Methods for controlling an engine

Abstract

Method for controlling an engine (12) comprising: an adapted fuel injection timing is generated when a fuel demand is detected and the engine (12) is operating in a transitional state, where the adapted fuel injection timing is based on a base fuel injection timing, an elapsed time since the detection of the fuel request, and a variety of engine operating parameters and where the adjusted fuel injection timing is advanced or retarded relative to the base fuel injection timing; based on the multitude of engine operating parameters, it is determined whether the adapted fuel injection timing is advanced or retarded relative to the base fuel injection timing; a fuel injection is controlled for a period of time based on the adjusted fuel injection timing; and The fuel injection is controlled according to the time duration based on the base fuel injection time, the multitude of engine operating parameters includes throttle position, engine load, engine speed and engine coolant temperature and where a timer is initialized and started when the fuel request is detected, and the timer represents the elapsed time since the fuel request was detected.

Description

AREA

[0001] The present disclosure relates to a method for controlling an engine and in particular a method for controlling a fuel injection timing to reduce emissions during a transitional operation of an engine. BACKGROUND

[0002] Internal combustion engines draw air into an intake manifold through an intake system, which can be regulated by a throttle. The air in the intake manifold is distributed to several cylinders and combined with fuel to create an air / fuel mixture (air / coolant mixture). In spark-ignition direct injection (SIDI) engines, fuel injectors spray the fuel directly into the cylinders. The cylinders contain pistons that compress the air / coolant mixture. Spark plugs generate a spark to ignite the compressed air / coolant mixture in the cylinders, thus driving the pistons. The movement of the pistons rotates a crankshaft, generating drive torque.

[0003] Documents DE 196 46 942 A1, DE 689 05 482 T2, and US 7 475 671 B1 disclose methods for controlling an engine, which include generating an adapted fuel injection timing when a fuel request is received and the engine is operating in a transitional state. The adapted fuel injection timing is based on a base fuel injection timing, an elapsed time since the fuel request, or at least one of a plurality of engine operating parameters. Furthermore, fuel injection is controlled for a duration based on the adapted fuel injection timing, and fuel injection is controlled after a duration based on the base fuel injection timing.

[0004] The invention is based on the objective of providing a method for controlling an engine by which emissions are reduced during transitional operation of the engine.

[0005] The problem underlying the invention is solved by the features of claim 1. Advantageous embodiments and further developments of the invention are specified in the dependent claims. SUMMARY

[0006] A method for controlling an engine comprises generating a modified fuel injection timing when a fuel request is received and the engine is operating in a transitional state, wherein the modified fuel injection timing is based on a base fuel injection timing, an elapsed time since the fuel request, and at least one of a plurality of engine operating parameters; that fuel injection is controlled for a duration based on the modified fuel injection timing; and that fuel injection is controlled after this duration based on the base fuel injection timing. The modified fuel injection timing is advanced or retarded relative to the base fuel injection timing.Based on at least one of the numerous engine operating parameters, it is determined whether the adjusted fuel injection timing is advanced or retarded relative to the base fuel injection timing. These numerous engine operating parameters include throttle position, engine load, engine speed, and engine coolant temperature.

[0007] Further areas of application of the present disclosure will become apparent from the detailed description provided below. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The present revelation will become more understandable with the help of the detailed description and the accompanying drawings, whereby: Fig. 1 a functional block diagram of an engine system according to an implementation of the present disclosure; Fig. 2 a functional block diagram of a control module according to an implementation of the present disclosure; and Fig. 3 a flowchart of a method for controlling a fuel injection timing to reduce emissions during a transitional operation of an engine according to an implementation of the present disclosure. DETAILED DESCRIPTION

[0009] The following description is for illustrative purposes only. For clarity, the same reference symbols are used in the drawings to identify similar elements. As used herein, the phrase A, B, and / or C should be interpreted as meaning a logical (A or B or C) using a non-exclusive logical OR. It is understood that steps within a procedure may be performed in different orders without altering the principles of this disclosure.

