EP2754875A1 - Procédé de gestion du fonctionnement d'un moteur à combustion interne - Google Patents

Procédé de gestion du fonctionnement d'un moteur à combustion interne Download PDF

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Publication number
EP2754875A1
EP2754875A1 EP13151306.1A EP13151306A EP2754875A1 EP 2754875 A1 EP2754875 A1 EP 2754875A1 EP 13151306 A EP13151306 A EP 13151306A EP 2754875 A1 EP2754875 A1 EP 2754875A1
Authority
EP
European Patent Office
Prior art keywords
pressure
cylinder
exhaust manifold
cylinder pressure
determined
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP13151306.1A
Other languages
German (de)
English (en)
Inventor
Vincenzo Rosito
Joachim Paul
Stefan Motz
Sebastian-Paul Wenzel
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Robert Bosch GmbH
Original Assignee
Robert Bosch GmbH
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Robert Bosch GmbH filed Critical Robert Bosch GmbH
Priority to EP13151306.1A priority Critical patent/EP2754875A1/fr
Publication of EP2754875A1 publication Critical patent/EP2754875A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
    • F02D—CONTROLLING COMBUSTION ENGINES
    • F02D35/00—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for
    • F02D35/02—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions
    • F02D35/023—Controlling engines, dependent on conditions exterior or interior to engines, not otherwise provided for on interior conditions by determining the cylinder pressure
    • 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
    • F02D41/1438—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor
    • F02D41/1444—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases
    • F02D41/1448—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an exhaust gas pressure
    • F02D41/145—Introducing closed-loop corrections using means for determining characteristics of the combustion gases; Sensors therefor characterised by the characteristics of the combustion gases the characteristics being an exhaust gas pressure with determination means using an estimation
    • 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
    • F02D41/24—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means
    • F02D41/26—Electrical control of supply of combustible mixture or its constituents characterised by the use of digital means using computer, e.g. microprocessor
    • F02D41/28—Interface circuits
    • F02D2041/286—Interface circuits comprising means for signal processing

