DE102007024891A1 - Exhaust gas purification system and method for purifying exhaust gas - Google Patents

Abstract

Reductions in the intake air volume in an internal combustion engine (1) in response to a change in the environment result in an increase in the amount of PM emissions. In view of this, a correction coefficient of a fuel supply interval is calculated based on the variation of the amount of PM emissions to adjust a reference fuel supply interval to determine a target fuel supply interval (steps ST4 and ST8). By adjusting the fuel supply interval, a fuel supply amount corresponding to the variation of the amount of PM emissions is provided, thereby preventing clogging of the injection port of an additional fuel valve (25) while maintaining fuel economy.

Description

BACKGROUND OF THE INVENTION

1. Field of the invention

The The present invention relates to a system and a method for Purify exhaust gas from an internal combustion engine using a catalyst. In particular, the invention relates to an exhaust gas purification system with an additional fuel valve, which supplies a fuel to an exhaust pipe, and an exhaust gas purification method for Respectively a fuel to the exhaust pipe.

2. Description of the relevant status of the technique

in the Generally, lean-burn engines work like diesel engines predominantly in the lean-burn mode with a high air-fuel ratio (lean Mixture). Thus, such internal combustion engines are generally in the exhaust pipe equipped with a NOx storage catalyst, to the exhaust gas by absorbing the nitrogen oxides contained in the exhaust gas (hereinafter referred to as "NOx") to clean.

If the amount of NOx that absorbs through the NOx storage catalyst becomes, a saturation achieved, a NOx reduction reaction is necessary to the NOx storage capacity of the catalyst restore. An approach For reducing NOx, it is a NOx reducing agent (light oil or a other fuel) upstream of the NOx storage catalyst in the Add exhaust pipe, around the oxygen concentration in the catalytic converter reduce and then reducing agents such as excess hydrocarbon and To use carbon monoxide to promote NOx reduction.

The Exhaust gas from these diesel engines contains particles whose main ingredient a carbon (and hereinafter referred to as "PM"), carbon black, a organically soluble Particle content (SOF) and so on. These emissions cause a Air pollution. A conventional one Emission control system for Diesel engines for that is designed to purify such PM and other emissions a particulate filter disposed in the exhaust passage. This particle filter starts the PM contained in the exhaust gas passing through the exhaust pipe, which reduces the amount of PM emissions that are released into the atmosphere, is reduced. A diesel particulate filter (DPF) or a diesel particulate NOx reduction system (DPNR) catalyst can be used as a particle filter.

The PM deposits accumulate on the particulate filter, while the Amount of PM caught in the filter increases, which causes the particulate filter through the PM deposits is clogged. Thus, a pressure loss of the exhaust gas that passes through enters the particulate filter, and accordingly decreases an engine exhaust back pressure to. As a result, the output power of the internal combustion engine as well reduces fuel economy. To the above problems to solve, is in the conventional Technology a fuel of the exhaust pipe (upstream of the particle filter) supplied to increase the exhaust gas temperature, causing oxidation (combustion) of PM deposits on the Particle filter promoted becomes (PM catalyst regeneration process).

As described above, in the NOx reduction process and the PM-catalyst regeneration process, both of which serve the exhaust gas purification performance of the catalyst maintain a fuel of the exhaust pipe using an additional one Fuel valve supplied, which is arranged in the exhaust pipe. Because the injection port of the additional Fuel valve is exposed to the inside of the exhaust pipe, some can In the exhaust gas contained substances such as soot and SOF, on the opening stick to the valve and form deposits. This gives rise to Make sure the deposits have a high temperature Be exposed to exhaust gas, the properties of the substances change and These substances can solidify and the opening of the Valve is clogged. An exemplary approach to preventing that extra Clogged fuel valve is in the Japanese patent 2003-222019, in which a fuel is supplied at any time, except during one NOx reduction and a PM catalyst regeneration to the temperature of the distal end of the additional Reduce fuel valve.

The Volume of the suction air in the internal combustion engine, for example due to changes in the area, such. B. Changes in the atmospheric Pressure when driving from a low altitude to an elevated altitude or when switching from a normal driving to a transient Driving, reduced. this leads to to an increase the amount of PM emissions. While the amount of PM emissions increases, so does the amount of PM to that at the injection port of the additional Stick fuel valve and enter into this, what to do contributes that PM deposits can expand there. The PM deposits can be the Einspritzeinöffnung of the additional Clog fuel valve.

Around such a problem as the obstruction of an injection port to solve, can the extra Fuel quantity (the additional Fuel quantity per unit time) to be adjusted when the quantity PM emissions reach the maximum value of allowable fluctuation. The adaptation of the additional However, fuel supply in this way gives cause for concern in the In view of the tendency to reduced fuel economy.

SUMMARY OF THE INVENTION

The The invention provides an exhaust gas purification system that saves fuel sustains while one Blockage of injection port of the additional Fuel valve is prevented.

One The first aspect of the invention relates to an exhaust gas purification system with a catalyst in an exhaust pipe in an internal combustion engine is arranged, and an additional Fuel valve for feeding of a fuel in the exhaust pipe. The emission control system includes an adjustment device for adjusting the amount of fuel, which, based on the variation of the amount of particle emissions from a combustion chamber in the internal combustion engine, the exhaust pipe from the additional Fuel valve supplied becomes.

One second aspect of the invention is similar to the first aspect, except that the exhaust gas purification system further includes an adaptation device, which adjusts the amount of fuel, based on the variation the amount of particulate (PM) emissions from the combustion chamber in the internal combustion engine, from the additional fuel valve the exhaust pipe is supplied per unit time.