[0010] As used herein, the term "module" may refer to an application-specific integrated circuit (ASIC); an electronic circuit; a logic circuit; a field-programmable gate array (FPGA); a processor (shared, dedicated, or as a group) that executes code; other suitable components that provide the described functionality; or a combination of some or all of the foregoing, such as a system-on-a-chip, being a part of, or comprising a single-chip system. The term "module" may also include memory (shared, dedicated, or as a group) that stores code executed by the processor.

[0011] The term "code," as used above, can include software, firmware, and / or microcode, and can refer to programs, routines, functions, classes, and / or objects. The term "shared," as used above, means that part or all of the code from multiple modules can be executed using a single (shared) processor. Additionally, part or all of the code from multiple modules can be stored in a single (shared) memory. The term "group," as used above, means that part or all of the code from a single module can be executed using a group of processors. Additionally, part or all of the code from a single module can be stored using a group of memories.

[0012] The devices and methods described herein can be implemented by one or more computer programs executed by one or more processors. The computer programs comprise instructions executable by a processor, stored on a non-volatile, accessible, computer-readable medium. The computer programs may also include stored data. Non-limiting examples of non-volatile, accessible, computer-readable media include non-volatile memory, magnetic memory, and optical memory.

[0013] Spark-ignition direct injection (SIDI) engines can inject fuel according to a base fuel injection timing. This base fuel injection timing might, for example, be a predetermined injection point for the start of an injection (SOI). Specifically, the base fuel injection timing might be calibrated to maximize fuel economy during steady-state engine operation. By way of example only, steady-state engine operation might include periods during which the engine's mass airflow (MAF) changes by less than a predetermined amount over a specified duration.

[0014] However, the base fuel injection timing may be advanced too far during engine transition (i.e., during non-steady-state operation). For example, engine transition may include periods during which the engine's MAF changes by more than a predetermined amount over a predetermined duration. Therefore, the base fuel injection timing may cause emissions to increase during engine transition due to the increased fuel supply.

[0015] Accordingly, a system and a method are presented for controlling fuel injection timing to reduce emissions during a transitional operating state of an engine. The system and method can detect a fuel demand and determine the magnitude of that demand. For example, the fuel demand may be detected following a deceleration fuel cut-off event (DFCO event) or when the driver requests more power by using a throttle (a "tap" of the throttle by the driver). Once the fuel demand is detected and its magnitude determined, the system and method can determine whether the engine is operating in a transitional state. By way of example only, the transitional state may include periods during which the MAF has changed by more than a predetermined amount over a predetermined duration.

[0016] When the engine is operating in the transition state, the system and procedure can generate a modified fuel injection timing. This modified fuel injection timing can be based on the base injection timing (e.g., the SOI), the elapsed time since the fuel demand was detected, and at least one of a variety of engine operating parameters. In other words, the modified fuel injection timing can include the base fuel injection timing adjusted as a function of the elapsed time since the fuel demand was detected and at least one of a variety of engine operating parameters. These parameters might include, for example, throttle position, engine load, engine speed, and engine coolant temperature.

[0017] The system and method can then control the fuel injection based on the adjusted fuel injection timing. Additionally, after a predetermined period, the system and method can switch from the adjusted fuel injection timing to the base fuel injection timing. Furthermore, when the engine is operating in steady state, the system and method can control the fuel injection based on the base fuel injection timing. Steady state can, for example, encompass periods during which the MAF (Maximum Air Flow) has changed by less than a predetermined amount over a specified time.

[0018] Now on Fig. Referring to 1, an engine system 10 comprises an engine 12. The engine 12 may, for example, be a SIDI engine. The engine 12 may also be another type of engine, such as a homogeneous compression ignition (HCCI) engine. The engine 12 introduces air through an intake system 14, which may be controlled by a throttle 16, into an intake manifold 18. For example, the throttle 16 may be electrically controlled by an electronic throttle control (ETC). A MAF sensor 20 measures a MAF rate into the intake manifold 18. A manifold absolute pressure (MAP) sensor 22 measures the pressure of the air in the intake manifold 18.

