DE4222162C2 - Process for rapidly achieving the ignition temperature of the pollutants in the exhaust gases of an internal combustion engine and device therefor - Google Patents

Description

The invention relates to a method for quickly achieving ignition temperature of the pollutants in the exhaust gases of an internal combustion engine Use of a reactor for exhaust gas purification, the passage cross section can be changed according to the preamble of claim 1 and a Device for this according to the preamble of claim 6.

Currently, in the field of exhaust gas purification from internal combustion machine catalysts and especially for diesel engine additives and Catalytically effective filter parts are used. When cleaning exhaust gases from Gasoline engines have established catalysts that make you happy achieve proper degree of purification for gaseous pollutants, with the regulated catalyst the best results are currently achieved. For all these systems is a fixed predetermined volume of the catalytic system different speeds and therefore exhaust gas volume available, which means under other in the "cold exhaust gas phases" with low exhaust gas volume these gases lose a large part of the available energy and the temperature There is no reduction in pollutants.

The problem of regeneration of soot filters on diesel is more difficult Engines. The low exhaust gas temperatures in the lower load and Speed ranges mean that the soot in a filter is not all Operating areas of the engine burns. Even a catalytic effect in the filter elements are not sufficient, the soot particles in all speed and Eliminate load ranges. This is u. a. due to the fact that this Systems deposit the soot in the large filter, as it is always a relatively free one Gas should pass through. The system volume of such filters is for this Case enormously enlarged, causing the soot particles on the filter walls deposit and settle through a constantly increasing exhaust gas back pressure Loss of performance and increased fuel consumption. These systems after reaching the storage capacity of an external or system subjected to internal thermal treatment by burning devices which, however, have to heat up the entire filter volume and thus lead to high energy consumption.  

Accelerating the regeneration of such filters by means such. B. Additives have the disadvantage that the soot particles are reduced in size, are more respirable and thereby increase their toxicity.

The oxidation catalyst, the main task of which is the Reducing gaseous pollutants represents the reduction of Soot particles are not a consistent solution. The conflict of interests, soot filter in their volume currently have to be interpreted so that the expansion of the Exhaust gases in the reactor the exhaust gas energy in the high speed and Load ranges of the machine are insufficient to burn the soot particles, is responsible for an unnecessarily large filter and system volume must be co-heated by means of the energy of the exhaust gases, so that their Loss of ability to ignite the soot particles.

Storing soot over long periods of operation leads to even larger ones System volumes (exhaust valve up to and including filter), whereby the exhaust gases lose additional energy. All the filter systems used transfer over a fixed predetermined volume for the entire operating range of the engine Available, the one with regard to the relatively free gas passage Full load (large exhaust gas masses and high temperature) and on the other hand the expected landfill of soot is designed. This can the inherent energy of the exhaust gases, especially in the lower load and rotation number ranges are not used to burn the soot particles. The clogging of the filter with soot is also permanent increasing exhaust gas back pressure in the engine for a possible, sudden uncontrolled burning of the soot mass in the filter responsible, in extreme cases, which can destroy the motor and filter system.

The Japanese patent application JP 55-10018 A2 is a burn tion engine became known in which the inlet cross section of the Reactor body depending on the negative pressure within the intake pipe can be changed in two positions by means of a mechanical spring. This should make two adjustments to the amount of exhaust gas be possible for highest and lowest speeds. With this device can the necessary exhaust gas volume, depending on the temperature of the Exhaust gas and the reactor, do not regulate.  

Japanese patent application JP 57-183511 A2 are a method and a device for achieving the ignition temperature of the pollutants in the Exhaust gas from an internal combustion engine with a catalytically active reactor become known for exhaust gas purification, by means of the negative Air pressure from the air intake tract depending on that in the reactor measured temperature the cross section of the gas entry surface in the exhaust gas reactor is regulated; two cover wings cover the gas inlet area of the reactor in the cold start phase of the internal combustion engine. With this The method and the device is a preservation of the pollutant igniter temperatures not possible in all operating states of an internal combustion engine Lich. The inertia of the measuring and control systems results in every posi tive load changes have a negative impact on the internal combustion engine in that an extreme pressure increase occurs in the reactor and this does not can be removed in a controlled manner. The disadvantage of this method is that no influence can be exerted on the exhaust gas back pressure.

