JP4858427B2 - Method and apparatus for adapting an internal combustion engine - Google Patents

Description

  The present invention relates to a method and apparatus for adapting an internal combustion engine, that is, a method and apparatus for determining a conforming value of a control parameter used in controlling an internal combustion engine.

  In general, control of an internal combustion engine is performed by adjusting the throttle opening, ignition timing, intake / exhaust valve on / off valve characteristics, fuel injection amount, etc. so as to satisfy the requirements for the characteristics of the internal combustion engine such as generated torque, exhaust emission and fuel consumption. This is done by changing the value of the control parameter. These control parameters have optimum values for each operating state determined by, for example, the engine load (generated torque) and the engine speed in accordance with the request for the internal combustion engine at that time. It is necessary to set the optimum value of the control parameter in advance as a target value.

The optimum value of the control parameter for each operating state is generally a value of a characteristic parameter that represents the characteristics of the internal combustion engine, such as the generated torque and NO _X emission amount, when the control parameter is set to various values. Is obtained by an operation for obtaining an optimum value (that is, an adapted value) of each control parameter for each operating state from the result, that is, an adapted operation.

  In such adaptation work, the range of the adaptive measurement engine control state, which is the engine control state to be measured for adaptation, is set to the control parameter setting limit values (for example, the upper limit value and the lower limit value) and other constraints (for example, It is necessary to determine in advance in consideration of misfire limit, knock limit, torque fluctuation, exhaust system (catalyst, etc.) temperature limit, and the like. As a technique for that purpose, for example, a predetermined engine control state is selected as an initial exploration point, and then the value of each control parameter is gradually changed to its set limit value to sequentially change the engine control state, and the above constraints When engine operation is performed that satisfies the conditions, there is a method of determining the range of the engine control state at that time, assuming that the engine control state is the adaptive measurement engine control state. More specifically, when the constraint condition is no longer satisfied, it is assumed that it is out of the range of the conforming measurement engine control state, and the value of any control parameter remains at the set limit value while satisfying the constraint condition. In such a case, the range of the relevant measurement engine control state and its boundary are determined (so-called radial exploration), assuming that it is within the range of the relevant measurement engine control state.

JP 2006-17698 A Japanese Patent Laid-Open No. 5-142089 Peter Renninger, Metodi Aleksandrov, Rapid Hull Determination: a new method to determine the design space for model based approaches, Design of Experiments (DoE) in Engine Development II, 3rd DoE Conference in Berlin, IAV, June 2005, p. 14 -29

  However, although the above method is effective in narrowing the range of the control state of the conforming measurement engine centered on the initial search point, this method satisfies the constraint conditions before the control parameter value reaches the set limit value. If the control parameter value is further brought closer to the set limit value, it will be out of the range of the applicable measurement engine control state from there. The engine control state is out of the range of the adaptive measurement engine control state. As a result, the engine control state in which the value of the control parameter becomes the set limit value or an engine control state close thereto may be inappropriately out of the range of the adaptive measurement engine control state.

  The above-described method is an example, and the engine control state in which the control parameter value becomes the set limit value or the engine control state close thereto is improperly determined to be out of the range of the above-described applicable measurement engine control state by other methods. It may be done. In practice, this is particularly a problem because an appropriate value is often obtained in an engine control state in which the value of the control parameter becomes the set limit value.

  The present invention has been made in view of the above problems, and its purpose is to determine whether or not the engine control state in which the value of the control parameter is a set limit value is also the above-described conforming measurement engine control state. To provide a method and apparatus for adapting an internal combustion engine to be determined.

  The present invention provides a method or an apparatus for adapting an internal combustion engine as set forth in each claim as a means for solving the above-mentioned problems.

  According to the first aspect of the present invention, the range of the adaptive measurement engine control state, which is the engine control state in which measurement for conformance is to be performed, sequentially changes the engine control state, and engine operation in which a predetermined constraint condition is satisfied. In the internal combustion engine adaptation method, when the range is determined, the predetermined engine control state is determined as the initial search point. The engine control state is changed by gradually changing the value of at least one control parameter among the plurality of control parameters that specify the engine control state from the initial exploration point to the set limit value. If there is another control parameter that has not yet reached the set limit value when the value of the control parameter has reached the set limit value while satisfying the condition, it is already set. The engine control state is further changed by gradually changing the value of the other control parameter to the set limit value while setting the value of the control parameter that has reached the limit value as the set limit value, Provide an adaptation method.