The Volume of suction air entering the internal combustion engine decreases with changes the environment from such. B. changes of the atmospheric Pressure due to driving from a low altitude on an increased altitude or when switching from a normal driving operation to a transient one Driving. this leads to to an increase the amount of PM emissions. In the face of such a situation becomes the fuel supply amount per unit of time based on the variation in the amount of PM emissions (eg variation in the actual intake air volume). This will provided a fuel supply amount, the variation the amount of PM emissions equals, resulting in an excessive fuel supply is prevented. Therefore, a blockage of the injection port of the addi tional Fuel valve prevents while the saving of fuel is maintained.

According to the second Aspect becomes a solution created to adjust the fueling amount per unit time, in which a reference fuel supply interval having a correction coefficient is multiplied to determine a desired fuel supply interval, wherein the reference fuel supply interval depends on the operating condition of the internal combustion engine and the correction coefficient of the variation of the amount of PM emissions depends. Especially with this approach, when the actual intake air volume in the internal combustion engine is lower as the reference suction air volume (when the air volume ratio (actual suction air volume divided by reference intake air volume) is small), the reference fuel supply interval multiplied by a correction coefficient by the target fuel supply interval determining, whereby the correction coefficient changes or shortens the fuel supply interval, d. H. an increase the fuel supply amount per Time unit makes.

In the exhaust gas purification system with the additional fuel valve for Respectively of a fuel in the exhaust pipe decreases the temperature of the distal End of the additional Fuel valve too, while the atmospheric pressure (exhaust gas temperature) at the distal end of the additional Fuel valve increases from a preset reference value, whereby PM deposits are generated. The PM deposits may be the injection port of the Kraftstoffzuführventils clog. Therefore, there arises the necessity of the fuel supply amount to increase. In view of this situation, according to a third aspect of the Invention the target fuel supply interval under consideration of Temperature of the distal end of the additional fuel valve certainly.

The third aspect of the invention is similar to the first aspect of the invention except that the exhaust gas purifying system further includes: adjusting means for adjusting the fuel supply interval for supplying a fuel from the additional fuel valve into the exhaust pipe based on the variation of the amount of particulate emission from the exhaust gas Combustion chamber in the internal combustion engine (variation of the amount of PM emissions); and additional fuel valve temperature estimating means for estimating a temperature of the additional fuel valve. The adjusting means compares first and second correction coefficients with each other, wherein the first correction coefficient changes or shortens the fuel supply interval when the actual intake air volume in the internal combustion engine is smaller than the reference intake air volume, and the second correction coefficient changes or shortens the fuel supply interval when the temperature of the first intake coefficient changes additional fuel valve, by the additional Fuel valve temperature estimator is estimated increases. The reference fueling interval is multiplied by either the first or second correction coefficient resulting in a shorter fueling interval to determine the desired fueling interval.

As As described above, the correction coefficient included in FIG shorter Kraftstoffzuführintervall (a larger fuel supply amount per unit time), selected to be the reference fueling interval adjust, with a correction coefficient of the variation of PM emissions depends, the other correction coefficient from the temperature of the distal End of the additional fuel valve depends. This will allow that the fuel delivery interval for each one of the two condition changes, where it is more likely that a blockage of the injection port of the additional Fuel valve is caused to be adjusted; in which the condition changes to increase the temperature of the distal end of the additional Fuel valve and an increase in the amount of PM emissions due to changes in the area or during Obtain driving conditions in transient driving. This can a blockage of the injection opening of the additional fuel valve effectively prevented. Furthermore becomes a fuel supply amount, the for the above specific conditional change is appropriate. This prevents excessive fuel supply. While Therefore, the fuel economy is maintained becomes a blockage the injection port of the additional Fuel valve prevents.

Even though an increase the fuel supply amount per unit time a blockage of the injection port of the additional Fuel valve prevents the fuel reacts with the oxygen in the catalyst, whereby the catalyst temperature can be caused exceeds a certain range of values (eg 750 C). There is a proposal for a solution to this situation avoid when, if a catalyst temperature is greater or is equal to a prescribed value, the fuel supply amount depending on time unit from the catalyst temperature (i.e., a variation of the catalyst temperature in relation to the preset value). This approach contributes to that at, the problem of thermal deterioration of the catalyst due to overly high Catalyst temperatures caused by the increased fuel supply be prevented.

An example approach is proposed to reduce the fuel delivery amount per unit time using the desired fuel delivery interval, which is shorter than the reference fuel delivery interval (eg, the corrected desired fuel delivery interval), to increase the fuel delivery duration per interval cut as in 8th is shown. This approach not only ensures a shorter fuel delivery interval, which can prevent clogging of the injection port of the additional fuel valve, but also ensures a smaller total fuel supply amount. Thus, while preventing an excessive increase in the catalyst temperature, clogging of the injection port of the additional fuel valve is also prevented.

It becomes another solution suggested an excessive increase to prevent the catalyst temperature, with a restrictive correction or an increase the fuel supply amount executed per unit time is, so the catalyst temperature based on the exhaust gas temperature estimated will not exceed a prescribed value.

The Inventions according to the second and third aspect further include a catalyst temperature detecting means, which detects a temperature of the catalyst. If the variation the catalyst temperature caused by the catalyst temperature detecting means is captured, greater or is equal to a preset value, the adjustment means the fuel supply amount depending on time unit from the variation of the catalyst temperature.

The Inventions according to the second and third aspect Further, a coolant temperature detecting means for detecting the temperature of the coolant of the internal combustion engine include. When the variation of the coolant temperature passing through the coolant temperature detecting means is captured, greater or is equal to a preset value, the adapter reduces the fuel supply amount depending on time unit from the variation of the coolant temperature.

at The internal combustion engine may be a diesel engine. The internal combustion engine may be installed in a vehicle.

Further is a fourth aspect of the invention to an exhaust gas purification method directed, which is a fuel of the exhaust pipe in an internal combustion engine supplies, wherein the exhaust pipe has a catalyst disposed therein. The exhaust gas purification method includes adjusting the amount of fuel, that of the exhaust pipe from the additional Fuel valve based on the variation of the particulate matter emission is supplied from a combustion chamber in the internal combustion engine.