From DE 36 29 945 A1 it has become known two catalysts of different diameters to build into each other concentrically and area of the exhaust gas duct behind the catalytic converter in two ways split, one of which is attached to the inner cylindrical catalyst body and the other to the annular catalyst surrounding it body is connected. By opening or closing the downstream Exhaust gas paths can be changed through the cross-section flowed through, so that the Catalytic converter the necessary temp. Even when starting or at partial load to reach or maintain temperatures quickly. The high is a disadvantage Manufacturing costs for the two-part body of the catalyst and the Arrangement of a second exhaust pipe, which inevitably in the annulus of the larger exhaust pipe must run, which is why the catalyst is unequal is flowed through.

DE 37 38 538 A1 is a catalyst device for exhaust gas purification supply became known in which the inlet cross section of the catalyst in Dependency on the operating state by a pre the catalyst body switched, axially movable tube can be changed. The clear cross Section of the pipe section is adapted to the exhaust pipe; when pushing the Pipe section towards the catalyst become the peripheral areas of the catalyst faded out and the exhaust gases only on the through the clear width of the pipe piece of free passage cross section of the reactor abandoned. The pipe piece  can only take two positions, namely either completely back drawn or advanced. In the intermediate positions they expand Exhaust gases into the reactor front housing, causing them to cool, and it there is turbulence due to the partially advanced pipe section, which is associated with a further loss of energy. An improvement in Reactor properties in the cold start phase is therefore in a filter system, as it is used for diesel engines, not possible because the exhaust gases expand directly in front of the reactor after leaving the pipe section would, which would result in an immediate lowering of the exhaust gas temperature.

DE 34 02 692 A1 describes a method for regenerating a Catalytic particle filter for internal combustion engines Combustion and one or more cylinders have become known, wherein the combustion air for during operation of the internal combustion engine one or more of the cylinders is made to pulsate with the Exhaust this or this cylinder for the catalyst exothermic one Generate temperature at which the merged in the filter Combustion particles can be ignited within the filter. This is supposed to a special heating of the one leaving the combustion source Exhaust gas flow to be superfluous. By releasing heat during the Oxidation will filter the point of ignition in the filter retained particles heated, which ignites these particles and be burned. For this u. a. the pressure and temperature at Reactor measured and as control variables of a control unit fed depending on these and other parameters flap valves in the entrance of the air supply to the cylinders of the internal combustion engine opens or closes more or less.

The invention has for its object in a method of the above The difference in the temperatures of the exhaust gas and the ignition temperature of the genus To reduce pollutants of an internal combustion engine for all operating states, that the additional energy expenditure for pollutant reduction decreases and the inherent Energy of the exhaust gases for the phase of pollutant reduction as far as possible should be preserved.

According to the invention, this object is achieved in the features of Claim 1. A device for performing the method is in  Claim 5 marked. Further configurations according to the invention are characterized in the other subclaims.

The inventive method has the essential advantage that the Temperature difference between the exhaust gas temperature and the reaction temperature temperature of the pollutants contained in an engine is significantly reduced, which ensures that the internal energy of the exhaust gases for the phase of Pollutant reduction is maintained. This is done by one of each resulting exhaust gas mass at the respective temperature adapted reactor volume achieved, whereby the thermal expansion of the exhaust gases within the Reactor or filter is avoided so far that the "hot" exhaust gases are not cool down more seriously. This can be done without additional energy over almost all operating conditions of the engine the ignition temperature of the harmful substances in reactors for exhaust gas purification can be achieved.

With diesel engines, the energy expenditure for exhaust gas cleaning and significantly reduce soot ignition by the process. At Otto Engines, the efficiency of exhaust gas cleaning increases significantly in the area in which the degree of conversion of the pollutants is currently insufficient is.

Because there is no constant exhaust gas over the entire speed range of an engine mass to the reactor, it is not necessary according to the invention Exhaust gas energy in all operating areas of the machine additionally to use to heat the entire reactor volume, which is more advantageous Way by detecting the temperature of the exhaust gases in the area of the reactor is achieved through an individually regulated area control system that is based on the Gas inlet side of the reactor is attached within the exhaust gas supply line.

This area control system fits the current cross section of the gas inlet area of the reactor the resulting exhaust gas masses depending on the Temperature. This means that only the volume of the reaction body flowed through by the exhaust gases and thus heated, which is necessary to the reaction at a given, necessary temperature by the existing one To achieve or maintain exhaust gas energy as far as possible without a unnecessary thermal expansion of the exhaust gases and thus cooling them entry.  