  According to the second aspect of the present invention, the range of the adaptive measurement engine control state, which is the engine control state in which measurement for compliance is to be performed, sequentially changes the engine control state, and the engine operation in which a predetermined constraint condition is satisfied. In the case where the engine control state at that time is determined to be the above-described conforming measurement engine control state, in the internal combustion engine conforming device, when determining the above range, the predetermined engine control state is the initial search point. The engine control state is changed by gradually changing the value of at least one control parameter among the plurality of control parameters that specify the engine control state from the initial exploration point to the set limit value. If there is another control parameter that has not yet reached the set limit value when the value of the control parameter has reached the set limit value while satisfying the condition, it is already set. The engine control state is further changed by gradually changing the value of the other control parameter to the set limit value while setting the value of the control parameter that has reached the limit value as the set limit value, Provide compatible equipment.

  The invention described in each claim has a common effect that whether or not the engine control state in which the value of the control parameter becomes the set limit value is appropriately determined as the adaptive measurement engine control state.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an internal combustion engine (that is, an internal combustion engine to be adapted) that is a target of the adaptation work and a measurement calculation device that is used for the adaptation work.

  Referring to FIG. 1, 1 is an engine body, 2 is a cylinder block, 3 is a piston that reciprocates in the cylinder block 2, 4 is a cylinder head fixed on the cylinder block 2, and 5 is a piston 3 and a cylinder head 4. A combustion chamber formed therebetween, 6 is an intake valve, 7 is an intake port, 8 is an exhaust valve, and 9 is an exhaust port. As shown in FIG. 1, a spark plug 10 is arranged at the center of the inner wall surface of the cylinder head 4, and a fuel injection valve 11 is arranged around the inner wall surface of the cylinder head 4. A cavity 12 extending from the lower side of the fuel injection valve 11 to the lower side of the spark plug 10 is formed on the top surface of the piston 3.

  The intake port 7 of each cylinder is connected to a surge tank 14 via a corresponding intake branch pipe 13, and the surge tank 14 is connected to an intake pipe 15. A throttle valve 18 driven by a step motor 17 is disposed in the intake pipe 15. On the other hand, the exhaust port 9 of each cylinder is connected to an exhaust manifold 19. Further, the intake valve 6 is provided with a variable valve mechanism 20 for changing the on-off valve characteristics of the intake valve 6, that is, the phase angle and the operating angle of the on-off valve.

  In general, the control of the internal combustion engine as shown in FIG. 1 is performed so as to satisfy the requirements for torque, exhaust emission, fuel consumption, etc. that change during operation of the internal combustion engine, that is, actual torque, exhaust emission, fuel consumption, etc. This is performed by changing the values of controllable parameters (that is, control parameters) that affect the operating state of the internal combustion engine so that the target torque, the target exhaust emission, the target fuel consumption, and the like are achieved.

  Such a control parameter has an optimum value for each operating state determined by, for example, the engine speed in accordance with a request for the internal combustion engine at that time. For example, with respect to the ignition timing by the spark plug 10, in consideration of the torque, fuel consumption, misfire, etc. of the internal combustion engine, generally, ignition is performed near the minimum advance timing at which the torque becomes the maximum, so-called MBT (Minimum Advance for Best Torque). Is preferably performed. This MBT is not the same for all operating states. For example, when the engine speed is different, the MBT is also at a different time. On the other hand, when it is necessary to increase the temperature of a catalyst (not shown) provided in the exhaust system of the internal combustion engine for exhaust purification of the internal combustion engine, the exhaust gas discharged from the engine body 1 In order to increase the temperature, it is preferable to perform ignition at a timing that is somewhat retarded from the MBT.

  Since it is difficult to calculate the optimum value (that is, the conforming value) of each control parameter for each operating state in accordance with the demand for such an internal combustion engine by only numerical calculation, usually, for each type of internal combustion engine Required by calibration work. Here, the conforming work is a characteristic parameter (a parameter whose value can be changed by changing the value of the control parameter, for each control parameter value, by setting a specific control parameter to various values. This means an operation of measuring the values of parameters representing the characteristics of the control parameters, and obtaining the optimum values (that is, conforming values) of the control parameters for the respective operating states from the measured values of these characteristic parameters.

