JP2007009895A - Method for measuring characteristic parameter in internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for measuring characteristic parameters, capable of obtaining measurements of the characteristic parameters in relatively high reliability by actually carrying out measurement at each measuring point while restricting manhours for measurement. <P>SOLUTION: Values of control parameters of an internal combustion engine are varied to generate transitive operation of the internal combustion engine, while a value of at least one characteristic parameter that can vary in accordance with variation of the values of the control parameters is measured, and the detected value of the characteristic parameter during transitive operation is taken as the value of the characteristic parameter during steady operation in this method for measuring characteristic parameters. During the transitive operation, changing speed of the values of the control parameters is adjusted in such a way that the value or changing speed of at least one characteristic parameter of all the measurable characteristic parameters is within a prescribed range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for measuring characteristic parameters of an internal combustion engine.

In general, control of an internal combustion engine changes the values of control parameters such as throttle opening, ignition timing, intake / exhaust valve on / off valve characteristics, and fuel injection amount so as to satisfy demands on torque, emission, fuel consumption, and the like. Is done by. Such control parameters have optimum values for each engine operating state (for example, engine load and engine speed). The optimum value of the control parameter for each engine operating state is generally set to various values for each engine operating state, and characteristics such as torque, fuel consumption or NO _X emission amount at that time are set. It is obtained by an operation for obtaining an optimum value of the control parameter from the measured value of the parameter, that is, a so-called adaptation operation.

  In such conforming work, since it is necessary to measure the characteristic parameter value during steady operation, for example, the torque, the intake pipe pressure, etc. are substantially constant after waiting for the engine operating state to stabilize at each measurement point. Wait until it converges to the value before measuring. For this reason, it takes time to obtain the measurement values of the characteristic parameters at each measurement point. In addition, in order to increase the matching accuracy, measurement is required at many measurement points, and in some cases, the number of measurement points reaches several thousand to several hundred thousand. For this reason, the measurement man-hour of the whole conforming work becomes enormous.

  Therefore, the interval between the measurement points is widened, that is, the difference in the value of the control parameter between the measurement points is increased to reduce the number of measurement points, and the model formula is obtained based on the measurement value of the characteristic parameter. It has been proposed to estimate a characteristic parameter value for each control parameter value based on a model equation (Patent Document 1). Thereby, a measurement man-hour can be reduced.

JP 2002-206456 A JP 2004-68729 A

  However, since the value of the characteristic parameter estimated in this way is an estimated value between the measurement points even if the model formula is used, the reliability is not so high. Therefore, in order to increase the reliability of the characteristic parameter value, it is necessary to actually perform measurement at each measurement point to obtain the value.

  Accordingly, an object of the present invention is to provide a characteristic parameter measurement method capable of obtaining a measurement value of a relatively reliable characteristic parameter by actually performing measurement at each measurement point while reducing the number of measurement steps. is there.

In order to solve the above-described problem, in the first invention, at least one characteristic that can be changed in accordance with a change in the value of the control parameter while the internal combustion engine is transiently operated by changing the value of the control parameter of the internal combustion engine. In the characteristic parameter measurement method of measuring the parameter value and obtaining the measured characteristic parameter value during transient operation as the characteristic parameter value during steady operation, The change speed of the control parameter value is adjusted so that the value of the at least one characteristic parameter or the change speed thereof falls within a predetermined range.
According to the first aspect, since the characteristic parameter value is measured during the transient operation of the internal combustion engine, the number of measurement steps is longer than that in the case where measurement is performed after the internal combustion engine waits until the internal combustion engine performs steady operation at each measurement point. Can be reduced. In addition, since the change speed of the control parameter is adjusted so that the value of the characteristic parameter or the change speed thereof is within a predetermined range, even if the value of the characteristic parameter is measured during transient operation, It can be used as a characteristic parameter value during steady operation with high reliability.
The control parameter is a controllable parameter that affects the operating state of the internal combustion engine. For example, the charging efficiency, the throttle opening, the ignition timing, the engine speed, the on-off valve characteristics of the intake valve or the exhaust valve, the fuel An injection amount, an air fuel ratio, etc. are mentioned. On the other hand, the characteristic parameter is a parameter whose value can be changed by changing the control parameter and represents the characteristic of the internal combustion engine. For example, the torque, output, engine speed, air-fuel ratio, exhaust gas Examples include temperature and exhaust emission. As can be seen from the above description, the same parameter can correspond to both the control parameter and the characteristic parameter. For example, the air-fuel ratio may be used as a control parameter or may be used as a characteristic parameter.

  In the second invention, in the first invention, when the value of at least one of the detected characteristic parameters or the change speed thereof is out of a predetermined range, the value of the control parameter is changed. Was temporarily stopped.

  In the third invention, in the first invention, when the value of at least one of the detected characteristic parameters or the change speed thereof is out of a predetermined range, the change speed of the value of the control parameter To slow down.

  In a fourth invention, in any one of the first to third inventions, the value of at least one of the detected characteristic parameters or the rate of change thereof is within a specific range smaller than the predetermined range. In this case, the change speed of the control parameter is increased.

  In a fifth invention, in any one of the first to fourth inventions, the control parameter is a charging efficiency, one of the characteristic parameters is an air-fuel ratio, and the value of the air-fuel ratio is a target air-fuel ratio. In this way, the fuel injection amount is controlled, and even if the air-fuel ratio deviates from the target air-fuel ratio, the change speed of the control parameter value is adjusted so that it falls within the predetermined range including the target air-fuel ratio.

  According to a sixth aspect, in the fifth aspect, during the measurement of the characteristic parameter value, the fuel injection amount is estimated for each charging efficiency value such that the air-fuel ratio value becomes the target air-fuel ratio, and the measurement conditions are changed. In the next measurement of the characteristic parameter value, the fuel injection is performed based on the estimated fuel injection amount.

  In the seventh invention, in any one of the first to sixth inventions, at least two characteristic parameter values are measured, and the control is performed so that one of the characteristic parameters has a target value. In addition to controlling parameters other than the parameters, even if the value of the one characteristic parameter deviates from the target value, the change speed of the value of the control parameter is adjusted so that it falls within the predetermined range including the target value. When the measured values of one characteristic parameter deviate from the target value, the measured values of characteristic parameters other than the one characteristic parameter are corrected based on the deviation of the measured value of the one characteristic parameter from the target value. I did it.

  In an eighth aspect based on the seventh aspect, the measurement value of the characteristic parameter other than the one characteristic parameter is corrected by calculating a correction value based on a deviation of the measurement value of the one characteristic parameter from the target value. The correction value is added to the measured value of the characteristic parameter other than the one characteristic parameter.

