Patent Grant
6928361
1. Field of the Invention
The invention relates to a control apparatus for a motor vehicle, and a storage medium that stores a program that causes a computer to perform the functions of the control apparatus.
2. Description of Related Art
In the development of a new internal combustion engine, for example, a so-called adaptation operation is conventionally performed so as to search for appropriate input control parameter values of the engine that can provide optimum engine output values. In the adaptation operation, the respective values of the input control parameters, such as a fuel injection amount and fuel injection timing, are gradually changed based on experiences over a long period of time, to provide adapted values of the input control parameters that can yield the optimum engine output values, for example, the optimum engine output torque, fuel economy, and amounts of exhaust emissions. A similar adaptation operation is also performed in the development of a new vehicle.
In searching for the adapted values of the input control parameters based on experiences, however, it becomes more difficult to find out the optimum adapted values of the respective input control parameters as the number of the input control parameters increases. In addition, it takes a long time to find out the adapted values of the input control parameters, resulting in increased time and labor required for the development of the vehicle.
It is an object of the invention to provide a control apparatus for a motor vehicle, which allows an adaptation operation for input control parameters of the vehicle or an engine to be automatically performed on-board, and a storage medium that stores a program for performing the adaptation operation.
To accomplish the above and/or other objects, there is provided according to one aspect of the invention a control apparatus for a motor vehicle, in which each of a plurality of output values of the vehicle varies depending upon a plurality of input control parameters for controlling the vehicle. The control apparatus includes (a) an adaptive control unit that changes the input control parameter or parameters so that each of the output values becomes substantially equal to a corresponding target output value, and (b) an adapted value setting unit that determines adapted values of the input control parameters, based on values of the input control parameters obtained when each of the output values becomes substantially equal to the corresponding target output value or falls within a permissible adaptation range of the target output value.
The foregoing and/or further objects, features and advantages of the invention will become more apparent from the following description of preferred embodiments with reference to the accompanying drawings, in which like numerals are used to represent like elements and wherein:
The internal combustion engine shown in
In the meantime, the exhaust manifold 5 is connected to a catalytic converter 14 via an exhaust duct 13. A NOx sensor 15 for detecting a NOx concentration of exhaust gas and a temperature sensor 16 for detecting an exhaust gas temperature are disposed in the exhaust dust 13. A portion of the intake duct 7 located downstream of the throttle valve 11 and the exhaust manifold 5 are connected to each other via an exhaust gas recirculation (hereinafter, referred to as EGR) passage 17. Further, an EGR control valve 19 that is driven by an actuator 18, such as a step motor, is disposed in the EGR passage 17.
In the meantime, the fuel injection valve 2 for each cylinder is connected, via a fuel supply duct 20, to a fuel reservoir, or so-called common rail 21. The common rail 21 is supplied with fuel from an electrically controlled fuel pump 22 capable of discharging a variable amount of fuel. The fuel thus supplied to the common rail 21 is supplied to the fuel injection valves 2 via the respective fuel supply ducts 20. A fuel pressure sensor 23 for detecting a fuel pressure is mounted in the common rail 21. On the basis of a signal generated by the fuel pressure sensor 23, a discharge amount of the fuel pump 22 (i.e., an amount of fuel discharged from the fuel pump 22) is controlled so that a fuel pressure in the common rail 21 becomes equal to the target fuel pressure.
The engine body 1 is provided with an engine speed sensor 24 for detecting an engine speed, and is also provided with a vibration sensor 25 for detecting vibration of the engine body 1. In addition, an acceleration pedal 26 disposed in the vehicle is connected to a load sensor 27 for generating an output voltage that is proportional to a depressed amount of the acceleration pedal 26.
A vehicle control apparatus 30 includes a digital computer including a ROM (read only memory) 32, a RAM (random access memory) 33, a CPU (microprocessor) 34, an input port 35, and an output port 36, which are connected to each other via a bidirectional bus 31. The digital computer further includes analog to digital (A/D) converters 37 connected to the input port 35, and driving circuits 38 connected to the output port 36. As shown in
The vehicle control apparatus 30 may be used in common for various types of vehicles or internal combustion engines. Also, the vehicle control apparatus 30 may be replaced by another one as needed. Further, a replaceable or removable storage medium 42, such as a CD-ROM, may be connected to the bidirectional bus 31 of the vehicle control apparatus 30. In addition, various detection sensors (not shown in
An adaptation operation for the vehicle is basically interpreted to mean an operation to search for appropriate values of input control parameters of the vehicle so that each of output values of the vehicle becomes equal to a corresponding target output value. In the following description, an adaptation operation for the engine, which is typically included in the adaptation operation for the vehicle, will be explained in detail by way of example.
Like the adaptation operation for the vehicle as described above, the adaptation operation for the engine is basically interpreted to mean an operation to search for appropriate values of input control parameters of the engine so that each of engine output values becomes equal to a corresponding target output value. In this case, the input control parameters include: the fuel injection amount, fuel injection timing, fuel injection pressure, amount of fuel subjected to pilot injection performed prior to main fuel injection, intake air amount, intake air temperature, oxygen concentration of the intake air supplied into the combustion chamber, and the like. The engine output values include: the engine output torque, fuel economy or fuel consumption, amounts of exhaust emissions, such as NOx, HC, and CO, smoke concentration in the exhaust gas, combustion noise, vibration of the engine, exhaust gas temperature, and the like.
As described above, many input control parameters of the engine and many engine output values as described above may be employed for the adaptation operation for the engine. For the sake of the brevity, however, there will be hereinafter explained an example of an adaptation operation in which the fuel injection amount, the fuel injection timing, the fuel injection pressure, the pilot injection amount, and the oxygen concentration in the intake air are used as the input control parameters of the engine, and the engine output torque, the fuel economy or fuel consumption, the NOx amount in the exhaust gas, the smoke concentration in the exhaust gas, and the combustion noise are used as the engine output values. In this connection, the fuel economy may be represented by a vehicle running distance per unit amount of fuel consumption, or an amount of fuel consumed per unit running distance of the vehicle. The fuel economy improves when the running distance per unit fuel amount increases, and deteriorates when the running distance decreases. In other words, the fuel economy improves when the fuel consumption amount per unit running distance decreases, and deteriorates when the fuel consumption amount increases. In order to avoid confusion, therefore, the fuel economy is simply said to be good (or improved) or to be poor (or deteriorated) in the description of the specification.
In operation, if one of the input control parameters, for example, the fuel injection amount, is changed, many output values, more specifically, the engine output torque, the fuel economy, the NOx amount, the smoke concentration and the combustion noise, change with the fuel injection amount. When an adaptation operation is performed according to one embodiment of the invention, each of the input control parameter values is changed so that each of the output values becomes equal to the corresponding target output value. More specifically, in the embodiment of the invention, a combination of one or more input control parameters suitable for adaptive control, with each output value, is predetermined, and the respective input control parameters are simultaneously feedback-controlled so that the output values that are in combination with each of the input control parameters become equal to the corresponding target output values, respectively.
As described above, when the respective input control parameters are simultaneously feedback-controlled, each of the input control parameter values is automatically changed while being coordinated with other parameters until each of the output values becomes equal to the corresponding target value, thereby to achieve adaptation of the input control parameters.
In some cases, however, no input control parameter values actually exist which can make all of the output values equal to the corresponding target output values. In these cases, even if the respective input control parameters are simultaneously feedback-controlled, all of the output values will not become equal to the corresponding target output values. However, adaptation of the input control parameters may be achieved provided that the output values are controlled to be within respective permissible ranges even if they do not become exactly equal to the target output values. Thus, in the present embodiment of the invention, adaptation of the input control parameters is judged as being accomplished when each of the output values falls within a permissible or adaptive range of the corresponding target output value even if it does not become exactly equal to the corresponding output value.
Referring next to
Referring to
The above-described control amount coordinator consists of a function block 53 called a control amount initial value, a function block 54 called an optimizer, and a function block 55 called convergence judgment. The vehicle model consists of a function block 56 called a design value model, a function block 57 called an optimizer, and a function block 58 called a learning model.
Next, the function of each function block in
As shown in
In addition to the information on the demanded torque and the environmental information, the target value coordinator 51 also receives output values of the vehicle model, and information relating to restricting conditions from the function block 52. The target value coordinator 51 sets target output values of the engine output values, based on the demanded torque, the environmental information, the output values of the vehicle model, and the restricting conditions.
