WO2008132588A2 - Vehicle control apparatus and control method - Google Patents
Vehicle control apparatus and control method Download PDFInfo
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- WO2008132588A2 WO2008132588A2 PCT/IB2008/001026 IB2008001026W WO2008132588A2 WO 2008132588 A2 WO2008132588 A2 WO 2008132588A2 IB 2008001026 W IB2008001026 W IB 2008001026W WO 2008132588 A2 WO2008132588 A2 WO 2008132588A2
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- predetermined parameters
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Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D11/00—Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated
- F02D11/06—Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated characterised by non-mechanical control linkages, e.g. fluid control linkages or by control linkages with power drive or assistance
- F02D11/10—Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated characterised by non-mechanical control linkages, e.g. fluid control linkages or by control linkages with power drive or assistance of the electric type
- F02D11/105—Arrangements for, or adaptations to, non-automatic engine control initiation means, e.g. operator initiated characterised by non-mechanical control linkages, e.g. fluid control linkages or by control linkages with power drive or assistance of the electric type characterised by the function converting demand to actuation, e.g. a map indicating relations between an accelerator pedal position and throttle valve opening or target engine torque
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- 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
- F02D41/0002—Controlling intake air
-
- 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
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
- F02D2041/1413—Controller structures or design
- F02D2041/1432—Controller structures or design the system including a filter, e.g. a low pass or high pass filter
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- 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
- F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
- F02D2041/1433—Introducing closed-loop corrections characterised by the control or regulation method using a model or simulation of the system
- F02D2041/1434—Inverse model
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- 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
- F02D2200/0402—Engine intake system parameters the parameter being determined by using a model of the engine intake or its components
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D2250/00—Engine control related to specific problems or objectives
- F02D2250/18—Control of the engine output torque
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/40—Engine management systems
Definitions
- the invention relates to a vehicle control apparatus and a control method.
- the invention relates to an apparatus for controlling a vehicle and a method of controlling an actuator installed in a vehicle, in which a desired value of a controlled variable of the actuator installed in the vehicle is calculated using model expressions.
- JP-A-2006-200466 an output control apparatus for an internal combustion engine is described.
- the desired throttle valve opening degree is calculated using an inverse model of the intake system model and an inverse model of the throttle model in order to achieve a desired torque of the internal combustion engine with good response.
- the engine speed and the valve timing which are parameters to be inputted into the inverse model, are processed with a filter to stabilize the control of output from the internal combustion engine.
- the invention provides an apparatus for controlling a vehicle and a method of controlling an actuator installed in a vehicle, which favorably reduce superposition of large noise on the desired value of a controlled variable of the actuator installed in the vehicle without impairing the response of a system.
- a first aspect of the invention relates to a vehicle control apparatus.
- the vehicle control apparatus calculates a desired value of a controlled variable of an actuator installed in a vehicle, using a model expression including a derivative portion in which at least one of predetermined parameters that are inputted is differentiated with respect to time.
- the predetermined parameters are divided into a first parameter group, to which part of the predetermined parameters belong that oscillate at frequencies higher than a first frequency, and a second parameter group, to which remaining part of the predetermined parameters belong that oscillate at frequencies lower than a second frequency that is lower than the first frequency. Only the remaining part of the predetermined parameters that belong to the second parameter group are included in subjects of differentiation in the model expression.
- the first parameter group, to which the parameters belong that oscillate at a frequency higher than the first frequency is excluded from the subjects of differentiation with respect to time, so that it is possible to prevent high-frequency noise from being amplified in the process in which the output of the model expression, that is, the desired controlled variable value of the actuator installed in the vehicle is calculated.
- the second parameter group, to which the parameters belong that oscillate at a frequency lower than the second frequency lower than the first frequency is included in the subjects of differentiation with respect to time, it is possible to ensure the accuracy of calculation using the model expression.
- every derivative portion of the predetermined parameter of the first parameter group may be approximated to zero.
- every derivative portion in which one of the part of the predetermined parameters that belong to the first parameter group is differentiated with respect to time, may be transformed into a product of a first derivative portion, J in which the one of the part of the predetermined parameters that belong to the first parameter group is differentiated with respect to one of the remaining part of the predetermined parameters that belong to the second parameter group, and a second derivative portion, in which the one of the remaining part of the predetermined parameters that belong to the second parameter group is differentiated with respect to time.
- the parameters that oscillate at high frequencies and therefore belong to the first parameter group are differentiated with respect to time, so that it is possible to favorably reduce superposition of large noise on the desired controlled variable value of the actuator installed in the vehicle.
