FR2781523A1 - DEVICE AND METHOD FOR EXHAUSTING EXHAUST GASES FROM A DIESEL INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

In this device for discharging the exhaust gas stream (2) from a diesel engine (1) comprising an exhaust pipe (3), a blocking member (8) is arranged in the exhaust pipe (3 ) and a separation channel (5) extends from the blocking member (8) and there is provided a cyclone separator (4) comprising an accumulator (11) receiving solid particles mixed with the flow of exhaust (2) by means of a particle pipe (7); the blocking member (8) and a blocking member (9) in the pipeline (7) can be switched by a control unit (10), connected to a device (18) recording the operating state of the engine. Application in particular to diesel engines of motor vehicles.

Description

The invention relates to a device and a method for the evacuation of

  exhaust gases from a diesel internal combustion engine, in which particles, which appear during combustion in the internal combustion engine, are removed from the exhaust gases and

  eventually ejected into the environment.

  Exhaust gases from diesel internal combustion engines contain particles of solid bodies, in particular soot particles, as combustion residues from burnt diesel fuel. If the diesel internal combustion engine operates at a lower range of loads and rotational speeds, soot particles are deposited in the exhaust system on all surfaces which are in contact with the exhaust gas stream. exhaust. In the case of a sudden acceleration of the internal combustion engine and the sudden increase, which this causes, of the gas flow, the soot particles are simultaneously entrained and blacken the exhaust gases ejected into

the environment.

  To avoid the visible black smoke cloud produced by the internal combustion diesel engine, DE 195 42 587 Al proposes to standardize the emissions of particles which

  appear with varying intensities over time.

  It describes a filter device which is crossed by exhaust gases, the particles contained in the exhaust gas stream being collected in a filter element, in accordance with their instantaneous appearance from the exhaust gas stream. who

  enters the filter device.

  The soot particles must again be removed from the filter element along with the exhaust gas stream leaving the filter device. The soot particles collected, however, interfere with the passage of the filter and, to avoid clogging of the filter element, in the known device is provided a filter element which moves circumferentially. Under the effect of the circumferential displacement of the filter element, new parts, lightly charged with particles, of the filter element are permanently available to be charged by the exhaust gases which are not yet filtered. In the case of significant emission of soot particles, this arrangement makes it possible to delay the clogging of the filter element, but does not prevent it. Combustion of the collected soot particles is most of the time not possible since the temperatures in the filter element and in the sections behind the filter element of the exhaust pipe are

  below the ignition temperatures of the soot.

  The German document DE 43 19 283 Cl disclosed a method and a device for reducing the soot particles in the exhaust gases of diesel engines, the stream of exhaust gases passing through a particle separator arranged in the form of a cyclone and being subdivided into a partial stream free of particles and a partial stream enriched in particles. Particle-free exhaust gases are exhausted to the open air. The exhaust gases enriched in particles are subjected to an electromagnetic field, in which case there is a coupling of the particles in free flight with microwave energy of an order of magnitude such that the particles are heated to the temperature of combustion and burn. Before entering the cyclone, the relatively small particles, which fly freely in the exhaust gas, agglomerate in a high-voltage field of an electrostatic precipitator, reaching a size such that they can be separated in the cyclone. Admittedly, the known device makes it possible to reduce the particles in the exhaust gases and avoids the formation of a cloud of black smoke visible at the level of the outlet of the exhaust pipe in the case of sudden increases in the flow of gas, but this requires a high construction expense and a

  additional energy use for the agglomeration.

  The object of the invention is to reduce, by simple means, the emission of particles from a diesel internal combustion engine and to avoid in a sustainable manner the formation of a cloud of black smoke visible during of

  exhaust gas evacuation.

  This problem is solved in accordance with the invention using a device for discharging an exhaust gas stream from a diesel internal combustion engine comprising an exhaust pipe, in which a blocking member is arranged, and a separation channel which extends in diversion upstream of the blocking member in the direction of flow flow and in which a cyclone separator is arranged, which comprises an accumulator serving to receive particles of solid bodies deposited, which can be mixed with the exhaust gas stream by means of a particulate pipe which can be blocked and opens into the exhaust pipe, the blocking member located in the exhaust pipe and a blocking member located in the particulate pipeline which can be switched, by means of transmission lines for switching signals, by a control unit, the input side of which is connected to a device for save

  the operating condition of the internal combustion engine.