It is thus achieved by the area control system that over the entire Operating range of the engine only the reactor volume available to the exhaust gas is provided, the actually occurring exhaust gas volume given exhaust gas temperature must allow free passage. The Regulation of the free gas inlet area in front of the reactor causes the Exhaust gases do not exceed the total volume of the respective filter or reactor expand and thus lose energy. With "cold" exhaust gases flow through a smaller reactor volume than "hot" Exhaust is the case.

External heating of the reactor can also be carried out in the cold start phase take place and to ensure a smooth engine running and the ensure that the pollutant ignition temperature is reached quickly. This heater can individually controlled then be switched on in the reactor when the Ignition temperature of the pollutants is not reached. In addition, this Heating only heat up the reactor or filter area that actually is released by the area control system. This can cause the inherent Exhaust gas energy are energetically supported, which causes the reactor heats up quickly and the heating energy to be used, e.g. B. with electrical Additional heating, drops drastically.

In addition, a bypass can be provided in a known manner, which before the filter in the event of unwanted exhaust back pressure ensures that this is derived. The derived exhaust gases are the air intake tract or Exhaust system supplied. This exhaust gas recirculation in the air intake tract causes a reduction in the NOx values, which causes the carbonaceous Pollutants in the exhaust gases rise, but due to the sufficient Pollutant ignition precautions and dwell times of the pollutants compel them burn frequently in the reactor and be used exothermically in the reactor.

The reduction of pollutants in the operating states in which the Temperature is insufficient to ignite the pollutants, can be caused by a system-internal heating, which depends on the temperature and / or Pressure to be regulated must be maintained. The special advantage compared to conventional heating processes can be seen in the fact that only the active sub-area (which actually necessary volume) of the catalytic system is heated and thus that for Exhaust gas heating of the system reduces the necessary energy expenditure in that  not the entire volume, but only the active volume heated must be, the energy of the heating to the total active Exhaust gas mass can be transferred.

The additional energy consumption caused by the operation of the internal third party heating arises compared to conventional heaters, which is the volume of the entire reactor, significantly reduced. The energy loss of the due to unnecessary pressure build-up (e.g. during load changes) of the exhaust gases in the reactor arises, can be derived through the bypass in front of the reaction body and in the air intake or exhaust tract are passed, so that in the reactor unwanted exhaust back pressure can no longer arise.

This individually regulated exhaust gas recirculation is in the air intake tract Regulated with regard to the exhaust gas back pressure so that the pollutant Reduction of the necessary ignition temperature, caused by the exhaust gas counter pressure, is always used when this is the lowest energy represents effort.

The combination, the exhaust gases in the cold smoke phases by the additional Heating and the exhaust gas back pressure to the pollutant temperature of the exhaust gases is to heat by the current, small volume of the reactor in the operating areas without significant energy losses. Under The term catalytic reactor is used both for tubular reactors and Filter reactors understood.

Brief description of the drawing, in which:

Fig. 1 is a schematic representation of a tube reactor which has been equipped with a temperature-dependent controlled surface control system,

Fig. 2 is a plan view of the gas inlet-side of the reactor of Fig. 1 along line AA,

Fig. 3 shows schematically a filter reactor with additional external heating, which is also equipped with a regulated area control system and

Fig. 4 is a plan view of the gas inlet-side of the reactor of FIG. 3.

The reactors 4 and 13 shown in FIGS. 1 and 2 can be used both for a spark ignition engine and a compression ignition engine.

In Fig. 1, a tubular reactor 4 is arranged within a housing 3 for exhaust gas purification for internal combustion engines, the reactor 4 being designed according to the combustion principle of the machine. An exhaust gas feed line 1 is connected to the housing 3 , into which a plurality of exhaust manifolds 2 can open. In the area in front of the reactor, a bypass 7 with a pressure relief valve 8 is arranged in the exhaust gas feed line 1, which bypasses the exhaust gases into the air intake tract if the exhaust gas back pressure is undesirably high.

Furthermore, a temperature sensor 9 is arranged in the area of the reactor 4 or on the same, which is able to take the instantaneous temperature of the exhaust gases in the immediate vicinity of the reactor 4 or the same itself. In addition, a further temperature sensor 9 'can be arranged in the vicinity of the corresponding exhaust valve or at the beginning of the manifold 2 , which is able to decrease the temperature of the exhaust gases immediately after leaving the cylinder.

