JP4650082B2 - Ideal value arithmetic unit - Google Patents

Description

  The present invention relates to an ideal value calculation device that calculates an ideal value of a physical quantity such as a flow rate of air flowing through a pipe and a pressure in the pipe.

  In general, measured values of physical quantities such as the flow rate of air flowing through the intake passage of an internal combustion engine and the pressure in the intake passage are quantitatively calculated by converting the physical phenomenon into another phenomenon such as an electrical signal of the air flow meter. Can be measured.

  The value measured by the air flow meter is good in accuracy, but when the air flow rate of the internal combustion engine is increasing, the response is delayed from the actual flow rate in the process of conversion and calculation. An error will occur. In addition, since the air flow meter outputs even intake pulsation and noise as a signal, the influence on the measured value was great.

On the other hand, in Patent Documents 1 to 4, the response delay in the air flow meter is corrected by advancing and correcting only the response delay by a primary advance correction model or the like, and the time error is reduced by the averaging means. The impact was reduced.
Japanese Patent No. 3297890 JP 2003-314347 A Japanese Patent No. 3356799 JP 2002-130042 A

  However, in the correction model, a time error occurs unless the response of the air flow rate becomes the first order lag, and the influence of the intake pulsation and noise is amplified by the advance correction, resulting in a fluctuation error between the true flow rate. Become. In addition, there are side effects such as deterioration of responsiveness by means of averaging.

  The present invention has been made in view of the above problems, and based on physical quantity measurement values such as air flow rate and pressure, and model measurement values to be measured, the ideal value of the physical quantity while suppressing the influence of response delay and error. The purpose is to calculate

  Therefore, in the present invention, the physical quantity is measured and the change amount of the measurement value is integrated, while the measurement target is calculated as a model measurement value by the model, the change amount is integrated, and the model measurement value change integration value and the measurement value are integrated. The deviation is calculated from the change amount integrated value, and the ideal value is calculated by adding the deviation to the physical quantity measurement value.

  According to the present invention, the physical quantity of the measurement target is accurately measured based on the physical quantity measurement value, and the response delay of the physical quantity measurement value is suppressed based on the model measurement value, while the physical quantity of the measurement target varies. Since the ratio of the influence of the physical quantity measurement value or the model measurement value is changed by the deviation, there is an effect that the ideal value of the physical quantity to be measured can be calculated while improving the responsiveness and removing the fluctuation component of the physical quantity measurement value.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a system configuration diagram of a control device for an engine 1 according to the first embodiment.

  The combustion chamber 4 defined by the cylinder 2 and the piston 3 of each cylinder of the engine 1 is provided with an intake valve 6 and an exhaust valve 7 so as to surround the spark plug 5. 8 is an exhaust passage, and 9 is an intake passage.

  An air cleaner 12 and an electric throttle valve (butterfly valve) 13 are disposed in the intake passage 9 from the upstream side, and air is introduced into the cylinder 2 in accordance with the valve opening area of the electric throttle valve 13. The electric throttle valve 13 has a valve opening area determined based on a throttle opening command of an engine control unit (ECU) 30.

  A fuel injection valve 10 is disposed in the manifold branch portion of the intake passage 9 downstream of the collector 11.

  In addition, signals from the air flow meter 23, the throttle opening sensor 24, the boost sensor (pressure sensor) 25, the temperature sensor 26, the crank angle sensor 27, and the atmospheric pressure sensor 28 are input to the ECU 30.

  The air flow meter 23 is a hot-wire flow meter provided in the intake passage 9 upstream from the electric throttle valve 13 and outputs a signal corresponding to the amount of air passing through the electric throttle valve 13.

  The throttle opening sensor 24 outputs a signal corresponding to the opening degree of the electric throttle valve 13.

  The boost sensor 25 is provided in the collector 11 downstream from the electric throttle valve 13 and outputs a signal corresponding to the pressure in the collector 11.

  The temperature sensor 26 is provided in the collector 11 and outputs a signal corresponding to the intake air temperature. The temperature sensor 26 may be provided integrally with the air flow meter 23 or the boost sensor 25.

  The crank angle sensor 27 is provided in the engine 1 and outputs a signal corresponding to the crank angle of the engine 1. The engine speed can be detected from the signal of the crank angle sensor 27.