  FIG. 1 shows a measurement calculation device 40 that measures the value of a characteristic parameter of the internal combustion engine and performs a necessary calculation in addition to the target internal combustion engine. As shown in the figure, a throttle opening sensor 31 for measuring the opening degree of the throttle valve 18 is attached to the throttle valve 18 and flows through the intake pipe 15 for the internal combustion engine to be subjected to the adaptation work. An air flow meter 32 for measuring the flow rate of air is mounted in the intake pipe 15 upstream of the throttle valve 18. Further, an exhaust gas temperature sensor 33 for measuring the temperature of the exhaust gas discharged from the engine body 1 and an air-fuel ratio sensor 34 for measuring the air-fuel ratio of the exhaust gas discharged from the engine body 1 are attached to the exhaust port or the exhaust manifold 19. . Further, a torque sensor (not shown) for detecting a generated torque that is a driving force of the internal combustion engine is attached to a crankshaft (not shown) of the engine body 1. These sensors are connected to the measurement calculation device 40, and the measurement calculation device 40 displays, saves, and calculates the values of the characteristic parameters measured by these sensors.

  On the other hand, the ignition plug 10, the fuel injection valve 11, the step motor 17 for driving the throttle valve, the variable valve mechanism 20, and the like described above are connected to the measurement arithmetic device 40, and these ignition plugs 10 are driven by the measurement arithmetic device 40. Be controlled. That is, the value of the control parameter is changed by the measurement arithmetic device 40.

  By the way, the measurement of the values of various characteristic parameters in the adaptation work is usually performed at each measurement point with various control parameters set as described above. Here, a measurement point is specified by a combination of setting values of each control parameter, and one measurement point corresponds to one combination of setting values for each control parameter. That is, each set measurement point corresponds to each engine control state that is the state of the internal combustion engine specified by the combination of the values of the control parameters.

  In the adaptation work, before measuring the values of the various characteristic parameters, the range of the engine control state in which the measurement point is to be set, that is, the engine control state in which the measurement for calibration is to be performed Set the range of the measurement engine control state, such as setting limit values of each control parameter (for example, upper limit value and lower limit value) and other restrictions (for example, misfire limit, knock limit, torque fluctuation, exhaust system (catalyst, etc.) temperature limit, etc.) It is necessary to determine in advance in consideration.

  For this reason, for example, a predetermined engine control state is selected as the initial exploration point, and from there, the values of the respective control parameters are gradually changed to the set limit values, and the engine control state is sequentially changed to satisfy the above-mentioned constraint conditions. When engine operation is performed, the range of the engine control state at that time is determined to be the adaptive measurement engine control state. In other words, normally, when the constraint condition is no longer satisfied, it is assumed that it is out of the range of the conforming measurement engine control state, and the value of any control parameter becomes the set limit value while satisfying the constraint condition. In such a case, the range of the adaptive measurement engine control state and its boundary are determined (so-called radial exploration), assuming that it is within the range of the adaptive measurement engine control state.

  However, although the above method is effective in narrowing the range of the control state of the conforming measurement engine centered on the initial search point, this method satisfies the constraint conditions before the control parameter value reaches the set limit value. If the control parameter value is further brought closer to the set limit value, it will be out of the range of the applicable measurement engine control state from there. The engine control state is out of the range of the adaptive measurement engine control state. As a result, the engine control state in which the value of the control parameter becomes the set limit value or an engine control state close thereto may be inappropriately out of the range of the adaptive measurement engine control state.

  FIG. 2 shows an example of such a case. FIG. 2 shows the range of the engine control state specified by the control parameters X and Y. Here, Xu is the upper limit value of the control parameter X, and Xl is the lower limit value of the control parameter X. Further, Yu is the upper limit value of the control parameter Y, and Yl is the lower limit value of the control parameter Y. A region P is an engine control state that does not satisfy the constraint conditions. In such a situation, when the engine control state is changed from the initial exploration point S through the route indicated by the arrows a, b, and c, and it is determined whether or not it is the adaptive measurement engine control state, as a result The engine control state in the region indicated by Q in the figure including the engine control state in which the control parameter value becomes the set limit value is inappropriately excluded from the range of the adaptive measurement engine control state.

