DE102008039586B4 - Coking counteracting injection system for particulate filter - Google Patents

Abstract

A system comprising: an injection valve (52) for injecting fuel directly into an exhaust system; a control module (32) supplying fuel to the exhaust system using the injector (52) to combust particulate matter in the particulate filter (31) when the control module (32) determines regeneration is required and selectively supplies the fuel operating the injector (52) during periods in which the control module (32) determines that regeneration is not required; an exhaust gas temperature sensor (34) that detects an exhaust gas temperature; and a timer (67) that determines a time since a last injection using the injector (52); characterized in that a degradation module (65) is provided which detects degradation of the injector (52) based on exhaust temperature and time by determining a degradation factor based on the exhaust temperature and the period of time it integrates until greater is a minimum degradation value, with the control module (32) performing the selective delivery of fuel only when the integrated degradation factor value is greater than the degradation minimum value.

Description

Cross-reference to related applications

area

The present invention relates to a system according to the preamble of claim 1 and a correspondingly designed method according to the preamble of claim 4 for ensuring the functionality of a fuel injection valve, with which fuel can be injected into the exhaust system.

Such a system is for example from the JP 2005-106047 A known.

background

Internal combustion engines, such as diesel engines, produce particulates that are typically filtered out of exhaust by a particulate filter (PF). The PF is arranged in an exhaust system of the internal combustion engine. The PF reduces the emission of particulate matter that is generated during combustion. Over time, the PF becomes full and the retained particulate matter must be removed. During regeneration, the particulate matter in the PF is burned.

An engine control system may estimate the deposition of the particulate matter and determine when the filter requires regeneration. Once regeneration is required, the control system allows regeneration by injecting fuel into the exhaust system. The heat released during the combustion of the injected fuel in the diesel oxidation catalyst increases the exhaust gas temperature that burns the retained particulate matter in the PF. In some systems, the injection valves of the internal combustion engine are used to increase fuel by temporarily enriching the fuel / air mixture. The excess fuel in the exhaust gas after combustion is used to raise the temperature of the PF.

Other systems use a fuel injector that is separate from the injectors associated with the fuel system. The injector injects fuel into the exhaust system. Due to coking or deposit formation in fuel injectors exposed to exhaust conditions, performance problems may occur. Thereby, the fuel injectors may have poor durability.

The invention is based on the object of specifying a system and a method, with which the functionality of such a fuel injection device can be ensured permanently.

Summary

This object is achieved by a system having the features of claim 1 and by a method having the features of claim 4.

In other features, an exhaust gas temperature sensor senses an exhaust gas temperature. A timer determines a time since a last injection using the at least one second injector. A degradation module determines a degradation of the at least one second injector based on the exhaust temperature and the time since a last injection using the at least one second injector. The control module selectively releases actuation of the at least one second injector based on release conditions. The release conditions include at least one of: exhaust temperature, engine mode, and a period of time since a last use of the at least one second injector.

Other areas of applicability will be apparent from the description provided herein.

drawings

1 FIG. 10 is a functional block diagram of an exemplary engine system according to the present disclosure; FIG.

2 FIG. 10 is a functional block diagram of a regeneration system according to the present disclosure; FIG.

3 shows an exemplary regeneration injection valve;

4 shows a method for reducing coking deposits; and

5 shows injection quantity as a function of temperature and time.

Detailed description

It should be understood that throughout the drawings, like reference characters designate like or corresponding parts and features. As used herein, the term module refers to an Application Specific Integrated Circuit (ASIC), an electronic circuit, a processor (shared, dedicated, or group), and a memory containing one or more software modules. or perform firmware programs, a combinational logic circuit, and / or other suitable components that provide the described functionality.

The coking and deposit formation described herein may present a problem, particularly in fuel injectors, which are exposed to exhaust conditions and which are relatively rarely used. In these fuel injectors, there may be periods of inactivity during which residual fuel oxidation and polymerization may occur.

Injectors, for example, may be used to facilitate or assist the regeneration of diesel particulate filters (PF). The regeneration interval can be sporadic. For example, the regeneration interval may be as long as several hundred miles. The injector can only be operated as an example only when needed. Typically, the injector may be used every 8-10 hours of operation for about 15-30 minutes. The regeneration intervals described above provide for periods during which problems of deposit formation or fuel coking may occur.