The target output values set in the target value coordinator 51 may include the engine output torque, the fuel economy, the NOx amount, the smoke concentration, the combustion noise, and the like. In this case, since the engine is required to generate an output torque in accordance with the demanded torque, the target value of the output torque is set to the demanded torque. In some cases, however, the output torque must be restricted due to, for example, restrictions on the amounts of exhaust emissions, or the like. The target value coordinator 51 determines whether the output torque must be restricted, and if the coordinate 51 determines that the output torque must be controlled, information relating to a limit value of the output torque is transmitted from the target value coordinator 51 to the torque manager 50, as shown in FIG. 2.
When the torque manager 50 receives the information about the limit value of the output torque, it restricts the demanded torque so that the demanded torque received by the target coordinator 51 does not exceed the limit value of the demanded torque. In this case, therefore, the target value of the output torque is set to the restricted demanded torque.
One of the above-indicated target output values set in the target value coordinator 51 may be that of the fuel economy. It is, however, not necessary to particularly determine or set a target value of the fuel economy because the better the fuel economy is, the more desirable it is. To the contrary, deterioration of the fuel economy may result in an increased amount of CO2 that is released to the air. Thus, in order to restrict the emission amount of CO2, a limit to the fuel consumption may be set so that the fuel consumption is kept less than the set limit.
With regard to the other target value, it is naturally desirable to reduce the NOx amount, the smoke concentration and the combustion noise as much as possible. However, an attempt to reduce the NOx amount, the smoke concentration, or the combustion noise may result in a reduction in the engine output torque or deterioration of the fuel economy. Therefore, it may not be impossible to easily determine target values of the NOx amount, the smoke concentration and the combustion noise. In addition, different regulation values are imposed in different countries on the amounts of exhaust emissions, in particular, the NOx amount and the smoke concentration. Thus, the regulation values must also be taken into consideration in determining the target output values of the exhaust emission amounts.
In this case, typical regulations on the exhaust emissions are so-called mode emission regulations, which are imposed on the amounts of exhaust emissions when the vehicle is running in a predetermined driving mode. In the embodiment of the invention, the target output values of the exhaust emission amounts are set so as to satisfy the mode emission regulations. The setting of the target output values of the exhaust emission amounts involves the restricting conditions of the function block 52 and the vehicle model as shown in
In the embodiment as shown in
On the other hand, the vehicle model outputs estimated output values of the actual vehicle 45 when it receives the input control parameters of the vehicle. For example, if the vehicle model receives the input control parameters, such as the fuel injection amount, the fuel injection timing, the fuel injection pressure, the pilot injection amount, and the oxygen concentration in the intake air, the vehicle model outputs estimated values, such as the engine output torque, the fuel economy, the NOx amount, the smoke concentration, and the combustion noise, in accordance with the input control parameters.
For example, the output torque of the engine is a function of the energy delivered to the engine, the ignition timing, and the combustion speed. Accordingly, once the specifications of the engine, such as the structure and dimensions of the combustion chambers, are determined, the engine output torque can be calculated from the input control parameter values, such as the fuel injection amount, the fuel injection timing, the fuel injection pressure, the intake air amount, the EGR gas amount, and the intake air temperature. The vehicle model outputs the thus calculated engine output torque as the estimated output torque of the actual vehicle 45.
With regard to the internal combustion engine, certain relationships are established between the input control parameters and the output values once the specifications of the engine, such as the structure, shape, and dimensions of the engine, are determined, as described above. The relationships may be represented by arithmetic expressions including coefficients that are determined by the dimensions, and the like, of each portion of the engine. In the embodiment as shown in
In the embodiment as shown in
Meanwhile, the vehicle model, or the design value model 56, contains coefficients determined by the dimensions, and the like, of each portion of the vehicle to be controlled, namely, coefficients determined by the specifications data of the vehicle to be controlled. Thus, the vehicle model, or the design value model 56, is completed once the specifications data of the vehicle to be controlled are determined. Accordingly, the specifications data of the vehicle to be controlled may be stored in the replaceable storage medium 42, and the vehicle model, or the design value model 56, may be completed by transmitting the specifications data of the vehicle to be controlled from the storage medium 42 to the vehicle model.
