JPS5872652A - Internal-combustion engine - Google Patents

Abstract

PURPOSE:To aim at a reduction in the cost of material, by applying flame- spraying to a slide face between a hollow cylinder liner and a piston of ceramic system base material with a coating layer composed of a ceramic base material being more excellent in wearproofness than said ceramic base material. CONSTITUTION:A hollow cylindrical liner 9 is fitly inserted into a cast iron cylinder 1 and this liner 9 is entirely made up of a ceramic base material 15 being excellent in workability, which comprises mica, spodumene, etc., as the principal constituents. At the slide face between said liner and a piston 10 of the ceramic base material 15, a coating layer 16 of a ceramic system material being more excellent in wearproofness, heat resistance and shock resistance than the ceramic base material 15 is applied with flame-spraying to secure the coating. With this, as inexpensive ceramic system materials can be used in the liner 9 for such parts as requiring not so much wearproofness and heat and shock resistance, a reduction in the cost of material can be much expected.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an internal combustion engine whose liner is made of ceramic material.

General (2) A liner (also called a sleeve) is installed inside the cylinder of a gasoline engine or diesel engine, and this liner is usually made of a metal material such as cast iron with heat resistance and wear resistance ≦ double-stranded cast iron. ing.

By the way, recently, research is underway to make this liner out of a ceramic material that is much more heat resistant than cast iron, lighter, and more resistant to corrosion. However, this type of liner requires a high degree of heat resistance, abrasion resistance, and strength, and so far only 42 liners have been published.
Among ceramic materials, silicon nitride (s+sN+) and silicon carbide (Sj
It is limited to those containing C) as the main component.

However, this type of ceramic material is not only expensive, but also cannot be machined, so a method of polishing the sintered molded product with diamonds has to be adopted, which results in poor productivity and high costs. There are problems such as.

As a countermeasure for this, instead of constructing the entire liner with a ceramic thread material, a cylindrical base material made of metal such as cast iron with high heat resistance is thermally sprayed to a thickness of several hundred microns. It is known that it is coated with a curse film. In this way, the melting point can be solved in terms of cost and processability, but of course it cannot be expected to reduce the weight at all, and the above film is porous due to its small thickness. Therefore, there is a risk that corrosion may occur on the metal base material side.

In other words, when the engine is overcooled during operation, the sulfur, oxygen, and water contained in the smoldering gas react and form sulfuric acid (Htso) on the sliding surface of the ceramic coating.
This sulfuric acid penetrates through the film and attaches to the metal base material (2), resulting in corrosion of the metal base material (4). Measures are required.

Furthermore, it is necessary that the ceramic material used for thermal spraying be compatible with the metal base material, making it extremely difficult to select the material.

The present invention was made based on the above situation 4, and its purpose is to provide an internal combustion engine that is low cost and has excellent productivity even though the entire liner is made of ceramic material. This is what I am trying to do.

That is, in order to achieve the above object, the entire liner is constructed of a ceramic base material such as Myco, which has a slightly lower wear resistance than other ceramic materials, but is highly workable and inexpensive. We have formed a coating layer on the finger surface of the base material that connects to the piston by spraying not only the heat-resistant and thermal shock-resistant silicon nitride and silicon carbide mentioned above, but also another ceramic material with high wear resistance. Features.

An embodiment of the present invention will be described below based on drawings in which the present invention is applied to a diesel engine for a small boat.

In the figure, 1 is a cylinder made of cast iron. A cylinder head 3, also made of cast iron, is attached to this cylinder 1, and this cylinder head 3 forms a combustion chamber 4 between its balancing surfaces with the cylinder 1.

The cylinder head 3 is provided with an intake boat 5 and an exhaust port 6 connected to the combustion chamber 4, and these intake boats 5 and exhaust port 6 are opened and closed by the intake pulp 1 and the exhaust pulp 8. There is. A liner 9 having a hollow cylindrical shape is fitted into the cylinder I, and a piston 1° is accommodated in the liner 9 so as to be slidable in the axial direction. In addition, in the figure, numeral 11 is a water jacket, 12 is a connecting rod, 1
3 indicates a piston pin that connects the piston 10 and the connecting rod 12, and 14... indicate piston rings, respectively.

By the way, the liner 9 is entirely composed of a ceramic base material 15 made of a ceramic material mainly composed of mica, soothumene, etc., and the sliding surface of the ceramic base material 15 with the piston 10 is coated with silicon nitride or the like. A coating layer I6 having a thickness of several hundred μm is formed by thermally spraying a high-purity ceramic material containing as a main component. That is, the ceramic thread material such as mica, which is low in material cost and has excellent workability among ceramic materials, is used for the ceramic mother jf4I5, and the finger movement surface with the piston 10, in other words, A coating layer 16 of a ceramic material, which has better heat resistance, thermal shock resistance, and wear resistance than the ceramic base material 15, is applied to the parts where heat resistance, heat impact resistance, and abrasion resistance are required.
was formed.

In this structure, expensive ceramic materials with high wear resistance are used only in a very limited area of the sliding surface with the piston 10, so the liner 9
The overall quality is not excessive. In other words, inexpensive ceramic materials can be used in the parts of the liner 9 that do not require much wear resistance or thermal shock resistance, thereby reducing material costs. Moreover, since the material used for the ceramic base material 15 side does not require wear resistance, it has good workability, and ceramic materials such as silicon nitride are simply thermally sprayed, so they cannot be used in conventional polishing equipment. No special processing equipment is required. Therefore, even though the entire liner 9 is made of a ceramic material, there are advantages such as improved productivity and the ability to provide an inexpensive liner 9.

Note that the internal combustion engine according to the present invention is not limited to diesel engines and engines for small ships, but can be applied not only to vehicles such as motorcycles, but also to gasoline engines used in small portable generators, etc. Needless to say.

In the present invention described in detail above, the mica installed in the cylinder is thermally sprayed onto the base material made of a ceramic material and the sliding surface of the piston in this ceramic base material, which has higher wear resistance than the ceramic base material. It is composed of a coating layer made of an excellent ceramic material. According to this, inexpensive ceramic materials such as mica can be used in parts of the liner that do not require much wear resistance or heat resistance, while expensive ceramic materials with high wear resistance can be used with Reston. Since only a limited area of the sliding surface of the mica is used, the overall quality of the mica does not become excessive, and material costs can be reduced. In addition, the ceramic material on the base material side does not require wear resistance, so it is easy to process, and the ceramic material, which has excellent wear resistance, can be simply thermally sprayed, so it can be easily processed using conventional polishing equipment. No special processing equipment or processes are required. Therefore, even though the entire liner is made of ceramic material, excellent effects such as good workability and low cost can be achieved.

[Brief explanation of drawings]

The drawing is a sectional view showing an embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Cylinder, 9... Liner, 1o... Piston, I5... Ceramic base material, 16... Coating layer.

Claims (1)

[Claims] In an internal combustion engine, a hollow cylindrical liner is installed in the cylinder, and a piston-like sliding pattern (two pistons) is housed inside the cylinder.
The above-mentioned liner has a base material made of a ceramic material, and a sliding surface C between the piston and the ceramic base material-1: a coating made of a ceramic thread material that is thermally sprayed and has better wear resistance than the ceramic base material. An internal combustion engine characterized by comprising layers.