  In a ninth invention, in the seventh or eighth invention, the control parameter is a charging efficiency, the one characteristic parameter is an air-fuel ratio, and a characteristic parameter other than the one characteristic parameter is an output torque.

  According to the present invention, since the characteristic parameter value is measured during the transient operation of the internal combustion engine, the number of measurement steps can be reduced, and the change speed of the control parameter is set so that the characteristic parameter value or the change speed thereof falls within a predetermined range. Therefore, the characteristic parameter value can be estimated with relatively high reliability. Therefore, it is possible to obtain measurement values of characteristic parameters with relatively high reliability by actually performing measurement at each measurement point while reducing the number of measurement steps.

  Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 shows an internal combustion engine that is an object of an adaptation operation described later and a measuring device used for the adaptation operation.

  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. The intake valve 6 is provided with a variable valve mechanism 20 for changing the opening / closing valve timing of the intake valve 6, that is, the phase angle and the operating angle.

  In general, the control of the internal combustion engine as shown in FIG. 1 is intended to satisfy the demands 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 done by changing the values of controllable parameters (hereinafter referred to as “control parameters”) that affect the operating state of the internal combustion engine so that the torque, target exhaust emission, target fuel efficiency, and the like are obtained.

  Such control parameters have optimum values for each request for the internal combustion engine and engine operating conditions (for example, engine load and engine speed). 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 engine 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 raise the temperature of an exhaust purification catalyst (not shown) provided in the exhaust passage of the internal combustion engine for exhaust purification of the internal combustion engine, the exhaust gas is discharged from the engine body 1. In order to increase the temperature of the exhaust gas (hereinafter referred to as “exhaust temperature”), it is preferable to perform ignition at a timing that is somewhat advanced from the MBT.

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

  In FIG. 1, in addition to the internal combustion engine that is the subject of the adaptation work, a characteristic parameter measuring device for the internal combustion engine is shown. 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 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 31 to 34 are connected to the measurement apparatus main body 40, and the measurement apparatus main body 40 displays and stores the values of the characteristic parameters measured by these sensors 31 to 34.

  On the other hand, the step motor 17 for driving the throttle valve, the fuel injection valve 11 and the spark plug 10 are connected to the measuring device main body, and these step motor 17 and the like are driven and controlled by the measuring device main body 40. That is, the value of the control parameter is changed by the measuring device body 40.

  For example, considering the case of obtaining MBT in various engine operating states by conforming work, first, at a plurality of measuring points in which only the ignition timing is changed in a certain engine operating state, the torque or the characteristic parameter for each measuring point Measure misfires. Based on the measured values such as torque and misfire, the MBT in the engine operating state is obtained. Then, after slightly changing the engine operation state, for example, only changing the air-fuel ratio, the MBT in the control state is obtained again by the above method. Such an operation is performed for all engine operating states that are assumed to be actually operated (hereinafter, simply referred to as “all engine operating states”). In this way, MBT in all engine operating states is obtained. However, if the characteristic parameter values are measured in all engine operating states in this way, the number of measurement points becomes very large.

  On the other hand, for example, when the ignition timing by the spark plug is changed, the torque and the exhaust temperature discharged from the engine body 1 change relatively quickly, but the temperature of the hydraulic oil flowing in the internal combustion engine does not change immediately, and the ignition timing If a certain amount of time does not elapse after the change, the hydraulic oil temperature is not stabilized. If the measurement is performed before the value of the characteristic parameter is stabilized as described above, the accurate value of the characteristic parameter in the engine operating state cannot be measured. Therefore, in such adaptation work, the measurement of characteristic parameter values at a certain measurement point is usually performed after a certain amount of time has elapsed after changing the control parameters, and the values of most characteristic parameters have stabilized. Done. Thereby, the value of the characteristic parameter at the time of steady operation in the engine operation state is measured.

  However, if the measurement is performed after waiting for the characteristic parameter value to stabilize for each engine operating state in this way, the number of measurement steps becomes enormous, considering that the number of measurement points is very large as described above. End up.

  Therefore, in this embodiment, instead of waiting for all the characteristic parameter values to be completely stabilized at each measurement point, the characteristic parameter value is measured while gradually changing a certain control parameter value. Is done. For example, when the ignition timing is used as a control parameter, parameters other than the ignition timing (for example, throttle opening, intake and exhaust valve opening / closing valve timing, engine speed, etc.) are fixed so as not to change. Then, the ignition timing is gradually changed from the retard side to the advance side, and characteristic parameters at each measurement point, that is, torque and exhaust temperature are measured. That is, the characteristic parameter value is measured in a state where the internal combustion engine is performing a transient operation in which the ignition timing gradually changes.

  In particular, when the value of the characteristic parameter is measured while changing each ignition timing in this way, the torque and exhaust temperature change relatively quickly with respect to the change in the ignition timing as described above. Even if the value of the characteristic parameter is measured without waiting for stability, it is almost the same as the value of the characteristic parameter measured after waiting for stabilization of the engine operation state. For this reason, even when the characteristic parameter value is measured while gradually changing the ignition timing, the measured value is substantially the same as the characteristic parameter value measured after the engine operating state is stabilized. . That is, even if the characteristic parameter is measured while the internal combustion engine is in a transient operation, depending on the type of the characteristic parameter, it is used as the characteristic parameter value in a state in which the internal combustion engine is performing a steady operation relatively accurately. be able to.

  This can be said even when the values of other control parameters are gradually changed as well as the ignition timing. Therefore, in general terms, even if the value of a characteristic parameter is measured while fixing the value of another control parameter and gradually changing the value of one control parameter, the engine operation is relatively accurate. The value of the characteristic parameter measured after the state is stabilized can be obtained.

  Therefore, in the present embodiment, basically, a characteristic parameter value (hereinafter referred to as “characteristic parameter during transient operation” measured while transiently operating the internal combustion engine by gradually changing only one control parameter. "Value") is acquired as a value of a characteristic parameter in a state where the internal combustion engine is in steady operation (hereinafter referred to as "value of a characteristic parameter during steady operation").

  However, when the characteristic parameter value is measured while gradually changing the control parameter value as described above, the time change rate of the characteristic parameter value may increase. Such a situation is likely to occur when the change amount of the characteristic parameter value is large relative to the change amount of the control parameter value. In this way, when a certain characteristic parameter changes suddenly, the value of the characteristic parameter and the measured value of other characteristic parameters while the characteristic parameter changes abruptly are measured after the engine operating state is stabilized. The error tends to be large with respect to the characteristic parameter value.

