WO2014025939A1 - Firing fraction management in skip fire engine control - Google Patents
Firing fraction management in skip fire engine control Download PDFInfo
- Publication number
- WO2014025939A1 WO2014025939A1 PCT/US2013/054027 US2013054027W WO2014025939A1 WO 2014025939 A1 WO2014025939 A1 WO 2014025939A1 US 2013054027 W US2013054027 W US 2013054027W WO 2014025939 A1 WO2014025939 A1 WO 2014025939A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- engine
- firing fraction
- skip fire
- recited
- lookup table
- Prior art date
Links
Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/008—Controlling each cylinder individually
- F02D41/0087—Selective cylinder activation, i.e. partial cylinder operation
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/021—Introducing corrections for particular conditions exterior to the engine
- F02D41/0215—Introducing corrections for particular conditions exterior to the engine in relation with elements of the transmission
- F02D41/0225—Introducing corrections for particular conditions exterior to the engine in relation with elements of the transmission in relation with the gear ratio or shift lever position
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/14—Introducing closed-loop corrections
- F02D41/1497—With detection of the mechanical response of the engine
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/02—Circuit arrangements for generating control signals
- F02D41/18—Circuit arrangements for generating control signals by measuring intake air flow
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02P—IGNITION, OTHER THAN COMPRESSION IGNITION, FOR INTERNAL-COMBUSTION ENGINES; TESTING OF IGNITION TIMING IN COMPRESSION-IGNITION ENGINES
- F02P9/00—Electric spark ignition control, not otherwise provided for
- F02P9/002—Control of spark intensity, intensifying, lengthening, suppression
- F02P9/005—Control of spark intensity, intensifying, lengthening, suppression by weakening or suppression of sparks to limit the engine speed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/04—Engine intake system parameters
- F02D2200/0406—Intake manifold pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/04—Engine intake system parameters
- F02D2200/0414—Air temperature
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/02—Input parameters for engine control the parameters being related to the engine
- F02D2200/10—Parameters related to the engine output, e.g. engine torque or engine speed
- F02D2200/101—Engine speed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/50—Input parameters for engine control said parameters being related to the vehicle or its components
- F02D2200/501—Vehicle speed
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2200/00—Input parameters for engine control
- F02D2200/70—Input parameters for engine control said parameters being related to the vehicle exterior
- F02D2200/703—Atmospheric pressure
Definitions
- the present invention relates generally to skip fire control of internal combustion engines and particularly to mechanisms for determining a desired operational firing fraction.
- data structures such as lookup tables are used to determine the desired firing fraction.
- thermodynamic efficiency results in improved fuel efficiency.
- variable displacement engine will have a very small set of available operational modes.
- some commercially available 8 cylinder variable displacement engine are capable of operating in a 4 cylinder mode in which only four cylinders are used, while the other four cylinders are deactivated (a 4/8 variable displacement engine).
- Another commercially available variable displacement engine is a 3/4/6 engine which is a six cylinder engine that can be operated with 3, 4, or 6 active cylinders.
- a 4 cylinder engine might be operable in 1, 2, 3, or 4 cylinder modes.
- skip fire engine control contemplates selectively skipping the firing of certain cylinders during selected firing opportunities.
- a particular cylinder may be fired during one firing opportunity and then may be skipped during the next firing opportunity and then selectively skipped or fired during the next.
- even finer control of the effective engine displacement is possible. For example, firing every third cylinder in a
- skip fire engine control is understood to offer a number of potential advantages, including the potential of significantly improved fuel economy in many applications.
- the concept of skip fire engine control has been around for many years, and its benefits are understood, skip fire engine control has not yet achieved significant commercial success in part due to the challenges it presents.
- NVH noise, vibration & harshness
- a stereotype associated with skip fire engine control is that skip fire operation of an engine will make the engine run significantly rougher than conventional operation.
- a firing fraction determining unit is arranged to determine a firing fraction suitable for delivering a requested engine output.
- the firing fraction determining unit may utilize data structures such as lookup tables in the determination of the desired firing fraction.
- a firing controller may then be arranged to direct firings in a skip fire manner that delivers the desired operational firing fraction.
- the desired engine output and one or more operational power train parameters are used as indices to a lookup table used to select a desired firing fraction.
- transmission gear serves as another index to the lookup table.
- additional indices to the data structure may include any one of: manifold absolute pressure (MAP); cam position; a parameter indicative of mass air charge (MAC); cylinder torque output; maximum permissible manifold pressure; vehicle speed; estimated manifold temperature; and barometric pressure.
- the lookup table is arranged to dictate operation in an all-cylinder operational mode in selected operational states.
- the output of the engine may be modulated primarily based on throttle position.
- each entry in the lookup table includes a firing fraction field that stores an associated firing fraction indicator indicative of a desired firing fraction associated with such entry.
- the table entries may further include a second field arranged to store a value indicative of a second desired operational parameter.
- the second field may be a MAC field arranged to store a MAC indicator indicative of a desired operational mass air charge.
- the MAC indicator may be a relative or fixed reference value.
- a desired engine output is determined in terms of a desired engine torque fraction.
- the desired torque fraction is indicative of the desired engine output relative to a reference maximum available engine output.
- a desired operational firing fraction is then determined based at least in part on the desired torque fraction and engine speed. Cylinder firings are then directed in a skip fire manner that delivers the desired engine output by firing the percentage of available working cycles indicated by the desired operational firing fraction.
- FIG. 1A is a block diagram of a skip fire engine controller that incorporates a firing fraction calculator in accordance with some embodiments of the present invention.
- FIG. IB is a block diagram of another exemplary skip fire engine controller that incorporates a firing fraction calculator.
- FIG. 1C is a block diagram of another exemplary skip fire engine controller that incorporates a torque calculator.
- FIG. 2 is a representation of a table data structure suitable for use in determining the firing fraction in accordance with one described embodiment of the present invention.
- FIG. 3 is a representation of a table data structure suitable for use in determining the firing fraction in accordance with another embodiment.
- FIG. 4 is a representation of a table data structure suitable for use in determining the firing fraction in accordance with a third embodiment.
- FIG. 5 is a functional block diagram showing a firing fraction control structure in accordance with another embodiment.
- FIG. 6 is a representation of a table data structure suitable for use in determining a minimum firing faction in accordance with one described embodiment of the present invention.
- the present invention relates generally to methods, data structures and devices for determining the firing fraction in skip fire control.
- Fig. 1A is a block diagram that diagrammatically illustrates a representative skip fire controller that utilizes a firing fraction calculator in accordance with one described embodiment.
- the skip fire controller 90 includes a firing fraction determining unit 92 (sometimes referred to as a firing fraction calculator) and a firing timing determining unit 94.
- the firing fraction calculator 92 is arranged to determine a firing fraction that is suitable for delivering the desired engine output and informs the firing timing determining unit 94 of the desired firing fraction.
- the firing timing determining unit 94 is responsible for determining a firing sequence that delivers the desired firing fraction.
- the firing sequence can be determined using any suitable approach.
- the firing may be determined dynamically on an individual firing opportunity by firing opportunity basis as described in some of the incorporated patents.
- pattern generators or predefined patterns may be used to facilitate deliver of the desired firing fraction.
- the controller 100 includes a skip fire controller 110 arranged to work in conjunction with an engine control unit (ECU) 140.
- ECU engine control unit
- the functionality of the skip fire controller 110 may be incorporated into the ECU 140.
- the illustrated skip fire controller 110 includes a firing fraction calculator 112, an optional filter unit 114, a power train parameter adjusting module 116, and a firing timing determining module 120.
- the skip fire controller receives an input signal 111 indicative of a desired engine output and is arranged to generate a sequence of firing commands that cause an engine 150 to provide the desired output using a skip fire approach.
- the input signal 111 is treated as a request for a desired engine output.
- the signal 111 may be received or derived from an accelerator pedal position sensor (APP) or other suitable sources, such as a cruise controller, a torque calculator, an ECU, etc.
- APP accelerator pedal position sensor
- an optional preprocessor 168 may modify the accelerator pedal signal prior to delivery to the skip fire controller 110.
- the accelerator pedal position sensor 163 may communicate directly with the skip fire controller 110.
- the desired engine output may also be based on factors in addition to, or instead of the accelerator pedal position.
- current operational conditions such as engine speed, vehicle speed and/or gear may be used in conjunction with the accelerator pedal position when determining the desired engine output.
- various environmental conditions such as barometric pressure, ambient temperature, etc. may be used in substantially the same way.
- the firing fraction calculator 112 can be arranged to provide the firing fraction calculator 112 with a single value/signal indicative of the total requested torque, (e.g., in place of signal 111) or to provide one or more separate values/signals (not shown) to the firing fraction calculator 112 such that the firing fraction calculator itself determines the total requested torque based on multiple inputted torque requests.
- co-owned patent application No. 61/682,135 discloses some torque calculators that can be used to determine the desired engine output.
- the desired engine output signal 111 or a supplemental input signal may come from a cruise controller, a transmission controller, a traction control system (to reduce wheel slippage) and/or from any other suitable source.
- the firing fraction calculator 112 receives input signal 111 (and when present other suitable sources) and is arranged to determine a skip fire firing fraction that would be appropriate to deliver the desired output under selected engine operating conditions.
- the firing fraction is indicative of the fraction or percentage of firings under the current (or directed) operating conditions that are required to deliver the desired output.
- the firing fraction may be determined based on the percentage of optimized firings that are required to deliver the driver requested engine torque (e.g., when the cylinders are firing at an operating point substantially optimized for fuel efficiency).
- different level reference firings, firings optimized for factors other than fuel efficiency, the current engine settings, etc. may be used in determining the appropriate firing fraction.
- an optional power train parameter adjusting module 116 is provided that cooperates with the firing fraction calculator 112.
- the power train parameter adjusting module 116 directs the ECU 140 to set selected power train parameters appropriately to insure that the actual engine output substantially equals the requested engine output at the commanded firing fraction.
- the power train parameter adjusting module 116 may be responsible for determining the desired mass air charge (MAC) and/or other engine settings that are desirable to help ensure that the actual engine output matches the requested engine output.
- MAC mass air charge
- the power train parameter adjusting module 116 may be arranged to directly control various engine settings.
- the firing timing determining module 120 is arranged to issue a sequence of firing commands (e.g., drive pulse signal 113) that cause the engine to deliver the percentage of firings dictated by a commanded firing fraction 119.