  The above-described method is an example, and the engine control state in which the control parameter value becomes the set limit value or the engine control state close thereto is improperly determined to be out of the range of the above-described applicable measurement engine control state by other methods. It may be done. In practice, this is particularly a problem because an appropriate value is often obtained in an engine control state in which the value of the control parameter becomes the set limit value.

  Therefore, in the present embodiment, in consideration of the above, the measurement calculation device 40 implements a method as described below, and the engine control state in which the value of the control parameter becomes the set limit value is also appropriately set. It is determined whether or not it is in the above-described conforming measurement engine control state.

  In short, this method can be applied to engine operation in which the engine control state is changed in order, and the range of the engine control state that is the engine control state that should be measured for compliance, and the predetermined constraints are satisfied. Is performed, the engine control state at that time is determined to be the conforming measurement engine control state, and when the range is determined, a predetermined engine control state is selected as the initial search point. The engine control state is changed by gradually changing the value of at least one control parameter of the plurality of control parameters that specify the engine control state from the initial exploration point to the set limit value, and satisfies the above constraint conditions. If there is another control parameter that has not yet reached the set limit value when the value of the same control parameter has reached the set limit value, it has already reached the set limit value. While the value of the serial control parameters and their setting limits is that the further addition engine control state value of the control parameter gradually by changing to its set limit value is changed.

  Hereinafter, this method implemented in this embodiment will be described in more detail with reference to FIG. FIG. 3 is a flowchart showing a method implemented in the present embodiment to determine the range of the applicable measurement engine control state and its boundary.

  As shown in the flowchart of FIG. 3, when this method starts, first, in step 101, the target control parameter is determined. Examples of control parameters in the present embodiment include throttle opening, fuel injection amount, on-off valve characteristics of the intake valve 6, ignition timing, engine speed, and the like. In other embodiments, when the on / off valve characteristics of the exhaust valve 8 are variable, the on / off valve characteristics of the exhaust valve 8 can also be selected as a control parameter. In step 101, a plurality of control parameters are selected.

  When the control parameter is determined in step 101, the process proceeds to step 102. In step 102, the constraint conditions to be satisfied in the adaptive measurement engine control state are determined. Examples of the constraints in the present embodiment include those related to misfire limits, knock limits, torque fluctuations, exhaust system (catalyst, etc.) temperature limits, and the like. More specifically, for example, for the exhaust system temperature limit, a constraint condition that the exhaust temperature is 300 ° C. or less can be set. Further, a constraint condition that the hydrocarbon concentration THC contained in the exhaust gas is less than 7000 ppm can be set. In step 102, a plurality of constraints can be set.

  When the constraint condition is determined in step 102, the process proceeds to step 103. In step 103, an initial exploration point that is in the engine control state for starting the exploration of whether or not the adaptive measurement engine control state is in effect is determined. In the present embodiment, information on an internal combustion engine similar to the internal combustion engine that is the subject of the current adaptation work is utilized, and the engine control state that is expected to satisfy the constraint condition determined in step 102 is determined as the initial search point. And

  When the initial search point is determined in step 103, the process proceeds to step 104. In step 104, a search direction which is a change pattern of the engine control state when the search is performed to determine whether or not the adaptive measurement engine control state is performed is determined. That is, it is determined in which direction the engine control state is to be changed in the space representing the engine operation state defined by a plurality of control parameters. Various methods for determining the exploration direction have been known. In this embodiment, the exploration from the initial exploration point repeatedly performs a radial exploration in which at least one value of the control parameter is gradually changed to the set limit value from the initial exploration point and the engine control state is sequentially changed. It is assumed that the direction of exploration is set uniformly in all directions. The number of directions of exploration is determined according to the required accuracy. In other embodiments, the search direction may not be set uniformly in all directions.