  On the other hand, in a control region where the amount of change of a certain characteristic parameter is large relative to the amount of change of the control parameter, if the value of the control parameter slightly shifts, the value of the characteristic parameter changes greatly. For example, in a certain ignition timing region, if the ignition timing is slightly advanced, the amount of decrease in the exhaust gas temperature is larger than in other ignition timing regions. In such an ignition timing region, depending on the target exhaust temperature, it is necessary to precisely control the ignition timing during actual engine operation. For this purpose, the characteristic parameter value with respect to the control parameter value is accurately measured. There is a need.

  Therefore, in the present invention, when measuring the value of the characteristic parameter during the transient operation and acquiring the value of the measured characteristic parameter as the value of the characteristic parameter during the steady operation, at least one of the measured characteristic parameters The change speed of the control parameter value is adjusted so that the change speed of the measured value of the characteristic parameter falls within a predetermined range.

  A case where the exhaust temperature and torque are measured as characteristic parameters while gradually changing the ignition timing as control parameters will be described below as an example.

FIG. 2 is a time chart of ignition timing, torque, exhaust temperature, and exhaust temperature change rate when measurement is performed according to the present embodiment. As can be seen from the figure, in the measurement of the characteristic parameters of the present embodiment, the range in which the ignition timing is assumed to be executable during actual engine operation (for example, if misfire or knocking occurs reliably at the ignition timing). Within the range other than the possible ignition timing range), the ignition timing is gradually changed from the most retarded ignition timing to the advanced timing side. When the ignition timing is advanced from the most retarded ignition timing (time 0 in the figure), first, as the ignition timing is gradually advanced, the exhaust gas temperature gradually decreases and the torque is increased. It gradually rises (time 0 to t ₁ in the figure).

In general, the exhaust gas temperature decreases approximately in proportion to the advance angle of the ignition timing, but such a decrease in exhaust gas temperature is not completely proportional to the advance angle of the ignition timing. For this reason, while the advance speed of the ignition timing is constant, the rate of decrease in the exhaust temperature is not constant. In the example shown in FIG. 2, the ignition timing is advanced at a constant speed from time 0 to time t ₁ , whereas the measured exhaust temperature decrease rate gradually increases.

  As described above, when the exhaust gas temperature decrease rate increases, the measured value of the characteristic parameter during transient operation tends to be different from the value of the characteristic parameter during steady operation as described above.

  That is, the value of each characteristic parameter does not change depending only on the change in the value of the control parameter, but also changes depending on the change in the value of another characteristic parameter due to the change in the value of the control parameter. For example, when the ignition timing changes, the exhaust temperature changes, and when the exhaust temperature changes, the temperature of the exhaust purification catalyst (not shown) in the engine exhaust passage changes. Here, since the exhaust purification catalyst has a certain heat capacity, its temperature does not change immediately with changes in the exhaust temperature, but changes with some response delay. Therefore, the temperature of the exhaust purification catalyst measured when the exhaust temperature change rate is slow is almost equal to the temperature of the exhaust purification catalyst during steady operation, whereas the exhaust temperature change rate is fast. The temperature of the exhaust purification catalyst measured in the step tends to be different from the temperature of the exhaust purification catalyst during steady operation.

  Also, the exhaust temperature itself does not change immediately when the ignition timing changes due to the temperature of the hydraulic oil flowing in the internal combustion engine, the heat capacity of the exhaust port, or the like, but changes with some response delay. Therefore, the exhaust temperature measured when the exhaust temperature change rate is slow is almost equal to the exhaust temperature during steady operation, whereas the exhaust temperature measured when the exhaust temperature change rate is fast. Tends to be different from the exhaust temperature during steady operation.

Therefore, in the present embodiment, when the exhaust gas temperature changes faster than a certain range, changing the ignition timing is stopped and the ignition timing is fixed. In the illustrated embodiment, the change in the ignition timing is stopped when the exhaust gas temperature changes at a speed outside the continuation region (that is, the continuation lower limit speed V ₁ or more and the continuation upper limit speed V ₁ ′ or less). (Time t ₁ ). As a result, the exhaust temperature decrease rate rapidly decreases. However, as described above, since the exhaust temperature changes with a slight response delay with respect to the change in the ignition timing, the rate of decrease in the exhaust temperature is zero immediately after stopping the change in the ignition timing. It does n’t mean.

Then, when the exhaust temperature lowering speed becomes a speed within the restart region (that is, the restart lower limit speed V ₂ or more and the restart upper limit speed V ₂ ′ or less), the change of the ignition timing is restarted (time t ₂ ). . The restart area is an area within the continuation area. Therefore, the restart lower limit speed V ₂ is higher than the continuation lower limit speed V ₁ , and the restart upper limit speed V ₂ ′ is lower than the continuation upper limit speed V ₁ ′. As a result, the measurement of the exhaust temperature and other characteristic parameter values corresponding to each ignition timing is resumed. In resuming changing the ignition timing, the rate of decrease in the ignition timing is set to be slower than the rate of decrease in the ignition timing before stopping. For this reason, after restarting changing the ignition timing, it is possible to prevent the exhaust gas temperature from decreasing at a higher rate and again to be out of the continuation region.

As a result, it is possible to prevent the change rate of the exhaust gas temperature from being outside the continuation region. For this reason, the exhaust temperature and the catalyst temperature corresponding to each ignition timing measured during the transient operation are substantially equal to the actual exhaust temperature and catalyst temperature corresponding to each ignition timing during the steady operation. Incidentally, continuous upper limit speed V ₁ A is continuously lower velocity V ₁ or more ', if any exhaust temperature change rate is continued in the area of the large measured value of the characteristic parameter during transient operation and characteristic parameters of operating steadily It is determined in advance experimentally or by calculation so as not to have different values.

  FIG. 3 is a flowchart showing a control routine for adjusting the change rate of the ignition timing when measuring characteristic parameters such as torque, exhaust temperature, and catalyst temperature.

First, in step 101, it is determined whether or not the exhaust gas temperature changing speed Vet is equal to or higher than the continuation lower limit speed V _{1 and} lower than the continuation upper limit speed V ₁ ′. The exhaust temperature change rate Vet is calculated based on the output of the exhaust temperature sensor 33. If it is determined that the exhaust gas temperature change speed Vet is equal to or higher than the continuation lower limit speed V _{1 and} lower than the continuation upper limit speed V ₁ ′, the control routine is terminated, and the ignition timing change speed is The speed is maintained as it is.