- the firing timing determining module 120 may take a wide variety of different forms.
- sigma delta convertors work well as the firing timing determining module 120.
- a number of the assignee's patents and patent applications describe various suitable firing timing determining modules, including a wide variety of different sigma delta based converters that work well as the firing timing determining module. See, e.g., U.S. Patent Nos.
- the sequence of firing commands (sometimes referred to as a drive pulse signal 113) outputted by the firing timing determining module 120 may be passed to an engine control unit (ECU) or combustion controller 140 which orchestrates the actual firings.
- ECU engine control unit
- combustion controller 140 which orchestrates the actual firings.
- the output of the firing fraction calculator 112 is optionally passed through a filter unit 114 before it is delivered to the firing timing determining module 120.
- the filter unit 114 is arranged to mitigate the effect of any step change in the commanded firing fraction such that the change in firing fraction is spread over a longer period. This "spreading" or delay can help smooth transitions between different commanded firing fractions and can also be used to help compensate for mechanical delays in changing the engine parameters.
- the filter unit 114 may include a first filter that smoothes the abrupt transition between different commanded firing fractions to provide better response to engine behavior and so avoid a jerky transient response.
- a change in the commanded firing fraction and/or other factors will cause the power train adjusting module 116 to direct a corresponding change in the engine (or other power train) settings (e.g., throttle position which may be used to control manifold pressure / mass air charge).
- throttle position which may be used to control manifold pressure / mass air charge
- the mechanical response time associated with implementing such changes is much slower than the clock rate of the firing control unit.
- a commanded change in manifold pressure may involve changing the throttle position which has an associated mechanical time delay. Once the throttle has moved there is a further time delay to achieve of the desired manifold pressure.
- the filter unit 114 may also include a second filter to help reduce such discrepancies.
- the second filter may be scaled so its output changes at a similar rate to the engine behavior; for example, it may substantially match the intake manifold filling/discharge dynamics.
- the filters within the filter unit 114 may be constructed in a wide variety of different manners.
- the firing fraction calculator 112, the filter unit 114, and the power train parameter adjusting module 116 may take a wide variety of different forms and their functionalities may alternatively be incorporated into an ECU, or provided by other more integrated components, by groups of subcomponents or using a wide variety of alternative approaches. In various alternative implementations, these functional blocks may be accomplished algorithmically using a microprocessor, ECU or other computation device, using analog or digital components, using programmable logic, using combinations of the foregoing and/or in any other suitable manner.
- the firing fraction calculator 112 may be arranged to determine a "requested" firing fractions in terms of a reference cylinder output.
- the reference can be a fixed value or it may be variable based on selected powertrain, vehicle or environmental parameters/conditions.
- the requested firing fraction may then be used in the selection of an operational firing fraction which might have preferred attributes (such as better NVH characteristics).
- an adjustment is made to the requested firing fraction, it is typically desirable to adjust other engine or powertrain parameters correspondingly to insure that desired engine output is actually delivered.
- such architecture is described in co-assigned patent application No. 13/654,244 and 13/654,248 which are incorporated herein by reference.
- a torque calculator 175 is used to determine a desired engine output 111(c) that is provided to the firing fraction calculator 112.
- the components of the skip fire controller 110(c) may be similar to described above with respect to Figs 1A or IB.
- the accelerator pedal position (APP) and vehicle speed (RPM) are used as indices into a lookup table 176 that returns a target throttle position (TP).
- This table is designed to give good driv ability and such tables are implemented in various commercially available engines.
- a target or desired torque can be determined.
- the desired torque can be calculated algorithmically, obtained from a lookup table or in any other suitable manner.
- the desired torque is characterized as a fraction - specifically, the fraction or percentage of the torque generated under reference or nominal cylinder conditions. (Note that the fraction can potentially be greater than one).
- the desired output may be characterized in other ways - such as the number of cylinders required (e.g., 3.1) out of the total number of cylinders, a total torque output, or in other ways.
- the reference cylinder conditions may be a set predefined value or a value that varies with certain environmental or operational conditions (e.g., barometric pressure, engine speed, etc.).
- the torque calculator 175 may be arranged to account for the load utilized by engine accessories by adding estimates that account for the energy required to drive such accessories to the driver requested output indicated by the accelerator pedal position when determining the desired torque fraction. Additionally, the torque calculator 175 may be arranged to consider inputs from other control systems within the vehicle when determining the desired torque. Such inputs may be intended to override or supplement the desired output as indicated by the accelerator pedal position.
- an ECU or transmission controller may request transitory torque reductions during transmission shifts; a traction controller may request reduced or specific engine output during potential traction loss events; and/or a cruise controller may direct engine output while the vehicle is under cruise control.
- the firing fraction calculator 112 uses the desired torque fraction 111(c) (desired engine output) provided by torque calculator 175 to determine the desired firing fraction.
- the appropriate firing fraction for a given torque fraction may vary somewhat based on selected operational condition such as engine speed (and potentially gear) and thus the lookup tables used may have multiple indices - as for example desired torque fraction (i.e., desired engine output) and RPM in some particular implementations.
- the firing fraction table may be arranged to assume a nominal or reference engine settings, or may be arranged to direct the associated engine settings.
- the desired firing fraction is then sent to the firing timing determination module.
