Patent Application
20120191314
This application claims priority to British Patent Application No. 1101175.6,filed Jan. 24, 2011, which is incorporated herein by reference in its entirety.
The technical field relates in general to a method for controlling internal combustion engines operation and, in particular, to a method for controlling the engine torque delivered during engine operation.
Technologies and systems currently used on vehicles, such as automatic transmission, BAS+, LNT and DPF devices need to maintain the engine in correct operating conditions (i.e., correct operating points), and in particular there is the need of a correct engine torque management, in order to control the engine torque delivered, especially during transient conditions. For these purposes, on internal combustion engines mounted on vehicles calibration activities are carried out wherein a set of nominal operation points are established in order to obtain a correct engine operation, in every functioning conditions, and to maintain some functional parameters such as fuel consumptions, emissions, noise, performances and others, on nominal values. The nominal values are established from the engine or vehicle manufacturer in order to improve the driver feelings and vehicle performances but also in order to comply with national and international regulations relating to emissions, noise, etc.
During every day driving and using conditions, it could happen that deterioration of the engine, or at least of a part or a subsystem of the engine, caused by a plurality of factors such as aging, incorrect use or maintenance conditions, etc., adversely affects the correct engine operation, and in particular determine difficult to reach the nominal value (i.e., nominal operating points) established during the calibration activities. In detail, errors caused by engine aging, injectors drift, engine-to-engine dispersion, adversely affect the correct engine operation, and the nominal values established during the calibration process of the engine are not reached, thus the fuel consumption, emissions, performances and noise values are different from those declared and established during the engine calibration process.
The above-reported problems, caused mainly by the deterioration of the engine, lead to different engine operating conditions during everyday use and, as verified by the applicant by means of experimental tests, these problems determine engine operation in different points with respect to those established during the calibration activities. For these reasons, the engine torque amount delivered is different from the nominal requested values.
In view of the above, there is at least a need to control the engine operating conditions and, in particular, to perform an accurate and efficient management of the torque delivered by the engine in order to eliminate adverse effects caused by deterioration, and in particular by engine aging, injectors drift, engine to engine dispersion, etc. It is at least on object to provide a method for controlling the engine torque delivered in order to reach the correct nominal value established during calibration activities. At least another object is to provide a method for controlling the engine, and in particular the engine torque delivered, independently from the deterioration errors, reported above, for example, engine aging, injectors drift, etc., in order to ensure that fuel consumption, emission and noise are always the nominal declared during calibration activities. In addition, other objects, desirable features and characteristics will become apparent from the subsequent summary and detailed description, and the appended claims, taken in conjunction with the accompanying drawings and this background.
A method is provided that comprises setting a brake torque request value during the engine operation, deriving a request fuel quantity value on the basis of said brake torque request value, comparing said value of the brake torque requested with a measured and/or estimated brake torque value for calculating a brake torque error value, and modifying directly or indirectly the request fuel quantity injected in said engine on the basis of the brake torque error value. The control method acts on the “engine brake torque” and it should be noted that this expression is used in the present disclosure to indicate the “input gearbox torque”. In other words, according to an embodiment, the method allows to control the engine brake torque delivered by the engine which represents the “real” torque amount requested by the driver during the use, taking also into account the torque amount requested by accessories and other systems or subsystems, for example the air conditioning compressor.
The method allows to perform a control of the torque delivered by the engine, and in particular of the engine brake torque, in order to operate the engine in the nominal set points established during the calibration activities, independently from engine aging, injection drifts, and other errors caused by deterioration effects or malfunctioning conditions. In greater detail, comparing the value of the brake torque requested with a measured and/or estimated brake torque value allows calculating a brake torque error value that is used for modifying directly or indirectly the request fuel quantity injected in the engine. It has to be noted that the brake torque value is measured by means of suitable sensors, and/or estimated on the basis of models, maps, etc. As will be disclosed in greater detail later, the method on the engine brake torque acts in a closed loop control type.
Advantageously, the control of the fuel quantity injected is performed directly or indirectly: in other words, the method allows controlling the torque delivered by the engine by adjusting directly the fuel quantity injected in the engine, or indirectly, for example, by acting on functional parameters of the injection systems. According to an embodiment, the method acts by adjusting the energizing time of the injectors. As already mentioned above, the modification of the injected fuel quantity, directly or indirectly, determine the correction of the operating points of the engine, in order to maintain not only the delivered torque on the nominal set value, but also fuel consumptions, emissions, performances and noise are maintained in the nominal values declared during calibration activities. Usually, in the method, the request fuel quantity is derived on the basis of the value of the brake torque requested, taking also into account the total friction, in order to calculate a brake torque indicated value, which is then used for deriving the request fuel quantity value taking into account at least the engine speed value.
According to an embodiment, the method comprises the step of deriving a request fuel injection quantity delta value on the basis of the brake torque error value, the request injection quantity delta value is then compared with the request fuel quantity value in order to calculate a request fuel quantity adjusted value. The request fuel quantity adjusted value is the output of the closed loop control based on the measured and/or estimated brake torque, which is used for evaluating the error with respect to the request brake torque value, and allows to perform an accurate control on the “real” engine torque requested, in order to maintain the engine operation points in correspondence of the nominal points established during calibration activities.