[0019] The air in the intake manifold 18 can be distributed to several cylinders 24. The engine 12 can have fewer or more than the six cylinders shown. Each of the cylinders 24 can have a fuel injection device 26 and a spark plug 28. The fuel injection device 26 can inject fuel directly into the cylinder 24 to create an air-fuel mixture. A piston (not shown) in the cylinder 24 can compress the air-fuel mixture, and the spark plug 28 can ignite the compressed air-fuel mixture. The combustion of the air-fuel mixture drives the piston (not shown), which rotates a crankshaft 30 and generates a drive torque. An engine speed sensor 32 measures the rotational speed of the crankshaft 30 (“engine speed”). The engine speed sensor 32 can measure the engine speed, for example, in revolutions per minute (RPM).

[0020] An engine temperature sensor 34 measures the temperature of the engine 12. For example, the engine temperature sensor 34 can measure the temperature of an engine coolant. Exhaust gas resulting from the combustion of the L / K mixture can be expelled from the cylinder 24 into an exhaust manifold 36. An exhaust aftertreatment system 38 can treat the exhaust gas in the exhaust manifold 36. Specifically, the exhaust aftertreatment system 38 can reduce emissions before the exhaust gas is released into the atmosphere. For example, the exhaust aftertreatment system 38 can include an oxidation catalyst (OC), a selective catalytic reduction (SCR) system, nitrogen oxide absorbers / adsorbers (NOx absorbers / adsorbers), a particulate filter (PM filter), and / or a catalytic converter.

[0021] A control module 50 controls the engine system 10. The control module 50 receives signals from the throttle 16, the MAF sensor 20, the MAP sensor 22, the fuel injectors 26, the spark plugs 28, the engine speed sensor 32, the engine temperature sensor 34, and / or the exhaust aftertreatment system 38. The control module 50 controls the throttle 16, the fuel injectors 26, the spark plugs 28, and / or the exhaust aftertreatment system 38. The control module 50 can also implement the system or method of this disclosure.

[0022] Now on Fig. 2 Referring to, the control module 50 comprises a fuel demand detection module 70, a transition operation detection module 74, an injection timing adaptation module 78 and an injection control module 82.

[0023] The fuel request detection module 70 detects a fuel request based on a driver input 60. Specifically, the fuel request can be detected based on the magnitude of the driver input 60. For example, the fuel request can occur after a DFCO event or in response to the driver tapping the throttle 16. The fuel request detection module 70 can also initialize and start a timer when the fuel request is detected. The timer can represent the elapsed time since the fuel request was detected.

[0024] The transitional operating detection module 74 detects when the motor 12 is operating in the transitional state. For example, the transitional operating detection module 74 can detect that the motor 12 is operating in the transitional state if the MAF rate in the motor 12 has changed by more than a predetermined amount during a predetermined time period. However, the transitional operating detection module 74 can also detect the transitional operation of the motor 12 based on other motor operating parameters. When a transitional operation is detected, the transitional operating detection module 74 can generate a signal for the injection timing adaptation module 78.

[0025] The injection timing adaptation module 78 receives the signal indicating the detection of transitional operation. The injection timing adaptation module 78 also receives the elapsed time since the fuel request was detected by the fuel request detection module 70. The injection timing adaptation module 78 can also receive signals indicating a variety of engine operating parameters. For example, the injection timing adaptation module 78 can receive signals from the throttle 16 (e.g., from a throttle position sensor or TPS), from the MAF sensor 20, from the engine speed sensor 32, and from the engine coolant temperature sensor 34, indicating the throttle position, engine load, engine speed, and engine temperature, respectively.