- the desired firing fractions may be used in the selection of an operational firing fraction.
- various engine settings such as valve (cam) timing, throttle position, and/or spark timing may be adjusted appropriately to insure that the engine delivers the desired output at the operational firing fraction.
- the torque determination, the firing fraction determination and the determination of whether to skip or fire a cylinder during any particular working cycle are preferably made individually on a working cycle by working cycle basis. That is, the torque and firing fraction determinations are preferably updated each firing opportunity and the firing decision is preferably made each firing opportunity.
- the currently desired firing fraction can be re-determined before each firing opportunity.
- Facilitating such dynamic tracking of the desired firing fraction allows the controller to be particularly responsive to changing demands while maintaining the benefits of skip fire operation.
- firing opportunity by firing opportunity updates are desirable in many applications, it should be appreciated that in alternative embodiments, any of the updated calculations and/or the firing decisions may be made less frequently as appropriate for any particular skip fire controller.
- the firing fraction determining unit 112 is arranged to determine the desired firing fraction based on such factors and/or any other factors that the skip fire controller designer may consider important.
- the firing fraction determining unit 112 is arranged to utilize a lookup table to determine the desired firing fraction.
- Fig. 2 diagrammatically illustrates a lookup table 200 that may be used to determine the appropriate firing fraction in some implementations.
- the lookup table can be implemented in any appropriate type of memory using a variety of conventional table constructs.
- three independent indices are provided and each table entry 203 has a firing fraction field 204 that stores a firing fraction indicator value 205 which indicates the desired firing fraction associated with that entry.
- the first index 207 is based on a requested engine output which as described above, may be determined in any suitable manner by the torque calculator, a accelerator pedal position sensor or by any other appropriate component.
- the second index 209 is based on a first power train operating parameter - specifically, engine speed in the illustrated embodiment.
- the third index 211 is based on a second power train operating parameter - specifically, transmission gear.
- various other indices based on other power train operating parameters may be used in addition to, or in place of one or more of the described indices.
- ambient environmental conditions such as ambient air pressure (which varies with altitude and other factors) and/or ambient air temperature may be used as table indices in addition to engine and vehicle operational parameters.
- the requested engine output index value can be based on a wide variety of different inputs.
- the requested engine output index may be directly or indirectly based on the output of the accelerator pedal position sensor.
- the requested engine output may be indicative of a requested torque or other indicator of desired engine output.
- Such a request could come from a cruise controller, the ECU, a torque calculator, a logic block (e.g. a preprocessor) that converts the pedal position sensor signal to a requested torque, a traction control system or from any other suitable source.
- the firing fraction calculator (or a torque calculator that determines the total requested torque) may be arranged to sum the torque request from multiple sources and/or to otherwise determine, calculate or select a desired engine output based on current operating conditions using any criteria that may be deemed appropriate by the engine control designer.
- the requested engine output may be provided in terms of an absolute number (e.g., a particular requested torque), in terms of a fraction or percentage (e.g., a particular torque fraction as described above with respect to FIG. 1C), or in any other manner and the tables may be scaled accordingly.
- various power train operating parameters such as current engine speed (e.g., RPM) and/or the current transmission gear may influence the desired firing fraction.
- Operational conditions such as the torque output of each cylinder, or factors that influence that output such as the mass air charge (MAC), cam position (e.g. cam phaser position), manifold absolute pressure (MAP), and/or estimated manifold temperature could be used as indices as well.
- MAC mass air charge
- cam position e.g. cam phaser position
- MAP manifold absolute pressure
- estimated manifold temperature could be used as indices as well.
- engine speed and transmission gear that is currently in use are used as additional indices for the lookup table 200 so that the firing fraction can be better tailored to the vehicle current operating state at any given time.
- the engine speed can be useful for several reasons. Initially, it may be desirable to require a minimum firing fraction even when the requested engine output is low, as for example at idle or engine speeds below a designated threshold (e.g., 1000 or 1500 RPM, etc.). This can be helpful to mitigate NVH issues. For example, higher engine speeds have higher firing frequencies (for a given firing fraction) - which tend to have better vibration characteristics in the frequency ranges that are most noticeable to passengers. Furthermore, for a given requested engine output, the firing fraction that is desirable for an engine that is currently operating at 1500 RPM may be higher than the desirable firing fraction at a higher engine speed (e.g., 4000 RPM).
- a higher engine speed e.g., 4000 RPM
- the transmission gear can also be an important factor when determining the desired firing fraction.
- One reason that transmission gear can be important is that different gears tend to have different NVH (noise, vibration and harshness) characteristics. That is, different gears may have different vibration and/or acoustic characteristics given similar operating parameters such as engine speed, firing fraction, etc. For example, a certain firing fraction may run smoothly in 4 th gear at a particular engine speed, while the same firing fraction may generate undesirable vibrations in another gear at the same engine speed. This is, in part, because the same torque pulse generated from an engine will be transferred to the driveline differently by different gears.
- NVH noise, vibration and harshness
- the described lookup tables can be used to implement a wide variety of different firing fraction determining algorithms.