  The atmospheric pressure sensor 28 outputs a signal corresponding to the atmospheric pressure.

  Note that the throttle opening sensor 24 and the crank angle sensor 27 use signals that are output in time before the signal from the air flow meter 23.

  The ECU 30 performs various calculations and various controls based on output signals from various sensors. For example, in various calculations, calculations such as throttle opening, intake air amount, engine speed, collector pressure, throttle opening, intake temperature, atmospheric pressure, and the like are performed. In various controls, opening control of the electric throttle valve 13, control of the fuel injection timing and fuel injection amount from the fuel injection valve 10, control of ignition timing of the spark plug 5, and the like are performed.

  Here, in the case where the engine 1 is in a steady state, when the physical quantity measurement value Qa is measured by a sensor such as the air flow meter 23, there is an advantage that the accuracy of the measurement value is good, but the ECU 30 is based on the sensor output. Since the calculation must be performed, the measured value Qa in a state where a response delay occurs when the flow rate of air flowing through the intake passage 9 increases and fluctuations (disturbances) such as intake pulsation and noise occur. There is a problem that is measured.

  On the other hand, when the air flow rate to be measured by the air flow meter 23 is calculated as a model measured value Qm using a model, the model measured value Qm is calculated based on parameters other than the air flow rate, such as throttle opening and engine rotation. Although there is an advantage that the responsiveness of the measured value Qm is good without receiving fluctuations in the air flow rate, there is a problem that the accuracy of the model measured value Qm is lowered.

  Therefore, in the present invention, the air flow rate flowing through the intake passage 9 of the engine 1 as an example of the physical quantity measurement will be described as an example. The system is an MSF (Model & Sensor value Fusion System) that combines the advantages of the air flow rate Qa and the model measurement value Qm. The ideal value (target value) Q of the object to be measured is calculated while satisfying both the robustness (degree of response) and the removal of variable elements at a high level. The ideal value Q is a value that is calculated so that an error from a true value of a physical quantity to be measured (a value that is suitable for calculation of a fuel injection amount or the like) becomes substantially zero. Even if there is a steady fluctuation component (intake pulsation or noise), the value at which the fluctuation is substantially zero.

  FIG. 2 is a block diagram showing the ideal value calculation of the present invention, and these calculations are performed in the ECU 30.

  The ideal value calculation apparatus includes a physical quantity measurement unit 100, a model measurement value calculation unit 101, and a fusion unit 102.

  The physical quantity measuring means 100 measures the air flow rate Qa flowing through the intake passage 9 with the air flow meter 23. The physical quantity measurement value Qa thus measured has an advantage that the engine 1 has substantially the same accuracy as the true air flow rate when the engine 1 is in a steady state.

  The model measurement value calculation means 101 calculates the air flow rate as a model measurement value Qm using a model described later. Specifically, the model measurement value Qm is calculated based on the engine speed and the throttle opening of the electric throttle valve 13. The model measurement value Qm calculated in this way has good responsiveness to the true air flow rate, and is influenced by fluctuation factors (intake pulsation, noise, etc.) with respect to the measurement value Qm by the air flow meter 23. There is an advantage that it is difficult.

  Based on the air flow rate Qa measured by the physical quantity measurement unit 100 (air flow meter 23) and the model measurement value Qm calculated by the model measurement value calculation unit 101, the fusion unit 102 determines the flow rate of air flowing through the intake passage 9. The ideal value Q is calculated.

  Details of these will be described below.

  FIG. 3 is a block diagram showing the calculation by the model measurement value calculation means 101.

  Here, as shown in FIG. 1, in the intake passage 9, the collector 11 is disposed between the electric throttle valve 13 and the cylinder 2. Therefore, in the model of FIG. The balance between the flow rate of air flowing in (the amount of air passing through the electric throttle valve 13) and the flow rate of air flowing out of the collector 11 (the amount of air flowing into the cylinder 2) is considered.

  The model measurement value calculation means 101 includes a throttle model 31, a cylinder model 41, and a collector model 51, and calculates a model measurement value Qm.

  As the model measurement value Qm, one of the flow rate of air flowing through the intake passage 9, that is, the flow rate of air flowing into the collector 11 and the flow rate of air flowing out of the collector 11 is used. Hereinafter, the model measurement value Qm will be described as the air flow rate flowing into the collector 11.