- the parameters that oscillate at low frequencies and therefore belong to the second parameter group are differentiated with respect to time, so that it is possible to ensure the accuracy of calculation using the model expression.
- One of the predetermined parameters that belongs to the first parameter group may be engine speed.
- a second aspect of the invention relates to a vehicle control apparatus.
- This vehicle control apparatus uses a model expression, of which inputs include predetermined parameters and a desired controlled object value of a controlled object in a vehicle, to calculate a desired controlled variable value of an actuator installed in a vehicle that is required to control the controlled object to the desired controlled object value.
- the desired controlled object value is included in subjects of differentiation, and, of the predetermined parameters, every parameter that oscillates at a frequency higher than a predetermined frequency is excluded from the subjects of differentiation.
- the desired controlled object value of the controlled object in the vehicle is included in the subjects of differentiation, so that it is possible to favorably ensure the accuracy of calculation using the model expression.
- the predetermined parameters other than the desired controlled object value, that are inputted into the model expression
- every parameter that oscillates at a frequency higher than the predetermined frequency is excluded from the subjects of differentiation, so that it is possible to prevent high-frequency noise from being amplified in the process in which the output of the model expression, that is, the desired controlled variable value of the actuator installed in the vehicle is calculated.
- every derivative portion in which one of the predetermined parameters that oscillates at a frequency higher than the predetermined frequency is differentiated with respect to time, may be approximated to zero.
- every parameter that oscillates at a relatively high frequency is excluded from the subjects of differentiation in the model expression.
- the model expression may be obtained as an inverse function of an expression with which the desired controlled object value is calculated by inputting the desired controlled variable value of the actuator installed in the vehicle into a first order lag element with a time constant containing at least part of the predetermined parameters.
- the expression is used with which the desired controlled object value is calculated by inputting the desired controlled variable value of the actuator installed in the vehicle into the first order lag element with the time constant containing at least part of the predetermined parameter, even when the predetermined parameter, such as the intake air pressure P m , contained in the time constant varies depending on the conditions of the vehicle, such as the operational conditions of the internal combustion engine, it is possible to easily determine characteristics of the response of the controlled object to the adjustment of the actuator installed in the vehicle if the time constant is determined by obtaining the value of the parameter contained in the time constant at every time point when the vehicle is in certain conditions.
- the predetermined parameter such as the intake air pressure P m
- the model expression is defined as the inverse function of such an expression, it becomes possible to obtain the desired controlled variable value of the actuator installed in the vehicle that is required to achieve good response of the controlled object by inputting the desired controlled variable value of the actuator installed in the vehicle into the first order lead element with the above-described time constant.
- the desired controlled object value may be a desired torque value or a desired in-cylinder air amount value of an internal combustion engine.
- the desired controlled object value may contain a first desired torque value, which requires, of the actuator, a response within a first response time, and a second desired torque value, which requires, of the actuator, a response within a second response time longer than the first response time.
- the vehicle control apparatus may generate a final desired controlled object value by differentiating only the first desired torque value of the desired controlled object value and then summing a thus obtained derivative of the first desired torque value and the second desired torque value.
- One of the predetermined parameters that oscillates at a frequency higher than the predetermined frequency may be engine speed.
- the actuator installed in the vehicle may be a throttle valve that is disposed in an intake passage of an internal combustion engine and driven by a motor.
- a third aspect of the invention relates to a method of controlling a desired value of a controlled variable of an actuator installed in a vehicle.
- the control method includes: receiving predetermined parameters; dividing the predetermined parameters into a first parameter group, to which the parameters belong that oscillate at a frequency higher than a first frequency, and a second parameter group, to which the parameters belong that oscillate at a frequency lower than a second frequency that is lower than the first frequency; and differentiating only the parameters that belong to the second parameter group with respect to time.
- a fourth aspect of the invention relates to a method of controlling a desired value of a controlled variable of an actuator installed in a vehicle.
- the control method includes: receiving predetermined parameters and a desired controlled object value of a controlled object in a vehicle; including the desired controlled object value in subjects of differentiation; and excluding, of the predetermined parameters, every parameter that oscillates at a frequency higher than a predetermined frequency from the subjects of differentiation.
- FIG. 1 is a diagram for describing a configuration of an internal combustion engine system included in a vehicle control apparatus of a first embodiment of the invention
- FIG. 2 is a diagram for describing an outline of an intake system model constructed in an ECU shown in FIG. 1;
- FIGS. 3 A and 3B individually show characteristics of maps that are stored in the ECU to obtain f mt ( ⁇ ) and g m t(P m );
- FIG. 4 shows characteristics of a map stored in the ECU to obtain g mc (P m , ne, vvt);
- FIG. 5 is a diagram for describing a process in which a desired throttle valve opening degree ⁇ ref is obtained from a desired torque value trq ref of an internal combustion engine in a method that is referred to for the purpose of comparison with a method according to the first embodiment;.