- One of the advantages of the described lookup table approach is that the correlations between specific operating parameters and the directed firing fraction can be defined in any manner deemed appropriate by the engine controller designer. This allows the designer to determine the desired mappings between various operating parameters and the desired firing fraction experimentally, analytically or using any combination of such approaches. Accessing the tables is a time and processing efficient mechanism for determining the firing fraction since the tables can be accessed very quickly, which facilitates firing opportunity by firing opportunity updating of the desired firing fraction. Thus, if desired, the "current" firing fraction can be determined and updated before each firing opportunity.
- lookup tables can also readily be used in other implementations, where such frequent re-determination of the desired firing fraction is not necessary.
- lookup tables also allows the entry values and thus the desired mappings to be easily updated if desired.
- the tables could be updated, if desired, as part of vehicle maintenance.
- multiple tables can be provided for use under different driving or environmental conditions.
- the lookup table can be implemented as a single multi-dimensional lookup table, or may be constructed as a set of different lookup tables that are each associated with a particular operating parameter. For example, a separate lookup table may be provided for use with each transmission gear, etc.
- a separate lookup table may be provided for use with each transmission gear, etc.
- - table structures that utilize physically separate lookup tables based on a particular parameter e.g. a separate physical or logical table for each gear
- multi-dimensional lookup table that utilizes that particular parameter (gear in the given example) as an additional index.
- multidimensional lookup table as used herein is intended to encompass any data structure or set of data structures that are arranged to be accessed using two or more different variables (e.g. indices). These may include physically or logically separated tables, arrays, etc.
- one of the indices to the table is based on engine speed or RPM.
- such an index can be based on a value that is directly or indirectly indicative of engine speed such as the rotational speed of a camshaft, the rotational speed of a drive train component, etc. or even vehicle speed.
- the inputs to the firing fraction calculator 112 may be quantized and the table may be sized appropriately so that all possible input parameters are explicitly defined in the lookup table.
- conventional interpolation techniques may be used to determine the desired firing fraction based on the nearest available table entries. In the table shown in Fig. 2, only a few entries are provided for each index value for illustrative purposes. Even when such coarse index steps are provided in the table, standard interpolation techniques can be used to determine the appropriate firing fractions for intermediate conditions. In practice it will often be desirable to have much finer steps between table index values and the ranges of values will vary widely based on the expected operational range of the engine's skip fire control.
- low (but non-zero) firing fractions can sometimes have poor vibration characteristics, particularly when the engine is operating at a relatively low engine speed. Therefore, in some implementations it will be desirable to dictate a minimum firing fraction or firing frequency. When a minimum firing fraction is used, it may be desirable to reduce the output of each firing appropriately so that the total engine output matches the desired output with the minimum firing fraction in place. This can readily be accomplished by adjusting other parameters such as the spark timing, mass air charge (MAC), cam phaser position, cam lift, or intake manifold absolute pressure (MAP) in conjunction with the firing fraction. A number of approaches can be used to appropriately control the output of each firing.
- MAC mass air charge
- MAP intake manifold absolute pressure
- the lookup tables may be arranged to set the firing fraction to a desired minimum firing fraction for the associated engine speed in response to relatively small torque requests.
- Another component or logical block (such as power train parameter adjusting module 116 or ECU 140) may then be arranged to set other engine parameters as appropriate to insure that the engine delivers the desired output at the requested firing fraction.
- a number of the firing fraction values in the table are identified as "1" - which means that all of the cylinders would be fired all of the time. See in particular, the lower right quadrant of the Gear 6 table illustrated in Fig. 2.
- the torque request associated with a "1" simply cannot be met by the engine at the associated engine speed (which would be especially true for the entries in the lower right corner of that table).
- adjusting other engine parameters in conventional ways - such as by advancing the camshaft or increasing the mass air charge can be used to provide the desired engine torque.
- the lookup tables themselves may be arranged to define other operating parameters in addition to the firing fraction.
- One such arrangement is illustrated in Fig.
- each table entry 303 has two separate fields.
- the first field is a firing fraction (FF) field 304 that holds a firing fraction indicator value 305 as described above with respect to Fig. 2.
- the second field is a relative MAC field 316 which stores an indicator of the relative percentage of a designated reference MAC 307 which is to be used in conjunction with the designated firing fraction.
- This field is sometimes referred to herein as the MAC adjust field and is labeled "MAC" in the table of Fig. 3.
- the reference MAC may be a fixed absolute value, however more frequently it would be a value that is determined based on current operating conditions.
- the reference MAC is a mass air charge that facilitates operation of the cylinders under substantially optimal conditions (thermodynamic or otherwise).
- the reference mass air charge may be set to equal the mass air charge that provides substantially the highest thermodynamic (fuel) efficiency at the current operating state of the engine (e.g., engine speed, environmental conditions, etc.).
- the reference MAC may be optimized for other factors including emissions, vibration considerations, total torque output or may be optimized in a manner that accounts for multiple factors including these and various environmental and operational features such as altitude or desired intake manifold vacuum levels.
- the reference MAC may be a variable that varies with the operational state of the engine. For example, the engine speed and ambient barometric pressure are two factors that can affect the optimal MAC at any given time.
- the value stored in relative MAC Adjust field 316 is a relative value which indicates a fraction or percentage of the reference MAC that is to be used rather than an absolute value of the MAC.
- the relative value is particularly useful in embodiments that utilize a variable reference MAC so that the actual engine output scales appropriately.
- set MAC values may be used.
