JPS59170445A - Ceramic engine - Google Patents

Abstract

PURPOSE:To make the setting of a piston ring ever so easy, by dividedly combining the piston ring of ceramics of an engine whose piston and cylinder consist of a ceramics sintered body each. CONSTITUTION:A piston ring is manufactured in the following process that B4C of 0.5wt% and carbon of 1wt% are added to submicron SiC and mixed altogether and, after molding the mixture into desired form, it is burned at a temperature of 2,200 deg.C in a nonoxidation ambience for 30min long, then its surface is ground with a diamond wheel. This piston ring is divided into two parts, and it is designed so as to be slidable at an oblique contact part being halved so that not only it can be easily installed in a piston but also airtightness can be amply kept up.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to engine parts, and particularly to a ceramic piston ring part suitable for use with a ceramic piston.

[Prior art]

Engines, which are a type of internal combustion engine, have traditionally been made of metal materials, and ceramic parts have rarely been used, with the only example of a spark plug being used. However, it has not yet been put into practical use as a main part of an engine.

[Purpose of the invention]

The purpose of this research is to provide a ceramic engine having a ceramic piston ring that is extremely easy to install.

[Summary of the invention]

S' C+ 8'2N4. Ceramic materials such as Sialon have a significantly higher heat resistance than metal materials, and if these ceramic materials can be used as main parts of engines, the combustion temperature can be dramatically increased compared to conventional metal engines, resulting in energy savings. It can greatly contribute to the development of

Conventional engine parts made of metal materials do not have high heat resistance, so they are used with water or air cooling. For this reason, a piston ring is attached to the outer periphery of the piston between the piston and the cylinder liner using lubricating oil. Therefore, it was possible to reduce the coefficient of friction between the piston and the cylinder liner. However, if these engine parts are made of ceramics and the combustion temperature is raised, the lubricating oil will burn and become unusable.

Additionally, while it was easy to attach a piston ring to a piston with conventional metal engine parts, attaching a ceramic piston ring to a ceramic piston is extremely difficult because ceramic is a brittle material. Have difficulty. For this reason, a piston structure may be considered in which no piston ring is provided and the entire outer circumference of the piston is in contact with the cylinder liner.

However, in this case, the contact area is extremely large, and therefore the coefficient of friction between the piston and the cylinder liner is extremely large, resulting in extremely large energy losses.

The present invention can be operated at high temperatures without the use of lubricants.

The present invention makes it extremely easy to attach ceramic engine parts to the piston, which was difficult to do with conventional techniques, by dividing the piston ring to be attached to the outer periphery of the piston into at least two parts and assembling them together. It's in the piston ring. By using the ceramic engine parts of the present invention, it is possible to manufacture engines that do not use ceramic lubricants, and in particular, engines that require a high compression ratio such as diesel engines can have sufficient airtightness. This made it possible to increase the combustion temperature of the engine and shift the operation bias. The piston ring has a springy mechanism so as to be pressed against one surface inside the cylinder liner. It may have spring properties itself. It is preferable to provide a plurality of piston rings.

Moreover, as a piston ring material according to the present invention, S I
Add 5 to sowt% of BN or graphite to the ceramic material selected from C+ Sis Nat SiAlON.
By using the attached sintered body, BN or graphite is dispersed in the sintered body as its crystal grains, and therefore, these serve as a lubricant and can be used in a non-lubricated state at high temperatures. It was also found that the friction coefficient was small. Therefore, by using a piston ring using the sintered body, operation can be performed with high temperature lubrication.

Example (Example 1) Submicron SiC was mixed with 0.5 W t% of B4C and 1% Vi% of carbon, molded into a desired shape, and fired at 2200C for 30 minutes in a non-oxidizing atmosphere. The surface was polished using a diamond grindstone to obtain a piston ring.

FIG. 1 is a diagram showing an embodiment of a ceramic piston ring according to the present invention. In this embodiment, the piston ring is divided into two parts, and the two parts are combined. As can be easily imagined from FIG. 1, the piston ring is not limited to being divided into two parts, but may be divided into three or more parts as necessary. As you can see from Figure 2, the piston ring is divided into two halves and is designed to be able to slide at the diagonal contact area, so it not only can be easily attached to the piston, but also maintains sufficient airtightness. I can do it.

FIG. 1 is a diagram showing an overall view of the central part of the engine. Reference numeral 1 denotes a piston and a two-piece cylinder liner, and the piston 1 slides on the inside of the cylinder liner 2 in an airtight manner. A piston ring 1o is provided between the piston l and the cylinder liner 2, and this piston ring 1o
It maintains airtightness.

(Embodiment 2) FIG. 3 shows the structure of a piston ring showing another embodiment. In this embodiment, the ends of the divided piston rings are processed into a stepped shape. Even in the case of the structure of this embodiment, the piston ring may be divided into two or more parts. Since the piston ring of this embodiment can slide during expansion and contraction at the stepped contact portion, it can be easily attached to the piston and can maintain sufficient airtightness.

(Example 3) 20 wt% of BN powder with an average particle size of 1 μm was added to SiC powder with an average particle size of 2 μm, and after mixing, the mixed powder was filled into a mold material made of graphite having a desired shape, and 2050C, 20
A sintered body was obtained by hot pressing at MPa and lh. The surface of the sintered body was polished using a diamond grindstone to obtain a piston ring. Since the added BN is dispersed in the form of crystal grains in the SiC sintered body, the piston ring has a very small coefficient of friction, and good operating conditions were obtained at high temperatures without lubrication.

〔Effect of the invention〕

According to the present invention, an engine having a ceramic piston ring that is easy to install can be obtained.

[Brief explanation of drawings]

FIG. 1 is a partial sectional view showing a part of the center of an engine, and FIGS. 2 and 3 are configuration diagrams showing a piston ring showing an example of the present invention. 1... Piston, 2... Cylinder liner, 3...
Piston pin, 4... Connecting rod, 5...
Sub-combustion chamber, 6... Exhaust pulp, 7... d air port liner, 8... Glow plug, 9... Fuel injection pump, 10... Piste No. 1 mouth service 2nd-283-

Claims (1)

[Claims] 1. At least the piston and the cylinder liner are made of a sintered ceramic body, and the piston has a piston ring made of ceramic movably embedded in the sliding surface with the cylinder liner, and the piston ring is divided into two or more parts. Ceramic engine is characterized by: