FR2875267A1 - Internal combustion engine for vehicle includes auxiliary turbine downstream of exhaust treatment unit, to supply generator and gas compressor via clutch - Google Patents

Abstract

An auxiliary turbine (4) is located downstream of an exhaust treatment unit (3) and is able to drive energy conversion equipment (6, 8) through a clutch (5). The treatment unit is a particulates filter. Energy is supplied as a function of exhaust gas parameters. The conversion equipment comprises an auxiliary compressor feeding a pressurized gas reservoir (9) for temporary storage. This supplies the engine under certain operational conditions, via a control valve (1). The conversion equipment comprises an electrical generator feeding the vehicle battery. The engine unit also includes a turbocompressor (2). The engine is a diesel engine.

Description

Internal combustion engine having a post-processing unit

exhaust 5

  The invention relates to an internal combustion engine comprising an exhaust aftertreatment unit. The present invention relates more particularly to a device for the aftertreatment of gaseous emissions at the exhaust of a diesel engine with direct injection by turbocharger.

  At the beginning of the transients, supercharged diesel engines are penalized by a lack of torque due to the response time of their supercharging system. Indeed, the fresh air is not immediately available because of the thermal and mechanical inertia of the turbocharger. As a result, it is not possible to inject large quantities of fuel since the operating richness limits are reached in the combustion chamber. This point of operation of the internal combustion engine is detrimental from the point of view of efficiency and produces emissions of smoke polluting the environment.

  Current supercharging technologies do not significantly reduce the response time, since we must overcome the thermal and mechanical inertia. It is possible to improve the response time by reducing these inertia but it is not possible to achieve the response times of an atmospheric engine for which the torque is available almost immediately. It is therefore necessary to have an available source of energy to overcome these disadvantages relating to the supercharged diesel engine.

  Internal combustion engines produce large exhaust emissions in the exhaust gases of the engine as a result of the combustion of the fuel. Emissions produced, such as particulate matter, carbon monoxide (CO) or nitrogen oxides (NOx), are toxic to the environment and are subject to strict regulation. To reduce the amounts of pollutants emitted by an engine, a particulate filter placed in the exhaust line can store the polluting particles and burn at the end of each filter regeneration period. The operation of removing the particles is done during an exothermic reaction whose thermal energy is not exploited. In other words, the gases leaving the post-treatment system are particularly hot and give off available energy.

  US-4253031 and JP-7071241 disclose turbocharging supercharger systems coupled to a conventional electrical power conversion means, such as a dynamo, for powering the vehicle electrical circuit. One of the drawbacks of such systems is that they fail to fill the lack of torque of the internal combustion engine during transients.

  The object of the present invention is to provide an improved aftertreatment device gaseous emissions of an internal combustion engine by using the energy released by the gases from the exhaust aftertreatment unit.

  The present invention provides an internal combustion engine mounted in a vehicle of the type comprising an exhaust line intended to evacuate the gases coming from combustion in the engine, an exhaust aftertreatment unit located on said line of combustion. exhaust system, characterized in that it comprises an auxiliary turbine located downstream of the post-treatment unit and capable of driving receiving members which convert energy.

  One of the advantages of the present invention is that the thermal energy released by the exhaust gas at the particulate filter outlet is converted to compensate for the lack of torque of the internal combustion engine. The present invention furthermore makes it possible to supply additional electrical energy to the vehicle network for the vehicle functions and to discharge the alternator. According to the invention, the device for the aftertreatment of gaseous emissions from an internal combustion engine has other characteristics: - a controlled coupling member is located between the auxiliary turbine and the receiving members, - the post-exhaust gas treatment unit is a controlled particle filter delivering thermal energy as a function of parameters specific to the exhaust gases, - one of the receiving members is an auxiliary compressor driven by the auxiliary turbine, - the auxiliary compressor supplies a reserve of pressurized gas intended to temporarily store the pressurized gas which is intended to supply the engine with internal combustion in certain phase of operation, - a pilot valve located downstream of the gas supply the motor in certain operating phases, - one of the receiving members is a current generating means driven by the auxiliary turbine, - the current generating means feeds the vehicle electrical network, - the internal combustion engine is supercharged by a turbocharger system, and - the internal combustion engine is a diesel engine.

  Other advantages of the present invention will appear on reading an embodiment taken by way of non-limiting example and illustrated by the accompanying drawing in which Figure 1 shows an internal combustion engine according to the invention.

