DE102008008492A1 - Internal combustion engine arrangement e.g. diesel engine arrangement, controlling method for motor vehicle, involves opening low pressure exhaust gases recycling pipeline by opening exhaust gases recycling-control valve - Google Patents

Abstract

The method involves determining exhaust gas temperature using an exhaust gas temperature sensor (9) when the exhaust gas temperature lies below a constant limit value in a cold running phase, where the temperature of the cold running phase ranges between 200 degree Celsius and 300 degree Celsius. A cooling agent circuit (58) is closed by actuating cooling agent circuit-control elements (32, 33). A low pressure exhaust gas recycling pipeline (54) is opened by opening an exhaust gas recycling-control valve (2).

Description

The The invention relates to a method for controlling a cold running phase a motor vehicle engine assembly.

modern Internal combustion engine arrangements are adjacent to the internal combustion engine and a coolant circuit with a control for on-demand coolant flow control to Cooling the Internal combustion engine on other ancillaries, the various Have functions. In particular, in internal combustion engines is always frequently a charge air supercharger with a drive turbine in the exhaust stream and and a compressor turbine provided on the charge air side.

Further is used for exhaust gas purification in both diesel and gasoline internal combustion engines Catalytic converter provided, usually before the inlet of the Catalytic converter is associated with an exhaust gas temperature sensor. Further is to reduce in particular of nitrogen oxides low pressure exhaust gas recirculation with an exhaust gas recirculation line from the engine exhaust side in the flow direction behind the catalytic converter to the charge air side in the flow direction provided in front of the compressor turbine. The gas flow through the exhaust gas recirculation line let yourself through an exhaust gas recirculation control valve Taxes.

The Requirements for reducing pollutant emissions from internal combustion engine arrangements rise constantly. By far the most emission-rich phase is that between the start of the cold combustion engine and reaching the operating temperature the internal combustion engine and all aggregates and fluids involved.

at the internal combustion engine arrangements according to the prior art this requirement by appropriate control and regulation of the engine assembly Taken into account. However, refer to the known controls and Regulations for the internal combustion engine assembly essentially on the operation at Operating temperatur.

task The invention is a control method for an automotive engine assembly to create that for a reduction of pollutant emissions ensures as long as the engine arrangement the operating temperature has not reached.

• • Der Kühlmittelkreislauf wird durch Betätigung des Kühlmittelkreislauf-Steuerelementes geschlossen, d. h. das Kühlmittel zum Kühlen des Verbrennungsmotors zirkuliert nicht mehr, sondern steht jedenfalls weitgehend still. Hierdurch werden während der Kaltlaufphase der Verbrennungsmotor und alle Aggregate, die darüber hinaus im Kühlmittelstrom angeordnet sind, nicht aktiv gekühlt. Das Kühlwasser entzieht dem Verbrennungsmotor und den von ihm darüber hinaus durchströmten Aggregaten nur ein unvermeidliches Minimum an Wärme. Auf diese Weise wird der Verbrennungsmotor durch den Verbrennungsprozess schnellstmöglich erwärmt und werden insbesondere auch die entstehenden Verbrennungsgase geringstmöglich durch den Verbrennungsmotor gekühlt. Im Ergebnis weisen die aus dem Abgas-Auslass des Verbrennungsmotors austretenden Gase eine höhere Temperatur auf, als dies bei bereits zirkulierendem Kühlmittel der Fall wäre.
• • Ferner wird während der Kaltlaufphase das Abgasrückführungs-Steuerventil der Niederdruck-Abgasrückführung geöffnet. Das aus dem Abgaskatalysator austretende Abgas wird mit der größtmöglichen Rate zurückgeführt auf die Ladeluftseite der Verbrennungsmotoranordnung. Hierdurch werden jedenfalls ein Teil des Abgases und damit jedenfalls ein Teil der Abgas-Wärme in die Ladeluftseite eingespeist. Die Wärme des aus dem Abgaskatalysator austretenden Abgases geht also nicht vollständig verloren, sondern wird zu einem erheblichen Teil der Ladeluft zugeführt, so dass diese Wärme der Verbrennungsmotoranordnung erhalten bleibt.