- FIGS. 6 A and 6B are diagrams showing an example in which FF control is performed in which dynamics of the intake system is not taken into consideration;
- FIGS. 7A and 7B are diagrams showing an example in which FF control is performed according to the method shown in FIG. 5 in which the dynamics of the intake system is taken into consideration;
- FIGS. 8A and 8B are diagrams for describing problems with the method shown in FIG. 5;
- FIGS. 9A to 9C are diagrams for describing a method that is used, in the first embodiment, to calculate a desired throttle valve opening degree ⁇ re f that is required to achieve a desired in-cylinder air amount value;
- FIGS. 1OA and 1OB are diagrams for describing advantageous effects achieved by the method shown in FIGS. 9Ato 9C;
- FIG. 11 is a diagram for describing a control scheme including conversion of a torque value, which is referred to for the purpose of comparison with the second embodiment;
- FIGS. 12A and 12B are diagrams for describing problems with the method shown in FIG. 11;
- FIG. 13 is a diagram for describing a method that is used, in the second embodiment, to calculate a desired throttle valve opening degree ⁇ ref that is required to achieve a desired torque value trq ref ;
- FIGS. 14A and 14B are diagrams for describing advantageous effects achieved by the method shown in FIG. 13;
- FIG. 15 is a diagram showing a torque control scheme according to the second embodiment
- FIG. 16 is a diagram showing a vehicle control system in which a system having a first order lag element on the downstream side of an internal combustion engine system shown in FIG. 15;
- FIGS. 17A and 17B are diagrams showing a torque controller suitable for a first desired torque value Ti f that requires fast response, and a torque controller suitable for a second desired torque value Ti 5 that requires slow response;
- FIG. 18 is a diagram for describing a method that may be adopted to avoid a problem described in the description of a third embodiment for the purpose of comparison with a method of the third embodiment shown in FIG. 20;
- FIG. 19 is a diagram for describing advantages achieved when a torque controller described in the description of the second embodiment is used.
- FIG. 20 is a diagram for describing a torque controller according to the third embodiment.
- FIGS. 21A and 21B are time charts for describing advantageous effects achieved when the torque controller shown in FIG. 20 is actually used to control an internal combustion engine; and FIGS. 22A and 22B are time charts for describing advantageous effects achieved when the torque controller shown in FIG. 20 is actually used to control an internal combustion engine.
- FIG. i is a diagram for describing a configuration of an internal combustion engine system included in a vehicle control apparatus according to a first embodiment of the invention.
- the system according to this embodiment includes a multi-cylinder internal combustion engine 10.
- a piston 12 is provided in each of cylinders of the internal combustion engine 10.
- a combustion chamber 14 is formed on the head side of the piston 12.
- An intake passage 16 and an exhaust passage 18 are connected to the combustion chamber 14.
- An air flow meter 20 that outputs a signal corresponding to the flow rate of air taken into the intake passage 16 is provided near the inlet of the intake passage 16.
- a throttle valve 22 is provided downstream of the air flow meter 20.
- the throttle valve 22 is an electronically-controlled valve that is driven by a throttle motor 24 according to the accelerator pedal operation amount.
- a throttle position sensor 26 for detecting the throttle valve opening degree ⁇ is disposed near the throttle valve 22.
- a fuel injection valve 28 for injecting fuel toward the intake port of the internal combustion engine 10 is disposed downstream of the throttle valve 22.
- the internal combustion engine includes a cylinder head, in which a spark plug 30 is provided for each of the cylinders so as to protrude from the top portion of the combustion chamber 14 into the combustion chamber 14.
- the intake port and the exhaust port are provided with an intake valve(s) 32 and an exhaust valve(s) 34, respectively, that cause the combustion chamber 14 to communicate with and to be shut off from the intake passage 16 and the exhaust passage 18, respectively.
- the intake valve 32 and the exhaust valve 34 are driven by a variable intake valve (Variable Valve Timing (WT)) system 36 and a variable exhaust valve (VVT) system 38, respectively.
- the variable valve timing systems 36 and 38 open and close the intake valve(s) 32 and the exhaust valve(s) 34 in synchronization with the rotation of a crankshaft, and vary the open/close timing of the intake valve(s) 32 and the exhaust valve(s) 34, respectively.
