FR2995352A1 - Car, has exhaust manifold for discharging exhaust gas through exhaust duct having gas treatment system provided with catalyst, and catalyst isolation device placed between catalyst and upstream of fresh air intake manifold - Google Patents

Abstract

The car has an internal combustion engine i.e. petrol engine (10) having a cylinder (11), a fresh air intake manifold (12) for supplying fresh air to the cylinder, and an exhaust manifold (13) for discharging exhaust gas from the combustion through an exhaust duct (16) having a gas treatment system provided with a catalyst (17). A catalyst isolation device (19) is placed between the catalyst and upstream of the intake manifold. The gas treatment system includes a closed chamber (18a) surrounding the catalyst.

Description

The invention relates to the field of motor vehicles and in particular the field of depollution of internal combustion engines of the diesel type, or gasoline. More particularly, the invention relates to exhaust gas treatment systems, in particular catalytic converters or catalysts capable of treating nitrogen oxides (NOx), especially NO and NO2. Internal combustion engines produce exhaust gases that include polluting substances, such as nitrogen oxides, unburned hydrocarbons, carbon monoxide, soot particles. The accepted release rates of these different pollutants are strictly regulated and subject to periodic downward revisions. However, catalytic converters have the disadvantage of being effective only from a certain temperature. In order to reduce the heating time of the catalytic converters and to make them more efficient, it is known to create the vacuum between the catalytic converter and a casing surrounding the catalytic converter. The vacuum created in the envelope serves as thermal insulation of the catalytic converter which can then rise in temperature more quickly. The vacuum created around the catalytic converter also reduces the noise pollution due to the exhaust gas. Reference can be made in this regard to documents US 6 162 403 and US 6 203 764 which describe a catalytic converter comprising a vacuum chamber created during the manufacture of the catalytic converter, by the use of a vacuum welding technique.

Reference can also be made to DE 10 2008 051 278 which describes a catalytic converter comprising an envelope in which vacuum is created by the use of a vacuum pump disposed between the exhaust manifold and the catalytic converter.

However, the design of such catalytic converters is very expensive and does not recover any leaks from the catalytic converter. The present invention therefore aims to overcome these disadvantages. The object of the invention is therefore to provide a motor vehicle comprising a device for creating a vacuum in a chamber surrounding the catalytic converter while recovering any leaks of the catalytic converter.

The present invention relates to a motor vehicle comprising an internal combustion engine comprising at least one cylinder, a fresh air intake manifold capable of supplying fresh air to said cylinder, an exhaust manifold for evacuating the gases exhaust system from combustion by an exhaust duct having a gas treatment system comprising a catalyst. The motor vehicle comprises a catalyst isolation device disposed between the catalyst and the upstream of the intake manifold.

The thermal insulation of the catalyst makes it possible to raise the temperature very rapidly as well as to reduce the noise pollution due to the exhaust gas entering the catalyst. Advantageously, the gas treatment system comprises a closed chamber surrounding the catalyst.