Definitions

  • the present invention relates to a method of operating a combustion engine, wherein an exhaust manifold pressure within an exhaust manifold is determined.
  • the invention further relates to a corresponding control unit configured to operate a combustion engine.
  • the invention solves this object by a method according to claim 1. As well, the invention solves this object by a control unit according to claim 11.
  • the method according to the invention comprises operating a combustion engine wherein an exhaust manifold pressure within an exhaust manifold is determined.
  • a cylinder pressure of at least one cylinder of said combustion engine is determined and said exhaust manifold pressure is derived from said cylinder pressure.
  • This advantageously enables to determine an exhaust manifold pressure of the combustion engine without the need of providing a dedicated exhaust manifold pressure sensor in the exhaust manifold. Rather, since the exhaust manifold pressure is derived from the cylinder pressure, the provisioning of at least one cylinder pressure sensor is sufficient for also determining said exhaust manifold pressure. Thus, existing cylinder pressure sensor(s) may advantageously be used to also assess the exhaust manifold pressure.
  • a further advantage of the inventive principle is the fact that the exhaust manifold pressure, when being derived from the cylinder pressure, can be determined with a comparatively high sample rate. I.e., the inventive principle also enables to attain precise values for the exhaust manifold pressure even in non-stationary operation of the combustion engine, which is not possible with existing exhaust manifold pressure sensors that are mounted within the exhaust manifold.
  • a cylinder pressure of more than one cylinder of said combustion engine is determined.
  • the cylinder pressure values of a plurality of cylinders may be used for determining the exhaust manifold pressure, which ensures increased precision and reliability. I.e., even if due to some error the cylinder pressure of one specific cylinder cannot be determined any more, the cylinder pressure value(s) of further cylinder(s) may be used to perform the inventive determination of the exhaust manifold pressure depending on said cylinder pressure.
  • said cylinder pressure is determined by means of at least one cylinder pressure sensor which is assigned to a respective cylinder of the combustion engine.
  • the cylinder pressure could also be determined by a corresponding model which simulates the cylinder pressure, as long as the values of such model are sufficiently precise for also deriving the exhaust manifold pressure therefrom.
  • said cylinder pressure sensor is configured to provide sample values of said cylinder pressure with a rate of about at least one sample per 1 degree of a crankshaft angle of said combustion engine.
  • said cylinder pressure of a specific cylinder is determined during a phase in which an exhaust valve of said specific cylinder is open, and in which preferably also an intake valve of said specific cylinder is closed.
  • a particularly precise determination of the exhaust manifold pressure based on the cylinder pressure is enabled, since pressure variations due to gas exchange of the cylinder are comparatively low.
  • said phase is determined such that a change over time of the cylinder pressure is smaller than a predetermined first threshold value.
  • the "phase" in time for assessing the cylinder pressure in order to derive the exhaust manifold pressure therefrom is characterized by a rather “flat” cylinder pressure curve over time.
  • said exhaust manifold pressure is determined by averaging said cylinder pressures of one or more cylinders over a predetermined time.
  • various cylinder pressure values as obtained from one cylinder, i.e. during the abovementioned phase may be averaged.
  • various cylinder pressure values as obtained from several cylinders, i.e. during the abovementioned phase may be averaged. It is also possible to combine single cylinder pressure values of several sensors to perform averaging in the sense of the present embodiment.
  • a pressure difference, particularly drop, between a cylinder the cylinder pressure of which is determined and between a specific position in the exhaust manifold is taken into consideration when determining said exhaust manifold pressure.
  • a particularly precise value for the exhaust manifold pressure may be attained which takes into account e.g. the configuration of pipes and the geometry of the exhaust manifold.
  • said averaged cylinder pressure Pavg is modified to take into account pressure drops between the pressure in a cylinder and the pressure in the exhaust manifold, particularly by adding a correction value ⁇ P which represents said pressure drops.
  • a further solution to the object of the present invention is given by a control unit for operating a combustion engine, wherein said control unit is configured to determine an exhaust manifold pressure within an exhaust manifold, characterized in that said control unit is further configured to determine a cylinder pressure of at least one cylinder of said combustion engine and to derive said exhaust manifold pressure from said cylinder pressure.
  • FIG. 1 depicts a schematic block diagram of an embodiment of a combustion engine 10 according to the invention.
  • the combustion engine 10 comprises four cylinders only two of which are designated by reference numerals 13a, 13b in Fig. 1 .
  • An intake manifold section 11 is provided to supply to the cylinders a fuel/air mixture in a per se known manner.
  • an exhaust manifold 12 which receives exhaust gases from the cylinders 13a, 13b, .. in a per se known manner.
  • a turbocharger and/or an after treatment system for the exhaust gases may be arranged, which is not depicted by Fig. 1 .
  • first cylinder 13a two exhaust valves 16a are exemplarily depicted.
  • the further cylinders may also be equipped with such exhaust valves.
  • the exhaust valves control the flow of exhaust gases from the cylinder 13a to the exhaust manifold 12.
  • a cylinder pressure sensor 14 which is arranged directly in the cylinder 13a and which as such enables to directly measure a cylinder pressure in said cylinder 13a, especially during combustion.
  • the further cylinders may also be equipped with cylinder pressure sensors. However, for the operation of the invention, which is explained in detail below, a single cylinder pressure sensor 14 is sufficient.
  • control unit 20 which may also receive sensor signals such as a cylinder pressure signal of sensor 14a and the like.
  • FIG. 2 schematically depicts a block diagram of a method according to the embodiments.
  • a cylinder pressure p_c1 of at least one cylinder 13a ( Fig. 1 ) of said combustion engine 10 is determined, e.g. by means of sensor 14a, and an exhaust manifold pressure, which is present in the exhaust manifold 12, is derived from said cylinder pressure p_c1.
  • the exhaust manifold pressure may be determined without requiring a dedicated pressure sensor in said exhaust manifold 12.
  • Fig. 1 also depicts a dedicated pressure sensor 15, mounted at a position P within the exhaust manifold 12, which is an exhaust manifold pressure sensor.