This object is achieved in that after starting the engine continuously the exhaust gas temperature is determined with the exhaust gas temperature sensor. As long as the exhaust gas temperature determined with the exhaust gas temperature sensor is below a constant limit of over 200 ° C, the cold running phase continues, and the following measures are carried out:

• • The coolant circuit is closed by actuation of the coolant circuit control, ie the coolant for cooling the engine no longer circulates, but is at least largely quiet. As a result, during the cold running phase of the internal combustion engine and all units, which are also arranged in the coolant flow, not actively cooled. The cooling water draws the internal combustion engine and the power from him through aggregates only an unavoidable minimum of heat. In this way, the internal combustion engine is heated as quickly as possible by the combustion process and, in particular, the resulting combustion gases are cooled as little as possible by the internal combustion engine. As a result, the gases exiting the exhaust gas outlet of the internal combustion engine have a higher temperature than would be the case with already circulating coolant.
• • Furthermore, during the cold running phase, the exhaust gas recirculation control valve of the low-pressure exhaust gas recirculation is opened. Exhaust gas exiting the catalytic converter is returned at the highest possible rate to the charge air side of the engine assembly. In this way, in any case, a part of the exhaust gas and thus at least part of the exhaust gas heat are fed into the charge air side. The heat of the exhaust gas emerging from the catalytic converter is therefore not completely lost, but is supplied to a considerable part of the charge air, so that this heat of the internal combustion engine arrangement is maintained.

In the cold-running phase, in which the exhaust gas temperature is below a constant Limit of more than 200 ° C, the exhaust gas is the only heat carrier. By the two measures, namely Close the Coolant circuit and open the low-pressure exhaust gas recirculation is ensured, that the exhaust as possible heated quickly. In turn, this will be for it ensured that the exhaust gas catalyst as quickly as possible to the threshold temperature heated becomes. The catalytic converter of the prior art starts from physical reasons to work only at temperatures above 200 ° C, d. H. the pollutant emissions to reduce considerably. The limit is approximately equal to the minimum operating temperature of the catalytic converter. For Catalytic converters according to the current state of the art is the Limit value above 250 ° C.

Alternatively to the determination and the evaluation of the exhaust gas temperature to determine the Activity of the catalytic converter, this can also be determined with two λ probes, which are arranged in front of and behind the catalytic converter. If the difference in the oxygen content determined by the λ probes falls below a certain limit value, it is assumed that the catalytic converter is not working, which is a prerequisite for determining the cold-running phase. Instead of the condition relating to the exhaust gas temperature, the condition in this case would be that the difference of the oxygen concentrations determined by the two λ probes before and after the catalytic converter falls below a limit which indicates a non-exhaust gas purifying effect of the catalytic converter. In any case, the non-activity of the catalyst should be noted for the determination of the cold-start phase.

By the two described method steps, namely the closing of the Coolant circuit and opening the low-pressure exhaust gas recirculation is a heat or thermal management realizes that in the cold running phase, the fastest possible heating of the Has exhaust gas to the goal, since in this way the exhaust gas catalyst in shortest potential Time reaches its minimum operating temperature. In this way is achieved at a cold start, especially at low Outside temperatures the Pollutant emissions in the exhaust gas are reduced as quickly as possible.

To the internal combustion engine, the accessories and fluids the operating temperature have reached pass on small gasoline engines only a few minutes. During this time, however, up to 90% of the normed Driving cycles measured pollutant emissions. Because the nominal exhaust values of internal combustion engine assemblies or motor vehicles with specified Driving cycles are determined, and the cold running phase, for example at the for valid in the EU area NEDC has a relatively high share, especially in a huge Combustion engine significantly to the balanced pollutant emission contributes wear this heat-optimized thermal management and thus the fastest possible warming of the catalytic converter significantly to improve the nominal emissions of pollutants.

The Coolant circuit control in the coolant circuit can be used as a valve and / or as a coolant pump be realized. Size Benefits here can provide an electric coolant pump through Shutdown easily the coolant circuit, though not completely, close enough can. additional a corresponding valve can be arranged in the coolant circuit be that any significant flow within the coolant circuit in derogation. The decisive factor is that when the coolant circuit is closed by appropriate operation the coolant circulation control the coolant no longer circulating appreciably.

Especially in diesel internal combustion engines, the exhaust gas has relatively low temperatures, so that warming the internal combustion engine and the aggregates and the fluids relative takes long. Especially with big ones Diesel internal combustion engines will with the described control strategy the time until the exhaust gas catalyst reaches its working temperature, considerably shortened and in the normalized driving cycle determined exhaust gases significantly reduced.

According to one preferred embodiment, the limit is in a range between 250 and 300 ° C. conventional Catalytic converters of the prior art start at a Operating temperature of about 270 degrees to 280 ° C to work. The heat-optimized Control of the coolant circuit and the low-pressure exhaust gas recirculation is only then stops when an exhaust temperature of at least 250-300 ° C is.