In the case where the output values of the design value model 56 coincide with the output values of the actual vehicle 45, the output values of the design value model 56 may be used as the output values of the vehicle model. Actually, however, there are some cases where the output values of the design value model 56 do not coincide with the output values of the actual vehicle 45. Particularly, as the vehicle 45 is used over a long period of time, the output values of the design value model 56 come to deviate from the output values of the actual vehicle 45 due to chronological changes thereof. Accordingly, in the embodiment as shown in
In operation of the embodiment of
On the basis of a difference between each of the estimated output values of the vehicle model and the corresponding output value of the actual vehicle 45, the optimizer 57 adjusts the corresponding output value of the learning model 58 so that the difference becomes equal to zero. As a result, the estimated output values of the vehicle model respectively coincide with the output values of the actual vehicle 45 in the embodiment of FIG. 2. In this case, the output values of the design value model 56 may be corrected by the optimizer 57, without using the learning model 58, so that the output values of the vehicle model become equal to the output values of the actual vehicle 45.
In the embodiment of the invention as described above, the target coordinator 51 sets the target output values of the exhaust emission amounts so as to satisfy the mode emission regulations. In this case, the target coordinator 51 calculates the target output values of the exhaust emission amounts, based on the restricting conditions of the function block 52 and the vehicle model. Here, the restricting conditions are mode emission regulation values relating to NOx, HC, CO, and the smoke concentration in the exhaust gas. Next, a method of calculating the target output values of the exhaust emission amounts, or the like, using this vehicle model will be explained.
In the present embodiment of the invention, the driving mode that is predetermined for the mode emission regulations are stored in advance.
Further, when the vehicle is moving from one area to another area in which the exhaust emission regulation values or the driving mode for the exhaust emission regulations are different from those in the previous area, it is desirable to automatically switch or change the emission regulation values and the driving mode, based on information transmitted from a communications station. Thus, the system may be constructed such that communications means receives a desired driving mode from the outside of the vehicle.
In order to calculate the target output values of the exhaust emission amounts in the embodiment of the invention, the vehicle model is initially used to cause the vehicle to run according to the driving mode, thereby to obtain the frequency of use of each driving point (which will be described later) that is defined by the demanded engine torque TQ and the engine speed N. In
Using the frequency of use map shown in
If the frequency of use and the target value of NOx at each of the driving points as defined by the demanded torque TQ and the engine speed N are known, the amount of discharge of NOx at each driving point as defined by the demanded torque TQ and the engine speed N can be calculated by multiplying the frequency of use with the target value of NOx at the driving point in question.
Then, a sum of the products of the frequency of use and the target value of NOx at all of the driving points as defined by the demanded torque TQ and the engine speed N is calculated. In this manner, the estimated total amount of discharge of NOx during running of the vehicle according to the driving mode is obtained from the sum of the products as described above.
If the estimated total amount of discharge of NOx thus calculated is much lower than the mode emission regulation value of NOx, the respective boundary lines a, b and c of the target output value of NOx are moved as a whole toward the lower torque side in
The adjustment or correction of each of the boundary lines a, b, and c as described above is performed in the target value coordinator 51 until the estimated total amount of discharge of NOx satisfies the mode emission regulation value for NOx. Once the estimated total amount of NOx satisfies the mode emission regulation value for NOx, the target value of NOx is determined in accordance with the demanded torque TQ and the engine speed N.
Also, a map similar to that of
In this case, the estimated fuel economy or consumption can also be calculated when the vehicle is running in the above-indicated driving mode. However, it is not necessary to provide a map like that of
In the manner as described above, the target coordinator 51 calculates the target value of the engine output torque, the target values of the exhaust emission amounts, the target value of the combustion noise, and, in some cases, the target value of the fuel economy. In this case, the target value of the exhaust emission amount, or the like, may be set to different values depending upon the driving conditions of the engine, as is understood from FIG. 4A. In the example shown in
Further, at least part of the target output values, such as the target output value of NOx amount, may be stored in advance. In another example, the specifications data of the vehicle to be controlled may be stored in advance, and at least part of the target output values may be calculated from the specifications data thus stored. Moreover, at least part of the target output values may be stored in the replaceable storage medium 42, or part of the target output values may be received from the outside of the vehicle by communication means.