  • this dedicated sensor 15 may be avoided because the present invention enables to derive the exhaust manifold pressure p_em ( Fig. 2 ) from the cylinder pressure p_c1 as obtained by cylinder pressure sensor 14a.
  • a combustion engine according to the embodiments is not required to have a dedicated exhaust manifold pressure sensor 15.
  • the inventive method that considers the cylinder pressure p_c1 to determine the exhaust manifold pressure may be used to refine or verify the measurements of sensor 15.
  • the exhaust manifold pressure p_em as obtained according to the embodiments may e.g. be used to check operational conditions for a turbocharger (not shown) or an exhaust gas after treatment system (not shown), which may be arranged at the output 12a of the exhaust manifold and which are thus exposed to the exhaust manifold pressure.
  • the control unit 20 ( Fig. 1 ) may perform the method according to the embodiments and may monitor the exhaust manifold pressure. If the exhaust manifold pressure is increasing too much, to avoid damages of the turbocharger due to excessive exhaust manifold pressure, the control unit may perform some control routines to reduce the exhaust manifold pressure or shift the combustion engine 10 to a safety condition (e.g., reducing injected fuel quantity).
  • Fig. 3 depicts a simplified flow chart of the method according to an embodiment.
  • the cylinder pressure p_c1 ( Fig. 2 ) is determined by means of the cylinder pressure sensor 14a ( Fig. 1 ).
  • the exhaust manifold pressure p_em is derived 110 from said cylinder pressure p_c1.
  • the method may e.g. be performed by calculation means (processor) of the control unit 20.
  • Fig. 4 depicts a cylinder pressure graph over time for a specific cylinder 13a, which may e.g. be obtained by collecting a plurality of cylinder pressure values over time or a crankshaft angle, respectively, the values e.g. being obtained from the sensor 14a ( Fig. 1 ).
  • the time interval T1 of Fig. 4 denotes a phase in which the exhaust valves 16a are open.
  • the time interval T2 of Fig. 4 denotes a phase in which the intake valves (not shown) are open.
  • a compression and work cycle is indicated by a corresponding rise and fall of the cylinder pressure p_c1 in a per se known manner.
  • said cylinder pressure p_c1 of said specific cylinder 13a is determined during a phase ph ( Fig. 4 ) in which the exhaust valve 16a of said specific cylinder 13a is open, and in which preferably also an intake valve of said specific cylinder 13a is closed.
  • this phase ph is located in a crankshaft angle range between about 240 degrees and about 320 degrees. I.e., according to an embodiment, only the cylinder pressure values within said phase ph are considered for deriving the exhaust manifold pressure, in order to avoid errors due the cylinder pressure changes during compression/work cycle substantially not correlating with the exhaust manifold pressure.
  • said phase ph is determined such that a change over time of the cylinder pressure p_c1 is smaller than a predetermined first threshold value.
  • a predetermined first threshold value E.g., the gradient of cylinder pressure p_c1 over time may be determined, and only if it is sufficiently small, it is concluded that phase ph is reached.
  • Fig. 4 only depicts the cylinder pressure of one specific cylinder 13a, according to an embodiment, a cylinder pressure of more than one cylinder of said combustion engine 10, preferably of all cylinders of said combustion engine 10, is determined, for deriving said exhaust manifold pressure.
  • ⁇ start 240
  • ⁇ end 320
  • n cyl 1 (i.e., only one cylinder pressure sensor signal)
  • more than one engine cycle i.a. up to m many cycles
  • more than one engine cycle i.a. up to m many cycles
  • said averaged cylinder pressure Pavg is modified to take into account pressure drops between the pressure in a cylinder 13a and the pressure in the exhaust manifold 12, particularly by adding a correction value ⁇ P which represents said pressure drops.
  • the value of the correction value ⁇ P is implementation specific and may e.g. be determined during a development phase. For example, during development, a fast pressure sensor may be mounted at position P ( Fig. 1 ) to determine the actual exhaust manifold pressure, and the above equation(s) as well as the value of the correction value ⁇ P may be derived from differences in the cylinder pressure p_c1 and the actual exhaust manifold pressure as determined by the fast pressure sensor. After development, the fast pressure sensor may be removed from the exhaust manifold, and the inventive method ensures a precise determination of the exhaust manifold by means of the cylinder pressure only.
  • said correction value ⁇ P may be determined by calibrating a map in the control unit 20 ( Fig. 1 ), i.e. by means of corresponding software.
  • the map may provide said correction value ⁇ P depending on engine speed, inner torque and delta pressure measured by two sensors (wherein delta pressure characterizes a pressure difference as obtained e.g. according to equation for Pavg above and by the fast pressure sensor temporarily arranged at position P during development).
  • Another way to determine said correction value ⁇ P comprises calibrating two parameters of linear curve regression, between Pavg and the signal from a fast pressure sensor temporarily arranged at position P during development.
  • the values "a” and “b” could be calculated and fulfilled in two different curves. I.e. for four different engine speeds of : 1000 rpm, 2000 rpm, 3000 rpm, 4000 rpm, four different values a1, a2, a3, a4 for parameter "a” may be found. Likewise, for said four different engine speeds listed above, four different values b1, b2, b3, b4 for parameter "b” may be found.
  • a third variant it is proposed to measure the exhaust flow (for example with an existing software function of the control unit 20) and to determine Pavg depending on equation 1 above.
  • ⁇ P a'•Q 2 + b'•Q + c', where a', b', and c' are constants coming from data regression.
  • the exhaust manifold pressure may also be determined.
  • this third variant is less accurate due to the influence of the exhaust flow rate Q being calculated from a control unit software model.
  • the present invention advantageously enables to avoid dedicated exhaust manifold pressure sensors 15 during regular engine operation of the combustion engine, because the exhaust manifold pressure is derived from cylinder pressure values. Since cylinder pressure sensors 14a are usually faster, i.e. yield sensor data values at a higher data rate as compared to existing exhaust manifold pressure sensors 15, even under fast dynamic operating conditions more precise exhaust manifold pressure values may be obtained by the invention. Thus, particularly turbocharger damages may be avoided because overpressure conditions may promptly be detected using the invention and countermeasures may promptly be activated.
  • cylinder pressure sensors 14a of the "glow plug combustion pressor sensor” type may be used.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Combined Controls Of Internal Combustion Engines (AREA)
EP13151306.1A 2013-01-15 2013-01-15 Procédé de gestion du fonctionnement d'un moteur à combustion interne Withdrawn EP2754875A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP13151306.1A EP2754875A1 (fr) 2013-01-15 2013-01-15 Procédé de gestion du fonctionnement d'un moteur à combustion interne