- the engine controller may be arranged to adjust the engine settings (e.g., throttle position, valve timing, etc.) in a manner that causes the desired MAC to be delivered to the operating cylinders. Such adjustments may be controlled by the power train parameter adjusting module 116, the ECU 140, the firing fraction calculator 112 or by any other appropriate component using conventional engine settings control techniques.
- the second field of each table entry is the relative MAC.
- the lookup table may be arranged to provide values indicative of any desired operating parameters, or values that might be useful in calculating the appropriate values of such other desired operating parameters may be included together with the firing fraction indications.
- Such other operating parameter values may be provided in addition to or in place of the relative MAC.
- Additional operating parameters can readily be controlled by providing additional fields within each entry to define the other desirable parameters.
- a relative manifold absolute pressure e.g. relative to barometric pressure
- information about the intake and exhaust valve timing may readily be used in place of the MAC.
- MAC Adjust fields 316 are shown as storing the value "1" which indicates that the reference MAC is to be used.
- the MAC is adjusted to modulate the engine output.
- NVH considerations may make it desirable to utilize only a limited set of firing fractions or to avoid the use of certain firing fractions under selected operating condition.
- the table may be arranged to more actively vary the relative MAC (or other controlled power train parameters) as a function of the torque request. Such a table is illustrated in Fig. 4.
- the torque request index has finer granularity than the associated firing fraction (FF) values.
- FF firing fraction
- a lookup table is used to determine the desired firing fraction.
- each transmission gear may have a predefined set of firing fractions that may be use for different engine speeds. The appropriate firing fraction can then algorithmically be determined based on the current torque request.
- a firing fraction determiner 620 is arranged to calculate an optimal firing fraction given the engine RPM and torque request. The optimal nature of this calculation may be with respect to fuel efficiency, emissions, vibrations, or any other desired factor or any combination of these and other factors.
- the firing fraction determining block 620 can be implemented algorithmically on a processor, using equations, using a lookup table as shown in Fig. 2, using a lookup table with interpolation, or using any other suitable method.
- the minimum firing fraction is determined by a minimum firing fraction determiner block 622.
- This block takes the vehicle gear, the RPM, and optionally other variables such as nominal mass air charge as inputs. Based on these inputs, the minimum firing fraction determiner block determines a minimum allowed firing fraction. It can be implemented with equations, a lookup table as diagrammatically illustrated in Figure 6, (with or without interpolation) or using other suitable approaches.
- both the optimal firing fraction and the minimum firing fraction are input to a comparison block 624, the output of which is the maximum firing fraction of the two.
- the desired firing fraction may be directed to an appropriate firing timing determining module 120 as previously described.
- the comparison block 624 so informs a power train parameter adjusting module 116 or other appropriate component (e.g., the ECU) which in turn is arranged to adjust other engine parameters such that the target manifold absolute pressure and/or cam settings, etc. to effectively adjust the mass air charge in a manner such that the directed firing fraction produces the requested torque or power.
- An advantage of using the various described lookup table based approaches to the firing fraction determination is that the table designer has wide flexibility in defining the desired firing fraction for specific operational conditions. Such deterministic control tends to be more difficult to implement using logic based approaches when calculation of the desired firing fraction is not susceptible to simple algorithmic definition.
- the described approach also allows the skip fire controller to utilize a fairly wide range of firing fractions when desired.
- indices such as desired engine output, engine speed and gear are described.
- powertrain or vehicle parameters such as manifold absolute pressure (MAP), mass air charge (MAC), cam phase settings, throttle position, cylinder torque output, engine torque output, vehicle speed and estimated manifold temperature can be used in particular implementations.
- environmental parameters such as ambient barometric pressure may be used.
- other relevant parameters may be used as indices as well.
- MAP manifold pressure
- skip fire management does not need to be used to the exclusion of other types of engine control.
- there will often be operational conditions where it is desirable to operate the engine in a conventional (fire all cylinders) mode where the output of the engine is modulated primarily by the throttle position as opposed to the firing fraction.
- a commanded firing fraction is coextensive with an operational state that would be available in a standard variable displacement mode (i.e., where only a fixed set of cylinders are fired all of the time)
- the invention has been described primarily in the context of controlling the firing of 4-stroke piston engines suitable for use in motor vehicles.
- 4-stroke piston engines suitable for use in motor vehicles.
- the described approaches are very well suited for use in a wide variety of internal combustion engines. These include engines for virtually any type of vehicle - including cars, trucks, boats, aircraft, motorcycles, scooters, etc.; for non-vehicular applications such as generators, lawn mowers, models, etc.; and virtually any other application that utilizes an internal combustion engine.
- thermodynamic cycles including virtually any type of two stroke piston engines, diesel engines, Otto cycle engines, Dual cycle engines, Miller cycle engines, Atkins cycle engines, Wankel engines and other types of rotary engines, mixed cycle engines (such as dual Otto and diesel engines), hybrid engines, radial engines, etc. It is also believed that the described approaches will work well with newly developed internal combustion engines regardless of whether they operate utilizing currently known, or later developed thermodynamic cycles.
- the mass air charge introduced to the working chambers for each of the cylinder firings may be set at the mass air charge that provides substantially the highest thermodynamic efficiency at the current operating state of the engine (e.g., engine speed, environmental conditions, etc.).