The isolation device may comprise a pipe connected between the chamber and the upstream of the intake manifold. According to one embodiment, the isolation device is capable of creating a vacuum in said chamber by depression in the fresh air intake manifold, when the engine is in operation. Thus, in case of possible leakage of the catalyst, the leaks are sucked by the isolation device and are therefore not dispersed in the environment, but reinjected into the engine, which allows to heat the engine and avoid setting in place of a gas recirculation pipe in the gas exhaust pipe. The isolation device is further capable of cooling the catalyst when the engine is stopped by circulation of fresh air in the chamber of the gas treatment system. Indeed, when the engine is stopped, the catalyst is rapidly cooled by the ambient air passing through the vacuum line in the chamber surrounding the catalyst. The engine may be gasoline type having a butterfly housing disposed upstream of the intake manifold. According to one embodiment, the pipe is connected between the chamber and the downstream of the throttle body. The engine may be of diesel type comprising a turbocharger system comprising a turbine driven by the exhaust gas and a compressor mounted on the same axis as the turbine and providing compression of the incoming air. According to one embodiment, the pipe is connected between the chamber and the upstream of the compressor of the turbocharger system. Other objects, features and advantages of the invention will become apparent on reading the following description, given solely by way of nonlimiting example, and with reference to the appended drawings, in which: FIG. 1 schematically illustrates the structure of an internal combustion engine of a gasoline-type automobile engine provided with an isolation device according to the invention; and FIG. 2 schematically illustrates the structure of an internal combustion engine of a diesel type automotive engine provided with an isolation device according to the invention. FIG. 1 schematically illustrates an internal combustion engine 10, in particular of gasoline type operating at a constant air mixture. This gasoline engine 10 is intended to be mounted on the chassis of a motor vehicle (not shown). The gasoline engine 10 comprises a cylinder block, comprising for example four cylinders 11, located in the lower part of the engine connected by a cylinder head gasket to a built-in engine constituted in particular by a cylinder head generally covered with a cylinder head cover (no shown). Conventionally, the cylinder head houses the various distribution organs of the built-in engine, such as the fresh air intake and exhaust gas exhaust valves and the camshafts for the setting in motion of these valves (no shown). The high engine also comprises an intake manifold 12, an exhaust manifold 13 and an auxiliary member 14, such as for example a throttle body. The cylinders 11 of the engine 10 are supplied with air through the fresh air intake duct 12. The throttle body 14 generally consists of a body and a throttle valve where the fresh gases circulate and allows the regulation of the air admitted into the engine 10 as well as the regulation of the idling during a low rotation of the engine 10. The intake manifold 12 distributes the gases admitted into the engine 1 on all the cylinders 11. The throttle body 14 is mounted next to the cylinder head and is connected to the fresh air intake manifold 12 by an air inlet pipe 15. The exhaust manifold 13 recovers the exhaust gases from the combustion and evacuates these latter to the outside through a gas exhaust duct 16. The gas exhaust duct 16 comprises a gas treatment system comprising a catalyst or catalytic converter 17, such as, for example, a three-way catalyst, intended to treat o NOx nitrogen oxides, HC unburned hydrocarbons and CO carbon monoxide. The catalyst 17 comprises a casing 18 surrounding it so as to create a closed chamber 18a between the outer wall 17a of the catalyst 17 and the external environment. In order to increase the temperature rise of the catalyst 17, the motor 10 comprises a cooling device. insulation 19 of the catalyst 17.

The isolation device 19 comprises a pipe 19a connected to the air inlet pipe 15, upstream of the intake manifold 12, between the chamber 18a and the downstream of the butterfly housing 14. The vacuum is thus created in the chamber 18a surrounding the catalyst 17 by depression due to the Venturi effect created inside the fresh air intake duct 15 during operation of the engine 10. The Venturi effect is the phenomenon of formation of a depression in an area where the particles of the fluid are accelerated. When the engine 10 is operating, the air intake manifold 12 draws fresh air to the cylinders 11, as well as the air present in the vacuum pipe 19a and in the chamber 18a. By way of non-limiting example, the engine 10 may comprise a turbo compression system (not shown) between the throttle body 14 and the intake manifold 12, in order to increase the pressure of the gases admitted into the engine. The vacuum pipe 18a of the isolation device 18 would be connected between the chamber 18a of the catalyst 17 and the inlet of the turbo compressor system. FIG. 2 schematically illustrates an internal combustion engine 20, in particular of diesel type operating at a constant air volume. This diesel engine 20 is intended to be mounted on the chassis of a motor vehicle (not shown). The combustion engine 20 comprises, for example, four cylinders 21, a fresh air intake manifold 22, an exhaust manifold 23 and a turbo compression system 24.

The turbocharger 24 essentially comprises a turbine 24a driven by the exhaust gas and a compressor 24b mounted on a fresh air intake duct 25, on the same axis 24c as the turbine 24a and providing compression of the incoming air. , in order to increase the amount of air admitted into the cylinders 21 of the engine 20. The exhaust manifold 23 recovers the exhaust gases from the combustion and discharges the latter outwards, via a gas exhaust pipe 26. The gas exhaust duct 26 comprises a catalyst or catalytic converter 27, such as, for example, a two-way catalyst for converting unburned hydrocarbons HC and carbon monoxide. CO in carbon dioxide CO2 and water H20.