The present disclosure mitigates the degradation of fuel injectors used in the exhaust systems of automotive products. The present disclosure monitors and models the conditions in the vehicle exhaust system. The present disclosure identifies a suitable fuel injector operating schedule for operating the injector that minimizes fuel consumption and emissions control issues while improving fuel injector durability. This allows less expensive hardware and fuel injection components to be used. As can be seen, while the present disclosure describes a diesel engine application, the present disclosure may also be applied to internal combustion engines having a particulate filter and selective catalyst reduction (SCR) with hydrocarbon (HC).

Referring now to 1 includes a vehicle 10 an engine control system. The engine control system 12 includes an internal combustion engine 14 , an intake manifold 16 , a common rail fuel injection system 18 and a turbocharger 27 , The internal combustion engine 14 includes six cylinders 22 in adjacent cylinder banks 24 and 26 and are designed in a V-arrangement.

Even if 1 six cylinders 22 shows, of course, that the internal combustion engine 14 additional or less cylinders 22 may include. For example, engines of 2, 3, 4, 5, 8, 10, 12, and 16 cylinders are contemplated. It is also understood that the internal combustion engine 14 may have a Reihenzylinderauslegung. While a turbocharged diesel engine is shown, the present disclosure also applies to other internal combustion engines, such as naturally aspirated or charged internal combustion engines.

By the by an internal combustion engine turbocharger 27 generated intake negative pressure is air in the intake manifold 16 sucked. From the intake manifold 16 Air gets into the individual cylinders 22 guided and condensed in it. From the common-rail injection system 18 Fuel is injected and the heat of the compressed air ignites the fuel / air mixture. From the cylinders, exhaust gas is through exhaust pipes 28 drained. The exhaust gas drives the turbocharger 27 in the cylinder 22 provides additional air for combustion.

The exhaust gas enters a diesel oxidation catalyst (DOC, abbreviated to the English Diesel Oxidation Catalyst) 30 one facilitating chemical reactions with excess fuel in the exhaust gases. Exhaust gases from the DOC 30 pass through a particulate matter (PM) filter 31 , which withdraws the exhaust stream PM. The exhaust gases exit the PM filter 31 out.

A control module 32 controls the operation of the engine control system 12 , More precisely, the control module controls 32 the engine system sequences based on various parameters. The control module 32 For example, it may be implemented in an engine control module (ECM) or a vehicle computer, or may be an independent controller.

The control module 32 can also perform engine system diagnostics. The control module 32 For example, a proper operation of the DOC 30 check. Furthermore, the control module 32 by oxidizing fuel in the DOC 30 a post fuel injection process for heating the exhaust gases to the PM filter 31 trigger. The control module 32 can be from an inlet temperature sensor 34 , which determines the temperature of exhaust gases at the opening of the DOC 30 detected, receive a temperature signal. The control module 32 can also be from an outlet temperature sensor 36 that captures the temperature of exhaust gases coming out of the DOC 30 exit, receive a temperature signal. The control module 32 can be from an exhaust pressure sensor 37 , which detects the air pressure in the exhaust system, receive a pressure signal.

From a tachometer 38 in the internal combustion engine 14 can the control module 32 receive a speed signal. The control module 32 may be from an engine coolant sensor 39 that has a temperature of coolant in the internal combustion engine 14 detected, receive a temperature signal. From an intake air temperature sensor 40 , the an intake air temperature of the internal combustion engine 14 detected, the control module 32 receive a temperature signal. The control module 32 can be from an ambient pressure sensor 41 that is a pressure of air outside the engine 14 detected, receive a pressure signal. From an air mass sensor 42 detecting a rate at the air in the internal combustion engine 14 flows, the control module can 32 receive an airflow signal. There may be other inputs.

At various times, the control module sends 32 a command to an injection valve 50 To inject fuel into the exhaust system. It can be a valve 52 , For example, a poppet valve used. The control module 32 can arrange fuel when regeneration of the PF 31 is required. The control module 32 can also arrange fuel when regeneration is not required to the injector 50 to press.

Referring now to 2 may be a line from a fuel supply to the injector 50 Feed in fuel. Another line 62 can be an output of the injector with the valve 52 connect, which is disposed adjacent to the exhaust system. The valve 52 and the injection valve 50 may be spaced at a distance D sufficient to allow cooling and damage to the injector 50 due to high exhaust gas temperatures to prevent.

