US 11,236,690 B2 · Engine cylinder output level modulation

Abstract

A variety of engine controllers and methods are described for controlling engines operating in a cylinder output level modulation mode. In one aspect transitions between different effective firing fractions are managed by gradually ramping an effective firing density. In another, when an engine transitions to a multi-level skip fire firing density that has more than one possible high/low/skip sequence, the phase of the high/low pattern is set relative to the phase of the firing pattern to ensure that a preferred high/low/skip sequence is generated. In another aspect, rapid large torque changes can be implemented in part by immediately changing the operational high/low fraction in response to a command to increase or reduce the desired engine torque.

Claims24

Dependent claims

A method of controlling an output of an engine having a plurality of cylinders, the engine being configured to at least sometimes operate in a cylinder output level modulation mode in which at least some of the cylinders are configured to selectively be skipped, fired at a high output level or fired at a low output level during selected associated working cycles, wherein a current operational firing density of the engine can be defined by a firing fraction indicative of a fraction of individual cylinder working cycles that are fired and a high/low fraction indicative of a fraction of the fired working cycles that are fired at the high output level, wherein for a selected firing density that has more than one possible high/low/skip sequence, there is an associated desired high/low/skip sequence the method comprising:

when the engine enters an operational state having the selected firing density, setting a parameter so that the desired high/low/skip sequence is generated, wherein an engine controller is not constrained to always cause the engine to enter the selected firing density at a pre-defined phase of the associated operational firing fraction.

An engine controller configured to direct operation of an engine in a cylinder output level modulation mode in which at least some cylinders of the engine are selectively skipped, fired at a high output level or fired at a low output level during selected associated working cycles, wherein a current operational firing density of the engine can be defined by a firing fraction indicative of a fraction of individual cylinder working cycles that are fired and a high/low fraction indicative of a fraction of the fired working cycles that are fired at the high output level, wherein the engine controller is configured to direct operation at any of a set of pre-defined available firing densities in which at least some of the available firing densities have more than one possible high/low/skip sequence including an associated preferred high/low/skip sequence, the engine controller being further configured to:

direct a firing density transition to a selected one of the available firing densities having more than one possible high/low/skip sequence, wherein the selected firing density is entered at a phase of an associated firing sequence that is not pre-defined;
set an operational phase of a high/low pattern based at least in part on the phase of the firing sequence that the firing density is entered at to thereby cause the engine to utilize the preferred high/low/skip sequence for the selected firing density.

An engine controller suitable for directing cylinder output modulation operation of an engine having a plurality of cylinders, the engine controller comprising:

a firing density determining module configured to determine a desired operational firing fraction and a desired operational high/low fraction;
a firing determining unit arranged to determine which cylinder working cycles to skip, which cylinder working cycles to fire high, and which cylinder working cycles to fire low during operation of the engine during cylinder output modulation operation of the engine;
and
a transition management unit configured to manage transitions between operating states having different firing fractions and different high/low fractions, the transmission management unit being arranged to manage a transition from a first operational state having a first firing fraction and a first high/low fraction to a second operational state having a second firing fraction and a second high/low fraction by,
(a) gradually ramping an operational firing fraction from the first firing fraction to the second firing fraction over a plurality of firing opportunities;
and
(b) gradually ramping an operational high/low fraction from the first high/low fraction to the second high/low fraction over a plurality of firing opportunities.

4 more elements

Dependencies are inferred from the claim text.

Engine cylinder output level modulation

Life of this patent

Engine cylinder output level modulation

Life of this patent

Abstract

Claims24