  FIG. 1 represents an internal combustion engine supercharged by a turbocharger 2. The exhaust gases from the engine are discharged into an exhaust line comprising a post-treatment unit 3 of these gases. This post-treatment unit 3 is intended to reduce the pollutant emissions released into the exhaust gases. The post-processing unit 3 is a filter which collects particles. During certain operating phases of the post-treatment unit 3, often called the regeneration phase, the particles are destroyed during an exothermic catalytic reaction. The thermal energy released by this reaction is used to facilitate the driving of an auxiliary turbine 4 located downstream of the post-treatment unit. The turbine 4 is of the same type as the turbine of the turbocharger 2. The turbine 4 converts the energy from the gases leaving the post-treatment system 3 into mechanical energy. Classically, the energy delivered by this type of turbine is Erm.unr = iE XQ ,,,, x Cpee, x Trtmm, ix with t = isentropic efficiency of the turbine, Qech = gas flow, Cpecn = specific heat of the gases , Tamont = temperature at the inlet of the turbine, and P, En '= relaxation ratio.

  Panons When the upstream increases, the energy delivered by the turbine increases in proportion. The increase in the temperature related to post-treatment makes it possible to exploit the expansion ratio of the gases in the turbine. This expansion ratio is governed to the order of 1 depending on the design of the turbine, The introduction of the turbine 4 in the exhaust line leads to an increased pressure drop in this line, leading to a back pressure increased output of the engine gases.

  During the regeneration phases of the post-treatment unit 3, the turbine 4 is connected to receiving members 6 and 8 that can convert the mechanical energy from the turbine 4. This transmission of energy is via a controlled coupling member 5 which will selectively drive one of the receiving members 6 or 8.

  During the regeneration phases of the post-treatment unit 3, the auxiliary turbine 4 is coupled to the receiving member 8, an auxiliary compressor, which generates pressurized air. This pressurized air is stored in an air reserve 9 which is used temporarily during the transient phases of the internal combustion engine, to supercharge the engine with fresh air. Indeed, diesel engines supercharged conventionally by a turbocharger 2, suffer from a lack of torque at the beginning of transients. Fresh air is not immediately available due to the thermal and mechanical inertia of the turbocharger. The fact of injecting fresh air from the capacity 9 makes it possible to fill this deficiency during the transient operating modes of the engine. Thus, fuel can be injected in large quantities without reaching high operating wealth. The gas supply of the engine from the air supply 9 is via the opening of a pilot valve 1. For an air reserve 9 with a volume of 10 liters and a compressed air temperature of the order of 50 C, a pressure of 8.5 bar is sufficient to ensure the air flow at full load at 1500 rpm for 2 seconds on a 4-cylinder engine of 2 liters of displacement. These characteristics make it possible to ensure the availability of torque during the transient phases of the engine.

  When the maximum pressure level is reached in the capacity 9 and energy is still available from the auxiliary turbine 4, the drive of the turbine is diverted to the second receiver member 6, a dynamo, intended to convert the mechanical energy provided by the turbine in electrical energy. This dynamo 6 is connected to the vehicle's electrical circuit and provides additional energy to the operation of the system. Advantageously, this dynamo 6 can be used to recharge the battery and thus off the engine alternator.

  On the other hand, the receiving members 6 and 8 can be put in series via a common shaft so as to simplify the architecture of the system. In this embodiment of the invention, the compressor 8 is at the end of the chain and is decoupled when the maximum air pressure level is reached in the air reserve 9, When the compressor 8 is mechanically coupled to the turbine 4, the dynamo 6 is decoupled electrically, for example by a relay.

Claims (1)

7 2875267 Claims   1. An internal combustion engine on board a vehicle of the type comprising: an exhaust line intended to evacuate the gases resulting from the combustion in the engine; a post-treatment unit (3) for the exhaust gas located on the said engine; exhaust line, characterized in that it comprises an auxiliary turbine (4) located downstream of the post-treatment unit (3) and capable of driving receiving members (6, 8) which convert energy .   2. Internal combustion engine according to claim 1, characterized in that a controlled coupling member (5) is located between the auxiliary turbine (4) and the receiving members (6, 8).   3. Internal combustion engine according to one of claims 1 or 2, characterized in that the post-treatment unit (3) of the exhaust gas is a controlled particulate filter delivering thermal energy according to parameters exhaust gases.   4. Internal combustion engine according to one of the preceding claims, characterized in that one of the receiving members (6, 8) is an auxiliary compressor driven by the auxiliary turbine (4).   5. Internal combustion engine according to claim 4, characterized in that the auxiliary compressor (8) supplies a pressurized gas reservoir (9) for temporarily storing the gas under pressure which is intended to supply the combustion engine. internally in certain phases of operation.   6. Internal combustion engine according to claim 5, characterized in that a pilot valve (1) located downstream of the gas supply (9) supplies the engine in certain operating phases.   7. Internal combustion engine according to one of the preceding claims, characterized in that one of the receiving members (6, 8) is a current generating means driven by the auxiliary turbine (4).   8. Internal combustion engine according to one of the preceding claims, characterized in that the current generating means (6) feeds the vehicle electrical network.   9. Internal combustion engine according to one of the preceding claims, characterized in that the internal combustion engine is supercharged by a turbocharger system (2).   10. Internal combustion engine according to one of the preceding claims, characterized in that the internal combustion engine is a diesel engine.