According to one preferred embodiment, the internal combustion engine arrangement a high pressure exhaust gas recirculation line from the exhaust outlet of the internal combustion engine and before the catalytic converter to the charge air side behind the compressor turbine. According to the present Procedure is during the cold running phase of the internal combustion engine arrangement in such a Arrangement provided, the high-pressure exhaust gas recirculation control valve, the High-pressure exhaust gas recirculation line opens, closes and regulates, during the Cold running phase to close. Because the high pressure exhaust gas recirculation line in the flow direction Exhaust gas heated in front of the catalytic converter in the internal combustion engine branches off, would come the branched off exhaust first not directly the warming the catalytic converter to good. Therefore, if provided a high pressure exhaust gas recirculation line is while the cold running phase, the control valve of the high-pressure exhaust gas recirculation closed be.

According to one preferred embodiment, the internal combustion engine arrangement a charge air cooler between the compressor turbine and the charge air inlet of the internal combustion engine on. The intercooler is a bypass with a control valve for on-demand bypass assigned to the intercooler. While During the cold run phase, the bypass control valve is open, allowing the charge air not through the intercooler flows, but bypasses it by the bypass. That way, one becomes unnecessary Cooling the charge air in the intercooler avoided and the charge air is withdrawn so little heat, as possible is.

Both the drive turbine and the tur binenartigen compressor of the charge air supercharger can be assigned to each bypass with a bypass valve, which serve essentially to limit the pressure. The drive turbine removes heat from the exhaust gas. The compressor initially has the same temperature as the charged charge air during cold start. During operation, the compressor turbine heats the charge air through the compression.

If the internal combustion engine arrangement an exhaust manifold with a to a separate Cooling circuit or to the engine coolant circuit connected cooling device and a controller for controlling the coolant supply of the coolant device the control becomes the exhaust manifold cooling device while the cold run phase closed around the exhaust not unnecessarily much Heat too revoke.

Basically for all Heat exchanger of Combustion engine assembly that they are not in operation. Examples for further Heat exchangers are Engine oil heat exchangers or transmission oil heat exchangers, the one oil pipe, have an exhaust pipe and / or a coolant line. All cooling functions the combustion engine assembly are so turn off, so that all usable heat the engine and the catalytic converter is supplied.

In the following an embodiment of the invention is explained in more detail with reference to the drawing:
The drawing shows a schematic representation of an internal combustion engine arrangement.

In the figure is schematically a complex internal combustion engine arrangement 50 shown. In the arrangement 50 All essential components are shown, which are around the internal combustion engine 1 around with the charge air, the exhaust gas, several coolant circuits as well as two oil circuits.

Fresh charge air is through an air filter 5 sucked in and then passes an air mass meter 4 , The sucked charge air then enters a charge air supercharger 64 one in which they are in a turbine-like compressor 3 possibly compressed. The charge air then flows to a cooled with a coolant intercooler 38 which has a bypass 52 with a bypass valve 35 assigned. From there, the charge air flows through the gas control valve 42 in the form of a throttle to a mixer 43 in which the charge air is possibly mixed with recirculated exhaust gas from the high-pressure exhaust gas recirculation.

From the mixer 43 the charge air reaches via the intake manifold 34 and through a charge air inlet 94 in the internal combustion engine 1 , There, the charge air is enriched with fuel, and ignited the mixture obtained in this way. The resulting exhaust gas flows from an exhaust outlet 95 from the internal combustion engine 1 out.

That from the outlet 95 Exhaust gas is emitted in a water-cooled exhaust manifold 11 cooled and flows with its main stream on to a drive turbine 12 the charge air charger 64 , The drive turbine 12 drives the compressor turbine 3 at. The drive turbine 12 is a bypass 68 with a bypass valve 60 and the compressor turbine 3 is a bypass 66 with a bypass valve 61 assigned. From the charge air charger 64 Coming the exhaust gas passes an exhaust gas temperature sensor 9 , which is just before a catalytic converter 8th is arranged. From the catalytic converter 8th the exhaust gas flows through a first gas control valve 7 and a second gas control valve 6 in an exhaust, not shown. The stream of gas shown here is the main gas stream from the inlet of the air filter to the outlet into a muffler or exhaust.