Applications Claiming Priority (1)

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EP13151306.1A EP2754875A1 (fr) 2013-01-15 2013-01-15 Procédé de gestion du fonctionnement d'un moteur à combustion interne

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EP2754875A1 true EP2754875A1 (fr) 2014-07-16

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1162357A2 (fr) * 2000-06-10 2001-12-12 Volkswagen Aktiengesellschaft Procédé et dispositif pour surveiller le fonctionnement d'un moteur à combustion interne
EP1607605A1 (fr) * 2004-06-11 2005-12-21 Peugeot Citroen Automobiles SA Système d'estimation de la pression dans le collecteur d'échappement d'un moteur diesel et procédé de calibrage de ce système
GB2473435A (en) * 2009-09-09 2011-03-16 Gm Global Tech Operations Inc Estimating i.c. engine exhaust manifold pressure using combustion chamber pressure values

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1162357A2 (fr) * 2000-06-10 2001-12-12 Volkswagen Aktiengesellschaft Procédé et dispositif pour surveiller le fonctionnement d'un moteur à combustion interne
EP1607605A1 (fr) * 2004-06-11 2005-12-21 Peugeot Citroen Automobiles SA Système d'estimation de la pression dans le collecteur d'échappement d'un moteur diesel et procédé de calibrage de ce système
GB2473435A (en) * 2009-09-09 2011-03-16 Gm Global Tech Operations Inc Estimating i.c. engine exhaust manifold pressure using combustion chamber pressure values

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