According to the fourth Aspect, the amount of fuel may be an amount of fuel that the Exhaust pipe from the additional Fuel valve is supplied per unit time.

According to the fourth Aspect may be to adjust the amount of fuel the reference fuel supply interval multiplied by the correction coefficient obtained by the Variation of the particulate emission amount depends on the desired fuel supply interval to determine.

According to the fourth Aspect can be used to adjust the amount of fuel when the actual intake air volume in the internal combustion engine is lower than the reference suction air volume, the reference fuel supply interval with a correction coefficient to adjust or shorten the Kraftstoffzuführintervalls multiplied to determine the desired fuel supply interval.

According to the fourth Aspect, the amount of fuel can be an interval of a fuel be that of the extra Fuel valve is supplied to the exhaust pipe.

The Invention according to the fourth Aspect may further be an estimation the temperature of the additional Include fuel valve. To adjust the amount of fuel become the first and the second correction coefficient with each other compared with the first correction coefficient for changing or shorten the fuel supply interval serves if the actual intake air volume in the internal combustion engine is lower is the reference intake air volume, and the second correction coefficient to change or shortening the Kraftstoffzuführintervalls Serves when the temperature of the additional fuel valve rises, which by the additional Fuel valve temperature estimator estimated becomes. Then, the reference fuel supply interval with either the first or second correction coefficients, resulting in a shorter fuel delivery interval results, and the target fuel supply interval is determined.

The Invention according to the fourth Aspect may further include detecting the temperature of the catalyst temperature include. To adjust the amount of fuel when the catalyst temperature, detected by the catalyst temperature detecting means will, bigger or is equal to a preset value, the fuel supply amount depending on time unit reduced by the catalyst temperature.

According to the fourth Aspect may be a fuel injection amount per unit time Adjust or trim the fuel supply interval be reduced while the fuel delivery time is reduced per interval.

One fifth Aspect of the invention is directed to an exhaust gas purification system having the following features: one in an exhaust pipe in an internal combustion engine arranged catalyst; an additional fuel valve for Respectively a fuel in the exhaust pipe; and an adjustment area for adjusting an amount of fuel supplied to the exhaust pipe from the additional Fuel valve based on the variation of the particle emission quantities is supplied from a combustion chamber in the internal combustion engine.

In A sixth aspect of the invention may be an exhaust gas purification method Furthermore, an adjustment of the amount of fuel include that of the exhaust pipe from the additional Fuel valve based on the variation of the particulate emission amount is supplied from the combustion chamber in the internal combustion engine.

According to the above Aspects of the invention will be considered in view of the amount of PM emissions, that of the crowd under driving conditions on level and normal The road surface can increase, the fuel supply amount per unit time (fuel supply interval) adjusted based on the variation of the amount of PM emissions. This becomes a fuel supply amount provided that corresponds to the variation of the amount of PM emissions, causing a blockage of the injection port of the additional Fuel valve is prevented while the fuel economy is maintained.

BRIEF DESCRIPTION OF THE DRAWING

The above and further objects, features and advantages of the invention will become apparent from the foregoing description of exemplary embodiments Reference to the attached Drawing closer explains in the identical reference numerals used to represent identical elements become. Show it:

1 a schematic diagram illustrating an example of a diesel engine, which is equipped with an exhaust gas purification system according to the invention.

2 a block diagram of the configuration of a control system that includes an ECU.

3 5 is a flowchart illustrating an example of a correction process for a fuel supply interval executed by the ECU.

4 a map for calculating a reference fuel supply interval, which in the correction process of a Kraftstoffzuführintervalls of 3 is used.

5 a map representing a correction coefficient for a fuel supply interval included in the correction process of the fuel supply interval of 3 is used.

6 a map representing a λ correction coefficient for an amount of PM emissions included in the correction process of the fuel supply interval of FIG 3 is used.

7 a map representing a correction coefficient for a fuel supply interval included in the correction process of the fuel supply interval of 3 is used.

8th a fuel supply interval and a supply period.

9 Another example illustrating the map of the correction coefficient of a Kraftstoffzuführintervalls that varies depending on the temperature of the distal end of the additional fuel valve.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A description will be given of an embodiment of the invention with reference to the drawings. A general configuration of a diesel engine using a fuel supply device of the invention will be described with reference to FIG 1 described.

In this embodiment, the diesel engine 1 (hereinafter referred to as "internal combustion engine 1 ") is a four-cylinder engine with a common rail in-cylinder direct injection 1 includes as main components a fuel supply system 2 , Combustion chambers 3 , an inlet system 6 and an exhaust system 7 ,

The fuel delivery system 3 includes a fuel supply pump 21 , a common rail line 22 , Injectors (Fuel Injectors) 23 , an additional fuel valve 25 , an internal combustion engine fuel line 26 and a fuel line 27 ,

The fuel supply pump 21 draws fuel from the fuel tank and pressurizes the fuel to pressurize the common rail fuel 22 through the engine fuel line 26 supply. The common rail 22 functions as a collector for maintaining the pressure of the fuel supply pump 21 supplied fuel to a prescribed value (the high-pressure fuel supplied by the fuel supply pump 21 is supplied, is collected). The common rail 22 distributes the accumulated fuel to the injectors 23 , At a respective injection nozzle 23 it is an electromagnetically controlled valve that is designed to open when a specific voltage is applied and a fuel to the assigned combustion chamber 3 sprayed.

The fuel supply pump 21 is designed to take a portion of the fuel that is drawn from the fuel tank, the additional fuel valve 25 through the fuel line 27 supplies. The additional valve 25 is an electromagnetically driven valve that is designed to open when a specific voltage is applied and a fuel to the exhaust system 7 (from the outlet channels 71 to an exhaust manifold 72 ) feeds. An injection port of the additional fuel valve 25 lies to the inside of the exhaust system 7 free.