An area control system, which is arranged in front of the inlet of the reactor 4 on the gas inlet side, controls the effective cross section of the gas inlet surface of the reactor 4 and thus depending on the prevailing one depending on the temperature of the temperature sensor 9 or depending on the temperature difference between the two temperature sensors 9 and 9 ' Exhaust gas temperature or the temperature difference between the exhaust gas temperature directly after the cylinder and the temperature of the reactor 4 , so that the differently occurring exhaust gas masses and volumes of the internal combustion engine are available over all operating ranges only a reactor volume adapted to these masses and volumes. The reactor 4 is preferably installed in the vicinity of the exhaust manifold 2 . The entire exhaust gas purification system from the manifold 2 to the outlet of the reactor 4 can be insulated so as to prevent unnecessary heat dissipation.

The area control system preferably consists of a disc 5 which is pivotally arranged in front of the passage surface of the reactor 4 and a push rod 6 which is adjustable by motor or thermostatic (bimetal) or pneumatically or electrically within a control or control circuit, so that when the disc is pivoted the passage cross section of the reactor 4 is increased or decreased in the direction of the double arrow 10 . As one of the control variables of the control loop, the temperature of the temperature sensor 9 or the difference between the two temperature sensors 9 , 9 'is received.

Fig. 2 shows schematically the reactor 4 from the direct plan view of the gas inlet surface, the passage surface of the honeycomb-free tubes of a particle filter 4 (reactor) by covering the gas inlet surface, caused by the surface control system 5 , which is controlled by a temperature-dependent control drive 6 the existing temperature in the reactor 4 is driven, the position of the surface control system 5 is changed so that the exhaust gases can only flow through the volume of the reactor 4 , which corresponds to the actually occurring exhaust gas volume.

FIGS. 3 and 4 show another reactor system having a reactor, a filter reactor 13, according to an exhaust gas supply line 11 within a housing 12. The filter reactor 13 has an additional external heater 14 , which is preferably heated by means of electrical energy. The heater 14 , which is switched on in particular in the cold start phase, can heat the entire reactor volume and is due to the fact that it is only switched on when the temperature in the reactor 13 is low and thus a small reactor volume is released due to the area control system 5 , which is why the reactor works efficiently and without significant energy loss.

However, it is also possible to partially heat the reactor in accordance with the each released gas entry surface of the reactor, thereby reducing the energy consumption of the external heating system can be reduced. Fuel additives (Additives) are able to reduce the soot ignition temperature so enormously that the Efficiency of the process is increased by such soot ignition accelerators.

Reference list

1 , 11 exhaust gas supply lines
2 exhaust manifolds on the cylinder
3 , 12 housing
4 reactor
5 Cover plate of the area control system
6 push rod
7 By-pass system
8 pressure relief valve
9 , 9 ′ temperature sensor
10 double arrow
13 filters
14 additional heating

Claims (14)

