DE4317254A1 - Highly reflective, catalytic surfaces in the combustion chamber of internal combustion engines - Google Patents

Abstract

The main aim of the invention is to reduce the transmission of radiant heat (operating medium - wall) in internal combustion engines with mixture formation in the working or combustion chamber. This is possible with highly pure silver surfaces, because these firstly possess the best reflection characteristics and secondly the characteristic of catalytically promoting the oxidation of soot. The energy saved by the reduced radiant heat transmission produces more rapid and complete combustion of the fuel together with an improvement in efficiency.

Description

Internal combustion engines give through relaxation work from compressed, hot fuel gases. Higher Combustion temperatures make ignition easier of fuel that has not yet burned and enlarge the submission of useful labor.

The combustion chamber is through its boundary walls Heat radiation, heat conduction and convection energy withdrawn. The heat transfer by radiation is ent speaking of the high absorbency of surfaces soot very big. In diesel engines, this is Ener gie absorbed by the cooling medium and is therefore for the Working capacity of the fuel gas lost.

State of the art are combustion chamber surfaces,

• - without coating
• - with coating to increase strength (Hartan odized pistons, MTZ, 1993, pp. 262, 264)
• - With coating to reduce the thermal conductivity ability, ie "ceramic layers"
• - Mirror surfaces Pat. No. 425 082, DE
• - catalytic surfaces ignoring the beam heat transfer (Al silicates and others, IPC 46a 77 u. a.).

Combustion chamber walls without a coating have a diesel engine oren relatively high cooling losses and in the near-wall area rich relatively cold zones that complete ver hinder burning. Thin oxide layers for strength increases are only marginally different. Mirror surfaces alone have because of their inclination no permanent high reflectivity for sooting. Catalytic combustion chamber surfaces as they have been up to now are not very reflective  for light and heat radiation.

The invention relates to highly reflective burning or workspace surfaces of internal combustion with fuel injection directly into the Combustion chamber, to reduce the radiant heat gangs on these surfaces, characterized, that one that is reflected on this surface Soot is catalytically oxidized and at the same time the The ability to reflect is retained.

On a high-purity silver surface (999/1000) a settling soot is already at Tem temperatures of approx. 280 ° C oxidized away.

The following advantages can be achieved with the invention become:

• - lower cooling heat losses. the useful performance
• - higher combustion temperature possible
• - more complete combustion so less unburned in the exhaust gases
• - Lower ignition delay with the diesel engine
• - lower fuel consumption
• - lower surface temperatures possible (outlet vents tile, piston)
• - Greater engine capacity leads to lighter engines.

With the diesel engine they are the burning or working surfaces delimiting spaces

• - the cylinder head
• - the valve disc
• - the piston crown
• - the combustion chambers or troughs
• - the injectors

with a compact, highly reflective silver layer of purity 999/1000 coated.

The layer can be galvanized (workpiece temper ature (100 ° C) or by "thermal spraying" (factory  temperature below 200 ° C) can be applied. Polishing may be necessary.

Claims (2)

1. Highly reflective combustion or workspace surfaces of internal combustion engines, with fuel injection directly into the combustion chamber, to reduce the radiation heat transfer to these surfaces, characterized in that a soot precipitating on these surfaces is catalytically oxidized away and thus the ref lexibility is retained. 2. Surface according to claim 1, characterized, that the surface with silver of purity 999/1000 is formed.