The inlet system 6 has an intake manifold 63 connected to the intake passages formed in the cylinder head. A suction pipe 64 that is included in the intake pipe is with the intake manifold 63 connected. An air purifier 65 , an air flow meter 32 and a throttle valve 62 are arranged in the inlet pipe in an order from the upstream side. The air measuring device 32 is designed so that it emits an electrical signal that the volume of air flow into the suction line through the air purifier 65 displays.

The exhaust system 7 has an exhaust manifold 72 on, with exhaust ducts 71 is connected, which are formed on the cylinder head. The exhaust pipes 73 . 74 that are included in the exhaust pipe are with the exhaust manifold 72 connected. A catalytic converter 4 is also located in the exhaust pipe.

The catalytic converter 4 includes a NOx storage reduction catalyst 4a and a DPNR catalyst 4b , The NOx storage reduction catalyst 4a is designed to absorb NOx in the presence of a high oxygen concentration in the exhaust gas when the oxygen concentration in the exhaust gas is high and NOx to NO 2 or NO as emissions in the presence of a low oxygen concentration and a large amount of a reduction element (unburned fuel components such as HC) reduced in the exhaust gas when the oxygen concentration is low and an excess of a reducing agent (eg, unburned fuel such as HC) is present in the exhaust gas. NOx emissions in the form of NO2 or NO react directly with HC or CO contained in the exhaust gas, so that NO ₂ or NO is reduced to N ₂ . The reduction of NO ₂ or NO to N ₂ causes HC or CO to be reduced to H ₂ O or CO ₂ .

In one example, the DPNR catalyst uses 4b a porous ceramic structure including the NOx storage reduction catalyst. The PM in the exhaust are trapped as they pass through the porous wall. When the exhaust gas air-fuel ratio is lean, the NOx storage reduction catalyst absorbs NOx contained in the exhaust gas. When the air-fuel ratio is rich, the stored NOx is reduced. The DPNR catalyst 4b also oxidizes and burns the trapped particles.

The exhaust gas purification system includes the catalytic converter 4 , the additional fuel valve 25 and the fuel line 27 and an electronic control unit (ECU) 100 , The ECU 100 controls the operation of the additional fuel valve 25 ,

The internal combustion engine 1 has a turbocharger (compressor) 5 on. The turbocharger 5 includes a turbine shaft 5a , a turbine wheel 5b and a compressor impeller 5c , where the turbine wheel 5b and the compressor impeller 5c with each other via the turbine shaft 5a are connected. The compressor impeller 5c is to the inside of the suction tube 64 directed while the turbine wheel 5b to the inside of the exhaust pipe 73 exposed. The configured turbocharger 5 uses an exhaust gas flow (exhaust gas pressure) passing through the turbine wheel 5b is taken to the compressor wheel 5c to turn to force air into the internal combustion engine. In this embodiment, the turbocharger is 5 a variable nozzle turbocharger with a variable nozzle impeller mechanism 5d on the side of the turbine wheel 5b , The boost pressure of the internal combustion engine 1 can be achieved by controlling the opening degree of the variable nozzle impeller mechanism 5d be regulated.

The inlet system 6 has a charge air cooler 61 on, in the intake manifold 64 is arranged. The intercooler 61 is designed to cool the intake air, its temperature due to the forced introduction by the turbocharger 5 has risen. The throttle valve 62 is also in the intake manifold 64 downstream of the intercooler 6l arranged. The throttle valve 62 is an electronically controlled valve whose opening changes continuously. The throttle valve 62 reduces the cross section of the suction air duct under certain conditions to control (reduce) the volume of suction air.

The internal combustion engine 1 has an exhaust gas recirculation (EGR) line 8th on that the inlet system 6 and the exhaust system 7 connects with each other. The EGR line 8th introduces some of the exhaust gas into the intake system as needed 6 back and returns such exhaust gas back into the combustion chambers 3 to lower the combustion temperature. This reduces the NOx emission amount. The EGR line 8th has an EGR valve 81 and an EGR cooler 82 which cools an exhaust gas that passes through the EGR passage (is returned). The volume of the EGR coming from the exhaust system 7 in the inlet system 6 is to be introduced (exhaust gas volume to be returned), by controlling the opening degree of the EGR valve 81 be adjusted.

There now follows a description of the sensors. The internal combustion engine 1 has several types of sensors installed at specific positions thereof. The sensors output signals indicating the environmental conditions of the specific positions as well as signals indicating the operating conditions of the internal combustion engine 1 Show.

The air flow measuring device 32 , upstream of the throttle valve 62 in the intake system 6 For example, outputs a signal indicating the detected flow rate of the suction air (suction air volume). The inlet temperature sensor 33 standing on the intake manifold 63 are arranged, outputs a signal indicating the detected temperature of the suction air. The inlet pressure sensor 34 standing on the intake manifold 63 is arranged, outputs a signal indicating the detected pressure of the suction air. An A / F (air / fuel ratio) sensor 35 downstream of the catalytic converter 4 in the exhaust system 7 , outputs a detection signal that continuously varies depending on the oxygen concentration in the exhaust gas. An exhaust gas temperature sensor 36 downstream of the catalytic converter 4 in the exhaust system 7 , outputs a signal indicating the detected exhaust gas temperature. A rail or pressure line pressure sensor 37 outputs a signal indicative of the sensed pressure of the fuel in the common rail 22 is stored. A fuel pressure sensor 38 outputs a signal indicating the sensed pressure of the fuel passing through the fuel line 27 flows (fuel pressure).

