DE1751606C3 - Combustion chamber insert for diesel engines - Google Patents

Description

The invention relates to a combustion chamber insert according to the preamble of claim 1 and a Process for the production of such a combustion chamber insert.

Combustion chamber inserts, such as e.g. B. vortex chamber, antechamber, Lanova air storage, etc. These combustion chamber inserts are subject to high thermal loads and are therefore made of highly heat-resistant, non-scaling material. They are usually installed in guiieisern »; Cylinder heads. The operating temperatures of the combustor liners lie in the interior at about 600 ⁰ C / end of the cooled cylinder head temperatures assumes wäi of 200 to 300 ° C. The combustion chamber inserts made of stainless steel expand much more than the mounting hole in the cast iron cylinder head due to the higher temperature and the higher thermal expansion coefficient, which results in strong internal stresses. As a result of the clamping and the uneven temperature of the combustion chamber inserts, a compressive stress arises in the warm state, the greater the temperature difference between the combustion chamber insert and the cylinder head or between individual combustion chamber areas. If this compressive stress exceeds the yield point of the material of the insert, it will eventually tear as a result of an intolerable tensile stress, following a damage mechanism that will not be discussed here. The yield strength decreases as the temperature of the material rises. This damage process is therefore doubly dependent on the temperature of the combustion chamber insert. It is therefore advisable to use constructions in which the combustion chamber inserts are well cooled. For this purpose, combustion chamber inserts and receiving bores are manufactured with narrow tolerances and sometimes with a press fit in order to achieve metallic contact at all times and thus good heat conduction between the combustion chamber insert and cylinder head "Is particularly warm, is already stressed beyond its yield point when the new engine is first warmed up and is compressed so far that it becomes loose in the cylinder head when it is cold. A tight press fit has a disadvantageous effect because it increases the initial stress and the yield point The opposite way of installing the combustion chamber insert with play and realizing a sliding fit has the disadvantage that the colder parts of the combustion chamber insert only come into contact with the cylinder head when the engine is subjected to a higher load and thus the insert is at a higher temperature come. Until then, however, combustion gases, soot and oil settle in the gap between the insert and the cylinder head and form carbon there. This results in a significant deterioration in the heat dissipation from the combustion chamber insert to the cylinder head, as a result of which the operating temperature of the insert increases and the durability is reduced.

The object of the invention is to create a combustion chamber insert for diesel engines that has the ensures a perfect fit and good heat dissipation throughout the operating area

This object is achieved according to the invention by the features according to claim 1. Included the use can be developed according to the feature according to claim 2, whereby a Recording for the excess jacket material formed when the insert is driven into the housing socket will. The German Auslegeschrift 11 02 474 shows in the figure H < Space between the insert parts and the cylinder head wall. But these serve so far they have even been described, for isolation between the two parts, d. H. so for a purpose that that of the invention is just the opposite, since this is precisely on an intimate contact with the Walls for the purpose of good heat transfer value.

J5 The manufacture of the combustion chamber insert can preferably be carried out in accordance with the preceding claim 3 marked procedure.

An explanatory known example and exemplary embodiments of the invention are shown in the drawing and are described in more detail in the following. It shows

F i g. 1 with a partial section through a cylinder head known combustion chamber insert,

Fig. 2 shows a combustion chamber insert according to the invention with a soft metal jacket (the latter in a larger Scale).

In the cylinder head 1 shown only partially in FIG. 1, it is embedded in a receiving bore 2 Combustion chamber insert 3. Combustion chamber insert 3 is set hot 'into the receiving hole 2 from above and is supported by its collar 4 in the cylinder head 1. In the bottom part 5 of the combustion chamber insert 3 arise the highest temperatures. Therefore this is also the most endangered part. As long as there is still enough There is metal contact between the combustion chamber insert 3 and the mounting hole 2, the heat can be good be discharged. In the previously common combustion chamber inserts, the thermal expansion is so great that the material is stressed beyond its elastic limit, so that it becomes a "forging" of the Combustion chamber insert 3 comes. After cooling, there is a hole between the combustion chamber insert 3 and the mounting hole 2 a gap in which oil carbon can settle; This is what makes the heat dissipation so strong

fi5 worsens that it causes local burns and Cracks in the bottom part 5 comes

In FIG. 2 is a combustion chamber insert 3 after Invention represented, which these phenomena

going off. The combustion chamber insert 3 is provided with a soft metal jacket S in which recesses 7 are arranged. This combustion chamber insert 3 is driven into the receiving bore 2 with play or with top cover. Excess material can settle in the recesses 7. The soft metal jacket 6, which can be made of lead, zinc or aluminum, for example, has good deformability and ensures perfect metal contact and good heat conduction between the combustion chamber insert 3 and the receiving hole 2 _{r over the entire operating range}

1 sheet of drawings

Claims (3)

Patent claims: 1. Combustion chamber insert made of highly heat-resistant material for diesel engines, characterized in that that it is made of a material with a good thermal conductivity, a low modulus of elasticity and a sufficiently high melting point, such as lead, Zinc, aluminum or the like is coated, 2. Combustion chamber insert according to claim 1, characterized in that it is in a manner known per se Is provided on its peripheral surface with depressions, notches, grooves, indentations or the like 3. A method for producing a combustion chamber insert according to claims 1 or 2, characterized characterized in that the jacketed combustion chamber insert (3) is heated during engine operation and then in the cold, deformed state is measured in order to determine further combustion chamber inserts according to these dimensions (3) to manufacture.