- the internal combustion engine 10 is provided with a crank angle sensor 40 near the crankshaft.
- the crank angle sensor 40 is a sensor that switches between Hi output and Lo output every time the crankshaft rotates by a predetermined rotation angle.
- the internal combustion engine 10 is provided with a cam angle sensor 42 near an intake camshaft.
- the cam angle sensor 42 is a sensor having a configuration similar to that of the crank angle sensor 40. With the use of the output from the cam angle sensor 42, it is possible to detect the rotational position of the intake camshaft (valve timing vvt), for example.
- the system shown in FIG. 1 includes an ECU (Electronic Control Unit) 50.
- FIG. 2 is a diagram for describing an outline of the intake system model constructed in the ECU 50 shown in FIG. 1.
- the intake system model is a mathematical model for estimating the amount of air taken into a cylinder (in-cylinder charged air amount, or intake-valve passing-through air amount) me. More specifically, the intake system model includes: a throttle model for estimating the amount m t of air that passes through the throttle valve 22 (throttle-valve passing-through air amount); an intake pipe model for estimating the intake air pressure P m (and the intake air temperature T m ) in the intake passage 16 (intake manifold) downstream of the throttle valve 22; and an intake valve model for estimating the amount m c of air (intake-valve passing-through air amount, or in-cylinder charged air amount) that passes through the intake valve 32.
- the throttle-valve passing-through air amount m t , the intake air pressure P m , and the in-cylinder charged air amount m c can be calculated using the following expressions.
- the throttle- valve passing-through air amount m t (g/sec) is expressed by the product of a coefficient f m t( ⁇ ) and a coefficient g m t(P m ) as shown by the following expression (1).
- FIGS. 3A and 3B show the characteristics of the maps stored in the ECU 50 to obtain f mt ( ⁇ ) and g mt (P m )-
- the value of the coefficient f mt ( ⁇ ) is uniquely determined based on the throttle valve opening degree ⁇ , and has a characteristic such that the greater the throttle valve opening degree ⁇ is, the higher the value of the coefficient f mt is, in principle.
- the value of the coefficient g m t(Pm) is uniquely determined based on the intake air pressure P m .
- the coefficient g mt (P m ) has a characteristic such that the lower the intake air pressure P m is below the upstream-of-the-throttle-valve air pressure (atmospheric pressure) Pa, the greater the value of the coefficient g mt (P m ) is, until the intake air pressure P m falls below a certain value.
- the intake air pressure P m (Pa) and the intake air temperature T m (K) can be calculated by solving the following expressions (2a) and (2b).
- R is the gas constant
- V m is the intake air manifold volume in the internal combustion engine 10
- K is the specific heat ratio
- IHc - ⁇ - gnic (Pa ne, vvt) ⁇ ⁇ ⁇ (3)
- the coefficient g mc is a function of the intake air pressure P m , the engine speed ne, and the valve timing vvt, and T 3 is the upstream-of-the-throttle-valve air temperature (atmospheric temperature) T 3 .
- FIG. 4 shows the characteristics of the maps stored in the ECU 50 to obtain g mc (P m , ne, vvt). More specifically, the ECU 50 stores maps that define the coefficient g mc in relation to the intake air pressure P n , as shown in FIG. 4 for each set of the values of the engine speed ne and the valve timing vvt.
- the map shown in FIG. 4 has a characteristic such that the higher the intake air pressure P m is, the greater the value of the variable g mt is. With the use of such a characteristic of the variable g mc , it is possible to obtain the result of calculation such that the higher the intake air pressure P m is, the greater the in-cylinder charged air amount m c is.
- the efficiency kl c with which the air taken into a cylinder is charged can be calculated using the following expression (4) based on the in-cylinder charged air amount m c obtained as described above.
- Vc is the cylinder volume
- p a is the air density
- Kt is a coefficient that collectively represents the parameters other than m c and ne.
- the system according to the present embodiment is characterized in that the desired throttle valve opening degree ⁇ ref that brings about the desired torque value trq ref According to the driver's demand is calculated by the method described later with reference to FIGS. 9A to 9C, using the inverse model expressions obtained by transforming the above-described intake system model expressions.
- FIG. 5 is a diagram for describing a process in which the desired throttle valve opening degree ⁇ ref is obtained from the desired torque value trq ref of the internal combustion engine 10 in the related art.
- the desired value of the in-cylinder air amount that is required to achieve the desired torque value trq ref is acquired based on the torque maps that define the relation between the desired torque value trq ref and the desired in-cylinder air amount value (kl cre f or m cref ) of the internal combustion engine 10. More specifically, the torque map is a map that defines the desired in-cylinder air amount value in the form of the desired charging efficiency kl cref in relation to the desired torque value for each set of predetermined engine parameters, such as the engine speed ne and the ignition timing SA.
