Systems and methods for selective hydrocarbon injection

Abstract

A method of selective hydrocarbon injection in in-cylinder late post injection in an exhaust manifold of a diesel engine comprises providing the exhaust manifold of the diesel engine comprising a plurality of cylinders, an exhaust gas recirculation valve disposed adjacent the exhaust manifold, a diesel particulate filter disposed adjacent the exhaust manifold, an exhaust gas recirculation cooler disposed adjacent the exhaust manifold offset from the exhaust gas recirculation valve, and an engine control unit operatively connected with the diesel engine for controlling at least the plurality of cylinders. At least a first cylinder is disabled via the engine control unit to reduce post injection of hydrocarbons during regeneration of the diesel particulate filter. The diesel particulate filter is regenerated. In-cylinder late post injection of hydrocarbons is conducted during regeneration of the diesel particulate filter via cylinders other than the first cylinder.

Claims

1. A method of selective hydrocarbon injection in in-cylinder late post injection in an exhaust manifold of a diesel engine, the method comprising the steps of: providing the exhaust manifold of the diesel engine, the diesel engine comprising a plurality of cylinders, an exhaust gas recirculation valve disposed adjacent the exhaust manifold, a diesel particulate filter disposed adjacent the exhaust manifold, an exhaust gas recirculation cooler disposed adjacent the exhaust manifold offset from the exhaust gas recirculation valve, and an engine control unit operatively connected with the diesel engine for controlling at least the plurality of cylinders; disabling at least a first cylinder of the plurality of cylinders closest to the exhaust gas recirculation valve relative to the other cylinders via the engine control unit to reduce post injection of hydrocarbons around and through the exhaust gas recirculation valve from the at least first cylinder during an in-cylinder late post injection of hydrocarbons during regeneration of the diesel particulate filter; regenerating the diesel particulate filter; and conducting in-cylinder late post injection of hydrocarbons during regeneration of the diesel particulate filter via cylinders comprising the plurality of cylinders other than the first cylinder.

2. The method of claim 1 further comprising the step of: disabling a second cylinder of the plurality of cylinders closest to the exhaust gas recirculation valve relative to the other cylinders via the engine control unit to prevent post injection of hydrocarbons from the second cylinder during in-cylinder late post injection during regeneration of the diesel particulate filter.

3. The method of claim 2 further comprising the step of: disabling a third cylinder of the plurality of cylinders closest to the exhaust gas recirculation valve relative to the other cylinders via the engine control unit to prevent post injection of hydrocarbons from the third cylinder during in-cylinder late post injection during regeneration of the diesel particulate filter.

4. The method of claim 3 further comprising the step of: routing exhaust gases from at least one of the remaining plurality of other cylinders to a turbocharger.

5. The method of claim 1 further comprising the steps of: detecting a stationary regeneration event request; and conducting in-cylinder late post injection of hydrocarbons when the stationary regeneration event is requested.

6. The method of claim 1 further comprising the step of: reducing an amount of hydrocarbons through the exhaust gas recirculation cooler during the in-cylinder late post injection of the hydrocarbons compared to when the first cylinder is not disabled.

7. The method of claim 1 further comprising the step of: closing the exhaust gas recirculation valve during an in-cylinder late post injection of the hydrocarbons during the regeneration of the diesel particulate filter.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a diagram of prior art exhaust gas recirculation system for a vehicle; and

(2) FIG. 2 is a chart showing an exemplary methodology for reducing fouling of exhaust components by reducing hydrocarbons near an EGRV of an exhaust gas recirculation system for a vehicle.

DETAILED DESCRIPTION

(3) The present disclosure relates to a method for selective hydrocarbon injection in in-cylinder late post injection of hydrocarbons during regeneration of a diesel particulate filter. Specifically, in stationary diesel particulate filter regeneration, selective restriction of at least one cylinder comprising a diesel engine in in-cylinder late post injection reduces hydrocarbons near an exhaust gas recirculation valve, thereby reducing hydrocarbons passed through to an exhaust gas recirculation cooler or other exhaust components, thereby protecting the same.