- the described control approach works very well when used in conjunction with this type of optimized skip fire engine operation. However, that is by no means a requirement. Rather, the described control approach works very well regardless of the conditions that the working chambers are fired under.
- the described firing control unit may be implemented within an engine control unit, as a separate firing control co-processor or in any other suitable manner.
- conventional operation may be preferable in certain engine states such as engine startup, engine idle, low engine speeds, etc.
- the described skip fire control can readily be used with a variety of other fuel economy and/or performance enhancement techniques - including lean burning techniques, fuel injection profiling techniques, turbocharging, supercharging, etc.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Output Control And Ontrol Of Special Type Engine (AREA)
- Electrical Control Of Ignition Timing (AREA)
- Combined Controls Of Internal Combustion Engines (AREA)
- Control Of Vehicle Engines Or Engines For Specific Uses (AREA)
Priority Applications (6)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR20157004132A KR20150038113A (ko) | 2012-08-10 | 2013-08-07 | 스킵 점화 기관 제어에서의 점화 부분 관리 |
DE201311003999 DE112013003999T5 (de) | 2012-08-10 | 2013-08-07 | Zündungsbruchteilmanagement bei der Zündungsauslassungs-Kraftmaschinensteuerung |
BR112015002675-3A BR112015002675B1 (pt) | 2012-08-10 | 2013-08-07 | Controlador de motor de salto de disparo, controlador de motor que inclui o controlador de motor de salto de disparo, controlador de motor de salto de disparo para um motor de ignição de faísca, método de operar motor de ignição de faísca, unidade de controle de motor, e método de controle da operação de salto de disparo de um motor |
CN201380041485.2A CN104520563B (zh) | 2012-08-10 | 2013-08-07 | 跳过点火发动机控制中的点火分数管理 |
JP2015526683A JP6255018B2 (ja) | 2012-08-10 | 2013-08-07 | スキップ点火エンジン制御における点火比管理 |
US13/963,686 US9650971B2 (en) | 2010-01-11 | 2013-08-09 | Firing fraction management in skip fire engine control |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US201261682065P | 2012-08-10 | 2012-08-10 | |
US61/682,065 | 2012-08-10 |
Related Parent Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/004,844 Continuation-In-Part US8701628B2 (en) | 2008-07-11 | 2011-01-11 | Internal combustion engine control for improved fuel efficiency |
Related Child Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US13/963,686 Continuation US9650971B2 (en) | 2010-01-11 | 2013-08-09 | Firing fraction management in skip fire engine control |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2014025939A1 true WO2014025939A1 (en) | 2014-02-13 |
Family
ID=50068555
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US2013/054027 WO2014025939A1 (en) | 2010-01-11 | 2013-08-07 | Firing fraction management in skip fire engine control |
Country Status (6)
Country | Link |
---|---|
JP (1) | JP6255018B2 (de) |
KR (1) | KR20150038113A (de) |
CN (1) | CN104520563B (de) |
BR (1) | BR112015002675B1 (de) |
DE (1) | DE112013003999T5 (de) |
WO (1) | WO2014025939A1 (de) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2019206968A (ja) * | 2014-11-10 | 2019-12-05 | トゥラ テクノロジー インコーポレイテッドTula Technology,Inc. | 多段スキップファイア |
Families Citing this family (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US10337441B2 (en) * | 2015-06-09 | 2019-07-02 | GM Global Technology Operations LLC | Air per cylinder determination systems and methods |
US9878718B2 (en) * | 2016-06-23 | 2018-01-30 | Tula Technology, Inc. | Coordination of vehicle actuators during firing fraction transitions |
US9903283B1 (en) | 2016-08-24 | 2018-02-27 | GM Global Technology Operations LLC | Method to optimize engine operation using active fuel management |
US10233852B2 (en) * | 2016-10-11 | 2019-03-19 | Ford Global Technologies, Llc | System and method for operating engine cylinders |
US10077726B2 (en) * | 2016-12-21 | 2018-09-18 | Ford Global Technologies, Llc | System and method to activate and deactivate engine cylinders |
US20190003443A1 (en) * | 2017-07-03 | 2019-01-03 | Tula Technology, Inc. | Dynamic charge compression ignition engine with multiple aftertreatment systems |
JP6863166B2 (ja) * | 2017-08-08 | 2021-04-21 | トヨタ自動車株式会社 | 燃焼気筒比率の可変制御装置 |
CN114382629A (zh) * | 2022-03-23 | 2022-04-22 | 潍柴动力股份有限公司 | 一种发动机的控制方法、装置、设备及存储介质 |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5553575A (en) * | 1995-06-16 | 1996-09-10 | Servojet Products International | Lambda control by skip fire of unthrottled gas fueled engines |
US5826563A (en) * | 1997-07-28 | 1998-10-27 | General Electric Company | Diesel engine cylinder skip firing system |
US20030105577A1 (en) * | 2001-12-05 | 2003-06-05 | Dino Bortolin | Autonomous control of engine operation via a lookup table |