A description of the ECU will now be given. As in 2 shown includes the ECU 100 a CPU 101 , a ROM 102 , a ram 103 and a backup RAM 104 , The ROM 102 stores several control programs, maps to be used to run these control programs, and other data. The CPU 101 performs various operations according to the respective control programs and maps provided in the ROM 102 are stored out. The results of operations in the CPU 101 and those of the ever Transmitted data is temporarily stored in RAM 103 saved. The backup RAM 104 is a non-volatile memory for saving stored data when the power is turned off, such as B. at a shutdown of the engine 1 ,

The ROM 102 , the CPU 101 , the RAM 103 and the backup RAM 104 are with each other via a bus 107 connected while using an input interface 105 and an output interface 106 are connected.

The input interface 105 connects the air flow meter 32 , the inlet temperature sensor 33 , the inlet pressure sensor 34 , the A / F sensor 35 , the exhaust gas temperature sensor 36 , the pressure line pressure sensor 37 and the fuel pressure sensor 38 , In addition, the input interface connects 105 a water temperature sensor 31 , an atmospheric pressure sensor 39 , an accelerator pedal travel sensor 40 and a crankshaft position sensor 41 , The water temperature sensor 31 outputs a signal that the detected coolant temperature in the internal combustion engine 1 displays. The atmospheric pressure sensor 39 detects the atmospheric pressure variable due to environmental conditions involving altitude. The accelerator pedal travel sensor 40 outputs a signal indicating the detected displacement of the accelerator pedal. The crankshaft position sensor 41 gives an impulse when the output shaft (crankshaft) of the internal combustion engine 1 turns around a given angle. The output interface 106 in turn connects the injector 23 , the additional fuel valve 25 , the variable nozzle impeller mechanism 5d , the throttle valve 62 , the EGR valve 81 and other.

The ECU 100 performs the respective controls in the internal combustion engine 1 based on the outputs from the above-mentioned sensors. The ECU 100 also executes a PM catalyst regeneration control and a correction process of the fuel supply interval, which will be described later.

Next, a description will be given of the catalyst regeneration control. The ECU 100 first estimates the amount of PM deposits in the DPNR catalyst 4b one. One approach to estimating the amount of PM deposits is to use a map that has been plotted with experimentally determined data on the amount of PM adhesion that is dependent on the operating conditions of the internal combustion engine 1 varies (eg, exhaust temperature, fuel injection amount, and engine speed). The amounts of PM adhesion read from the map are summed to obtain the amount of PM deposits. Another approach would be to estimate the amount of PM deposits based on vehicle travel distance or travel time. Still another alternative involves using a pressure differential sensor included in the catalytic converter 4 is arranged to increase the pressure difference between a point upstream and a point downstream of the DPNR catalyst 4b capture. The amount of PM deposits generated by the DPNR catalyst 4b is calculated based on the output from the pressure difference sensor.

If the estimated amount of PM deposits is greater than or equal to a specified reference value, the ECU determines 100 that they are the regeneration of the DPNR catalyst 4b starts, and executes the PM catalyst regeneration control. In particular, the ECU calculates 100 a desired fuel delivery amount and a delivery interval based on the engine speed received from the crankshaft position sensor 41 with reference to the map to which previously experimentally obtained results have been plotted. According to the calculation result, the ECU controls 100 the operation of the additional fuel valve 25 through which a fuel is continuously flowing to the exhaust system 7 is supplied. The fuel supply leads to a temperature rise of the DPNR catalyst 4b , whereby oxidation of PM deposits in the DPNR catalyst 4b is promoted to H ₂ O and CO ₂ emissions.

In contrast to the PM catalyst regeneration control, the ECU 100 perform a sulfur poisoning recovery control or NOx reduction control. The sulfur poisoning recovery control releases sulfur from the NOx storage reduction catalyst 4a and the DPNR catalyst 4b free. This is accomplished by increasing the catalyst temperature by continuously feeding fuel from the additional fuel valve 25 achieved while the fuel-air ratio of the exhaust gas is controlled to a stoichiometric or richer ratio. The NOx reduction control should be the NOx that is in the NOx storage reduction catalyst 4a and the DPNR catalyst 4b is stored by intermittently supplying fuel from the additional fuel valve 25 to reduce N ₂ , CO ₂ and H ₂ O.

The PM catalyst regeneration control, sulfur poisoning recovery control and the NOx reduction control are individually performed as needed. If It may be necessary to run all three controllers at the same time Controls are executed in the sequence described above.

Subsequently, a description of the Correction process of the fuel supply interval. As stated previously, the intake air volume in the internal combustion engine 1 , which is installed in the vehicle, following certain changes in the environment from such. B. a change in atmospheric pressure or when switching from a normal driving operation to a transient driving operation. This increases the amount of PM emissions. As the amount of PM emissions increases, the amount of PM that enters the injection port of the additional fuel valve increases 24 and adhere to it, which helps build PM deposits. The PM deposits may be the injection port of the additional fuel valve 25 clog. Because the exhaust gas temperature at the distal end of the additional fuel valve 25 increases from the preset reference temperature decreases the temperature of the distal end of the additional fuel valve 25 also to, which PM deposits are generated. The PM deposits may be the injection port of the additional fuel valve 25 clog.

To solve this problem, in this embodiment, a correction coefficient of the fuel supply interval eminttemp used for correcting the fuel supply interval is based on the temperature of the distal end of the additional fuel valve 25 calculated. In addition, a correction coefficient of the fuel supply interval emintpm used for correcting the fuel supply interval is calculated based on the variation of the amount of PM emissions due to changes in the environment or during transient driving conditions. Between eminttemp and emintpm, the correction coefficient of the fuel supply interval resulting in a larger amount of fuel supply per unit time is selected as a target fuel supply interval. This provides the feature of maintaining fuel economy while obstructing the injection port of the additional fuel valve 25 is prevented.