- either of the desired charging efficiency kl cref and the desired in-cylinder air amount m cref can be used as the index representing the desired value of the in-cylinder air amount, and the desired value of the in-cylinder air amount may therefore be acquired from the torque maps in the form of either of kl cref and m C ref.
- the following inverse model expressions (5) to (9) are derived by transforming the above-described intake system model expressions (1) to (4). Then, the desired throttle valve opening degree ⁇ ref required to achieve the desired in-cylinder air amount value is calculated with the use of the inverse model expressions, using as inputs the desired charging efficiency kl cref acquired from the torque map and the predetermined engine parameters, such as the engine speed ne.
- the following expression (5) is obtained by transforming the above expression (4) so that the left-hand side has the in-cylinder charged air amount m c only. With this expression (5), it is possible to obtain the desired in-cylinder air amount m cref based on the desired charging efficiency kl cref .
- the following expression (9a) is obtained by integrating both sides of the above expression (2a). With the following expression (9b), it is possible to obtain the desired intake air temperature T mref from the desired intake air pressure P mref that is obtained using the above expression (6), and the desired value of the P m /T m that is obtained using the expression (9a).
- FIGS. 6 A and 6B are diagrams showing an example in which FF control is performed in which the dynamics of the intake system is not taken into consideration.
- FIGS. 6 A and 6B are diagrams illustrating the related art of the invention.
- the throttle valve opening degree ⁇ is controlled to the value ⁇ i that enables the desired in-cylinder air amount value to be achieved as shown in FIG. 6A.
- the in-cylinder air amount gradually gets close to the desired value with a delay in the response of air intake as shown in FIG. 6B, and therefore, good torque response is not achieved.
- FIGS. 7 A and 7B are diagrams showing an example in which FF control is performed according to the method shown in FIG. 5 in which the dynamics of the intake system is taken into consideration.
- FIGS. 7 A and 7B are diagrams illustrating the related art of the invention.
- the desired throttle valve opening degree ⁇ ref is determined so that the throttle valve opening degree becomes equal to a throttle valve opening degree ⁇ 2 that is greater than a throttle valve opening degree ⁇ i that is required to achieve the desired in-cylinder air amount value.
- FIGS. 8 A and 8B are diagrams for describing problems with the method shown in FIG. 5. More specifically, FIG. 8 A shows a waveform of the desired in-cylinder air amount value that is periodically varied. FIG. 8B shows a waveform of the desired throttle valve opening degree ⁇ ref that is successively calculated to continuously achieve such a desired in-cylinder air amount value.
- the throttle valve opening degree ⁇ is controlled to such a desired throttle valve opening degree ⁇ ref , the in-cylinder air amount that accurately follows the desired in-cylinder air amount value is obtained as shown in FIG. 8A.
- the above expression (7) for obtaining the desired throttle-valve passing-through air amount mt re f contains the term obtained by differentiating the desired intake air pressure P mre f with respect to time.
- the above-described expression (6) for obtaining the desired intake air pressure P mref contains measured values (engine parameters), such as the engine speed ne, that tend to oscillate and the signals indicative of which tend to be superposed with high frequency noise.
- FIGS. 9 A to 9C are diagrams for describing the method that is used, in the first embodiment, to calculate the desired throttle valve opening degree ⁇ ref that is required to achieve the desired in-cylinder air amount value. The method of the present embodiment shown in FIGS. 9A to 9C is the same as the method that is shown in FIG.
- the intake system model expressions are used after transforming and approximating the intake system model expressions into the state-dependent linear model (differential equations) as described below.
- the intake system model instead of merely inversely solving the intake system model expressions, the intake system model expressions are used after transforming and approximating the intake system model expressions into the state-dependent linear model (differential equations) as described below.
- the intake system model As shown in FIG. 9A, with the intake system model, as already described, it is possible to obtain the in-cylinder charged air amount m c by inputting, in addition to the throttle valve opening degree ⁇ , other engine parameters, such as the engine speed ne and the ignition timing SA.
- the above-described intake system model expressions are transformed into the expressions including the simple transfer function K/(l+ ⁇ s) as shown in FIG. 9B in which the state-dependent coefficient ⁇ is used.
- the expression (2b) can be expressed by the following expression (10a) by using the atmospheric temperature Ta as the approximation of the intake air temperature T m in the intake system model expression (2b).
- the expression (3) can be expressed by the following expression (10b) by using the atmospheric temperature Ta as the approximation of the intake air temperature T m in the expression (3) similarly.