[0026] Specifically, the adapted fuel injection timing, relative to the base fuel injection timing, can be modified (i.e., advanced or retarded) based on one or more of the numerous engine operating parameters and their corresponding thresholds. For example, the fuel injection timing, relative to the base fuel injection timing, can be retarded if one or more of the numerous engine operating parameters are less than a corresponding threshold. More specifically, and only by way of example, the adapted fuel injection timing can also be retarded relative to the base fuel injection timing if the throttle position is less than a predetermined threshold.Additionally, the adjusted fuel injection timing can subsequently be reset to the base fuel injection timing if the elapsed time since the fuel request was detected increases.

[0027] The injection control module 82 can subsequently control the fuel injection based on the base fuel injection timing or the adapted fuel injection timing. Specifically, the injection control module 82 can control the fuel injection during steady-state operation based on the base fuel injection timing and during transitional operation based on the adapted fuel injection timing. The injection control module 82 can generate control signals to control the fuel injection devices 26. For example, the control signals can include pulse-width modulated (PWM) signals. However, the control signals can also be other suitable types of control signals for fuel injection devices.

[0028] Now on Fig.3. Referring to this, a procedure for adjusting fuel injection timing to reduce emissions during transitional engine operation begins at 100. At 100, the control unit detects whether fuel is requested. If so, the control unit can advance to 104. If not, the control unit can return to 100. At 104, the control unit determines whether the engine is operating in a transitional state. If not, the control unit can advance to 108. If so, the control unit can advance to 112. At 108, the control unit can adjust fuel injection based on the base fuel injection timing. The control unit can then return to 100.

[0029] At position 112, the control unit can generate a modified fuel injection timing based on the base fuel injection timing, the elapsed time since the fuel demand was detected, and at least one of the many engine operating parameters. For example, the many engine operating parameters could include throttle position, engine load, engine speed, and engine coolant temperature. At position 116, the control unit can actuate the fuel injection based on the modified fuel injection timing. The control unit can then return to position 100.

Claims

[1] Method for controlling an engine (12) comprising: an adapted fuel injection timing is generated when a fuel demand is detected and the engine (12) is operating in a transitional state, where the adapted fuel injection timing is based on a base fuel injection timing, an elapsed time since the detection of the fuel request, and a variety of engine operating parameters and where the adjusted fuel injection timing is advanced or retarded relative to the base fuel injection timing; based on the multitude of engine operating parameters, it is determined whether the adapted fuel injection timing is advanced or retarded relative to the base fuel injection timing; a fuel injection is controlled for a period of time based on the adjusted fuel injection timing; and The fuel injection is controlled according to the time duration based on the base fuel injection time, the multitude of engine operating parameters includes throttle position, engine load, engine speed and engine coolant temperature and where a timer is initialized and started when the fuel request is detected, and the timer represents the elapsed time since the fuel request was detected. [2] Method according to claim 1, further comprising that the fuel injection is controlled based on the base fuel injection timing when the engine (12) switches from transitional operation to steady-state operation. [3] Method according to claim 2, wherein the steady-state operation comprises periods during which a mass airflow (MAF) into the motor (12) has changed by less than a predetermined amount during a predetermined period. [4] Method according to claim 1, wherein the time duration is a predetermined time duration. [5] Method according to claim 1, wherein the adapted fuel injection timing is modified relative to the base fuel injection timing based on one or more of the plurality of engine operating parameters and corresponding threshold values. [6] Method according to claim 1, further comprising resetting the fuel injection timing from the adapted fuel injection timing to the basic fuel injection timing for a period of time after the engine (12) has entered steady-state operation. [7] Method according to claim 1, wherein the transition state comprises time periods during which a mass airflow (MAF) into the engine (12) has changed by more than a predetermined amount during a predetermined time period. [8] Method according to claim 1, wherein the basic fuel injection time is a predetermined fuel injection time corresponding to the start of an injection (SOI). [9] Method according to claim 1, wherein the fuel request responds to the end of a deceleration fuel cut-off event (DFCO event).

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