Hereinafter, a description will be given of a specific example of the correction process of the fuel supply interval with reference to the flowchart in FIG 3 , The ECU 100 executes the correction process of the fuel supply interval. A routine of this correction process is repeated at a predetermined time interval.

At step ST1, the engine speed Ne becomes the output of the crankshaft sensor 41 is read to calculate a target fuel supply amount Q based on the engine speed Ne with reference to a map Ne, such as one shown in FIG 4 is shown. The relationship between the engine rotation speed Ne and the target fuel supply amount Q is obtained in advance experimentally, through calculations, etc. Then, the map used to calculate the target fuel supply amount Q is established by plotting the relationship between the engine speed Ne and the target fuel supply amount Q, and in the ROM 102 the ECU 100 saved.

At step ST2, a reference fuel supply interval Tb (see FIG 8th ) based on the target fuel supply amount Q and the engine speed Ne with reference to the map shown in FIG 4 shown is calculated. The map for calculating the reference fuel supply interval is also plotted with experimental data and calculation data on the relationship between the target fuel supply amount Q and the engine speed Ne and the reference fuel supply interval Tb. The ROM 102 in the ECU 100 saves this map in advance. At step ST2, a reference exhaust temperature (ambient temperature of the additional fuel valve 25 ) are also obtained when the reference fuel supply interval Tb is calculated.

At step ST3, the correction coefficient of the fuel supply interval is used, which is used to correct the fuel supply interval, based on the temperature of the distal end of the additional fuel valve 25 calculated.

More specifically, based on the difference between the reference exhaust gas temperature obtained at ST2 and the actual exhaust gas temperature (change in the exhaust gas temperature ΔTh), the correction coefficient of the fuel supply interval eminttemp will be described with reference to FIG 5 calculated map shown. The map for calculating the correction coefficient of the fuel supply interval shown in FIG 5 is plotted on the basis of experimentally obtained data and calculation data on the relationship between the variation of the exhaust gas temperature ΔTh and the correction coefficient of the fuel supply interval eminttemp. The ROM 102 in the ECU 100 saves this map in advance. The correction coefficient of the fuel supply interval eminttemp is preset as a smaller value while the variation of the exhaust gas temperature ΔTh increases. While the correction coefficient of the fuel supply interval eminttemp, which is calculated based on the temperature of the distal end of the additional fuel valve, is reduced, the fuel supply interval becomes shorter.

It should be noted that the exhaust gas temperature (ambient temperature of the additional fuel valve 25 ) using a specific map to calculate the exhaust gas temperature can be calculated. The map may use experimentally determined data and calculation data about an engine speed Ne, an intake temperature, an atmospheric pressure and so on as parameters. The ROM 102 in the ECU 100 can save this map in advance. Alternatively, an exhaust gas temperature sensor may be provided to adjust the exhaust gas temperature upstream of the exhaust gas turbocharger 5 to record and submit.

at Step ST4 becomes the correction coefficient of the fuel supply interval emintpm, which is used to correct the fuel delivery interval, based on the variation of the amount of PM emissions due to changes in the area or during transient driving conditions.

Especially will be first an air volume ratio and a λ (excess air ratio) correction coefficient for one Quantity of PM emissions calculated.

A description will now be given of the air volume ratio. The air volume ratio gnr is obtained by dividing the actual intake air volume into the internal combustion engine 1 calculated based on the output signal of the air flow meter 32 is obtained by the reference intake air volume via a flat road running condition (air volume ratio gnr = intake air volume divided by reference intake air volume).

Next, a description will be given of the calculation of the λ correction coefficient for an amount of PM emissions. Based on the air volume ratio gnr calculated in the aforementioned process and the atmospheric pressure (detected value) based on the output of the atmospheric pressure sensor 39 is obtained, the λ correction coefficient emgpmlmd for a set of PM emissions with reference to a map of 6 calculated. The λ correction coefficient map of 6 is plotted with experimentally obtained data and calculation data on the λ correction coefficient using the air volume ratio gnr and the atmospheric pressure as parameters. The ROM 102 in the ECU 100 saves this map in advance. The λ correction coefficient emgpmlmd increases with the reduction of the air volume ratio gnr and the atmospheric pressure.

Based on the λ correction coefficient emgpmlmd thus calculated, the correction coefficient of the fuel supply interval emintpm is determined by referring to a map of FIG 7 calculated. The map for calculating the correction coefficient of the fuel supply interval shown in FIG 7 is plotted with experimentally obtained data and calculation data on the relationship between the λ correction coefficient emgpmlmd and the correction coefficient of the fuel supply interval emintpm. The ROM 102 in the ECU 100 saves this map in advance. The correction coefficient of the fuel supply interval emintpm is preset as a smaller value because the variation of the amount of PM emissions (λ correction coefficient emgpmldm) increases. As the correction coefficient of the fuel supply interval emintpm decreases, the fuel supply interval becomes shorter.

In steps ST5 to ST7, the correction coefficient of the fuel supply interval eminttemp calculated in step ST3 is compared with the correction coefficient of the fuel supply interval emintpm calculated in step ST4. The lower value of the two is selected, that is, the one resulting in a larger amount of fuel supply per unit time. In particular, when the correction coefficient of the fuel supply interval eminttemp that of the temperature of the distal end of the additional fuel valve 25 is smaller than the correction coefficient of the fuel supply interval emintpm, which depends on the variation of the amount of PM emissions (if the result of the determination in step ST5 is true), the correction coefficient eminttemp is selected as a correction coefficient of the target fuel supply interval emintad (step ST6 ). On the contrary, if the correction coefficient of the fuel supply interval emintpm is less than the correction coefficient of the fuel supply interval eminttemp (if the result of the determination in step ST5 is false), the correction coefficient emintpm is selected as a correction coefficient of the target fuel supply interval emintad (step ST7).

at Step ST8 becomes the correction coefficient of the target fuel supply interval emintad selected at step ST6 or ST7 with the reference fuel supply interval, calculated at step ST2 multiplied by a target fuel supply interval to obtain (target fuel supply interval = [Reference Kraftstoffzuführintervall before correction] × emintad). Then the routine ends.