- Kt QtTIc / 1 1 u ⁇ approximation is made by n p jj. " " ⁇ I t Dj ⁇ regarding dne/dt as zero
- both sides of the above expression (4) are differentiated with respect to time to obtain the expression (Ha).
- dne/dt is regarded as zero to make an approximation of the expression (Ha) (specifically, the engine speed ne is treated as a constant). In this way, the engine speed ne is excluded from the subjects of differentiation in the expression (Ha), and it is possible to express the expression (Ha) as the expression (lib).
- the expression (lib) is transformed into the expression (Hc) using the intake air pressure P m as the intermediate variable, and thereafter the above expressions (1), (10a) and (10b) are substituted into the expression (Hc) to obtain the expression
- the Laplace transform of the expression (Hd) is calculated, in which the charging efficiency kl c is expressed as Y, and the variable f mt ( ⁇ ), which is in one to one relation to the throttle valve opening degree ⁇ , is expressed as X.
- the expression (Hd) is finally expressed by the expressions (12a) and (12b).
- the relation between the throttle valve opening degree ⁇ and the desired in-cylinder air amount value (desired charging efficiency kl ctef ) can be expressed using the simple transfer function (K/(l+ ⁇ s)) that is expressed using the coefficients K and ⁇ that depend on the state of the intake air pressure P m .
- FIGS. 1OA and 1OB are diagrams for describing advantageous effects achieved by the method shown in FIGS. 9 A to 9C.
- the desired value ⁇ ref of the throttle valve opening degree required to achieve the desired in-cylinder air amount value is calculated based on the expression (13b) derived as described above, the engine parameters, such as the engine speed ne, having high-frequency oscillatory components are excluded from the subjects of differentiation, and it is therefore possible to prevent high frequency noise from being amplified in the process in which the output (desired throttle valve opening degree ⁇ ref ) of the model is calculated.
- the desired in-cylinder air amount value (kl cref ) is included in the subjects of differentiation with respect to time, so that it is possible to ensure the accuracy of calculation using the model expression.
- the desired in-cylinder air amount value is periodically varied as shown in FIG. 1OA, it is possible to favorably eliminate noise from the waveform of the desired throttle valve opening degree ⁇ ref without impairing the response of the system (the response of torque) as shown in FIG. 1OB.
- FIG. 11 is a diagram for describing the control scheme including conversion of a torque value, which is referred to for the purpose of comparison. More specifically, with regard to the control scheme illustrated in FIG. 11, the charging efficiency kl c is expressed by the function f e (trq, ne, etc.) of the engine parameters, such as the torque trq and the engine speed ne. After the desired in-cylinder air amount value (kl cref or m cref ) that brings about the desired torque value trq ref is obtained based on such a relational expression, the desired value ⁇ ref of the throttle valve opening degree is obtained from the desired in-cylinder air amount value according to the method shown in FIGS. 9 A to 9C described above.
- FIGS. 12A and 12B are diagrams for describing problems with the method shown in FIG. 11.
- the relational expression shown in FIG. 11 involves the engine parameters, such as the engine speed ne, having high-frequency oscillatory components.
- large noise is superposed on the desired throttle valve opening degree ⁇ ref that is calculated to achieve the desired torque value trq ref as shown in FIG. 12 A. This is because, when the desired in-cylinder air amount value obtained using this relational expression is differentiated in the state-dependent model shown in FIGS. 9A to 9C, the influence of variation in the engine parameters is amplified, and unexpected noise is amplified.
- FIG. 13 is a diagram for describing the method that is used, in the second embodiment, to calculate the desired throttle valve opening degree ⁇ ref that is required to achieve the desired torque value trq ref .
- a state-dependent model is constructed that includes the relation between the desired torque value trq ref and the desired in-cylinder air amount value klcref-
- the desired throttle valve opening degree ⁇ ref is obtained that is required to achieve a desired torque value trq ref .
- the inputs to the model other than the desired torque value trq ref that is, the engine parameters, such as the engine speed ne, having high-frequency oscillatory components are excluded from the subjects of differentiation. More specifically, in this embodiment, differentiation of the desired in-cylinder air amount value (desired charging efficiency klc r ef) is approximated to the following expression (14b).
- the derivative of the charging efficiency kl c with respect to time is expressed by the expression (14a).
- derivatives of the parameters other than the torque trq that is, derivatives of the engine speed ne (dne/dt) etc., having high-frequency oscillatory components, for example, are approximated to zero to obtain the expression (14b).