On the other hand, if it is determined in step 101 that the exhaust temperature change speed Vet is lower than the continuation lower limit speed V ₁ or higher than the continuation upper limit speed V ₁ ′, the process proceeds to step 102. In step 102, the ignition timing changing speed Vsw is set to zero. Next, at step 103, it is determined whether or not the exhaust gas temperature changing speed Vet is equal to or higher than the restart lower limit speed V _{2 and} equal to or lower than the restart upper limit speed V ₂ ′. If it is determined that the exhaust gas temperature changing speed Vet is lower than the restart lower limit speed V ₂ or higher than the restart upper limit speed V ₂ ′, step 103 is repeated, during which the ignition timing is fixed. Thereafter, when the exhaust gas temperature changing speed Vet is equal to or higher than the restart lower limit speed V _{2 and} lower than the restart upper limit speed V ₂ ′, the routine proceeds to step 104. In step 104, the ignition timing change speed Vsw is set to a speed lower by a predetermined value α than the ignition timing change speed Vsw ′ before the ignition timing change is stopped (Vsw = Vsw′−α). It will be terminated.

  In the above-described embodiment, when the change of the ignition timing is resumed, the change speed of the ignition timing is set to be slower than the change speed of the ignition timing before the stop, but is the same as the change speed of the ignition timing before the stop. It may be speed.

  Next, a modified example of the first embodiment will be described. In the above embodiment, when the change speed of a certain characteristic parameter becomes faster than a certain range, changing the ignition timing is temporarily stopped. The change rate of the ignition timing is slowed without stopping the change.

FIG. 4 is a time chart of the ignition timing, the exhaust gas temperature, and the change rate of the exhaust gas temperature when measurement is performed according to this modified example. As in the embodiment shown in FIG. 2, when the advance of the ignition timing is started from the most retarded ignition timing (time 0 in the figure), first, as the ignition timing is gradually advanced, As a result, the exhaust temperature gradually decreases (time 0 to t _{3 in the} figure). At this time, the ignition timing changing speed Vsw ₁ (° / sec) is set to a predetermined initial speed.

Thereafter, when the exhaust temperature change rate increases beyond a certain range, the ignition timing change rate is slowed down. In the illustrated example, when the exhaust gas temperature decreasing speed becomes a speed outside the continuation region, the ignition timing changing speed is reduced by a predetermined value β, and the speed Vsw ₂ (Vsw ₂ = Vsw ₁ −β). (Time t ₃ ). As a result, the exhaust gas temperature decrease rate is reduced, and the characteristic parameters such as the exhaust gas temperature and the catalyst temperature can be accurately measured.

However, if the change rate of the ignition timing is made too slow, the measurement time increases. Therefore, when the exhaust temperature change rate is very low, in the illustrated example, the exhaust temperature change rate is within the acceleration region (that is, the acceleration lower limit speed V ₃ or more and the restart upper limit speed V ₃ ′ or less). If the speed is equal to the speed, the change speed of the ignition timing is increased by a predetermined value γ to obtain a speed Vsw ₃ (Vsw ₃ = Vsw ₂ + γ) (time t ₄ ). As a result, the change speed of the ignition timing is increased, and the measurement time is shortened. The acceleration amount γ when the ignition timing change rate is increased is set to a value smaller than the deceleration amount β when the ignition timing change rate is decelerated (γ <β).

  In the above-described embodiment and its modified examples, the case where the ignition timing is used as the control parameter and the exhaust temperature, torque, and catalyst temperature are used as the characteristic parameters has been described. Absent. In addition to the ignition timing, for example, charging efficiency, throttle opening, engine speed, intake / exhaust valve on / off valve characteristics, fuel injection amount, air-fuel ratio, and the like can be used as the control parameter. On the other hand, the characteristic parameters include, for example, output, engine speed, air-fuel ratio, exhaust gas temperature, exhaust emission, etc., in addition to the exhaust temperature, catalyst temperature, and torque. The same is true for the following embodiments.

  Next, a second embodiment of the present invention will be described. In the present embodiment, a case where charging efficiency is used as a control parameter and an air-fuel ratio is used as a characteristic parameter is shown. Also in the present embodiment, the air flow meter, the throttle opening sensor, the throttle valve, and the fuel injection valve are similarly connected to the measuring device main body. However, the throttle valve and the fuel injection valve are normally controlled based on the outputs of the air flow meter, the throttle opening sensor, and the like in the same manner as that controlled by an electronic control unit (ECU).

  By the way, when trying to measure the value of a characteristic parameter other than the air-fuel ratio by changing a certain control parameter while fixing the air-fuel ratio to a constant value, some parameter must be controlled so that the air-fuel ratio becomes a constant value. Don't be. For example, when the torque and the engine speed are measured by changing the charging efficiency while fixing the air-fuel ratio to the stoichiometric air-fuel ratio, it is necessary to control the fuel injection amount so that the air-fuel ratio becomes the stoichiometric air-fuel ratio.

  When the fuel injection amount is controlled so that the air-fuel ratio becomes the target air-fuel ratio in this way, the fuel injection amount is generally fed back so that the air-fuel ratio detected by the air-fuel ratio sensor provided in the exhaust passage becomes the target air-fuel ratio. Done by controlling.

  However, such feedback control of the fuel injection amount has a certain response delay. For this reason, for example, during a transient operation where the charging efficiency is changing, the control of the fuel injection amount may be delayed and the actual air-fuel ratio may deviate from the target air-fuel ratio. Thus, when the value of the characteristic parameter measured when the actual air-fuel ratio deviates from the target air-fuel ratio is acquired as the value of the characteristic parameter when the air-fuel ratio is fixed to the target air-fuel ratio, the air-fuel ratio actually becomes the target. When the air-fuel ratio is used, the characteristic parameter value is different.

  For example, when the air-fuel ratio is fixed to the stoichiometric air-fuel ratio, and the charging efficiency for each cylinder is gradually changed to measure the torque for each charging efficiency, the measurement is performed with the air-fuel ratio deviating from the stoichiometric air-fuel ratio. Then, the measured torque value for each charging efficiency is deviated from the actual value.

  Therefore, in the present embodiment, when measuring the value of the characteristic parameter during transient operation and estimating the measured characteristic parameter value as the value of the characteristic parameter during steady operation, at least one of the measured characteristic parameters is measured. The change speed of the control parameter value is adjusted so that the values of the two characteristic parameters are within a predetermined range.

  Hereinafter, a case where the air-fuel ratio and torque are measured as characteristic parameters while gradually changing the charging efficiency as control parameters will be described as an example.

  FIG. 5 is a time chart of the FB correction coefficient, the air-fuel ratio, and the charging efficiency related to the fuel injection amount when measurement is performed according to the present embodiment. In the illustrated example, the target air-fuel ratio is set to the theoretical air-fuel ratio (about 14.7), and the torque and the like are measured while changing the charging efficiency. As can be seen from the figure, in the measurement of the characteristic parameter values of the present embodiment, the filling efficiency is gradually increased from a substantially zero state (that is, the filling efficiency during idling). When the increase in the charging efficiency is started by increasing the throttle opening (time 0 in the figure), the fuel injection amount is increased by feedback control, and the air-fuel ratio is maintained substantially at the stoichiometric air-fuel ratio. .