  This problem is also solved in accordance with the invention by means of a method for discharging the exhaust gases from a diesel internal combustion engine, according to which a stream of the exhaust gases is guided in a pipe. exhaust and is ejected into the surrounding air at an end tube and a control unit detects operating states of the internal combustion engine and, in the case of the presence of determined operating states with an emission high of solid particles, triggers the closure of a blocking member located in the exhaust pipe so that the flow of exhaust gases is therefore directed, by means of a separation duct, in a separator cyclone, in which the exhaust gases are centrifuged and the separated particles are collected in an accumulator whereas, in the case of the presence of operating states of the internal combustion engine with a low emission of particles, the particles are sent from the accumulator to the exhaust pipe and are mixed with the stream of exhaust gases, the control unit releasing, under the effect of the opening of an organ blocking system, a particle pipe that connects

  the particle accumulator in the exhaust pipe.

  In the exhaust pipe of this internal combustion engine is arranged a blocking member, which, for certain operating states of the internal combustion engine, is brought by a control unit to the closed position. The exhaust gases containing particles are directed, by a separation channel which extends in bypass upstream of the blocking member in the direction of circulation, in a cyclone separator, which comprises an accumulator serving to receive the particles of solid bodies deposited. If, on the basis of the measurement data produced from the operating state of the internal combustion engine, the control unit identifies the presence of an acceleration which introduces an increase in the gas flow, the blocking member located in the exhaust pipe is closed and the exhaust pipe with its increased amount of particles is centrifuged in the

  cyclone separator before its ejection into the environment.

  The soot particles deposited in the cyclone are collected in the accumulator and, in operating states with low particle emission, are again mixed with the exhaust gas stream by means of a particle pipe. The particulate pipe opens behind the blocking member, into the exhaust pipe and also comprises a blocking member which is connected, like the blocking member located in the exhaust pipe, to the control via a signal transmission line. Depending on the diagnosis of the operating state of the internal combustion engine, in the case of operating states with low particle emission, the control unit releases the particulate line, which has the effect that the particles are sent from the accumulator, in the form of a stream of particles, to the exhaust gases. The formation of a visible black smoke cloud when ejecting exhaust gases due to very high concentrations of particles in

  exhaust gas is therefore excluded.

  The invention starts from the fact that, in the range of low loads and rotational speeds, the natural load of the particles and the mechanical forces which are caused thereby, lead to an agglomeration with a grain size which has the effect that in the case of gas flows which are higher or suddenly increase, the particles detach and are separated in the cyclone. Precisely in the case of operating states which pose problems with regard to the emission of particles, during acceleration from this operating range, a separation of the particles in the cyclone can be achieved without other auxiliary means for achieve agglomeration. Advantageously, the bypass of the separation channel in the direction of the cyclone is disposed behind a rear silencer disposed in the exhaust pipe and the particle accumulation action of which is sufficient, for operating states of the internal combustion engine with low particle formation, to obtain good quality exhaust gases. In a development of the invention, the blocking member located in the particle pipe is an adjustable mixing valve in relation to the passage cross section. The control unit determines, by adjusting the cross section of the particulate pipe, the quantitative flow rate of the particles to be mixed with the exhaust gases, depending on the state of

  operation of the internal combustion engine.

  Advantageously, the control unit is part of a control unit of the internal combustion engine. The function of the control unit can also be carried out in the motor control unit, which, for its essential task proper, namely controlling the operating behavior of the combustion engine

  internal, determines the operating state of this engine.

  On the basis of the already effective knowledge of the operating state of the internal combustion engine, the engine control unit also assumes, in a corresponding configuration, the control of the exhaust gas

exhaust according to the invention.

  According to another characteristic of the invention, the blocking member is located in the exhaust pipe between the bypass of the separation channel and the mouth

of the particulate pipe.

  According to another characteristic of the invention, the bypass of the separation channel is located, in the direction of flow of the exhaust pipe, behind a

rear silencer.

  According to another characteristic of the invention, the blocking member is arranged in the form of a valve with

  exhaust gas in the exhaust pipe.

  According to another characteristic of the invention, the control unit is part of a control unit of the

internal combustion engine.

  According to another characteristic of the invention, the cyclone separator and the rear silencer are housed in

a common housing.