- the derivative of the desired in-cylinder air amount value (dkl c /dt) can be expressed as the product of the derivative (dfe/dtrq) and the torque derivative (dtrq/dt).
- the derivative (df e /dtrq) can be obtained from the map defined in relation to the torque trq.
- the derivative (dklc/dt) of the desired in-cylinder air amount value as the product of the value from the map and the derivative of torque (dtrq/dt) with the terms, such as the derivative of the engine speed ne (dne/dt), that can be noise sources eliminated.
- the desired value ⁇ ref of the throttle valve opening degree required to achieve the desired torque value trq ref is obtained.
- the variable that is multiplied by the Laplace operator s and is therefore differentiated is Y only, that is, the desired torque value trq ref only, and it is therefore possible to exclude the parameters contained in the coefficient ⁇ ', that is, the engine parameters, such as the engine speed ne, other than the desired torque value trq ref , from the subjects of differentiation.
- FIGS. 14A and 14B are diagrams for describing advantageous effects achieved by the method shown in FIG. 13.
- the engine parameters such as the engine speed ne, having high-frequency oscillatory components are excluded from the subjects of differentiation, and it is therefore possible to prevent high frequency noise from being amplified in the process in which the output (desired throttle valve opening degree ⁇ ref ) of the model is calculated.
- the desired torque value (trq ref ) is the variable that is differentiated with respect to time, so that it is possible to ensure the accuracy of calculation using the model expression.
- FIG. 15 is a diagram showing a torque control scheme according to the second embodiment. Because the state-dependent model of this embodiment has the above-described characteristics, it is possible to eliminate the nonlinearity in the internal combustion engine system including the present model as shown in FIG. 15. In addition, this makes it possible to achieve the following excellent advantageous effects.
- FIG. 16 is a diagram showing a vehicle control system in which a system having a first order lag element on the downstream side of the internal combustion engine system shown in FIG. 15.
- a conceivable system that has such a first order lag element is a system for controlling the speed of wheels, for example.
- the entire internal combustion engine system comes to have a linearity as described above.
- FIG. 16 it is possible to favorably compensate the response of the downstream-side system of the internal combustion engine system by providing a linear compensator in the upstream side of the internal combustion engine system.
- the system according to the second embodiment is resistant to noise (does not amplify noise), so that it is possible to use a compensator having the first order lead element as shown in FIG. 16 as the linear compensator provided in the upstream side of the internal combustion engine system.
- noise does not amplify noise
- the engine parameters such as the engine speed ne, the valve timing vvt, and the ignition timing SA may be regarded as the "predetermined parameters" of the invention.
- the engine speed ne may be regarded as the "parameter that belongs to the first parameter group” of the invention.
- the above-described desired in-cylinder air amount value kl cref of the first embodiment and the above-described desired torque value trq ref of the second embodiment may be regarded as the "parameters that belong to the second parameter group" of the invention.
- FIGS. 17A, 17B, 22A and 22B A problem that arises when two desired torque values Ti f and Ti s that require different responses exist together. Torque control of the internal combustion engine 10 involves two desired torque values Ti f and Ti 8 that require different responses as described below. Control of behavior of a vehicle, such as speed change control of a transmission, for example, requires a response faster than the response required when a driver makes a demand for torque.
- the desired torque value in the former case is herein referred to as "the first desired torque value Ti f .”
- the desired torque value in the latter case where a driver makes a demand for torque is referred to as “the second desired torque value Ti 5 .”
- the above-described torque controller of the second embodiment is used without giving any consideration to this fact, improvement of the response is made equally for both desired torque values Ti f and Ti 5 , and it is therefore impossible to achieve the response such that both of the two desired torque values Ti f and Ti 5 are sufficiently achieved.
- the response required in the case of the first desired torque value Ti f is referred to as "the fast response”
- the response required in the case of the second desired torque value Ti s is referred to as "the slow response.”
- FIGS. 17A and 17B are diagrams showing a torque controller suitable for the first desired torque value Ti f that requires the fast response, and a torque controller suitable for the second desired torque value Ti 5 that requires the slow response.
- the torque controller shown in FIG. 17A is a controller using the state-dependent model described in relation to the second embodiment shown in FIG. 13. According to such a torque controller, it becomes possible to output torque according to the input given when the torque of the internal combustion engine 10 is controlled, and it therefore becomes possible to favorably improve the response.
- the torque controller shown in FIG. 17A is a torque controller suitable for the first desired torque value Ti f that requires the fast response.