After the respective target output values are calculated by the target coordinator 51, these target output values are transmitted to the control amount coordinator, in which an adaptation operation for the vehicle is performed. Namely, the control amount coordinator searches for appropriate values of the input control parameter values so that the output values of the vehicle become equal to the corresponding target output values or fall within the permissible adaptation ranges of the corresponding target output values.
As shown in
On the other hand, output values of the optimizer 54 are respectively added to the initial values of the input control parameters generated from the function block 53, and the results of the addition are transmitted to the vehicle model as temporary input control parameter values. The vehicle model calculates the output values based on the temporary input control parameter values, and the output values thus obtained are then transmitted to the optimizer 54 of the control amount coordinator. On the basis of these output values, the optimizer 54 outputs correction values for the input control parameters so that the output values of the vehicle model approach the target output values. In other words, the optimizer 54 searches for the input control parameters that make the output values of the vehicle equal to the target output values or held within the allowable adaptation range.
Next, an operation performed by the optimizer 54 for searching for the input control parameters will be explained.
As described above, a combination of one or more input control parameters suitable for adaptive control, with each of the output values of the vehicle, is predetermined for the purpose of searching for the input control parameters. In one embodiment of the invention, the combination is that of one input control parameter and one output value that changes with the highest sensitivity when the input control parameter is changed. A list of such combinations of the input control parameters and the output values used in the embodiment of the invention is provided as follows:
With regard to the combination (a), the engine output torque increases with high sensitivity in response to an increase in the fuel injection amount.
With regard to the combination (b), the fuel economy improves with high sensitivity when the fuel injection timing is advanced and the amount of unburned HC is reduced.
With regard to the combination (c), the combustion temperature is lowered with a reduction in the oxygen concentration in the intake air, and the NOx amount is accordingly reduced with high sensitivity in response to the reduction in the oxygen concentration.
With regard to the combination (d), when the fuel injection pressure is increased, atomization of the injected fuel is promoted, and therefore the smoke concentration is reduced with high sensitivity.
With regard to the combination (e), when the pilot injection amount is increased, the rate of increase of the fuel pressure during the main fuel injection is reduced, and therefore the combustion noise is reduced with high sensitivity.
Further, in the embodiment of the invention, the respective input control parameters are simultaneously controlled in a feedback manner so that each of the output values combined with a corresponding one of the input parameters becomes equal to the corresponding target output value. Thus, adapted values of the input control parameters can be found out. More specifically, the fuel injection amount is feedback-controlled so that the engine output torque becomes equal to a target output value thereof, while at the same time the oxygen concentration in the intake air is feedback-controlled so that the NOx amount becomes equal to a target output value that depends upon the operating state of the engine. At the same time, the fuel injection pressure is feedback-controlled so that the smoke concentration becomes equal to a target output value that depends upon the operating state of the engine. At the same time, the pilot injection amount is feedback-controlled so that the combustion noise becomes equal to a target output value that depends upon the operation state of the engine. The fuel injection timing is controlled so that the fuel economy is improved as much as possible.
As described above, when the respective input control parameters are simultaneously feedback-controlled, each of the input control parameter values is automatically changed while being coordinated with other parameters until each of the output values becomes equal to the corresponding target value, thereby to achieve adaptation of the input control parameters.
In the embodiment of the invention, the feedback control is performed by proportional integral control. Namely, when “P” represents a proportional component, and “I” represents an integral component, the correction amount ΔF for each of the input control parameters, which is generated from the optimizer 54, is calculated according to the following expressions:
I=I+Ki(the output value−the target output value)
P=Kp(the output value−the target output value)
ΔF=P+I
where Ki and Kp are proportional constants.
In the embodiment of the invention, the output values generated from the vehicle model are used as the output values for calculating the above-described component I and component P. However, the output values detected in the actual vehicle 45 may be used as the output values for calculating the component I and component P.
The feedback control of the input control parameters may be performed assuming that the input control parameters and the output values that are respectively in combination with the input control parameters are in proportional relationships. For example, the fuel injection amount as one of the input control parameters may be feedback-controlled on the assumption that the relationship between the fuel injection amount and the engine output torque is expressed as “engine output torque=K·fuel injection amount” where K is a proportional constant. In this case, the proportional constant Ki in the component I as indicated above has a constant value, and the proportional constant Kp in the component P also has a constant value.
