Abstract:
A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines based on skip fire operation of the engine are described.
Abstract:
Various methods and arrangements for determining a combustion control parameter for a working chamber in an engine are described. In one aspect, an engine controller includes a firing counter that stores a firing history for the working chamber. A combustion control module is used to determine a combustion control parameter, which is used to help manage combustion in the working chamber. The combustion control parameter is determined based at least in part on the firing history.
Abstract:
Arrangements for stabilizing valve timing adjustment mechanisms such as cam phasers during operation of an engine are described. The described approaches are particularly well suited for use during skip fire control, although they may be used advantageously in other applications as well. In general, the phase of an adjustable phase camshaft is controlled relative to a crankshaft of an engine. In one aspect, at least one of (i) firing events in a skip fire firing sequence, and (ii) dynamically determined valve actuation events are used in the control of the camshaft phase during operation of the engine. In some embodiments, hydraulic pressure within a cam phaser is varied in a manner that maintains the phase of the camshaft substantially more stable through transitory variations in torque applied to the camshaft by the actuation of the valves than would occur without the variations in hydraulic pressure.
Abstract:
A variety of methods and arrangements for improving the fuel efficiency of internal combustion engines based on skip fire operation of the engine are described.
Abstract:
Methods and devices are described that utilize skip fire techniques to rapidly meet requests for transitory changes in the output of an engine. Specifically, the fraction or percentage of the working cycles that are fired can be changed during a transitory event so that the engine delivers the desired transitory engine output. Once the transitory event is over, normal engine operation may be restored. The described techniques are useful in a variety of applications that require a relatively quick, but transitory, reduction in engine output to meet vehicle control requirements. One particularly useful application is during transmission shift events. Other representative applications include: loss of traction events, stability control events, wheel hop prevention events, etc.
Abstract:
In one aspect of the invention, an engine is operated in a skip cylinder engine braking mode. In the skip cylinder engine braking mode, selected working cycles of selected working chambers are deactivated. Other selected working cycles of the selected working chambers are operated in a braking mode. Accordingly, individual working chambers are sometimes deactivated and sometimes operated in the braking mode while the engine is operating in the skip cylinder engine braking mode. Various methods for cylinder control are described, which improve fuel economy, catalytic converter performance, and vehicle NVH characteristics.
Abstract:
A variety of methods and arrangements for controlling the operation of an internal combustion engine in a skip fire variable displacement mode are described. Generally, an engine is controlled to operate in a skip fire variable displacement mode. In one aspect, the spark timing associated with each fired working cycle is based at least in part on the firing history of the fired working chamber.
Abstract:
A method for improving the operation of an internal combustion engine implementing cylinder deactivation is described. Generally, the pattern of combustion events that are fired and skipped together with the geometry of the exhaust and/or intake system can create unpleasant acoustic issues. By slightly altering the timing of the cylinder intake and exhaust valves, these acoustic issues can be mitigated. The valve timing can be altered on a combustion event by combustion event basis. Alternatively, valve timing for different groups of cylinders can be modified together.
Abstract:
A variety of skip fire engine controllers and control methods are described that utilize look-up tables, state machines, or other data structures to determine the sequence or ordering of skip-fire firings. In one aspect, a skip fire engine controller utilizes a look-up table to determine when firings are appropriate to deliver a desired engine output. In some embodiments, a firing timing controller tracks a value indicative of the portion of a firing that has been requested, but not yet directed and such information is utilized in the determination of the timing of the firings. The accumulator value is particularly useful when transitioning between different requested firing fractions.
Abstract:
A variety of methods and arrangements for managing transitions between operating states for an engine are described. In one aspect, an engine is operated in a particular operating state. A transition is made to another operating state. During that transition, the engine is operated in a skip fire manner.