According to an embodiment, the request fuel injection quantity delta value and the injection fuel quantity request value relates to main/after injection pulses, and in general to “torque forming” injection pulses. Thus, it is possible to control the torque delivered by the engine and to maintain it in the nominal values. In another possibility, the request fuel injection quantity delta value is compared with the total fuel injection quantity, and/or with at least the fuel quantity requested by the rail system, and the air system, in order to calculate a request fuel quantity adjusted value for at least the rail system, the air system and the injection systems.
According to another embodiment, the method further comprises deriving an injectors energizing time delta value on the basis of the brake torque error value, which is compared with the energizing time request value derived from said request fuel quantity value, in order to calculate a request energizing time-adjusted value for indirectly modifying the fuel quantity injected in the engine. By modifying in closed loop control the fuel injection quantity, on the basis of a brake torque error value derived from the comparison of the requested brake torque and the current measured and/or estimated brake torque value, it can be obtained a more efficient and accurate control of the torque delivered by the engine during its operation. Moreover, maintaining the delivered brake torque amount in the calibrated nominal set points increases the confidence of reaching the nominal values established during calibration activities for fuel consumptions, noise, emissions, performances independently from the negative effects of deteriorations errors, and in particular, of engine aging, injectors drift effects, etc.
Furthermore, the closed loop control of the method allows a reduction in the time required for carrying out calibrations activities, and in particular, last minute calibration or re-calibration activities time is reduced in a sensible manner. In fact, the control on the request fuel quantity allows to reach the nominal operating points also with a less accurate calibration level because of a closed loop control based on, as mentioned above, a brake torque error value derived from a measured and/or estimated brake torque value.
Advantageously, improved vehicle driveability, gear-shifting quality are also obtained by the controlling method. Another embodiment provides a computer program comprising computer executable codes for carrying out the method for controlling engine torque delivered during engine operation, described above. The computer program, stored in a computer readable medium includes: a computer executable code for setting a brake torque request value during the engine operation; a computer executable code for deriving a request fuel quantity value on the basis of the brake torque request value; a computer executable code for comparing the value of the brake torque requested with a measured and/or estimated brake torque value for calculating a brake torque error value; a computer executable code for modifying directly or indirectly the request fuel quantity injected in the engine on the basis of the brake torque error value.
Another embodiment is an apparatus for controlling the engine torque delivered during engine operation, the apparatus comprising means for setting a brake torque request value BTREQ during the engine operation, means for deriving a request fuel quantity value I-REQ on the basis of said brake torque request value, means for comparing said value of the brake torque requested BTREQ with a measured and/or estimated brake torque value (BTMEAS) for calculating a brake torque error value (BTERR), means for modifying directly or indirectly the request fuel quantity injected I-REQ in said engine on the basis of said brake torque error value BTERR. The apparatus allows performance of a control of the torque delivered by the engine, and in particular, of the engine brake torque, in order to operate the engine in the nominal set points established during the calibration activities, independently from engine aging, injection drifts, and other errors caused by deterioration effects or malfunctioning conditions.
An embodiment of the apparatus has means for deriving a request fuel quantity value I-REQ configured to derive the request fuel quantity value by comparing (e.g., adding) the value of the brake torque requested BTREQ with total friction value TF for calculating a brake torque indicated value, deriving the request fuel quantity value I-REQ on the basis of the brake torque indicated BTIND value and at least the engine speed value.
Still another embodiment of the apparatus has means for deriving a request fuel quantity value I-REQ which are configured to derive a request fuel injection quantity delta value Δ on the basis of said brake torque error value BTERR, the request fuel injection quantity delta value Δ being compared with the request fuel quantity value I-REQ to calculate a request fuel quantity adjusted value I-ADJ. Yet another embodiment of the apparatus has means for deriving a request fuel quantity value I-REQ that are configured such that the request fuel injection quantity delta value Δ and the injection fuel quantity request value I-REQ are fuel injection quantity of main and/or after injection pulses and in particular torque forming injections.
Yet another embodiment of the apparatus is configured such that the request fuel injection quantity delta value Δ and the injection fuel quantity request value I-REQ are total fuel injection quantity considering all the injection pulses. A further embodiment of the apparatus has means for deriving a request fuel quantity value I-REQ that compare the request fuel injection quantity delta value Δ with the fuel quantity value request I-REQ for at least the rail system I-REQRAIL, the air system I-REQAIR, and for the injectors I-REQTOT, to calculate a request fuel quantity adjusted value for at least the rail system I-ADJRAIL, the air system I-ADJAIR, and the injectors I-ADJTOT.
Another embodiment of the apparatus comprises means for deriving an injectors energizing time delta value ΔET on the basis of the brake torque error value BTERR, the injectors energizing time delta value ΔET being compared with the energizing time request value I-REQET derived from said request fuel quantity value I-REQ, to calculate a request energizing time adjusted value I-ADJET.