  When the search direction is determined in step 104, the process proceeds to step 105. In step 105, measurement is performed to determine whether or not the constraint condition determined in step 102 is satisfied in the engine control state. That is, for example, when a restriction condition related to the exhaust gas temperature is set, the exhaust gas temperature is measured, and if a restriction condition related to the hydrocarbon concentration THC contained in the exhaust gas is set, the hydrocarbon contained in the exhaust gas The concentration THC is measured.

  When necessary measurement is performed in step 105, the process proceeds to step 106. In step 106, it is determined whether or not the constraint condition determined in step 102 is satisfied based on the measurement result in step 105. If it is determined in step 106 that the constraint condition is satisfied, the process proceeds to step 107. If it is determined that the constraint condition is not satisfied, the process proceeds to step 112.

  When the routine proceeds to step 112, the presence / absence of the next search direction is determined. If it is determined in step 112 that there is no next exploration direction, that is, if exploration has been performed as to whether or not all the exploration directions determined in step 104 are in the appropriate measuring engine control state. In this case, the control routine ends. On the other hand, if it is determined in step 112 that there is a next search direction, the process proceeds to step 113. In step 113, the value of the control parameter is changed from the value at the initial search point according to the next search direction. Then, following step 113, the routine proceeds to step 105, where control is performed as described above.

  On the other hand, when the routine proceeds to step 107, it is determined whether or not the value of any control parameter has reached its set limit value (for example, an upper limit value and a lower limit value). Here, the set limit value of the control parameter is, for example, a control limit value of an actuator that controls the control parameter. If it is determined in step 107 that the value of any control parameter is not the set limit value, the process proceeds to step 113, and the value of the control parameter is changed according to the current search direction. Thereafter, the routine proceeds to step 105, where control is performed again. If it is determined in step 107 that the value of any control parameter has reached the set limit value, the process proceeds to step 108.

  In step 108, it is determined whether or not there is a control parameter whose value is not the set limit value among the control parameters selected in step 101. When it is determined in step 108 that there is no control parameter that is not at the set limit value, the process proceeds to step 112, and the control from there is performed as described above. On the other hand, if it is determined in step 108 that there is a control parameter that is not the set limit value, the process proceeds to step 109, and at least one value of the control parameter that is not the set limit value is changed. At this time, the value of the control parameter that has previously reached the set limit value is set to the set limit value of the control parameter. In this way, the search point moves along the end portion of the range of the engine control state specified by the plurality of control parameters selected in step 101.

  If the value of the control parameter is changed in step 109, the process proceeds to step 110. In step 110, measurement is performed to determine whether or not the constraint condition determined in step 102 is satisfied. This control is the same as the control in step 105 described above.

  When necessary measurement is performed in step 110, the process proceeds to step 111. In step 111, it is determined whether or not the constraint condition determined in step 102 is satisfied based on the measurement result in step 110. If it is determined in step 111 that the constraint condition is satisfied, the process returns to step 108 and the control from there is performed again. On the other hand, when it is determined in step 111 that the constraint condition is not satisfied, the process proceeds to step 112 and the control from there is performed as described above.

  In the present embodiment, as a result of searching by such a method, measurement for conformity is performed only in the engine control state determined to be the conformity measurement engine control state.

  FIG. 4 shows an example when the above-described method is performed. As in the case of FIG. 2, FIG. 4 also shows the range of the engine control state specified by the control parameters X and Y, where Xu is the upper limit value of the control parameter X, Xl is the lower limit value of the control parameter X, and Yu is the control. The upper limit value of parameter Y, Yl is the lower limit value of control parameter Y. Further, the region P is an engine control state that does not satisfy the constraint conditions.

In such a situation, the method as described above is performed. In this example, first, a search is performed from the initial search point S in the search direction indicated by the arrow a ₁ . Then, the value of the control parameter Y is becomes the upper limit value Yu, turn exploration exploration direction indicated by arrow a ₂ is carried out. That is, in a state where the value of the control parameter Y is maintained at the upper limit value Yu, the search is performed so that the value of the control parameter X that has not yet reached the set limit value becomes the set limit value (in this example, the upper limit value Xu). Is called. As a result, an exploration point for exploring whether or not the engine is in the adaptive measurement engine control state moves along the end portion of the range of the engine control state specified by the control parameters X and Y.

