Fracture analysis of cylinder liner of diesel engine:
Cylinder bushing occurs when a crack is produced in use. Usually, the crack in the cylinder sleeve is lengthwise. From the cylinder sleeve flange (6105 Diesel engine, for example), the cylinder sleeve will be extended below the piston ring movement area. Some cylinder liner cracks (4135 as an example) start under the flange of the cylinder sleeve, through the flange section of the cylinder sleeve straight through. In addition to the upper part. In addition to the failure of the local fracture, the "brush table" accident may occur in the case of the 490 diesel engine. That is, it breaks out neatly at the shoulder of the top of the cylinder sleeve. The cylinder sleeve is taken out between the cylinder sleeve bump and the upper mounting belt, and the crack extension causes the cylinder sleeve to break into two halves.
What causes the diesel engine cylinder sleeve to break as follows:
The cylinder liner is divided into dry type and wet type, resulting in a variety of reasons for the rupture of cylinder liner. Some practical reasons are summarized as follows.
1 exorbitant protruding takes 6105 Diesel engine as an example. After the cylinder fits into the cylinder body, the stop plane of the cylinder sleeve should be slightly higher out of the cylinder body plane to ensure the tightness of the cylinder pad. But if the bulge is too high, the cylinder cover is easily extruded and cracked after the cylinder head is tightened. Generally, this value should be controlled in 0.05 to 0.20m. Within the range of M.
In order to avoid this factor, in order to avoid this factor, the cylinder sleeve can be broken. It is not necessary to put the waterproof rubber ring on the outer wall of the cylinder liner, and put it in the cylinder body to carefully measure the size of the cylinder block high out of the cylinder body. If it is not suitable, the cylinder sleeve can be adjusted to make it flat as far as possible. If it is still too low, it is still too low. Find an old cylinder pad to disassemble, cut the copper skin into a washer, and cushion the bottom of the cylinder sleeve to raise it. If it is too high, the plane of the cylinder body can be milling to increase the depth of the shoulder.
2 cylinder sleeve shoulder plane or cylinder body pressure surface and cylinder center line is not vertical to 4135 diesel engine as an example, in this case the cylinder fits into the cylinder body, it will appear on the lower plane side of the cylinder body pressure surface, the other side of the air condition. So the cylinder head nut is tightened, it is easy to cause cylinder sleeve fracture.
3 misuse the cylinder liner to take the 6105Q diesel engine as an example. At present, there are 9 kinds of variant 名媛直播 in our country, but there are only 6 types of cylinder sleeves, as shown in Figure 2-8.
4 cylinder sleeve and cylinder sleeve hole matching improper with 4102BQ diesel engine as an example, the cylinder sleeve is thin dry cylinder liner, its thickness is only 1.5mm, very thin and the upper stop positioning cylinder sleeve.
The cylinder sleeve of the diesel engine is in transition with the bore of the cylinder sleeve. This value shall be -0.03~-0.Olmm. if the cylinder sleeve is tight with the bore of the cylinder sleeve when the cylinder sleeve is assembled. The cylinder sleeve is broken when the bore is pressed into the bore. At this time, it is usually found to break at the back of the support shoulder of the cylinder sleeve. On the contrary, if the gap is too loose (the gap is greater than 0.003mm). Above), there may be a gap between the cylinder sleeve and the socket of the cylinder sleeve, resulting in poor local heat transfer. It may cause hot cracking of the cylinder liner for a long time.
This is because if the cylinder sleeve is loosely matched with its bearing hole and the cylinder sleeve will swing laterally in the hole of its bearing hole, the cylinder sleeve will break easily. When the diesel engine works at high speed, the piston rod group acts as a reciprocating movement, and the lateral swing of the piston will cause the transverse vibration of the cylinder sleeve and increase the vibration frequency of the cylinder sleeve. Rate and amplitude. The force generally tends to increase the lateral force of the cylinder sleeve and pass to the cylinder sleeve bearing hole because the cylinder sleeve bears the pressure of the combustion gas for a long time, the inertia force of the piston, the pressure of the piston ring, the vibration of the piston and the strike of the cylinder wall, which makes the cylinder sleeve outer diameter and cylinder liner bearing a stress percussion. The cylinder liner works under this alternating pressure condition for a long time, and eventually it will be overburdened, which will lead to the rupture of the cylinder liner.
5 modified 6108Q diesel engine produced by improper Guangxi Yulin diesel engine is a replacement product developed on the basis of inheriting many advantages of the 6105QC diesel engine of the factory. For this reason, some 6105QC diesel engine users have modified the 6105QC type into 6108Q diesel engine to improve the diesel engine's power and economy. On the basis of the 6105QC type, the 6105QC type is converted into a 6108Q diesel engine.
This is because some people simply think that the 6108Q type is a 6105QC type diesel engine, so the cylinder sleeve, piston, piston ring, piston pin, cylinder pad and other related components of the 6108Q diesel engine can be upgraded to 6108Q diesel engine. It is not clear that the assembly dimensions on the cylinder liner of 6108Q and 6105QC are different from the cylinder body. Same. Because the upper positioning flange of the upper position of the cylinder sleeve of the type 6108 diesel engine is larger than that of 6105QC, it is possible to press the cylinder sleeve to fracture when the cylinder sleeve is pressing the bore of the cylinder sleeve. Even if the cylinder sleeve can successfully press the bore of the cylinder sleeve, the upper flange part of the cylinder sleeve will also be unable to dissipate heat after the high temperature in the diesel engine. The cylinder liner is broken. Therefore, we must not blindly replace it.