However, as the charging efficiency increases, the control of the fuel injection amount by feedback control is delayed, and the actual air-fuel ratio decreases. As described above, if the air-fuel ratio decreases or increases too much, accurate measurement cannot be performed as described above. Therefore, in the present embodiment, the measured air-fuel ratio is equal to or greater than the continuation region (that is, the continuation lower limit air-fuel ratio AF ₁ (14.0 in the illustrated example) and the continuation upper limit air-fuel ratio AF ₁ ′ (15. 0) or less) Stop changing the charging efficiency when the air-fuel ratio is outside (time t ₅ ). As a result, the air-fuel ratio that has deviated from the stoichiometric air-fuel ratio due to a response delay in feedback control returns to the stoichiometric air-fuel ratio.

Then, when the measured air-fuel ratio reaches the air-fuel ratio in the restart region (that is, the restart lower limit air-fuel ratio AF ₂ or more and the restart upper limit air-fuel ratio AF ₂ ′ or less), the charging efficiency changing operation is started (time t ₆ ). Thereby, measurement of the value of characteristic parameters, such as torque corresponding to each filling efficiency, is restarted. In resuming the change of the filling efficiency, the changing speed of the filling efficiency is set to be slower than the changing speed of the filling efficiency before stopping. For this reason, it is prevented that the air-fuel ratio becomes an air-fuel ratio outside the continuous region again after restarting the change of the charging efficiency. Therefore, it is possible to prevent the actual air-fuel ratio from greatly deviating from the target air-fuel ratio during measurement, and to perform measurement effectively.

  In the above embodiment, when resuming the change of the charging efficiency, the changing speed of the charging efficiency is set to be slower than the changing speed of the charging efficiency before the cancellation, but is the same as the changing speed of the charging efficiency before the cancellation. It may be speed.

  By the way, as described above, when the fuel injection amount is controlled so that the air-fuel ratio becomes the stoichiometric air-fuel ratio, the fuel injection amount is determined as follows. That is, the ECU stores a reference fuel injection amount (hereinafter referred to as “reference fuel injection amount”) Qfbase with respect to the air flow rate mt detected by the air flow meter 32. That is, the ECU stores the reference fuel injection amount Qfbase as a function or a map with respect to the air flow rate mt. Basically, the reference fuel injection amount Qfbase to be injected from the fuel injection valve 11 is calculated based on the air flow rate mt detected by the air flow meter 32, and the calculated reference fuel injection amount Qfbase is calculated from the fuel injection valve. Be injected.

However, actually, even if the reference fuel injection amount Qfbase is injected from the fuel injection valve 11 due to the influence of the pulsation in the intake pipe 15 or the like, the air-fuel ratio hardly matches the target air-fuel ratio. Done. Specifically, the reference fuel injection amount is calculated using the following equation (1) based on the FB correction coefficient Ffb calculated based on the difference between the actual air-fuel ratio AF detected by the air-fuel ratio sensor and the target air-fuel ratio AFtrg. A corrected fuel injection amount Qf obtained by correcting Qfbase is injected from the fuel injection valve.
Qf = Qfbase (1 + Ffb) (1)

  As shown in FIG. 5, the FB correction coefficient Ffb is sequentially changed based on the air-fuel ratio sensor 34 during measurement, and when one measurement is completed, the FB correction coefficient adopted during the measurement for each value of the charging efficiency. The value of is obtained. That is, when one measurement is completed, the value of the FB correction coefficient is obtained as a function of the charging efficiency. In the next measurement performed by slightly changing the ignition timing, for example, it is considered that the fuel injection amount is corrected by the same FB correction coefficient value in order to make the actual air-fuel ratio the stoichiometric air-fuel ratio.

  Therefore, in this embodiment, in the second and subsequent measurements, in addition to feedback control, the fuel injection amount is determined using feedforward control using the FB correction coefficient obtained as a function of the charging efficiency by the first measurement. To do. Hereinafter, the determination of the fuel injection amount using the feedforward control will be specifically described.

In the first measurement, in addition to the FB correction coefficient Ffb (KL) as a function of the charging efficiency KL, the air-fuel ratio AF (KL) detected by the air-fuel ratio sensor 34 can be obtained. The reference fuel injection amount Qfbase is determined based on the air flow rate mt detected by the air flow meter 32. However, taking into account that the charging efficiency KL can be expressed as a function of the air flow rate mt, the reference fuel injection amount Qfbase is also determined. It can be considered as a function of the filling efficiency KL. Then, assuming that the actual in-cylinder charged air amount during measurement is Air (KL) as a function of the charging efficiency KL, there is a relationship as shown in the following equation (2) between these parameters.

On the other hand, if the correction coefficient when the reference fuel injection amount Qfbase is corrected so that the air-fuel ratio AF is always maintained at the stoichiometric air-fuel ratio (target air-fuel ratio) is FF correction coefficient Fff (KL), the following equation (3) is obtained. It holds.

By deleting the reference fuel injection amount Qfbase (KL) and the in-cylinder charged air amount Air (KL) from the above formulas (2) and (3), the following formula (4) is derived by combining these formulas.

In the second and subsequent measurements, the fuel injection amount calculated by the following equation (5) is injected from the fuel injection valve using the FF correction coefficient calculated in this way.

  In equation (5), (1 + Fff (KL)) is a so-called feedforward term, and the presence of such a feedforward term makes it possible to more accurately match the air-fuel ratio to the stoichiometric air-fuel ratio. However, since the air-fuel ratio cannot always be completely adjusted to the stoichiometric air-fuel ratio during measurement only by feedforward control, feedback control is also performed. Ffb in equation (5) is an FB correction coefficient calculated based on the output of the air-fuel ratio sensor during the measurement, and is a coefficient unrelated to the FB correction coefficient Ffb (KL) calculated in the first measurement. is there. As described above, by using both feedforward control and feedback control in calculating the fuel injection amount, the air-fuel ratio does not greatly deviate from the stoichiometric air-fuel ratio even if there is a response delay due to feedback control. Further, since the air-fuel ratio is not greatly deviated from the stoichiometric air-fuel ratio, the change rate of the charging efficiency can be increased.

  In the above embodiment, the measured air-fuel ratio AF, the FB correction coefficient Ffb, and the FF correction coefficient Fff are described as functions of only the charging efficiency KL. However, in actuality, these parameters are not only the charging efficiency KL but also the engine. It also changes depending on the number of revolutions. Therefore, in the above embodiment, the air-fuel ratio AF, the FB correction coefficient Ffb, and the FF correction coefficient Fff may be used as a function of the charging efficiency and the engine speed.