This main gas flow has three branches, namely a low-pressure exhaust gas recirculation, a high-pressure exhaust gas recirculation and a branch for the supply of two three-way heat exchangers 21 . 26 ,

The low pressure exhaust gas recirculation is from a pipe 54 formed in the exhaust branch between the catalytic converter 8th and the first gas control valve 7 branches off and in its course an exhaust gas recirculation control valve 2 having. This exhaust gas recirculation line 54 discharges into the charge air line in front of the charge air supercharger 64 ,

Furthermore, a high-pressure exhaust gas recirculation is provided, wherein the high-pressure exhaust gas recirculation line 56 on the exhaust side between the water cooled exhaust manifold 11 and the charge air charger 64 branches. After the branch is in the course of the line 56 an exhaust gas mass and temperature sensor 13 arranged, which detects the exhaust gas mass and the exhaust gas temperature at this point. The exhaust stream then flows through a high pressure exhaust gas recirculation cooler 15, which is a gas control valve 16 upstream. Furthermore, it is parallel to the radiator 15 a bypass 15 ' provided by the exhaust gas bypassing the radiator 15 can flow when the relevant gas control valves 16 . 17 . 18 are closed or opened accordingly. In the high pressure exhaust gas recirculation cooler 15 can that be through the pipe 56 recirculated exhaust gas can be cooled if necessary to the thermal load of the internal combustion engine 1 and reduce the lying in the main exhaust stream units, and to reduce nitrogen oxides in the exhaust gas.

In the flow direction behind the radiator 15 is in the course of the line 56 a high pressure exhaust recirculation cooler sensor 19 arranged, with the help of the cooling capacity of the exhaust gas recirculation cooler 15 can be regulated. The exhaust gas flows from there into the mixer 43 in which the charge air with the exhaust gas from the high-pressure exhaust gas recirculation line 56 is mixed.

Another exhaust pipe 70 branches in the exhaust main flow between the first gas control valve 7 and the second gas control valve 6 to the two three-way heat exchangers 21 . 26 from. In the first three-way heat exchanger 21 can be heated with the help of the warm exhaust gas, a target medium and cooled with the help of the also supplied coolant the same target medium as needed. Both three-way heat exchangers therefore have not only their exhaust gas inlets but also inlets for the coolant. The first three-way heat exchanger is via a lubricant supply line 80 and derivation 81 connected to corresponding lubricant connections of the internal combustion engine 1 , In the first three-way heat exchanger 21 Thus, the internal combustion engine lubricant is cooled by the cooling water or heated by the exhaust gas when needed.

The second three-way heat exchanger 26 is via a lubricant supply line 83 and a lubricant discharge 84 with a gear 62 connected. Through the lubricant supply and drain 83 . 84 and the associated three-way heat exchanger 26 If necessary, the gear lubricant can be cooled or heated. This is particularly useful in automatic transmissions, in which the amount of lubricant can often be 10 liters and more, and of which at low lubricant temperature, a high portion of the drive power is absorbed, and too high a slip occurs at too high a temperature.

In the present case, two coolant circuits are provided, namely a first high-temperature coolant circuit 58 and a second low temperature circuit 59 , The low temperature circuit 59 serves to cool the intercooler 38 and has for this purpose a low-temperature radiator 45 and a low temperature coolant pump 41 on.

The high-temperature coolant circuit 58 has a cooler 46 , a coolant pump 33 and a variety of lines and valves. The main coolant flow is from the radiator 46 coming from a coolant line 88 to the coolant pump 33 when operating the coolant in the internal combustion engine 1 inflated. That from the internal combustion engine 1 escaping coolant flows through a coolant control valve 32 back to the radiator 46 ,

Between the coolant outlet of the internal combustion engine 1 and the coolant control valve 32 branch several coolant lines to the exhaust manifold radiator 11 , the high pressure exhaust gas recirculation cooler 15 , to the first three-way heat exchanger 21 and to the second three-way heat exchanger 26 from there each to the radiator cooler 46 flow back.

The coolant flows are controlled by control valves 10 . 14 . 20 . 90 controlled or regulated as needed.

In the course of the lubricant lines 80 . 81 . 83 . 84 are each in front of and behind the three-way heat exchangers 21 . 26 temperature sensors 22 . 24 . 27 . 28 arranged, with the help of the relevant lubricant temperature can be controlled.

The two coolers 45 . 46 The two coolant circuits are cooled by outside incoming cooling air 64 cooled by a closable cooling air blind 44 passes through.