In another embodiment of the invention, in order to perform the optimum adaptation operation, the relationship between each of the input control parameters and a corresponding one of the output values takes the form of a function of sensitivity or responsiveness. In accordance with the sensitivity obtained from the sensitivity function, the input control parameters are controlled in a feedback manner. For example, the sensitivity function between the fuel injection amount and the engine output torque is shown in FIG. 5. In this connection, it is to be noted that each sensitivity function is obtained with respect to the vicinity of the initial value generated from the function block 53 of
When feedback control of each of the input control parameters is performed by using the sensitivity function, at least one of the proportional constant Kp in the component I and the proportional constant Kp in the component P of the proportional integral control as described above is changed according to the sensitivity obtained from the sensitivity function. In the example of
Thus, in the embodiment of the invention, the sensitivity function is set for each combination of the input control parameter and the output value, and the proportional constant Ki or Kp is set to a larger value as the sensitivity of the increase of the output value in response to the increase in the input control parameter is lowered. In this manner, each input control parameter is quickly converged on the parameter adaptation value while being coordinated with the other input control parameters.
In the embodiment of the invention, the sensitivity function for each input control parameter is determined by learning from the input control parameter supplied to the vehicle model and the output value of the vehicle model that is in combination with the input control parameter in question.
In actual situations, however, when one of the input control parameter values is changed, all of output values associated with the input control parameter are changed. In other words, each of the output values is affected by a plurality of the input control parameters. Accordingly, a combination of each of the output values and a plurality of input control parameters may be established, and each of the output values may be made equal to the corresponding target output value or controlled to be within the permissible range of the target output value, by changing the above-indicated plurality of input control parameters that are in combination of the output value in question.
As described above, adaptation of the input control parameters may be achieved when each of the output values falls within the permissible range of the corresponding target output value even if it is not exactly equal to the target output value. Therefore, in the embodiment of the invention, the adaptation of the input control parameters is judged as being accomplished if each of the output values is within the permissible adaptation range of the corresponding target output value even if it does not become equal to the target output value. In one embodiment of the invention, evaluation means is used for evaluating or determining whether each output value is within the permissible range of the target output value is evaluated by evaluation means. The evaluation means will be hereinafter explained.
In the embodiment of the invention, an evaluation point function is established for each of the output values in order to evaluate whether each of the output values is within the permissible range of the target output value. An example of a set of evaluation point functions is shown in
In the example as shown in
As described above,
As also described above,
Various methods may be considered for evaluating whether each of the output values is within the permissible adaptation range of the target value by using these evaluation point functions. Some of these methods will be hereinafter explained.
In the first evaluation method, which is the simplest one, each of the output values is determined to be within the permissible adaptation range of the target output value when all of the evaluation points for the respective output values exceed a certain value, for example, 0.9.
In the second evaluation method, different reference points are set for the respective output values; for example, the reference point is set to 0.9 for the output torque, and is set to 0.8 for the NOx amount. When each of the output values exceeds the corresponding reference point, it is evaluated or determined that each of the output values is within the permissible adaptation range.
In the third evaluation method, each of the output values is evaluated as being within the permissible adaptation range, when the relationship among the evaluation points relating to the respective output values satisfies a certain condition that indicates that adaptation of these output values is achieved. In this method, the relationship among the evaluation points refers to, for example, a sum of the evaluation points or a product of the evaluation points. Thus, in the third evaluation method, each of the output values is evaluated as being within the permissible range of the target output value, for example, when the sum of the evaluation points exceeds a predetermined reference point, or when the product of the evaluation points exceeds a predetermined reference point.
As mentioned above, there are various methods for evaluating whether each of the output values is within the permissible range of the target output value. However, there is no difference among the evaluation methods in terms of using the evaluation point for each of the output values.
In another evaluation method, a difference between each of the output values and the corresponding target output value may be used in place of the evaluation points. In this case, each of the output values is evaluated as being within the permissible adaptation range of the target value when the difference associated with each of the output values is smaller than a corresponding reference value, or when the relationship among the differences associated with the output values satisfies a certain condition that indicates that adaptation of these output values is achieved.