In this case, since the air-fuel ratio AF and the FB correction coefficient Ffb are not actually measured in the range of all engine speed NE and charging efficiency KL, actual measured values during the first measurement are measured. Then, the following formula (6) is created based on the calculated value, and when calculating the FF correction coefficient Fff, the values of the air-fuel ratio AF (KL, NE) and the FB correction coefficient Ffb (KL, NE) are calculated from this formula (6). It may be obtained and substituted into the above equation (4). In addition, the constants C1-C6 of following formula (6) are values calculated | required by the least squares method from a measured value.
Ffb (KL, NE) = C1 + C2 · KL + C3 · NE + C4 · KL ² + C5 · NE ² + C6 · KL · NE (6)

  Next, a modified example of the second embodiment will be described with reference to FIG. As described above, when the fuel injection amount is controlled using feedforward control so that the air-fuel ratio becomes the target air-fuel ratio, the actual air-fuel ratio is less likely to deviate from the target air-fuel ratio. For this reason, in the present embodiment, when the deviation of the air-fuel ratio from the target air-fuel ratio is small during execution of the feedforward control, the change rate of the charging efficiency is increased.

FIG. 6 is a time chart of the FB correction coefficient, the air-fuel ratio, the charging efficiency, and the changing speed of the charging efficiency with respect to the fuel injection amount when measurement is performed according to this modification. In the illustrated example, a case is shown in which the value of a characteristic parameter such as torque is being measured while fixing the air-fuel ratio to the stoichiometric air-fuel ratio and changing the charging efficiency. In the example shown in FIG. 6, the charging efficiency is increased when the measured air-fuel ratio is an air-fuel ratio within a continuation region (continuation lower limit air-fuel ratio AF ₁ or more and continuation upper limit air-fuel ratio AF ₁ ′ or less). stops the to, then, to resume the air-fuel ratio is to increase the and the charging efficiency becomes an air-fuel ratio in (resume upper air AF ₂ 'following a is resumed lower air-fuel ratio AF ₂ or more) resume region In addition, when the air-fuel ratio is in the acceleration region (the acceleration lower limit air-fuel ratio AF ₃ or more and the acceleration upper limit air-fuel ratio AF ₃ ′ or less), the increase rate of the charging efficiency is increased. Incidentally, It should be noted that the speed increasing region is a region in the resumption areas, thus accelerating the lower limit air-fuel ratio AF ₃ is greater than the resumption limit air-fuel ratio AF _2, also accelerated limit air-fuel ratio AF ₃ 'resume limit air-fuel ratio AF Less than ₂ '.

Similar to the second embodiment shown in FIG. 5, the charging efficiency is gradually increased from the substantially zero state even in the measurement of the characteristic parameter value of the present embodiment. At the start of increase in filling efficiency (time 0 in the figure), the change rate of filling efficiency is set to a predetermined initial speed. From time 0 to time t ₇ , since the measured air-fuel ratio is the air-fuel ratio in the acceleration region, the change rate of the charging efficiency is gradually increased.

Next, when the air-fuel ratio becomes an air-fuel ratio outside the acceleration region at time t ₇ , the increase in the charging efficiency change rate is stopped, and then the charging efficiency is increased unless the air-fuel ratio becomes the air-fuel ratio in the acceleration region again. The rate of change is kept constant. When the air-fuel ratio measured at time t ₈ becomes smaller than the continuation lower limit air-fuel ratio AF ₁ , changing the charging efficiency is stopped.

Thereafter, when the measured air-fuel ratio exceeds the restart lower limit air-fuel ratio AF ₂ , changing the charging efficiency is restarted. At this time, the changing speed of the filling efficiency is set to the initial speed. Subsequently kept constant rate of change of small the charging efficiency than again measured air-fuel ratio is expedited change rate of the charging efficiency becomes increased speed limit air-fuel ratio AF ₃ or more, the speed increasing lower air AF ₃ . Even when the measured air-fuel ratio is within the acceleration range, if the increase rate of the charging efficiency is equal to or higher than the upper limit speed, further increase of the change rate of the charging efficiency is stopped.

  FIG. 7 is a flowchart showing a control routine for adjusting control of the charging efficiency when the characteristic parameter is measured by changing the charging efficiency.

First, in step 121, it is determined whether or not the charging efficiency change rate Vkl is zero, that is, whether or not changing the charging efficiency is stopped. If it is determined in step 121 that the charging efficiency change rate Vkl is not zero (Vkl ≠ 0), the routine proceeds to step 122. In step 122, whether or not the air-fuel ratio which is measured is the air-fuel ratio of the continuous region (continuous lower air-fuel ratio AF ₁ Exceeded by continuous upper air AF ₁ 'hereinafter) in is determined. If it is determined in step 122 that the measured air-fuel ratio is the air-fuel ratio in the continuation region, the routine proceeds to step 123.

In step 123～ step 125, whether the air-fuel ratio in the measured air-fuel ratio is accelerated regions (speed increasing lower air-fuel ratio AF ₃ Exceeded accelerating lower air-fuel ratio AF ₃ and below), feed forward control And whether or not the charging efficiency changing speed Vkl is equal to or lower than the upper limit speed Vklmax is determined. If the measured air-fuel ratio is the air-fuel ratio in the acceleration region, the feedforward control is performed, and the charging efficiency change speed Vkl is equal to or lower than the upper limit speed Vklmax, the routine proceeds to step 126. In step 126, a value obtained by adding the predetermined speed b to the charging efficiency changing speed Vkl is set as the charging efficiency changing speed. That is, the charging efficiency change rate Vkl is increased. On the other hand, if the measured air-fuel ratio is an air-fuel ratio outside the acceleration region, feed-forward control is not performed, or the charging efficiency change speed Vkl is higher than the upper limit speed Vklmax, the charging efficiency changes The speed is maintained as it is.

On the other hand, when it is determined in step 122 that the measured air-fuel ratio is outside the continuation region (AF <AF ₁ or AF> AF ₁ ′), the routine proceeds to step 127. In step 127, the change rate Vkl of the charging efficiency is set to zero, and the change of the charging efficiency is stopped.

When the charging efficiency change rate Vkl is zero, in the next routine, it is determined in step 121 that the charging efficiency change rate Vkl is zero, and the routine proceeds to step 128. In step 128, it is determined whether or not the measured air-fuel ratio AF is an air-fuel ratio within a restart region (which is greater than or equal to the restart lower limit air-fuel ratio AF _{2 and} less than or equal to the restart upper limit air-fuel ratio AF ₂ ′). If it is determined in step 128 that the measured air-fuel ratio AF is outside the resuming range, the control routine is terminated. On the other hand, if it is determined in step 128 that the measured air-fuel ratio AF is the air-fuel ratio in the restart region, the process proceeds to step 129. In step 129, the charging efficiency changing speed Vkl is set to the initial speed Vklde.

