FR2702004A1 - Self-cleaning gas exhaust system for an internal combustion engine - Google Patents

Abstract

The system comprises, at the outlet from the cylinders, pipes (2) emerging in a manifold (4) which emerges in a flame-protection stack (8), and jackets (9-12) for external cooling of the gases and of the walls of the pipes, of the manifold and of the stack. The manifold (4) internally has means (15) for pyrolysis of the soot from the combustion gases, avoiding soiling of the stack.

Description

Gas exhaust system, self-cleaning,
an internal combustion engine
The subject of the present invention is an exhaust system of an internal combustion engine, of a diesel engine or of a petrol engine, in particular of an explosion-proof engine, which is at the origin of the invention of the present application, without however that this should be considered as limited to this particular application.

In such an engine, the gases leaving the cylinders are at a relatively high temperature. I1 results from this that the temperature of the wall of the exhaust manifold as well as of the gases leaving this exhaust manifold are too high to allow, without risk of explosion, the use, without special arrangement, of such a engine in an oxidizing atmosphere, such as for example on oil drilling platforms, or in premises where flammable or explosive pulverulent materials are produced, or certain chemicals.

This is why the exhaust pipes, at the outlet of the cylinders of an explosion-proof internal combustion engine, as well as the exhaust manifold, into which these pipes open, are often surrounded by envelopes in which circulate a liquid of external cooling, usually water, to cool the walls and exhaust gases.

This is also why the collector of an explosion-proof motor leads to an exhaust stack consisting of suitably spaced washers and acting as flame arresters.

The particles of scale, residue from the combustion of gases, have always been a concern for engine manufacturers. In explosion-proof motors fitted with an exhaust stack, these particles can clog the washers, obstruct the gaps between them and therefore block the passage of gases. In this case, the power drops and the motors collapse.

Various solutions for cleaning the exhaust stack have already been proposed, but none has been found to be perfectly satisfactory.

The present invention provides a good solution.

The invention relates to a system for exhausting combustion gases from cylinders of an internal combustion engine comprising, at the outlet of the cylinders, pipes leading into a manifold which opens into a flame-retardant stack and means for external cooling of the gas and the walls of the pipes, of the collector and of the stack, characterized in that the collector internally comprises means for pyrolysis of the scale of the combustion gases.

The advantage of the pyrolysis means is therefore to heat the scale particles, to burn them and to reduce them to dust.

The exhaust system of the invention, having regard to scale, is therefore a self-cleaning system.

However, the advantage of the invention, as already announced above, is not limited to an explosion-proof motor. It applies just as well to a conventional internal combustion engine to transform its exhaust system into a self-cleaning system.

Thus, and more generally, the invention therefore relates to a system for exhausting combustion gases from cylinders of an internal combustion engine comprising, at the outlet of the cylinders, pipes opening into a manifold, characterized in that the manifold internally comprises means for pyrolysis of the scale of the combustion gases.

Advantageously, the pyrolysis means comprise an electrical resistance supplied with current by an alternator and wound on a support made of perforated sheet.

Advantageously also, a refractory sheath is disposed between the pyrolysis winding and the wall of the collector to create an annular air gap between the sheath and the wall of the collector and reduce the heat exchange with the external cooling envelope of the collector. .

Preferably, and in addition to the pyrolysis means to even eliminate the fine dust resulting from the pyrolysis of the scale, a fresh air inlet is provided in the collector to cause the combustion of this dust.

As the dust may not be completely eliminated by the oxygen in the air, part of which may be prematurely burned, it is preferably still provided, at the outlet of the collector, or of the exhaust stack when it is provided, exhaust venturi creating, with the air intake, an air current which, with the resulting increase in the speed of the gases, sweeps away the residual dust and finishes eliminating all of them.

Finally, it may be particularly advantageous to have, inside the collector, near its outlet, a noise reduction cartridge of the type of that described in FR-A-734 341, whose primary function, thanks to a general expansion followed by a plurality of elementary helical expansion chambers, is to regulate the flow of gases, dampen and break up explosions and thus avoid exhaust noise. But this primary function induces a second which is to pump the exhaust gases out of the manifold. When such a cartridge is thus placed in the collector, it is preferable that the electrical pyrolysis winding also surrounds the cartridge.

