Use of a particular copolymer for preventing deposits on the valves of indirect injection petrol engines

Abstract

The invention relates to the use, in order to prevent deposits at low temperature on the fuel intake valves in indirect injection spark ignition engines, of one or more copolymer(s) comprising:at least one unit of following formula (I):andunits of following formula (II):The copolymers according to the invention are very particularly effective in preventing and / or cleaning the deposits on the valves while preventing the latter from sticking at low temperature.

Description

[0001]A subject matter of the present invention is the use of a specific copolymer to prevent the deposits which form at low temperature on the fuel intake valves in indirect injection spark ignition engines.PRIOR ART[0002]Liquid fuels for internal combustion engines contain components which can decompose during the operation of the engine. The problem of deposits in combustion engines is well known to auto mechanics. It has been shown that the formation of these deposits has consequences on the performance qualities of the engine and in particular has a negative impact on consumption and emissions of particles. Progress in the technology of fuel additives has made it possible to confront this problem. “Detergent” additives used in fuels have already been proposed to keep the engine clean by limiting deposits (“keep-clean” effect) or by reducing the deposits already present (“clean-up” effect). Mention may be made, by way of example, of U.S. Pat. No. 4,171,959, which describes a det...

AI Technical Summary

Benefits of technology

[0001]A subject matter of the present invention is the use of a specific copolymer to prevent the deposits which form at low temperature on the fuel intake valves in indirect injection spark ignition engines.

Problems solved by technology

It has been shown that the formation of these deposits has consequences on the performance qualities of the engine and in particular has a negative impact on consumption and emissions of particles.

In the case of indirect injection spark ignition engines (or gasoline engines), a specific problem is posed, related to the formation of deposits on the external parts of the engine and in particular on the stems of the intake valves for the mixture of air and fuel upstream of the combustion chamber, which results in a phenomenon of valve sticking.

The accumulation of such deposits on the valve stems hinders the movements of the latter, the stems stick to the valve guides, which causes poor closing of the valves, causes sealing problems in the combustion chamber, and can significantly affect the operation of the engine, and in particular can prevent it from starting in cold weather.

This phenomenon of valve sticking is thus the cause of sealing problems in the combustion chamber, responsible for a reduction in the compression force and thus in the efficiency of the engines.

In some extreme cases, the intake valve, which has remained open due to the accumulation of the deposits, can collide with the piston.

This collision can then lead to deformation of the valve and / or of the valve stem and thus to the breakdown of the engine.

On the other hand, a second type of deposit consists of viscous deposits, mentioned above, which form at low temperature, typically at a temperature of less than or equal to 5° C., and which appear on the stems of the intake valves of indirect injection spark ignition engines during the use of additive-treated fuels, thus causing the phenomenon of valve sticking described above.

Thus, the additivation of the fuel for the treatment and the prevention of the deposits which form at high temperature can cause the appearance of viscous deposits at low temperature.

In particular, the detergent additives conventionally incorporated in gasolines in order to keep the valves clean at high temperature have paradoxically proved to promote phenomena of valve sticking at low temperature.

However, this solution proves to be expensive, and the aim is as far as possible to avoid the use of such an oil, or to reduce the amount thereof as much as possible.

In the absence of such an oil, a phenomenon of valve sticking occurs.

The solutions proposed in the prior art are therefore not entirely satisfactory.

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