  In the above-described embodiment, when the measured air-fuel ratio is outside the continuation region, changing the charging efficiency is temporarily stopped. In such a case, without changing the charging efficiency. You may make it decelerate the change speed of filling efficiency.

  Next, a third embodiment of the present invention will be described. By the way, in the second embodiment, in order to measure the torque and the engine speed by changing the charging efficiency while fixing the air-fuel ratio to the stoichiometric air-fuel ratio, the air-fuel ratio is converted to the stoichiometric air-fuel ratio by feedback control or feedforward control. The fuel injection amount is controlled so that

  However, it is difficult to always make the actual air-fuel ratio coincide with the target air-fuel ratio while the charging efficiency is gradually changed even if feedback control or feed-forward control is performed. Deviation from the air-fuel ratio. For this reason, the value of a parameter other than the air-fuel ratio (such as torque in the above embodiment) is not a value corresponding to the target air-fuel ratio, and is a value corresponding to the actual air-fuel ratio that deviates from the target air-fuel ratio. It has become. Therefore, it is difficult to accurately obtain the relationship between the charging efficiency, the target air-fuel ratio, and the torque.

  Therefore, in this embodiment, the difference between the measured actual air-fuel ratio and the target air-fuel ratio is calculated, and the measured characteristic parameter value is corrected based on the calculated difference. Hereinafter, the characteristic parameter measurement method of the present embodiment will be described in detail with reference to FIGS. 8 and 9, taking as an example the case where the charging efficiency is used as the control parameter and the air-fuel ratio and torque are measured as the characteristic parameters.

  FIG. 8 is a time chart of air-fuel ratio, measured torque, charging efficiency, torque correction value, and calculated torque when measurement is performed according to the present embodiment. The torque correction value and the calculated torque are calculated based on the measured air-fuel ratio and the measured torque as will be described later. In FIG. 8, these torque correction value and calculated torque are calculated simultaneously with the measurement of the air-fuel ratio and the like. However, the torque correction value and the calculated torque may be calculated based on data at the time of measurement after all the measurements are completed.

  In the illustrated example, the target air-fuel ratio is set as the theoretical air-fuel ratio, and the torque is measured while changing the charging efficiency. As can be seen from the figure, in the measurement of the characteristic parameter value of the present embodiment, the filling efficiency is gradually increased from a substantially zero state. When the increase in the charging efficiency is started by increasing the throttle opening (time 0 in the figure), the fuel injection amount is accordingly controlled by feedback control or feedforward control in order to maintain the air-fuel ratio at the target air-fuel ratio. Increased.

  Also in this embodiment, as in the second embodiment, when the measured air-fuel ratio becomes an air-fuel ratio outside the continuation region, changing the charging efficiency is stopped, or the changing speed of the charging efficiency is slow. As a result, the actual measured air-fuel ratio basically fluctuates up and down within the continuous region. Conversely, as shown in the description of the second embodiment, it is difficult to always match the actual air-fuel ratio with the target air-fuel ratio while changing the charging efficiency even if feedback control or feedforward control is performed. The actual air-fuel ratio fluctuates up and down with respect to the target air-fuel ratio as shown in FIG.

  The actual torque to be measured gradually increases as it fluctuates up and down as shown in FIG. This is because the actual torque increases as the charging efficiency increases, and fluctuates up and down as the actual air-fuel ratio fluctuates up and down with respect to the target air-fuel ratio. That is, the actual torque changes not only due to the influence of the change in charging efficiency but also due to the influence of fluctuations in the air-fuel ratio. Therefore, if the actual torque is acquired as the torque value when the air-fuel ratio is fixed to the target air-fuel ratio, the torque value is slightly different from the value when the air-fuel ratio is actually the target air-fuel ratio.

Therefore, in the present embodiment, the measured torque value is corrected based on the difference ΔAF (= AF−AFT) between the actual air-fuel ratio AF and the target air-fuel ratio AFT. Specifically, in the present embodiment, first, a difference ΔAF (t) between the actual air-fuel ratio AF measured at each time t and the target air-fuel ratio AFT is calculated. Next, a torque correction value Ktq (t) is calculated by the following equation (7) based on the calculated difference ΔAF (t).
Ktq (t) = k · KL (t) · ΔAF (t) (7)

  In Equation (7), KL (t) is the charging efficiency at time t, and k is a correction coefficient. The reason why the charging efficiency KL (t) is multiplied is that the higher the charging efficiency, the greater the torque shift with respect to the air-fuel ratio shift. The correction coefficient k is a value determined based on the type of the internal combustion engine and the target air-fuel ratio. That is, the relationship between the difference in air-fuel ratio and the change in torque is not the same in all types of internal combustion engines. For example, in a large-sized internal combustion engine with a high engine output, the change in torque with respect to the difference in air-fuel ratio is large. In a small-sized internal combustion engine with a small value, the torque change with respect to the deviation of the air-fuel ratio is small. For this reason, in the present embodiment, the value of the correction coefficient k is determined based on the air-fuel ratio-torque characteristics of the internal combustion engine of that type according to the type of the internal combustion engine.

  Further, as shown in FIG. 9, since the air-fuel ratio and the torque are not in a proportional relationship, the torque increase amount with respect to the air-fuel ratio increase amount is not constant in all air-fuel ratio ranges. However, in the present embodiment, the actual air-fuel ratio measured as described above when changing the charging efficiency is maintained in the continuation region, and the continuation region is, for example, about ± 0.2 from the target air-fuel ratio. For example, when the target air-fuel ratio is the stoichiometric air-fuel ratio (14.7), the actual air-fuel ratio is maintained at 14.5 to 14.9. Here, as can be seen from FIG. 9, since the air-fuel ratio-torque curve is a gradual curve, the amount of increase in torque relative to the amount of increase in air-fuel ratio is not constant in all air-fuel ratio ranges, but 14.5-14 In a narrow air-fuel ratio range of about .9, it can be considered that the amount of increase in torque with respect to the amount of increase in air-fuel ratio is substantially constant. Therefore, in the present embodiment, as long as the actual air-fuel ratio varies within the continuation region, the air-fuel ratio and the torque can be considered to be in a proportional relationship, and the proportionality factor varies depending on the target air-fuel ratio. Therefore, in the present embodiment, the correction coefficient k is determined based not only on the type of the internal combustion engine but also on the target air-fuel ratio.