US20110213541A1 (en) * | 2008-07-11 | 2011-09-01 | Tula Technology, Inc. | Internal combustion engine control for improved fuel efficiency |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2976766B2 (ja) * | 1993-09-16 | 1999-11-10 | トヨタ自動車株式会社 | 可変気筒エンジンの制御装置 |
US6360724B1 (en) * | 2000-05-18 | 2002-03-26 | Brunswick Corporation | Method and apparatus for controlling the power output of a homogenous charge internal combustion engine |
US8131447B2 (en) * | 2008-07-11 | 2012-03-06 | Tula Technology, Inc. | Internal combustion engine control for improved fuel efficiency |
US8336521B2 (en) * | 2008-07-11 | 2012-12-25 | Tula Technology, Inc. | Internal combustion engine control for improved fuel efficiency |
US7963267B2 (en) * | 2008-07-17 | 2011-06-21 | Ford Global Technologies, Llc | Multi-stroke variable displacement engine |
US20120046853A1 (en) * | 2010-08-20 | 2012-02-23 | Silvestri Chester J | System and Methods for Improved Efficiency Compression Ignition Internal Combustion Engine Control |
-
2013
- 2013-08-07 KR KR20157004132A patent/KR20150038113A/ko not_active Application Discontinuation
- 2013-08-07 CN CN201380041485.2A patent/CN104520563B/zh not_active Expired - Fee Related
- 2013-08-07 BR BR112015002675-3A patent/BR112015002675B1/pt not_active IP Right Cessation
- 2013-08-07 JP JP2015526683A patent/JP6255018B2/ja active Active
- 2013-08-07 WO PCT/US2013/054027 patent/WO2014025939A1/en active Application Filing
- 2013-08-07 DE DE201311003999 patent/DE112013003999T5/de not_active Withdrawn
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5553575A (en) * | 1995-06-16 | 1996-09-10 | Servojet Products International | Lambda control by skip fire of unthrottled gas fueled engines |
US5826563A (en) * | 1997-07-28 | 1998-10-27 | General Electric Company | Diesel engine cylinder skip firing system |
US20030105577A1 (en) * | 2001-12-05 | 2003-06-05 | Dino Bortolin | Autonomous control of engine operation via a lookup table |
US20110213541A1 (en) * | 2008-07-11 | 2011-09-01 | Tula Technology, Inc. | Internal combustion engine control for improved fuel efficiency |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2019206968A (ja) * | 2014-11-10 | 2019-12-05 | トゥラ テクノロジー インコーポレイテッドTula Technology,Inc. | 多段スキップファイア |
JP7030341B2 (ja) | 2014-11-10 | 2022-03-07 | トゥラ テクノロジー インコーポレイテッド | 多段スキップファイア |
Also Published As
Publication number | Publication date |
---|---|
JP6255018B2 (ja) | 2017-12-27 |
CN104520563A (zh) | 2015-04-15 |
DE112013003999T5 (de) | 2015-05-07 |
BR112015002675B1 (pt) | 2021-09-28 |
CN104520563B (zh) | 2018-10-16 |
KR20150038113A (ko) | 2015-04-08 |
BR112015002675A2 (pt) | 2017-09-19 |
JP2015524541A (ja) | 2015-08-24 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
US9650971B2 (en) | Firing fraction management in skip fire engine control | |
US10968841B2 (en) | Firing fraction management in skip fire engine control | |
US10941722B2 (en) | Method and apparatus for determining optimum skip fire firing profile | |
US10557427B2 (en) | Multi-level firing engine control | |
JP6255018B2 (ja) | スキップ点火エンジン制御における点火比管理 | |
US8887692B2 (en) | Systems and methods for decreasing torque fluctuations during cylinder deactivation and reactivation | |
US8755987B2 (en) | System and method for torque control in a homogeneous charge compression ignition engine | |
US20130080023A1 (en) | System and method for securing engine torque requests | |
US9002623B2 (en) | Fully flexible exhaust valve actuator control systems and methods | |
EP2524129A1 (de) | Steuerung eines verbrennungsmotors für erhöhte kraftstoffeffizienz | |
CN109026493B (zh) | 控制内燃发动机的方法和点火控制器 | |
US10364765B2 (en) | Method to select optimal mode on a multi-mode engine with charging | |
CN109863291B (zh) | 改变点火序列的相位的方法以及跳过点火发动机控制器 | |
US10393085B2 (en) | Managing firing phase transitions | |
US9169787B2 (en) | Valve control systems and methods for cylinder deactivation and activation transitions |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
121 | Ep: the epo has been informed by wipo that ep was designated in this application |
Ref document number: 13827567 Country of ref document: EP Kind code of ref document: A1 |
|
ENP | Entry into the national phase |
Ref document number: 2015526683 Country of ref document: JP Kind code of ref document: A |
|
WWE | Wipo information: entry into national phase |
Ref document number: 1120130039990 Country of ref document: DE Ref document number: 112013003999 Country of ref document: DE |
|
ENP | Entry into the national phase |
Ref document number: 20157004132 Country of ref document: KR Kind code of ref document: A |
|
122 | Ep: pct application non-entry in european phase |
Ref document number: 13827567 Country of ref document: EP Kind code of ref document: A1 |
|
REG | Reference to national code |
Ref country code: BR Ref legal event code: B01A Ref document number: 112015002675 Country of ref document: BR |
|
ENP | Entry into the national phase |
Ref document number: 112015002675 Country of ref document: BR Kind code of ref document: A2 Effective date: 20150206 |