Next, the meaning of the shape of each of the evaluation point functions as shown in
In
On the other hand, since the evaluation point function is shaped as shown in
The evaluation point function having a shape as shown in
With regard to the evaluation point function as shown in
As described above, an attempt to improve the fuel economy may result in an increase in the NOx amount. Since the evaluation point is equal to 1.0 as long as the NOx amount is equal to or smaller than the target value NOxref, it is desirable to improve the fuel economy as much as possible by increasing the NOx amount to the target value. If the NOx amount exceeds the target value NOxref, on the other hand, the evaluation point for the NOx amount is reduced whereas the evaluation point for the fuel economy is increased since the fuel economy is improved in this case. The final NOx amount and fuel economy are determined in view of the balance of the evaluation points thereof, so that the sum of the evaluation points is maximized, for example.
In another embodiment of the invention, the evaluation function for the fuel economy as shown in
It will be understood from the above description that the evaluation point functions are used for evaluating whether each of the output values is within the permissible adaptation range or not. In addition to the above-described evaluation, the evaluation point function may also be used for adaptive control over input control parameters that are feedback-controlled so as to provide desired output values. The use of the evaluation point functions for the adaptive control will be hereinafter explained in detail.
When an evaluation point for a certain output value is lower than evaluation points for the other output values, it is desirable in terms of the adaptive control to make the output value having the lower evaluation point close to the target value before controlling the other output values. In this case, therefore, the input control parameter(s) that is/are in combination with the output value having the lower evaluation point is/are changed first (i.e., prior to control of the other input control parameters), so that the output value having the lower evaluation value approaches the target output value before the other output values do. For example, when the evaluation point for the output torque is lower than the evaluation points for the other output values, the fuel injection amount is controlled before the other input control parameters are controlled.
When the evaluation point function includes sharply inclined portions as shown in
Furthermore, it is desirable to make a selected one of the output values close to the corresponding target output value, in preference to the other output values, depending upon the operating state of the engine. For example, while the engine is in the steady driving mode, more importance or weight is placed on the fuel economy, and it is therefore desirable to preferentially change the input control parameter(s) associated with the fuel economy. While the engine is in the accelerating operating mode, on the other hand, more importance is placed on the output torque, and it is therefore desirable to preferentially change the input control parameter(s) associated with the output torque. Accordingly, in this embodiment of the invention, a selected input control parameter or parameters is/are changed prior to the other input control parameters, depending upon the operating state of the engine.
When the optimizer 54 as shown in
The above-described adaptation operation for the input control parameters may be performed in various timings. For example, the adaptation operation may be always performed while the vehicle is in operation. Alternatively, the adaptation operation may be performed as needed, for example, before launching the vehicle to the market.
In some cases, during the adaptation operation as described above, one of the output values fails to be within the permissible adaptation range of the target value, in other words, it comes out of the permissible adaptation range. In this case, it is judged that an error occurs in an engine control portion associated with the input parameter(s) that is/are in combination with the output value that is out of the permissible range. With this judgement made, an alarm is generated so as to inform the vehicle operator of the error.
Further, in one embodiment of the invention, each adaptation operation is performed within a limited computation period of time. In this case, when any of the output values does not become equal to the corresponding target output value or does not fall within the permissible adaptation range of the target output value within the limited computation time, it is judged that an error occurs in the control system, and an alarm or warning to this effect is generated.
When the output values become equal to the corresponding target values or fall within the permissible adaptation ranges of the target values within the limited computation time period, the input control parameters at this time are temporarily stored as normal input control parameters to be established in the engine operating state at this time. Then, the normal input control parameters thus stored may be used as the input control parameters in the same operating state of the engine when the output values do not come within the permissible adaptation range of the target output values within the limited computation time.
When an error occurs in the engine control portion or in the control system, the top priority is given to satisfaction of the mode emission regulation values, rather than the drivability of the vehicle. In this case, the evaluation point function for the output torque is designed as shown in
It is to be noted that a program associated with the adaptation operation as explained above may be stored in a storage medium, such as the storage medium 42.
With the system arranged as described above, the adaptation operation of the input control parameters of the vehicle or the engine may be automatically performed on-board.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2000-336348 | Nov 2000 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/IB01/02045 | 10/31/2001 | WO | 00 | 5/29/2003 |
| Publishing Document | Publishing Date | Country | Kind |
|---|---|---|---|
| WO02/37076 | 5/10/2002 | WO | A |
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| Number | Date | Country | |
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| 20040098190 A1 | May 2004 | US |
