil deflectors.

Valve clamp


Key points for assembling the vent pipe: The vent pipe guides the movement of the valve stem, prevents the valve head from tilting, and makes the valve and valve seat closely fit. The inner surface of the valve conduit requires high dimensional accuracy. The valve core is directly pressed into the cylinder head to guide the flow and ensure linear movement of the valve. The outer diameter of the tube should have a certain degree of tightness with the mounting hole of the tube on the cylinder head. During installation, press the tube firmly into the mounting hole of the cylinder head by hand. When hammering, the plate should be cushioned on the upper end of the conduit to prevent deformation or damage to the conduit. If there is no restriction on the outer circle of the valve guide, pay attention to the pressing depth when pressing, that is, the upper end of the valve guide should be higher than the cylinder head by a certain height. You can first measure the length of the exposed portion of the old conduit, and leave the same length after installing the new conduit to ensure sufficient distance to open and close the valve. The elevation between the upper end of the valve guide and the cylinder head of the 195 diesel engine is 20mm. If the upper end of the guide tube is higher than the cylinder head, the spring seat collides with the valve tube, preventing the valve from fully opening, resulting in insufficient air intake, poor emptying, and even bending the valve push rod, breaking the rocker arm. If the upper end of the guide tube is higher than the cylinder head, it will increase the intake pipe, exhaust resistance, and even cause valve leakage. The upper port of the valve guide bore has a chamfer for storing oil and supplying lubricating oil to the guide bore. Excessive chamfer, excessive oil storage, and oil flowing into the cylinder through the conduit hole for combustion, increasing oil consumption; The chamfer is too small, the oil supply is insufficient, and the wear of the inner hole is increased.

Key points of valve spring assembly: The function of the valve spring is to ensure a tight fit between the valve and the valve seat. Generally, each valve has two internal and external springs (double valve springs) that rotate in opposite directions and are sleeved together to prevent resonance of the springs during operation. Even if one of the springs breaks, the valve will not fall into the cylinder. The valve spring is sleeved on the valve stem, with one end supported on the cylinder head and the other end supported on the spring seat. The elastic seat is fixed in the ring groove at the tail end of the door lever with a locking plate. The valve spring has sufficient elasticity to overcome the inertial force of components such as the valve and quickly close the valve when the cam rotates. When installing the valve assembly, the lock must be installed correctly so that the spring can be securely installed.

Before installation, remove carbon deposits and parts, and then carefully inspect the valve spring clamp manufacturer for damage to the parts. The valve spring shall be inspected as follows: ① Appearance inspection. After cleaning the valve spring, first visually observe for cracks, corrosion, deflection, deformation, etc. Replace the valve spring with the above defects. ② Free length inspection. Generally, use a ruler, caliper, depth gauge, etc. to check the length, or compare the length of new and old springs. If the length of the valve core is found to be less than 3mm, it should be replaced. ③ Elasticity test. Check with a spring tester. During inspection, press the spring to the working height according to the specified spring pressure, and observe the reading of the measuring instrument. The spring force should meet the specified value. During installation, the installation sequence is the reverse of the removal sequence, but the tools used are the same. Install and discharge the valve springs, and then press the inner and outer valve springs into the valve spring seat; When installing the valve lock and valve spring, a set of pipe columns can be applied to the valve lock and valve spring to evenly tap the sleeve at the end of the valve stem to tighten the lock. After installing the valve lock, the valve lock must be placed in the groove above the valve stem and should be 0.7~2.5mm higher or lower than the spring seat. The height of the two locking tabs should be consistent, and the gap between the two locking tabs should be greater than 0.6mm. Measure the valve sinkage, which is the distance between the valve and the cylinder head plane. The valve depression of 195 diesel engine is 1~1.8 mm. Shake the spring seat by hand. If the spring seat swings relative to the valve stem, replace the spring seat or lock.


Website of this article: http://en.ltfv.com.cn/news/436.html

Recent Views:

Related products

Related news

What help do you need?What help do you need?