Advantageously, the turns of the pyrolysis winding surrounding the cartridge are very tight for, in the area of the cartridge where the dust could accumulate, increase the heating temperature and thus contribute to the burning of this dust.

It will be noted that in the case where the collector comprises a noise reduction cartridge and is traversed by a stream of air, part of the oxygen in the air being burned upstream of the cartridge, the stream of air and the gas flow thus accelerated complete the action of the cartridge to sweep the unburned dust in the cartridge for lack of oxygen.

The invention will be better understood using the following description of the exhaust system, with reference to the single appended figure in which it is shown in partially broken away view.

The exhaust system is that of an internal combustion engine, here explosion-proof, with, in particular, a cylinder block 1, exhaust pipes 2 for combustion gases from the cylinders and an electric alternator 3. The pipes 2 open out in a manifold 4. The manifold 4 has, on one side, a fresh air inlet 5, with an explosion-proof stack 6, and, on the other side, an outlet 13 opening into a pipe 7 for connection to a stack flame-retardant exhaust 8. The pipes 2, the manifold 4, the connection pipe 7 and the exhaust stack 8 are surrounded by an envelope for circulating water for cooling the external walls and the gases, 9, 10, 11 and 12 respectively.

Inside the collector 4 extends a support made of cylindrical perforated sheet 14 on which is wound an electrical resistor 15 whose turns, near the outlet 13, are very tight. The electrical winding 15 is supplied with current by the alternator 3. The portion 17 of the winding 15 with tight turns surrounds a noise reduction cartridge 16 of the type described in FR-A-734 341.

Between the winding 15 and the wall of the collector 4 extends a refractory sheath 18 creating an annular air space 19 inhibiting the exchange of calories with the cooling jacket 10.

The exhaust stack 8, moreover conventional and connected, by its inlet, to the connection pipe 7, is connected, by its outlet, to a discharge pipe 20 with venturi 21 to create, with the inlet d air 5, a current of air passing through the manifold 4 and the cartridge 16 and the exhaust stack 8. Air intakes 22 are formed in the most narrowed zone of the venturi 21.

The heated resistor causes pyrolysis of the scale particles transformed into dust. This dust is partly burnt in the collector and especially the cartridge 16 strongly heated by the tight turns 17 of the resistor 15 and partly swept by the air current, created between the venturi 21 and the air intake 5 of the collector 4, as well as by the exhaust gases thus accelerated.

Claims (10)

1. Combustion gas exhaust system  cylinders (1) of an internal combustion engine  comprising, at the outlet of the cylinders, pipes  (2) opening into a manifold (4), characterized  by the fact that the collector (4) comprises  internally means (15) for pyrolysis of the  scale of combustion gases. 2. Exhaust system according to claim 1, in  which the pyrolysis means comprise a  electrical resistance (15) supplied with current by  an alternator (3). 3. Exhaust system according to claim 2, in  which the resistor (15) is wound on a  support in perforated sheet (14). 4. Exhaust system according to claim 3, in  which the coils (17) of the resistance (15), near  of the outlet (13) of the manifold (4), are tightened  and surround a noise reduction cartridge  (16). 5. Exhaust system according to one of claims  3 and 4, in which a refractory sheath (18) is  disposed between the pyrolysis winding (15) and the  manifold wall to create an air gap  annular (19) between the sheath (18) and the wall of the  manifold (4). 6. Exhaust system according to one of claims  1 to 5, in which an air inlet is provided  fresh (5) in the collector (4). 7. Exhaust system according to claim 6, in  which is provided, at the outlet of the collector (4),  an evacuation pipe (20) with venturi (4) creating,  with the air inlet (5), an air stream. 8. Exhaust system according to one of claims  1 to 7, in which the manifold (4) opens into  a flame retardant stack (8). 9. Exhaust system according to claims 7 and  8, in which the discharge line (20) to  venturi is provided at the outlet of the barrier stack  flames (8). 10. Exhaust system according to one of claims  8 and 9, in which means are provided (9-12)  external cooling of gases and walls of  tubing (2), manifold (4) and stack  flame arrestor (8).