- the torque controller shown in FIG. 17B is a controller that is generally used in an internal combustion engine. With such a torque controller, it is possible to output torque while leaving the delay in the response of the internal combustion engine 10 to the given input when the torque of the internal combustion engine 10 is controlled. Thus, it is possible to obtain a favorable torque response when a too fast response should be avoided in view of ensuring ride comfort, for example.
- the torque controller shown in FIG. 17B is a torque controller suitable for the second desired torque value Ti 5 that requires the slow response.
- FIG. 18 is a diagram for describing a method that can be used to avoid the above-described problem and that is described for the purpose of comparison with the method according to the third embodiment shown in FIG. 20 described later.
- a filter is provided that gives a delay corresponding to the delay in the response of the internal combustion engine 10, in response to the input of the second desired torque value Ti 5 that requires the slow response.
- the final desired torque value trq ref to be inputted into the feed-forward (FF) controller inverse model
- FIG. 19 is a diagram for describing advantages achieved when the torque controller of the second embodiment of the invention described above is used.
- the FF controller in the form of the transfer function ((l+ ⁇ s)/K) using the state-dependent coefficient ⁇ . Because the FF controller is expressed by the transfer function ((l+ ⁇ s)/K), it becomes possible to input the desired torque value into the FF controller through separate channels, in one of which the differential operator term as is applied to the input, in the other of which the differential operator term as is not applied to the input.
- FIG. 20 is a diagram for describing a torque controller according to a third embodiment of the invention. More specifically, as shown in FIG.
- the coefficient ⁇ is a function that depends on the desired torque values Ti f and Ti 5 , and the engine speed ne, the coefficient ⁇ cannot be calculated until the desired torque values Ti f and Ti s are inputted.
- the coefficient ⁇ instead of using only the first desired torque value Ti f that is passed through the channel in which the differential operator term as is applied to the input, the sum of both the desired torque values Ti f and Ti s is used.
- FIGS. 21A and 21B are time charts for describing advantageous effects achieved when the torque controller shown in FIG. 20 is actually used to control the internal combustion engine 10.
- the waveform indicated as “Control without Response Compensation (A)” in FIGS. 21A and 21B shows the control performed when the above-described torque controller shown in FIG. 17B is used.
- the waveform indicated as “Control using Inverse Model of Engine (B)” in FIGS. 21 A and 21B shows the control performed when the above-described torque controller shown in FIG. 17A is used.
- the waveform indicated as "Control Adaptable to Both Cases (C)" in FIGS. 21 A and 21B shows the control performed when the above-described torque controller shown in FIG. 20 is used.
- FIGS. 21A and 21B are time charts for describing advantageous effects achieved when the torque controller shown in FIG. 20 is actually used to control the internal combustion engine 10.
- FIGS. 22A and 22B are diagrams for describing advantageous effects achieved when the invention is applied to control of an internal combustion engine in which the intake system model is expressed in the form of the second order lag.
Abstract
Description
Claims
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DE112008001102.8T DE112008001102B4 (en) | 2007-04-27 | 2008-04-25 | Vehicle control device and control method |
US12/597,801 US8538660B2 (en) | 2007-04-27 | 2008-04-25 | Vehicle control apparatus and control method |
CN200880013598.0A CN101675234B (en) | 2007-04-27 | 2008-04-25 | Vehicle control apparatus and control method |
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JP2008015250A JP4321656B2 (en) | 2007-04-27 | 2008-01-25 | Vehicle control device |
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Citations (4)
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US6047681A (en) * | 1996-07-26 | 2000-04-11 | Daimlerchrysler Ag | Process and apparatus for adjusting the torque of an interal-combustion engine |
US6256575B1 (en) * | 1998-09-08 | 2001-07-03 | Siemens Automotive S.A. | Process for controlling an internal combustion engine |
US20050056250A1 (en) * | 2003-09-17 | 2005-03-17 | Stroh David J. | Torque control system |
US20070068489A1 (en) * | 2005-09-27 | 2007-03-29 | Denso Corporation | Control device of internal combustion engine |
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2008
- 2008-04-25 WO PCT/IB2008/001026 patent/WO2008132588A2/en active Application Filing
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US6047681A (en) * | 1996-07-26 | 2000-04-11 | Daimlerchrysler Ag | Process and apparatus for adjusting the torque of an interal-combustion engine |
US6256575B1 (en) * | 1998-09-08 | 2001-07-03 | Siemens Automotive S.A. | Process for controlling an internal combustion engine |
US20050056250A1 (en) * | 2003-09-17 | 2005-03-17 | Stroh David J. | Torque control system |
US20070068489A1 (en) * | 2005-09-27 | 2007-03-29 | Denso Corporation | Control device of internal combustion engine |
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