(4) Now referring to the figures, FIG. 1 illustrates a prior art exhaust manifold 10 for a diesel engine 5 on a vehicle, such as a truck, a trailer tractor and the like. The exhaust manifold 10 comprises a plurality of cylinders 12, 14, 16, 18, 20, 22, six being shown but more or less cylinders can be used, each having a combustion chamber that is typically utilized to provide power for moving the vehicle. As particulate matter builds on a diesel particulate filter (DPF) disposed adjacent the exhaust manifold 10, a regeneration event is required to clear the particulate matter from the diesel particulate filter and increase life of the diesel particulate filter. Heat is generated using in-cylinder late post injection that delivers hydrocarbons into an exhaust stream. Specifically, additional fuel is injected into combustion chambers of the plurality of cylinders 12, 14, 16, 18, 20, 22 after a power stroke and just before an exhaust stroke of the diesel engine 5. The hydrocarbons of this additional fuel are then catalyzed in a diesel oxidation catalyst to produce heat for the DPF to regenerate, converting the particulate matter soot into ash and gaseous carbon dioxide.

(5) Typically, the in-cylinder late post injection of hydrocarbons occurs during either a stationary or a rolling regeneration event. During a stationary regeneration event, unfavorable conditions cause hydrocarbons to pass an exhaust gas recirculation valve (“EGRV”) 24 disposed adjacent the exhaust manifold 10, causing plugging and fouling of an exhaust gas recirculation cooler (“EGRC”) 26 disposed adjacent the exhaust manifold 10 and offset from the EGRV 24 in an engine exhaust path, indicated by arrow of FIG. 1. During certain diesel engine operating conditions, an engine control unit (ECU) operatively connected with the diesel engine commands the EGRV 24 to be in a closed position to reduce additional hydrocarbons from passing therethrough and fouling exhaust components.

(6) Typically, in-cylinder late post injection induces high differential pressure across the EGRV 24, which may be a cause of leakage of hydrocarbons through the EGRV 24. As the EGRV 24 wears over time, the EGRV 24 may reach a condition such that exhaust pressure against the EGRV 24 exceeds capability of the EGRV 24 to remain closed. Disabling one or more of the plurality of cylinders 12, 14, 16, 18, 20, 22 in the exhaust manifold 10 during a stationary regeneration event may reduce an amount of hydrocarbons near the EGRV 24, thereby reducing hydrocarbons that can pass through the EGRV 24 and foul the EGRC 26 and/or other exhaust components.

(7) FIG. 2 shows one embodiment of a methodology 100 wherein the ECU or other software component of the diesel engine that may disable at least one of the plurality of cylinders 12, 14, 16, 18, 20, 22 during an in-cylinder late post injection. Specifically, in a first step 102, the ECU or other software component may recognize that a “stationary” regeneration event is requested. The ECU or other software may then select at least one of the plurality of cylinders 12, 14, 16, 18, 20, 22 via step 104 to be disabled during the regeneration event so that the selected one of the plurality of cylinders 12, 14, 16, 18, 20, 22 may not be allowed to post inject hydrocarbons during the in-cylinder late post injection via step 106.

(8) For example, the plurality of cylinders 12, 14, 16, 18, 20, 22 may be arranged such that exhaust gases from cylinders 18, 20, 22 may be routed to the EGRV 24. In one embodiment, exhaust gases from cylinders 12, 14, 16 may be routed to a turbocharger (not shown), which may be positioned between third cylinder 16 and fourth cylinder 18. The ECU or other software may select at least one of the plurality of cylinders 12, 14, 16, 18, 20, 22 closest to the EGRV 24 to be disabled via step 104. Specifically, in one embodiment, a cylinder 22 may be selected to be disabled. Alternately, two of the cylinders 20, 22 may be selected to be disabled. Alternately, three of the cylinders 18, 20, 22 may be selected to be disabled. Disabling one or more of the plurality of cylinders 12, 14, 16, 18, 20, 22 may present less hydrocarbons around the EGRV 24 via step 108, thereby reducing passing of the hydrocarbons through the EGRV 24 to the EGRC 26 and/or other exhaust components via step 110.

(9) Although the exhaust manifold 10 is shown and described herein as having six cylinders 12, 14, 16, 18, 20, 22, it should be noted that other embodiments of the methodology 100 may be utilized with an exhaust manifold with any number of cylinders comprising the plurality of cylinders mentioned herein. Moreover, although embodiments of an improved system and embodiments of an improved method described herein are utilized to protect the exhaust gas regeneration cooler 26, other embodiments of an improved system and other embodiments of an improved method can protect another exhaust component, combination of exhaust components or the like as desired.