  According to another characteristic of the invention, a stream of particles deposited in the cyclone separator is mixed with the stream of exhaust gas, behind

  the exhaust pipe blocking member.

  According to another characteristic of the invention, the flow of exhaust gases is directed so as to pass through the cyclone separator during the acceleration process of the internal combustion engine and in particular from the lower ranges of loads and speeds

of rotation.

  According to another characteristic of the invention, the exhaust pipe is blocked for a short period of time for approximately 5 to 30 seconds for the centrifugation of the particle content of the exhaust gases. According to another characteristic of the invention, the control unit determines the quantitative current of the particles to be mixed with the exhaust gases by adjusting the cross section of the passage of the particulate pipe according to the state of

  operation of the internal combustion engine.

  Other features and advantages of the

  present invention will emerge from the description given

  below taken with reference to the attached drawing.

  The single figure of the drawing represents a diesel internal combustion engine 1, the exhaust gases of which are evacuated by an exhaust pipe 3, at the end section of which is disposed a rear silencer 6. The exhaust gases reach in the open air through an end tube 14 of the exhaust pipe 3, which connects to the rear silencer 6. The stream of exhaust gas 2, which leaves the internal combustion engine, contains particles of soot as a residue from the combustion of diesel fuel. A determined quantity of particles can be collected in the rear silencer 6. However, the quantity of particles contained in the exhaust gases 2 is variable during a fairly long operating period and depends on the operating state of the internal combustion engine. particularly significant emissions of particles in the exhaust gases could be visible, at the outlet of the end tube 14 of the exhaust pipe 3, in the form of a cloud of black smoke, but this is avoided thanks to

to the arrangements according to the invention.

  The critical operating states for the formation of black smoke are processes of acceleration of the internal combustion engine with relatively slow phases at low load and at low speed of rotation, in which case the particles of soot, which have settled due to the increased flow, are driven simultaneously at the walls of the exhaust pipe 3 and the rear silencer 6. In the end tube 14 is disposed a blocking valve 8 which is closed in the case of the presence of critical operating states related to black smoke, so that the flow of particulate-containing exhaust gases is directed by means of a separation channel 5 towards a cyclone separator 4. The gases d are centrifuged in the cyclone separator 4 and the particles

  soot deposits are collected in an accumulator 11.

  An exhaust gas stream 17, from which the particles have been removed, leaves the cyclone separator 4. The purified exhaust gas stream 17 can be discharged directly into the environment. One could also imagine returning the purified stream of exhaust gases 17 into the end tube 14 of the exhaust pipe 3. A connecting pipe extending from the cyclone separator 4 to the end tube 14 could lead downstream of the gas release valve

  exhaust 8, disposed in the end tube 14.

  The deposited soot particles can be mixed again with the exhaust gas stream by means of a particle pipe 7, which connects the particle accumulator 11 of the cyclone separator 4 to the end tube 14 and opens into the tube end 14 behind the exhaust gas release valve 8 in the direction of flow. The particle pipe 7 is released, during the operating states of the internal combustion engine 1, in the case of a low emission of particles by opening a mixing valve 9. A stream of particles 13 then arrives from the accumulator 11 in the end tube 13 and is mixed there with the exhaust gases downstream of the gas release valve

exhaust 8, which is open.

  A control unit 10 performs, by means of a line of transmission of switching signals, the switching of the exhaust gas release valve 8 located in the end tube 14 and, via a transmission line for switching signals 16 from the mixing valve 9 located in the particle pipe 7. The input side of the control unit 10 is connected to a device 18 used to detect

  the operating state of the internal combustion engine 1.

  In the exemplary embodiment shown, the operating state data 12 of the internal combustion engine 1, which are measured by the detection device 18, are sent to the control unit 10. The control unit suitably control 10 is part of an internal combustion engine control unit 1, uses the operating state data 12 not only for the control chain of the exhaust gas extraction system according to the invention, but also for the control chain of the operating behavior of the internal combustion engine. If the control unit identifies, on the basis of the entered operating state data 12, a critical operating state relating to the emission of particles and in particular the formation of black smoke, the gas release valve exhaust 8 is brought into the closed position, and the stream of exhaust gases containing particles is guided by the separation channel 5 towards the cyclone 4. In the case of the presence of such a critical operating state of the engine internal combustion with increased gas flow, the exhaust gas pipeline is closed for a short period of time, for about 5 to 30 s, to carry out the centrifugation of the particles, which allows

  avoid the formation of black smoke.

