Tula Technology, Inc.

Gm Global Technolgoy Operations, Inc.

Cummins Inc.

Steven E Carlson

Louis Joseph Serrano

Xin Yuan

Joshua P Switkes

Mohammad R Pirjaberi

Mark A Wilcutts

Vijay Srinivasan

Li-Chun Chien

Kian Eisazadeh-Far

Shikui Kevin Chen

Mark A Shost

Siamak Hashemi

Andrew W Phillips

Adya S Tripathi

Matthew Aaron Younkins

Allen B Rayl, Jr

Randall S Beikmann

Joel D Van Ess

Eric J Defenderfer

Nitish J Wagh

Ying Ren

Steven J Haase

Jinbiao Li

Srihari Kalluri

Ryan A Kuhlenbeck

Donavan L Dibble

J Steven Kolhouse

Ihab S Soliman

John W Parsels

Aaron William Beinborn

Lisa A Orth-Farrell

Christopher W Chandler

Ronald D Yuille

Biswa R Ghosh

Jerry F Fuschetto

Christopher C Hand

John F Impeduglia

Norman C Lo

Engine controllers and control schemes that facilitate skip fire engine operation in conjunction with use power take-off devices are described. In one aspect, a skip fire mode is exited when the power take-off unit is engaged and the current torque request exceeds a torque threshold. In some embodiments, the exit is delayed when the temperature of an after treatment system is below a designated temperature threshold. In another aspect, the engine transitions to the skip fire mode when the power take-off unit disengages. In some embodiments, exiting is conditioned on the current torque request being less than a torque threshold. In some embodiments, the transition is made immediately, whereas in others the transition only occurs when the power take-off unit is not reengaged for a period of time or is further conditioned on determining that the power take-off unit is likely to remain disengaged for the period of time.

Using skip fire with power take-off

An internal combustion engine operates so that it delivers zero or negative torque. The engine operates in either a deceleration cylinder cut off (DCCO) mode or skip cylinder compression braking mode. In the skip cylinder compression braking mode, selected working cycles of selected working chambers are operated in a compression release braking mode. Accordingly, individual working chambers are sometimes not fired and sometimes operated in the compression release braking mode while the engine is operating in the skip cylinder compression braking mode.

Skip cylinder compression braking

Controllers and methods for managing transitions into and/or out of a cylinder cut off mode are described. In some embodiments, a skip fire based transition into a cylinder cut off mode is used in which the fraction of working cycles that are fired is gradually reduced to a threshold firing fraction. Once the threshold firing fraction has been reached, all of the working chambers are deactivated.

Deceleration cylinder cut-off

Various methods and arrangements for improving fuel economy and noise, vibration, and harshness (NVH) in a skip fire controlled engine are described. An engine controller dynamically selects a gas spring type for a skipped firing opportunity. Determination of the skip/fire pattern and gas spring type may be made on a firing opportunity by firing opportunity basis.

Dynamic valve control in a skip fire controlled engine

Methods, devices, estimators, controllers and algorithms are described for estimating the torque profile of an engine and/or for controlling torque applied to a powertrain by one or more devices other than the engine itself to manage the net torque applied by the engine and other device(s) in manners that reduce undesirable NVH. The described approaches are particularly well suitable for use in hybrid vehicles in which the engine is operated in a skip fire or other dynamic firing level modulation manner&#x2014;however they may be used in a variety of other circumstances as well. In some embodiments, the hybrid vehicle includes a motor/generator that applies the smoothing torque.

Engine torque smoothing

In one aspect, a skip fire engine controller is described. The skip fire engine controller includes a skip fire module arranged to determine an operational firing fraction and associated cylinder load for delivering a desired engine output. The skip fire engine controller also includes a firing controller arranged to direct firings in a skip fire manner that delivers the selected operational firing fraction. Various methods, modules, lookup tables and arrangements related to the selection of a suitable operational firing fraction are also described.

Method and apparatus for determining optimum skip fire firing profile

A variety of methods and arrangements are described for controlling transitions between firing fractions during skip fire or dynamic firing level modulation operation of an engine. In general, actuator first transition strategies are described in which an actuator position (e.g., cam phase, TCC slip, etc.) is changed to, or close to a target position before a corresponding firing fraction change is implemented. When the actuator change associated with a desired firing fraction change is relatively large, the firing fraction change is divided into a series of two or more firing fraction change steps. A number of intermediate target selection schemes are described as well.

Coordination of vehicle actuators during firing fraction transitions

Methods and arrangements are described for controlling transitions between firing fractions during skip fire operation of an engine in order to help smooth the transitions. Generally, firing fractions transitions are implemented gradually, preferably in a manner that relatively closely tracks manifold filling dynamics. In some embodiments, the commanded firing fraction is altered each firing opportunity. Another approach contemplates altering the commanded firing fraction by substantially the same amount each firing opportunity for at least a portion of the transition. These approaches work particularly well when the commanded firing fraction is provided to a skip fire controller that includes an accumulator functionality that tracks the portion of a firing that has been requested, but not delivered, or vice versa. In various embodiments, commanded firing fraction changes are delayed relative to initiation of the change in throttle position to help compensate for inherent delays associated with changing the manifold air pressure.

Skip fire transition control

A variety of methods and arrangements are described for controlling transitions between firing fractions during skip fire or other dynamic firing level modulation operation of an engine. In general, actuator first transition strategies are described in which an actuator position (e.g., cam phase, TCC slip, etc.) is changed to, or close to a target position before a corresponding firing fraction change is implemented. When the actuator change associated with a desired firing fraction change is relatively large, the firing fraction change is divided into a series of two or more firing fraction change steps. A number of intermediate target selection schemes are described as well.

A variety of methods and arrangements are described for controlling transitions between firing fractions during skip fire and potentially variable displacement operation of an engine. In general, cam first transition strategies are described in which the cam phase is changed to, or close to a target cam phase before a corresponding firing fraction change is implemented. When the cam phase change associated with a desired firing fraction change is relatively large, the firing fraction change is divided into a series of two or more firing fraction change steps&#x2014;with each step using a cam first transition approach. A number of intermediate target selection schemes are described as well.

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Oakland, CA, United States of America

Steven E Carlson