A variety of methods and arrangements for reducing noise, vibration and harshness (NVH) in a skip fire engine control system are described. In one aspect, a firing sequence is used to operate the engine in a skip fire manner. A smoothing torque is determined that is applied to a powertrain by an energy storage/release device. The smoothing torque is arranged to at least partially cancel out variation in torque generated by the skip fire firing sequence. Various methods, powertrain controllers, arrangements and computer software related to the above operations are also described.

In a catalyst warming-up control, a first time injection is performed by an injector in an intake stroke. A second time injection is performed with an amount smaller than the first time injection in an expansion stroke after a compression top dead center. In the catalyst warming-up control, an interval from the start of the ignition period of an spark plug to the completion of the second time injection is controlled by the ECU so that the initial flame generated from an air-fuel mixture containing the fuel spray injected by the first time injection is brought into contact with the fuel spray injected by the second time injection.

An intake stroke injection and a compression stroke injection are performed during catalyst warm-up control (upper section in FIG. 7). During the catalyst warm-up control, a discharge period at an electrode portion is set on a retard side of compression top dead center, and an expansion stroke injection is performed during the discharge period. However, when a distance between a spray contour surface and the electrode portion increases, an additional injection (first injection) is performed in advance of the expansion stroke injection (second injection) (lower section in FIG. 7). The additional injection is performed at a timing that is on the retard side of compression top dead center and is on an advance side relative to a start timing of the discharge at the electrode portion.

A method for heating an exhaust gas aftertreatment component in an exhaust system of an internal combustion engine. At the combustion chamber, a fuel injector for injecting a fuel into the combustion chamber and a spark plug for igniting a flammable fuel-air mixture are arranged. The internal combustion engine has a valve lift curve switching mechanism, which allows for a shift and/or change of the opening times of the exhaust valve. The method includes: intake of fresh air into the combustion chamber, injection of a fuel into the combustion chamber, ignition of an ignitable fuel-air mixture in the combustion chamber when the piston is in a range of 10° KW to 30° KW after the upper ignition dead point, and opening of the exhaust valve when the piston is in a range of 55° KW to 95° KW after the upper ignition dead point.

Disclosed is a four-stroke direct injection engine comprising a camshaft, and exhaust valve, and a control system. The control system is configured to change the timing of the camshaft to advance a closing of the exhaust valve, control a first fuel injection step during a compression stroke of the piston, control a second fuel injection step during a power stroke of the piston, and control a third fuel injection step, after the second fuel injection step, during the power stroke of the piston.

A method for controlling a valve arrangement for an internal combustion engine, the valve arrangement including a piston arrangement comprising a piston having a piston end portion facing an inlet valve of the valve arrangement. The method includes receiving a signal indicative of a temperature level of an exhaust gas after treatment system and when the signal indicates a temperature level below a predetermined threshold level: advancing an exhaust event of the internal combustion engine; and controlling the piston arrangement for reducing the distance between the piston end portion and the inlet valve before the internal combustion engine assumes an air intake event.

A system and method of controlling operation of an internal combustion engine are provided. The method includes performing a cylinder deactivation operation while running the engine, selecting at least one of the plurality of temperature maintenance actions to increase an exhaust temperature, and performing at least one of the plurality of temperature maintenance actions effective to increase the exhaust temperature. The plurality of temperature maintenance actions may include one or more of a charge air cooler bypass operation, an EGR cooler bypass operation, an aftertreatment system heater operation, a turbocharger bypass operation, a turbocharger geometry adjustment operation, an intake air throttle adjustment operation, and a delayed injection timing operation, or combinations thereof.

Methods and systems are provided for actuating an advanced cam profile switch (CPS) assembly. In one example, a system may include a first cylinder and a second cylinder of the CPS assembly that may be independently coupleable to a valve stem via two separate locking mechanisms. A first cam may be selectively engage with the first cylinder and the valve stem and a second cam may be selectively engaged with the second cylinder and the valve stem.

A method is disclosed for controlling an engine assembly comprising an internal combustion engine and an exhaust gas treatment apparatus. The aftertreatment assembly may require cleaning from time to time, and where this involves active thermal management of the aftertreatment assembly, the method involves performing the following steps: (a) imposing a first limit on engine speed; (b) awaiting an engine safe state; and (c) implementing a cleaning process comprising: (i) injecting fuel into the engine such that the fuel passes through the engine without combusting for the fuel to combust in the diesel oxidation catalyst so as to target an increase in exhaust gas temperature in the diesel oxidation catalyst; and (ii) removing the first limit on engine speed and targeting an engine speed set point, wherein the engine speed set point is at a higher speed than the first limit on engine speed.

Methods and systems for enabling regeneration of a particulate filter of an engine system are provided. In one embodiment, a method includes: receiving, by a processor, a request for particulate filter regeneration; in response to the request, determining, by the processor, at least one of a compression ratio and an expansion ratio; generating, by the processor, control signals to actuators of the engine system to adjust the at least one of the compression ratio and the expansion ratio to achieve a desired exhaust temperature; generating, by the processor, control signals to actuators of the engine system to optimize torque output based on the desired exhaust temperature, engine speed, and a desired engine load; and initiating, by the processor, regeneration of the particulate filter based on the command signals.