According to the correction process of the fuel supply interval, either the correction coefficient of the fuel supply interval eminttemp or emintpm is selected to correct the target fuel supply interval. Specifically, the correction coefficient resulting in a shorter fuel supply interval (a larger amount of fuel supply per unit time) is selected. This allows the fuel supply interval to become a respective one of the conditional changes in which the likelihood is greater that a blockage of the injection hole of the additional fuel supply valve 25 is corrected accordingly; the temperature of the distal end of the additional fuel valve 25 increases or the amount of PM emissions increases due to changes in the environment or during transient driving conditions. This will block the injection port of the additional fuel valve 25 effectively prevented. In addition, according to the correction process of the fuel supply interval, a fuel supply amount (fuel supply amount per unit time) corresponding to the above specific condition change is provided. This maintains a fuel economy over the case where the fuel supply amount is adjusted when the amount of PM emissions reaches the maximum value of allowable fluctuation.

Although, by increasing the fuel supply amount per unit time, plugging of the injection port of the additional fuel valve 25 is prevented, the fuel also reacts with the oxygen in the catalyst, which may cause the catalyst temperature exceeds a certain range of values (eg, 750 ° C). An approach to avoid such a situation is provided below. The temperature of the DPNR catalyst 4b is estimated based on the exhaust gas temperature passing through the exhaust temperature sensor 35 is detected. When the estimated catalyst temperature is greater than or equal to a prescribed temperature, the fuel supply amount per unit time is reduced in accordance with the estimated catalyst temperature (specifically, a variation of the catalyst temperature with respect to a preset value). Thus, an excessive increase in the catalyst temperature is prevented. It is noted that the prescribed temperature for the catalyst temperature may be empirically determined by taking into account the particular range of catalyst temperature (eg, 750 ° C).

In one approach to reducing the fuel delivery rate per unit time, the fuel delivery duration per interval that may occur in 8th is shown to be shortened while the target fuel supply interval remains unchanged after the Kraftstoffzuführintervall has been corrected. By this approach, not only a shorter Kraftstoffzuführintervall is ensured, whereby a blockage of the injection port of the additional fuel valve 25 is prevented, but also ensures a lower total Kraftstoffzuführmenge. Thus, while preventing an excessive increase in the catalyst temperature, there is also a blockage of the injection port of the additional fuel valve 25 prevented.

To prevent an excessive increase in the catalyst temperature, the following approach can also be considered. The temperature of the DPNR catalyst 4b can be estimated based on the exhaust gas temperature passing through the exhaust temperature sensor 35 is detected. Then, based on the estimated actual catalyst temperature and the target fuel supply interval, the increase in the catalyst temperature resulting from the fuel supply in a target fuel supply interval is estimated. A restrictive correction or increase in the fuel supply amount per unit time is performed so that the estimated catalyst temperature does not exceed a prescribed value (a value determined based on the maximum allowable catalyst temperature).

It is a further description of another embodiment. In the embodiment described above, one of the respective Correction coefficients of the fuel supply interval, eminttemp or emintpm, used to set the target fuel delivery interval to determine. The invention is based on the above embodiment limited. Instead, the desired fueling interval may be using of only the correction coefficient of the fuel supply interval emintpm be calculated.

Also in the above-described embodiment, the reference fuel supply interval Tb is multiplied by the correction coefficient of the fuel supply interval, eminttemp or emintpm, to correct the fuel supply amount. Alternatively, the reference fuel supply duration per interval (see 8th ) may be multiplied by the correction coefficient of the fuel supply interval, eminttemp or emintpm, to correct the fuel supply amount per unit time. In order to correct the reference fuel supply period per interval, the correction coefficient eminttemp of the fuel supply interval is set larger as the variation of the exhaust gas temperature ΔTh increases. Moreover, the correction coefficient emintpm of the fuel supply interval is set larger, while the variation of the amount of PM emissions (λ correction coefficient emgpmlmd) increases.

In the embodiment described above, the correction coefficient eminttemp of the Kraftstoffzuführintervall, the temperature of the distal end of the additional fuel valve 25 is calculated based on the variation of the exhaust gas temperature ΔTh. Alternatively, the correction coefficient eminttemp of the fuel supply interval may be based on the coolant temperature of the internal combustion engine 1 calculated from a signal provided by the water temperature sensor 31 is issued, where on the map of 9 Reference is made.

In The embodiment described above is a four-cylinder diesel engine equipped with direct injection with the exhaust gas purification system according to the invention. However, the invention is not limited to this embodiment. alternative can other diesel engines with any number of cylinders, such as B. a six-cylinder diesel engine with direct injection, also equipped with the exhaust gas purification system according to the invention be. About that however, the invention is for use with diesel engines limited to direct injection, but it can also be applied to other types of diesel engines become. Furthermore, the invention can not only be applied to vehicle engines, but also at for used for other purposes internal combustion engines.

In the embodiment described above, the catalytic converter includes 4 the NOx storage reduction catalyst 4a and the DPNR catalyst 4b , Alternatively, the catalytic converter 4 a DPF in addition to the NOx storage reduction catalyst 4a or an oxidation catalyst.

Although the invention with reference to exemplary embodiments It is noted that the invention not to the described embodiments and constructions limited is. In contrast, the invention is intended to be various modifications and corresponding arrangements. In addition, there are others Combinations and configurations that have more or less elements or only a single element, also within the scope of protection of the invention, although the various elements of the embodiments are shown in various combinations and configurations.