Any suitable valve or injector may be used, including a valve or injector with a low spray nozzle, as described, for example, in US Pat 3 will be shown. In 3 becomes an exemplary valve 52 shown. Only, for example, the valve 52 an upper case 70 , an inner leadership 72 , a valve body 73 , a feather 74 , a needle 76 and a bottom guide 78 include.

Referring now to 4 and 5 the control starts at step 200 , At step 204 the controller polls a fuel degradation factor as a function of exhaust gas temperature and a time since the last injection. In 5 For example, an exemplary relationship between injection amount, time, and temperature is shown. At step 208 the degradation factor is integrated. A new degradation factor is set equal to an old degradation factor plus a new lookup value. The time since the last injection is incremented.

At step 210 the controller determines if the degradation factor is greater than a minimum degradation value. If not, control returns to step 204 back. Otherwise, the controller moves to step 214 continued. At step 214 the controller determines whether the time or the integrated time since the last actuation is greater than a predetermined period of time t _min . If not, control returns to step 204 back. Otherwise, the controller moves to step 218 and checks the release conditions for injector actuation. Exemplary release conditions include exhaust gas temperature, ambient temperature, and catalyst temperature. Other exemplary release conditions may be based on an engine operating mode.

The controller moves from step 218 away, and at step 222 the controller determines whether the exhaust gas temperature is greater than a predetermined temperature temp _min . When step 222 is wrong, the controller returns to step 218 back. When step 222 is correct, the controller provides a predetermined amount of fuel (eg, Q grams) to operate the injector (despite the fact that regeneration is not required). The controller moves to step 230 and fuel degradation factor, injector amount and time since last injection to zero. The controller moves to step 204 continued.

This approach provides an optimal balance between durability, fuel economy and emission control. This control reduces coking by operating the injector during the period in which it is not normally used or needed. The frequency of operation depends u. a. from operating time, temperature and exhaust gas flow rate. The operation is more common under particularly problematic conditions. Overall fuel economy and impact on emissions are negligible while injector durability is improved.

Claims (6)

System comprising: an injection valve ( 52 ) for injecting fuel directly into an exhaust system; a control module ( 32 ), the exhaust system using the injector ( 52 ) Supplies fuel to particulate matter in the particulate filter ( 31 ) burn when the control module ( 32 ) determines that regeneration is required and selectively supplies fuel to the injector ( 52 ) during periods in which the control module ( 32 ) determines that regeneration is not required; an exhaust temperature sensor ( 34 ) detecting an exhaust gas temperature; and a timekeeper ( 67 ), which has been a period since a last injection using the injection valve ( 52 ) determined; characterized in that a degradation module ( 65 ) is provided, which is a degradation of the injection valve ( 52 ) is determined based on the exhaust gas temperature and the period of time by determining a degradation factor based on the exhaust gas temperature and the time period, which it integrates until it is greater than a degradation minimum value, wherein the control module ( 32 ) performs the selective supply of fuel only when the value of the integrated Degradationsfaktors is greater than the Degradationsmindestwert. The system of claim 1, wherein the control module ( 32 ) an injection of fuel using the injector ( 52 ) selectively releases based on release conditions. The system of claim 2, wherein the release conditions of at least one of: exhaust gas temperature, engine mode and a period of time since a last use of the injection valve (FIG. 52 ). Method comprising: providing an injection valve ( 52 ) injecting fuel directly into an exhaust system; Supplying fuel to the exhaust system using the injector ( 52 ) to remove particulate matter in the particulate filter ( 31 ) when a control module ( 32 ) determines that regeneration is required; selective supply of fuel to the injector ( 52 ) during periods in which the control module ( 32 ) determines that regeneration is not required; Detecting an exhaust gas temperature; and determining a period of time since a last injection using the injector ( 52 ); characterized in that a degradation of the injection valve ( 52 ) is determined based on the exhaust gas temperature and the period by determining a degradation factor based on the exhaust gas temperature and the period, which is integrated until it is greater than a Degradationsmindestwert, wherein the selective supply of fuel is carried out only when the Value of the integrated degradation factor is greater than the minimum degradation value. The method of claim 4, further comprising: selectively enabling fuel injection using the injector (10). 52 ) based on release conditions. The method of claim 5, wherein the release conditions of at least one of: exhaust gas temperature, engine mode and a period of time since a last use of the injector ( 52 ).

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