  The cross section of passage in the mixing valve 9 located in the particle pipe 7 is adjustable. The control unit determines, as a function of the operating state of the internal combustion engine 1, the quantitative flow rate 13 of the particles to be mixed with the exhaust gas, by adjusting the cross section of passage of the particulate pipe. , i.e. by modifying the opening stroke of

the adjustment valve 9.

  The cyclone separator 4 and the rear silencer 6 can be housed in a common housing, which makes it possible to obtain a compact arrangement of the device for the evacuation of exhaust gases from the combustion engine.

internal diesel 1.

11 t

Claims (12)

  1. Device for discharging an exhaust gas stream (2) from a diesel internal combustion engine (1) comprising an exhaust pipe (3) in which a blocking member (8) is arranged, and a channel separation (5) which extends in bypass upstream of the blocking member (8) in the direction of flow flow and in which is disposed a cyclone separator (4), which comprises an accumulator (11) serving to receive particles of solid bodies deposited, which can be mixed with the stream of exhaust gases (2) by means of a particle pipe (7) which can be blocked and opens into the exhaust pipe (3), the locking member (8) located in the exhaust pipe (3) and a locking member (9) located in the particulate line (7) which can be switched, by means of transmission lines (15, 16) of switching signals, by a control unit (10), the input side of which is connected to a device (18) used to record the state of   operation of the internal combustion engine.   2. Device according to claim 1, characterized in that the locking member (8) is located in the exhaust pipe (3) between the bypass of the separation channel (5) and the mouth of the pipe to particles (7).   3. Device according to one or other of the   claims 1 and 2, characterized in that the derivation   of the separation channel (5) is located, in the direction of flow of the exhaust pipe (3), behind a rear silencer (6).   4. Device according to claim 3, characterized in that the cyclone separator (4) and the silencer   rear (6) are housed in a common housing.   5. Device according to any one of   claims 1 to 4, characterized in that the   blocking located in the particulate pipe (7) is a mixing valve (9) adjustable in relation to the section transverse passage.   6. Device according to any one of   Claims 1 to 5, characterized in that the   blocking is arranged in the form of a gas valve   in the exhaust pipe (3).   7. Device according to any one of   claims 1 to 6, characterized in that the unit of   control (10) is part of an engine control unit internal combustion (1).   8. Method for discharging exhaust gases from a diesel internal combustion engine (1), according to which a stream of exhaust gases (2) is guided in an exhaust pipe (3) and is ejected into the surrounding air at an end tube (14) and a control unit (10) detects operating states of the internal combustion engine (1) and, in the case of the presence of determined operating states with a high emission of solid particles, triggers the closure of a blocking member (8) located in the exhaust pipe (3) so that therefore the flow of exhaust gases (2) is directed, by means of a separation conduit (5), in a cyclone separator (4), in which the exhaust gases are centrifuged and the separated particles are collected in an accumulator (11) whereas, in the case of the presence operating states of the internal combustion engine (1) with low emiss ion particles, the particles are sent from the accumulator (11) to the exhaust pipe (3) and are mixed with the flow of exhaust gases, the control unit (10) releasing, under the effect of l opening of a blocking member (9), a particle pipe (7) which connects the particle accumulator (11) to the pipe exhaust (3).   9. Method according to claim 8, characterized in that a stream (13) of the particles deposited in the cyclone separator (4) is mixed with the stream of exhaust gases, behind the blocking member (8) of the exhaust pipe (3).   10. Method according to either of the   claims 8 and 9, characterized in that the current of   exhaust gas (12) is directed so as to pass through the cyclone separator (4) during the acceleration process of the internal combustion engine (1) and in particular from the   lower ranges of loads and rotational speeds.   11. Method according to any one of   Claims 8 to 10, characterized in that the hose   exhaust (3) is blocked for a short time for approximately 5 to 30 seconds for centrifugation of the particulate content of the gases exhaust.   12. Method according to any one of   claims 8 to 11, characterized in that the unit of   control (10) determines the quantitative current of the particles to be mixed with the exhaust gases by adjusting the cross section of the passage of the particulate pipe (16) according to the state of   operation of the internal combustion engine (1).