1. A method for rapidly achieving the ignition temperature of the pollutants in the exhaust gases of an internal combustion engine, using a reactor ( 4 , 13 ) for exhaust gas purification, the passage cross section of which can be changed and the temperature of the exhaust gases in the region of the reactor ( 4 , 13 ) is continuously measured , characterized in that the gas-flowed volume of the reactor ( 4 , 13 ) depending on the temperature and pressure of the exhaust gases quantitatively by regulating the cross-section ( 5 , 6 ) of the gas inlet area of the reactor ( 4 , 13 ) proportional to the actually occurring exhaust gas volumes the internal combustion engine is regulated, namely enlarged or reduced, in such a way that thermal expansion of the exhaust gases within the reactor ( 4 , 13 ) is avoided as far as possible in all operating areas while maintaining the inherent energy of the exhaust gases. 2. The method according to claim 1, characterized in that an area control system ( 5 ) distributes the exhaust gas to the volume of the reactor ( 4 , 13 ) in all operating areas such that the exhaust gases only flow through that part of the reactor ( 4 , 13 ) that is necessary in order to ensure that the exhaust gases have a relatively free passage of gas, so that, on the one hand, with "cold" exhaust gases and the resulting lower exhaust gas volume, a correspondingly smaller reactor volume is available and, on the other hand, the exhaust gases flow through the entire reactor ( 4 , 13 ) at high exhaust gas temperatures, the operating states are regulated accordingly in between. 3. The method according to claim 1 or 2, with an additional externally heatable reactor, characterized in that partially only the part of the reactor ( 13 ) is additionally heated, which is currently released for the passage of the exhaust gases. 4. The method according to claim 1, characterized in that in addition to the temperature control of the gas-flow volume of the reactor ( 4 , 13 ) this in dependence on the back pressure of the exhaust gas by means of an exhaust pipe arranged in front of the reactor, which tracts in the air intake or is guided into the exhaust system , is regulated in such a way that the ignition temperature required for pollutant reduction, caused by the exhaust gas back pressure, is used when this represents the lowest energy expenditure. 5. Device for rapidly achieving the ignition temperature of the pollutants in the exhaust gases of internal combustion engines, using a reactor ( 4 , 13 ) for exhaust gas purification, the passage cross section of which can be changed, with a temperature sensor ( 9 , 9 ) arranged in the region of the reactor ( 4 , 13 ) ') For recording the temperature of the exhaust gases or the reactor ( 4 , 13 ), characterized by an area control system ( 5 , 6 ) over the entire cross section on the gas inlet side of the reactor ( 4 , 13 ), which has the total cross section of the reactor ( 4 , 13 ) as a function of the temperature and the pressure of the exhaust gases or of the reactor ( 4 , 13 ) in accordance with the resulting exhaust gas quantities in all operating areas, while maintaining the inherent energy of the exhaust gases. 6. The device according to claim 5, characterized in that the area control system ( 5 , 6 ) works mechanically, thermostatically, pneumatically or electronically and from a front of the reactor ( 4 , 13 ) on the gas inlet side arranged cover device ( 5 ), which the Gas inlet surface of the reactor ( 4 , 13 ) is more or less able to cover. 7. Apparatus according to claim 5 or 6, characterized in that a temperature sensor ( 9 , 9 ') is arranged both in the region of the reactor ( 4 , 13 ) and in the region after the exhaust valve of the engine for continuous measurement of the corresponding temperatures and the manipulated variable for regulating the cross section of the instantaneous gas entry surface ( 4 a) of the reactor ( 4 , 13 ) can be derived from the difference. 8. Device according to one of the preceding claims 5 to 7, characterized in that the reactor ( 4 , 13 ) has a heating system through which the same by supplying external energy, for. B. electrical energy is heatable. 9. The device according to claim 8, characterized in that partially only the part of the reactor ( 4 , 13 ) is additionally heated, which is currently released for the passage of the exhaust gases by means of the area control system ( 5 , 6 ). 10. The device according to claim 9, characterized in that it has a by-pass system ( 7 , 8 ) for discharging the exhaust gases at an undesirable exhaust gas pressure upstream of the reactor ( 4 , 13 ). 11. Device according to one of claims 5 to 10, characterized in that the reactor ( 4 , 13 ) is installed within the exhaust system at the point at which the exhaust gases from all cylinders of the internal combustion engine are brought together. 12. Device according to one of claims 5 to 11, characterized in that the reactor ( 4 , 13 ) is installed within the exhaust system prior to the management of the exhaust gases from all cylinders of the internal combustion engine, which can be coupled together. 13. Device according to one of the preceding claims 5 to 12, characterized in that the surface control system ( 5 , 6 ) comprises a disc ( 5 ) which is pivotally arranged in front of the reactor ( 4 , 13 ) on the gas inlet side. 14. A method for rapidly achieving the ignition temperature of the pollutants in the exhaust gases of an internal combustion engine, using a reactor ( 4 , 13 ) for exhaust gas purification, the passage cross section of which can be changed and the temperature of the exhaust gases in the region of the reactor ( 4 , 13 ) is continuously measured , characterized in that the volume of the reactor ( 4 , 13 ) through which gas flows is controlled quantitatively as a function of the temperature of the exhaust gases by regulating the cross-section ( 5 , 6 ) of the gas inlet area of the reactor ( 4 , 13 ) in proportion to the actually occurring exhaust gas volumes of the internal combustion engine , namely increased or decreased, and both the temperature of the exhaust gases in the area of the reactor ( 4 , 13 ) and the temperature of the exhaust gases in the area after the exhaust valve of the engine are measured continuously, and from the difference the manipulated variable for controlling the cross section ( 5 , 6 ) the current gas entry area of the react ors ( 4 , 13 ) is obtained in such a way that thermal expansion of the exhaust gases within the reactor ( 4 , 13 ) is avoided as far as possible in all operating areas while maintaining the inherent energy of the exhaust gases.