Claims (20)

Emission control system with a catalyst ( 4 ), which in an exhaust pipe of an internal combustion engine ( 1 ) and an additional fuel valve ( 25 ) which supplies a fuel to the exhaust pipe, characterized in that the system comprises the following features: 100 ) for adjusting an additional amount of fuel supplied by the additional fuel valve ( 25 ) is supplied based on a variation of an amount of particles from a combustion chamber of the internal combustion engine ( 1 ) is emitted. An exhaust gas purification system according to claim 1, wherein the adaptation device ( 100 ) adjusts the additional amount of fuel supplied by the additional fuel valve ( 25 ) is supplied to the exhaust pipe per unit time. An exhaust gas purification system according to claim 2, wherein the adaptation device ( 100 ) multiplies a reference fuel supply interval by a correction coefficient that depends on the variation of the amount of the emitted particulates to determine a target fuel supply interval. An exhaust gas purification system according to claim 3, wherein the adaptation device ( 100 ) multiplies the reference fuel supply interval by a correction coefficient to change the fuel supply interval to determine the target fuel supply interval when an actual intake air volume into the internal combustion engine ( 1 ) is less than a reference suction volume. The exhaust gas purification system of claim 1, wherein: the adapter ( 100 ) adjusts a fuel supply interval of a fuel supplied from the additional fuel valve ( 25 ) is supplied to the exhaust pipe per unit time. An exhaust gas purification system according to claim 5, further comprising: a temperature estimating means for an additional fuel valve ( 25 ) for estimating a temperature of the additional fuel valve ( 25 ), the fitting device ( 100 ) compares a first correction coefficient with a second correction coefficient, wherein the first correction coefficient is used to change the fuel supply interval when the actual intake air volume into the internal combustion engine ( 1 ) is less than the reference intake air volume, wherein the second correction coefficient is used to change the fuel supply interval when the estimated temperature of the additional fuel valve ( 25 ), and wherein the reference fuel supply interval is multiplied by the correction coefficient from the first or the second correction coefficient giving a shorter fuel supply interval to determine the target fuel supply interval. An exhaust purification system according to any one of claims 1 to 6, further comprising: a catalyst temperature detecting means (15); 36 ) for detecting a temperature of the catalyst ( 4 ), the fitting device ( 100 ) reduces the additional amount of fuel per unit time according to the detected catalyst temperature when the detected catalyst temperature is greater than or equal to a preset value. An exhaust purification system according to any one of claims 1 to 6, further comprising: a catalyst temperature detecting means (15); 35 ) for detecting a temperature of the catalyst ( 4 ), the fitting device ( 100 ) reduces the additional amount of fuel per unit time according to the detected catalyst temperature when the variation in the detected catalyst temperature is greater than or equal to a preset value. The exhaust gas purifying system according to any one of claims 1 to 6, further comprising: coolant temperature detecting means (16); 31 ) for detecting a coolant temperature in the internal combustion engine 1 ), the fitting device ( 100 ) reduces the additional amount of fuel per unit time according to the detected catalyst temperature when the variation of the detected coolant temperature is greater than or equal to a preset value. Exhaust gas purification system according to one of claims 7 to 9, wherein a fuel injection amount per unit time by shortening the Kraftstoffzuführintervalls is reduced while the fuel delivery time is reduced per interval. An exhaust purification system according to any one of claims 1 to 10, wherein the internal combustion engine ( 1 ) is a diesel engine. An exhaust purification system according to any one of claims 1 to 11, wherein the internal combustion engine ( 1 ) is mounted in a vehicle. Exhaust gas purification method, which is a fuel of an exhaust pipe for an internal combustion engine ( 1 ), wherein the exhaust pipe is arranged therein a catalyst ( 4 ), characterized in that the method comprises the steps of: adjusting an additional quantity of fuel supplied by the additional fuel valve ( 25 ) based on a variation of the amount of particulates coming from a combustion chamber of the internal combustion engine ( 1 ) is emitted is supplied. An exhaust gas purification method according to claim 13, wherein the additional amount of fuel supplied by the additional fuel valve ( 25 ) is supplied to the exhaust pipe per unit time, is adjusted to adjust the additional amount of fuel. An exhaust gas purification method according to claim 14, wherein a reference fuel supply interval is multiplied by a correction coefficient derived from the Variation of the emitted particulate amount depends on a target Kraftstoffzuführintervall to determine the extra Adjust fuel quantity. The exhaust purification method according to claim 15, wherein the reference fuel supply interval is multiplied by a correction coefficient that adjusts the fuel supply interval to determine the target fuel supply interval when an actual intake air volume into the combustion engine. 1 ) is less than a reference intake air volume to adjust the amount of fuel. An exhaust gas purification method according to claim 13, wherein the amount of fuel is an interval of a fuel discharged from the additional fuel valve (10). 25 ) is supplied to the exhaust pipe. The exhaust gas purification method according to claim 17, further comprising the steps of: estimating a temperature of the additional fuel valve (FIG. 25 ), wherein a first correction coefficient and a second correction coefficient are compared with each other, wherein the first correction coefficient is used to change the fuel supply interval when the actual intake air volume into the internal combustion engine ( 1 ) is less than the reference intake air volume, and wherein the second correction coefficient is used to change the fuel supply interval when the estimated temperature of the additional fuel valve ( 25 ), and wherein the reference fuel supply interval is multiplied by the correction coefficient of the first or second correction coefficient giving a shorter fuel supply interval, whereby the target fuel supply interval is determined. An exhaust gas purification method according to any one of claims 13 to 18, further comprising the steps of: Detecting the catalyst temperature, in which the extra Fuel quantity per unit time is reduced if the detected Catalyst temperature is greater or is equal to a preset value to the additional Adjust fuel quantity. An exhaust gas purification method according to claim 19, wherein a fuel injection amount per unit time by shortening the Kraftstoffzuführintervall is reduced while the fuel delivery time is reduced per interval.