The catalyst 27 comprises a casing 28 surrounding it so as to create a closed chamber 28a between the outer wall 27a of the catalyst 27 and the external environment. In order to increase the temperature rise of the catalyst 27, the motor 20 comprises a cooling device. Isolation 29 of the catalyst 27. The isolation device 29 comprises a pipe 29a connected to the air inlet pipe 25, upstream of the intake manifold 22, between the chamber 28a and the inlet of the turbocompressor 24, that is to say, upstream of the compressor 24b.

The vacuum is thus created in the chamber 28a surrounding the catalyst 27 by depression created inside the fresh air intake duct 25 during the operation of the engine 20. When the engine 20 is operating, the compressor e intake manifold air 22 draws fresh air to the cylinders 21, as well as the air present in the vacuum line 29a and in the chamber 28a. To further reduce the amount of harmful particles at the outlet of the catalytic converter 27, the diesel engine 20 may be provided with a particulate filter (not shown) for retaining fine particles contained in the flue gas. The particulate filter can be separated from the catalytic converter, or juxtaposed with said catalytic converter, or even that the catalytic materials can be disposed within a single device playing the dual role of particulate filter and catalytic converter.

Thanks to the isolation device described, the vacuum in the chamber surrounding the catalyst is created by depression, in particular by the Venturi effect, inside the fresh air intake manifold during the operation of the engine. The thermal insulation of the catalyst thus makes it possible to raise the catalyst in temperature very rapidly and to reduce the noise pollution due to the exhaust gas entering the catalyst. Moreover, in case of possible leakage of the catalyst, the leaks are sucked by the isolation device, in particular by the vacuum line to the intake manifold and are therefore not released into the environment, but reinjected into the engine , which allows the engine to be warmed up and to prevent the installation of a gas recirculation line in the gas exhaust duct. Finally, when the engine is stopped, the catalyst is rapidly cooled by the ambient air passing through the vacuum pipe to the isolation chamber surrounding the catalyst.

Claims (9)

REVENDICATIONS1. Motor vehicle comprising an internal combustion engine (10, 20) having at least one cylinder (11, 21), a fresh air intake manifold (12, 22) capable of supplying fresh air to said cylinder (11, 21), an exhaust manifold (13, 23) for exhausting exhaust gases from combustion through an exhaust duct (16, 26) having an intake treatment system (12, 22). The motor vehicle according to claim 1, wherein the gas treatment system comprises a closed chamber (18a, 28a) surrounding the catalyst (17, 27). 3. Motor vehicle according to claim 2, wherein the isolation device (19, 29) comprises a pipe (19a, 29a) connected between the chamber (18a, 28a) and the upstream of the intake manifold (12, 22). 4. Motor vehicle according to claim 2 or 3, wherein the isolation device is capable of creating a vacuum in said chamber (18a, 28a) by depression in the intake manifold of fresh air (12, 22), when the motor (10, 20) is in operation. 5. Motor vehicle according to any one of claims 2 to 4, wherein the isolation device (19, 29) is capable of cooling the catalyst (17, 27) when the motor (10, 20) is at the stopping by circulation of the fresh air in the chamber (18a, 28a) of the gas treatment system. 6. Motor vehicle according to any one of the preceding claims, wherein the motor (10) is gasoline type having a throttle body (14) disposed upstream of the intake manifold (12). gases comprising a catalyst (17, 27), characterized in that it comprises an isolation device (19, 29) for the catalyst (17, 27) placed between the catalyst (17, 27) and the upstream of the collector 7. Motor vehicle according to claims 2 and 6, wherein the pipe (19a) is connected between the chamber (18a) and downstream of the throttle body (14). 8. Motor vehicle according to any one of the preceding claims, in the engine (20) is of the diesel type comprising a turbocharger system (24) comprising a turbine (24a) driven by the exhaust gas and a compressor (24b) mounted on the same axis (24c) as the turbine (24a) and providing compression of the incoming air. 9. A motor vehicle according to claims 2 and 8, wherein the pipe (29a) is connected between the chamber (28a) and the upstream of the compressor (24b) of the turbocharger system (24).