The present invention will hereinafter be described in conjunction with the following drawing figures, wherein like numerals denote like elements, and:
The following detailed description is merely exemplary in nature and is not intended to limit application and uses. Furthermore, there is no intention to be bound by any theory presented in the preceding background or summary or the following detailed description.
The method for controlling the engine torque delivered during engine operation, comprises the steps of setting a brake torque request value BTREQ during the engine operation and deriving a request injection fuel quantity value, generally indicated as I-REQ on the basis of the brake torque request value. Generally, the request fuel quantity value I-REQ is derived by adding to the value of the brake torque requested BTREQ with a total friction value TF, which describes with both measured and/or estimated values the total amount of friction in the engine, subsystems, etc., for calculating a brake torque indicated value BTIND. A request injection fuel quantity value I-REQ is derived on the basis of the brake torque indicated value BTIND, obtained as explained above, and at least the engine speed value ES.
In greater detail, the request fuel quantity value I-REQ, which is the injection fuel quantity necessary for engine operation and for delivering a desired brake torque amount taking into account also friction effects, is measured and/or estimated trough a map function of engine speed ES and the indicated brake torque value BTIND. According to an embodiment of the method, the comparison of the value of the request brake torque BTREQ with a measured and/or estimated brake torque value BTMEAS allows to calculate a brake torque error value BTERR; which is used for modifying directly or indirectly the request fuel quantity value I-REQ injected in the engine. Advantageously, the method acts as a closed loop control on the request fuel quantity value I-REQ by means of a brake torque error value BTERR which represents the difference between the desired brake torque request BTREQ value and the measured-and/or estimated brake torque value BTMEAS, i.e., the real input gearbox torque requested by the driver.
It has to be noted that the expression modifying “directly or indirectly” the request fuel quantity I-REQ injected in the engine is used to indicate that the fuel quantity request is modified directly by deriving an injection quantity delta value Δ, which is compared with the request fuel quantity value I-REQ to calculate a request fuel quantity adjusted value I-ADJ, or indirectly by modifying the fuel quantity request value I-REQ acting on other parameters, such as injectors functional parameters.
According to an embodiment, the method comprises modifying the request fuel quantity by acting indirectly on the energizing time of the injectors, this embodiment will be disclosed later in connection to
Although
The total fuel injection request value I-REQTOT, which comprises fuel injection request data for all the injections pulses, is then used for deriving in a known manner, for example by the “injection splitting map” of the engine, the fuel quantity request data for the torque forming injections, and in particular for the main and/or after injections by deriving a main and/or after fuel quantity injection request value I-REQMAIN. (See the block injection splitting in the upper part of
As shown in the lower part of the flow chart of
As visible in the lower part of the flow chart of
In view of above, the control method schematically represented in
Having regard to the lower part of the flow chart of the method of
The upper part of the flow chart of
As shown in lower part of the flow chart of
As already disclosed above, all the embodiments described in connections to
The direct or indirect modification of the request injection fuel quantity I-REQ of the engine by means of a closed loop type control on the basis of the brake torque error value BTERR allows to improve the engine torque management with the confidence of reaching the nominal values established during the calibration activities of the torque delivered and also of the fuel consumptions, emissions, noise, etc. In other words, by means of the present method the torque delivered value is maintained on the calibrated operating nominal points, and by doing so also fuel consumptions, emission and other engine functional parameters are maintained in correspondence of the nominal points established during the calibration activities.
It is clear that the closed loop control type of the method, based on the “real” brake torque value request by the driver is not negatively affected by aging or deteriorations errors of the engine, or of engine parts, such as injectors drift, etc. Moreover, the controlling method allows improving the vehicle drivability, the gear-shifting quality and the clutch durability. Furthermore, a shorter calibration time is requested, in particular for last minute calibration or re-calibrations activities, thanks to the closed loop control actuated by the claimed controlling method on the request fuel quantity.
Moreover, the preferred implementation embodiment of the controlling method described above in connection to
The method for controlling the torque delivered during engine operation described above, may be carried out by means of a computer program comprising program codes (i.e., computer executable codes) for performing the controlling steps already described in connection to
The computer program comprises computer executable code for setting a brake torque request value BTREQ during the engine operation; a computer executable code for deriving a request fuel quantity value I-REQ on the basis of the brake torque request value; a computer executable code for comparing the value of the brake torque requested with a measured and/or estimated brake torque value BTMEAS for calculating a brake torque error value BTERR; a computer executable code for modifying directly or indirectly the request fuel quantity injected I-REQ in the engine on the basis of the brake torque error value.
According to an embodiment, the computer program is stored on storage unit or a computer readable medium that is connected, or integrally produced with an electronic control apparatus for an internal combustion engine. The electronic control apparatus is provided with a microprocessor, or any suitable means known in art, for receiving the computer codes of the computer program and for executing them.
While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1101175.6 | Jan 2011 | GB | national |