Then, by adding the torque correction value Ktq (t) calculated at the time t in this way to the torque TQ (t) measured at the time t, the target of the air-fuel ratio is expressed by the following equation (8). A torque TQr (t) that eliminates the influence of deviation from the air-fuel ratio is calculated.
TQr (t) = TQ (t) + Ktq (t)

  By performing the operation as described above for all times, that is, for all charging efficiencies, the relationship between the charging efficiency and the torque when the air-fuel ratio is the stoichiometric air-fuel ratio can be obtained fairly accurately, and then the target By performing the same operation after setting the air-fuel ratio to another air-fuel ratio, the relationship between the charging efficiency and torque at that air-fuel ratio can be obtained fairly accurately. By repeating such an operation, the relationship between the air-fuel ratio, the charging efficiency, and the torque can be accurately obtained.

  Thus, in the present embodiment, the relationship between the air-fuel ratio, the charging efficiency, and the torque can be obtained fairly accurately. Further, since the air-fuel ratio is corrected even if the air-fuel ratio slightly deviates from the target air-fuel ratio during measurement, the allowable range of the air-fuel ratio deviation, that is, the continuation region can be widened as compared with the second embodiment.

When this embodiment is generalized and described, in this embodiment, the values of at least two characteristic parameters (for example, air-fuel ratio and torque) are detected as in the second embodiment. For example, two characteristic parameter values, a first characteristic parameter (air-fuel ratio) and a second characteristic parameter (for example, torque), are detected. Then, parameters (for example, fuel injection amount) other than the control parameters are controlled so that the value of the first characteristic parameter (for example, air-fuel ratio) becomes the target value. At the same time, the change speed of the control parameter value (for example, the change speed of the charging efficiency) is adjusted so that the value of the first characteristic parameter falls within the continuation region even if the value of the first characteristic parameter deviates from the target value. In this embodiment, when the measured value of the first characteristic parameter deviates from the target value, the measured value of the second characteristic parameter is corrected based on the difference between the measured value of the first characteristic parameter and the target value. Like to do. Further, the correction of the measurement value of the second characteristic parameter is performed by calculating a correction value based on the difference and adding the correction value to the measurement value of the second characteristic parameter. Thus, by correcting the measured value of the second characteristic parameter based on the difference, the value of the second characteristic parameter can be calculated fairly accurately. In particular, in the above embodiment, the case where the torque is measured as the second characteristic parameter is shown, but the exhaust gas temperature and the exhaust emission (that is, the exhaust gas) are added as the second characteristic parameter in addition to the torque or without measuring the torque. The concentration of hydrocarbons (HC), carbon monoxide (CO), nitrogen oxides (NO _x ), etc.) may be measured.

It is a figure which shows the measuring device used for the internal combustion engine used as an object of adaptation work, and adaptation work. 6 is a time chart of ignition timing, torque, exhaust temperature, and exhaust temperature change rate when measurement is performed according to the first embodiment. 6 is a flowchart showing a control routine for adjusting control of the change rate of ignition timing when measuring characteristic parameters such as torque, exhaust temperature and catalyst temperature. 6 is a time chart of ignition timing, exhaust temperature, and exhaust temperature change rate when measurement is performed according to a modification of the first embodiment. It is a time chart of the FB correction coefficient regarding the fuel injection amount, the air-fuel ratio, and the charging efficiency when measurement is performed according to the second embodiment. It is a time chart of the change rate of the FB correction coefficient regarding the fuel injection amount, the air-fuel ratio, the charging efficiency, and the charging efficiency when the measurement is performed according to the modified example of the second embodiment. It is a flowchart which shows the control routine of adjustment control of filling efficiency in the case of measuring a characteristic parameter by changing filling efficiency. 12 is a time chart of air-fuel ratio, measured torque, charging efficiency, torque correction value, and calculated torque when measurement is performed according to the third embodiment. It is a figure which shows the relationship between an air fuel ratio and a torque.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine main body 5 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 Measuring device main body

Claims (9)

While transiently operating the internal combustion engine by changing the value of the control parameter of the internal combustion engine, measure the value of at least one characteristic parameter that can change with the change of the value of the control parameter, and during the measured transient operation In the characteristic parameter measurement method for acquiring the characteristic parameter value as the characteristic parameter value during steady operation,
During the transient operation, an internal combustion engine that adjusts the change speed of the value of the control parameter so that the value of the measured characteristic parameter or the change speed thereof is within a predetermined range. Characteristic parameter measurement method.   When the value of at least one of the detected characteristic parameters or the rate of change thereof is out of a predetermined range, the change of the value of the control parameter is temporarily stopped. Item 2. A method for measuring a characteristic parameter of an internal combustion engine according to Item 1.   2. The change rate of the control parameter value is decreased when the value of at least one of the detected characteristic parameters or the change rate thereof is out of a predetermined range. Characteristic parameter measurement method for internal combustion engine.   The speed of change of the control parameter is increased when the value of at least one of the detected characteristic parameters or the speed of change thereof is within a specific range smaller than the predetermined range. The characteristic parameter measurement method for an internal combustion engine according to any one of claims 1 to 3.   The control parameter is the charging efficiency, one of the characteristic parameters is the air-fuel ratio, the fuel injection amount is controlled so that the value of the air-fuel ratio becomes the target air-fuel ratio, and the air-fuel ratio deviates from the target air-fuel ratio. 5. The characteristic parameter measurement method for an internal combustion engine according to claim 1, wherein the change speed of the value of the control parameter is adjusted so as to be within the predetermined range including the target air-fuel ratio.   During the measurement of the characteristic parameter value, the fuel injection amount is estimated for each charging efficiency value such that the air-fuel ratio value becomes the target air-fuel ratio, and the next characteristic parameter value measurement is performed by changing the measurement conditions. 6. The characteristic parameter measurement method for an internal combustion engine according to claim 5, wherein fuel injection is performed based on the estimated fuel injection amount. At least two characteristic parameter values are measured, and parameters other than the control parameters are controlled such that one of the characteristic parameters has a target value, and the one characteristic parameter value is the target value. Even if it deviates from the value, the change speed of the value of the control parameter is adjusted so that it falls within the predetermined range including the target value,
When the measured value of the one characteristic parameter deviates from the target value, based on the deviation of the measured value of the one characteristic parameter from the target value, the measured values of characteristic parameters other than the one characteristic parameter are The characteristic parameter measuring method for an internal combustion engine according to claim 1, wherein the characteristic parameter is corrected.   The correction of the measurement value of the characteristic parameter other than the one characteristic parameter is performed by calculating a correction value based on the deviation of the measurement value of the one characteristic parameter from the target value, The method for measuring a characteristic parameter of an internal combustion engine according to claim 7, wherein the method is performed by adding to a measured value of the characteristic parameter.   9. The characteristic parameter measuring method for an internal combustion engine according to claim 7, wherein the control parameter is a charging efficiency, the one characteristic parameter is an air-fuel ratio, and a characteristic parameter other than the one characteristic parameter is an output torque. .

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