When the value of the control parameter X reaches the upper limit value Xu, both the control parameters X and Y become the set limit values, so that the search returns to the initial search point and the search is performed in the next search direction, that is, the search direction indicated by the arrow b _1. Done. The search in the search direction indicated by the arrow b ₁ ends when the region P is entered because the constraint condition is not satisfied. Subsequently, a search is performed from the initial search point S in the next search direction, that is, the search direction indicated by the arrow c ₁ .

Then, the value of the control parameter X is becomes the upper limit value Xu, turn exploration exploration direction indicated by arrow c ₂ is carried out. That is, in a state where the value of the control parameter X is maintained at the upper limit value Xu, the search is performed so that the value of the control parameter Y that has not yet reached the set limit value becomes the set limit value (in this example, the upper limit value Yu). Is called. As a result, as in the case of the exploration in the exploration direction indicated by the arrow a ₂ described above, the adaptive measurement engine control state is in line with the end portion of the engine control state range specified by the control parameters X and Y. The exploration point for exploring whether or not will move. When the value of the control parameter Y reaches the upper limit Yu, both the control parameters X and Y reach the set limit value, so that the search returns to the initial search point and the search is performed in the next search direction (not shown).

  As is clear from the above description, according to the above-described method, a search is performed as to whether or not the engine is in the adaptive measurement engine control state along the end portion of the range of the engine control state specified by a plurality of control parameters. The exploration point will move. Therefore, according to this method, it is possible to appropriately determine whether or not the engine control state in which the value of the control parameter is the set limit value is also the above-described adaptive measurement engine control state. As a result, even when the appropriate value is obtained in the engine control state where the value of the control parameter becomes the set limit value, the appropriate value can be obtained.

  In the above description, the case where there are two control parameters has been described as an example in order to simplify the explanation and illustration, and to facilitate understanding. However, the present invention is not limited to this, and related control is performed. It can be applied even when there are more parameters.

FIG. 1 shows an internal combustion engine (ie, an internal combustion engine to be adapted) that is a target of the adaptation work and a measurement calculation device that is used for the adaptation work. FIG. 2 is a diagram for explaining a conventional method for determining the range of the adaptive measurement engine control state. FIG. 3 is a flowchart illustrating a method performed in an embodiment of the present invention. FIG. 4 is a diagram for explaining a case where the method shown in FIG. 3 is performed.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine body 6 Intake valve 8 Exhaust valve 10 Spark plug 11 Fuel injection valve 18 Throttle valve 31 Throttle opening sensor 32 Air flow meter 33 Exhaust temperature sensor 34 Air-fuel ratio sensor 40 Measurement arithmetic device

Claims (2)

If the engine control state, which is the engine control state that should be measured for compliance, changes the engine control state sequentially, and engine operation that satisfies the predetermined constraints is performed, then the engine control at that time In a method for adapting an internal combustion engine, wherein the state is determined as being the above-described conforming measurement engine control state,
When determining the range, a predetermined engine control state is selected as an initial search point, and the engine control state is at least one control parameter among a plurality of control parameters that specify the engine control state from the initial search point. If the value of the control parameter is gradually changed to the set limit value, and the control parameter value becomes the set limit value while satisfying the above-mentioned constraints, another control parameter that has not yet reached the set limit value. If there is, the engine control state is further changed by gradually changing the value of the other control parameter to the set limit value while setting the value of the control parameter that has already reached the set limit value as the set limit value. An adaptation method, characterized in that If the engine control state, which is the engine control state that should be measured for compliance, changes the engine control state sequentially, and engine operation that satisfies the predetermined constraints is performed, then the engine control at that time In the internal combustion engine adaptive device, wherein the state is determined as being the above-mentioned adaptive measurement engine control state,
When determining the range, a predetermined engine control state is selected as an initial search point, and the engine control state is at least one control parameter among a plurality of control parameters that specify the engine control state from the initial search point. If the value of the control parameter is gradually changed to the set limit value, and the control parameter value becomes the set limit value while satisfying the above-mentioned constraints, another control parameter that has not yet reached the set limit value. If there is, the engine control state is further changed by gradually changing the value of the other control parameter to the set limit value while setting the value of the control parameter that has already reached the set limit value as the set limit value. A fitting device, characterized in that

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