The cold running phase of the internal combustion engine runs as follows: The cold running phase is defined by the exhaust gas temperature, that of the exhaust gas temperature sensor 9 in front of the catalytic converter 8th is measured. The cold running phase lasts as long as that of the exhaust gas temperature sensor 9 measured temperature is below 280 ° C. During the cold-running phase, the coolant circuit is activated by actuation of the coolant circulation control element, in this case by the coolant pump 33 is formed, closed. In this way it is ensured that no appreciable flow of coolant flows through the coolant lines. In particular, the internal combustion engine 1 not significantly active cooled. Also all other accessories supplied with coolant ancillaries, so the exhaust manifold 11 , the high pressure exhaust gas recirculation cooler 15 and the two three-way heat exchangers 21 . 26 are not actively cooled, which is done by closing the relevant control valves 10 . 14 . 20 . 90 is realized.

Further, the coolant control valve 32 closed, the return flow of the coolant to the cooling water cooler 46 controls. Also this control valve 32 represents an alternative or supplementary refrigerant circuit control element in the sense of the claims. As a second important measure during the cold-running phase, the low-pressure exhaust gas recirculation by opening the exhaust gas recirculation control valve 2 open. This can be achieved by the low-pressure exhaust gas recirculation line 54 the exhaust from a branch behind the catalytic converter 8th and pressure increased by the subsequent throttling gas control valve 7 be returned and fed into the charge air line 92 between the compressor turbine 3 and the intercooler 38 , In this way, the residual heat, which from the exhaust catalyst 8th exiting exhaust still has, fed back to a large extent the charge air, so that this heat is not lost. As a result, a total of faster heating of the in the catalytic converter 8th incoming exhaust gas reaches, so that the exhaust catalyst 8th faster reaches its operating temperature of about 270 to 280 ° C, starting from the catalytic converter a large part of the internal combustion engine 1 helps to convert exiting harmful emissions into harmless emissions.

During the cold running phase, the high pressure exhaust gas recirculation remains closed, which in particular by closing all the control valves 16 . 17 . 18 in the pipes 56 the high-pressure exhaust gas recirculation is realized.

Claims (4)

Method for controlling a motor vehicle internal combustion engine arrangement ( 50 ) with an internal combustion engine ( 1 ) with a charge air inlet ( 94 ) and an exhaust outlet ( 95 ), a charge air charger ( 64 ) with a drive turbine 12 and a compressor ( 3 ), a coolant circuit ( 58 ) with a control ( 32 . 33 ) to the coolant flow control for the required cooling of the internal combustion engine ( 1 ), one with the outlet ( 95 ) associated exhaust gas catalyst ( 8th ), an exhaust gas temperature sensor ( 9 ) in front of the catalytic converter ( 8th ), a low-pressure exhaust gas recirculation line ( 54 ) from the exhaust side behind the catalytic converter ( 8th ) to the charge air side behind the compressor turbine ( 3 ), and an exhaust gas recirculation control valve ( 2 ) for controlling the exhaust gas flow through the exhaust gas recirculation line ( 54 ), with the method steps: determination of the exhaust gas temperature with the exhaust gas temperature sensor ( 9 ), if the exhaust gas temperature in the cold-running phase is below a constant threshold: closing the coolant circuit ( 58 ) by actuation of the coolant circulation control element ( 32 . 33 ), and opening the low-pressure exhaust gas recirculation line ( 54 ) by opening the exhaust gas recirculation control valve ( 2 ). Method for controlling a motor vehicle internal combustion engine arrangement ( 50 ) according to claim 1, characterized in that the cold-running phase at an exhaust gas temperature above a limit of 200 ° C, and preferably at a threshold between 250 and 300 ° C. Method for controlling a motor vehicle internal combustion engine arrangement ( 50 ) according to claim 1 or 2, with a high-pressure exhaust gas recirculation line ( 56 ) from the outlet ( 95 ) and in front of the drive turbine ( 12 ) to the charge air side behind the compressor ( 3 ), with the method step: closing the high-pressure exhaust gas recirculation control valve ( 18 ) during the cold running phase. Method for controlling a motor vehicle internal combustion engine arrangement ( 50 ) according to one of claims 1 to 3, wherein the arrangement ( 50 ) an intercooler ( 38 ) between the compressor turbine ( 3 ) and the inlet ( 94 ), wherein the intercooler ( 38 ) a bypass ( 52 ) with a control valve ( 35 ) for bypassing the intercooler as required ( 38 ), with the method step: opening the bypass control valve ( 35 ) during the cold running phase.