  The throttle model 31 calculates the substance flow rate [mol / s] based on the atmospheric pressure, the throttle opening, and the collector pressure calculated by the collector model 51.

  The cylinder model 41 calculates a substance flow rate [mol / s] based on the rotational speed of the engine 1 and the collector pressure by the boost sensor 25.

  The collector model 51 calculates the current collector pressure based on the substance amount flow rate by the throttle model 31 and the substance amount flow rate by the cylinder model 41. The collector pressure calculated by the collector model 51 is inputted to the throttle model 31 as the previous value in the next calculation for performing cyclic calculation.

  FIG. 4 is a block diagram showing the throttle model 31.

  The pressure ratio calculating means 32 calculates the pressure ratio (collector pressure / atmospheric pressure) by dividing the atmospheric pressure from the collector pressure calculated by the collector model 51.

  The Mach coefficient calculation means 33 searches for the Mach coefficient M corresponding to the pressure ratio by referring to the Mach coefficient search table. The Mach coefficient search table shows that when the pressure ratio is 0 to 0.53, the Mach coefficient M is a constant value (approximately 0.54), and when the pressure ratio is 0.53 to 1.0, the Mach coefficient M increases as the pressure ratio increases. Decrease. The Mach coefficient M is a coefficient indicating the flow velocity u (u / C) with respect to the sound velocity C.

  The sonic speed calculation means 34 calculates the sonic speed C [m / s] from the intake air temperature T (absolute temperature; K), the specific heat ratio κ, and the gas constant R (C = √ (κ × R × T)).

  The flow velocity calculating means 35 calculates the flow velocity [m / s] of the air flowing through the intake passage 9 by multiplying the Mach coefficient M by the sound velocity C.

The opening area calculation means 36 searches the opening area [m ² ] corresponding to the throttle opening by referring to the opening area search table. The opening area search table is set so that the opening area increases as the opening degree of the electric throttle valve 13 increases to a predetermined value (near the maximum opening degree).

The volume flow rate calculating means 37 calculates the volume flow rate [m ³ / s] by multiplying the opening area and the flow velocity.

The molar density calculating means 38 calculates the molar density n ₀ [mol / m ³ ] by dividing the atmospheric pressure P ₀ by the gas constant R and the temperature T of the air flowing in the intake passage 9 (n ₀ = P _0). / (RT)).

The substance flow rate calculating means 39 calculates the air flow rate flowing into the collector 11, that is, the substance amount flow rate n _in [mol / s] by multiplying the volume flow rate and the molar density n ₀ .

As described above, the substance amount flow rate n _in [mol / s] flowing into the collector 11 is set as the model measurement value Qm by the models shown in FIGS.

  FIG. 5 is a block diagram showing the cylinder model 41.

  The efficiency calculating means 42 searches for the efficiency η according to the rotational speed Ne of the engine 1 by referring to the efficiency search table. The efficiency search table is set so that the efficiency η increases as the engine speed Ne increases to a predetermined value, and the efficiency η decreases when the engine speed Ne exceeds a predetermined value.

The volume flow rate calculating means 43 calculates the volume flow rate [m ³ / s] based on the engine displacement V, the engine speed Ne, and the efficiency η (volume flow rate = V × Ne / 120 × η).

The molar density calculating means 44 divides the collector pressure P ₁ by the gas constant R and the temperature T of the air flowing in the intake passage 9 based on the intake air temperature T and the collector pressure P ₁ by the boost sensor 25 to thereby obtain the molar density n. ₁ [mol / m ³ ] is calculated (n ₁ = P ₁ / (RT)).

The substance flow rate calculating means 45 calculates the flow rate of air flowing out from the collector 11, that is, the substance flow rate n _out [mol / s] by multiplying the volume flow rate and the molar density n ₁ .

As described above, the substance flow rate n _out [mol / s] flowing out from the collector 11 may be used as the model measurement value Qm according to the models shown in FIGS.

  FIG. 6 is a block diagram showing the collector model 51.

The collector pressure calculation means 52 (collector model 51) is based on the substance quantity flow rate n _in by the substance quantity flow rate calculation means 39 of the throttle model 31 and the substance quantity flow rate n _out by the substance quantity flow rate calculation means 45 of the cylinder model 41. the state equation of gas to calculate a collector pressure P _2.

When calculating the collector pressure P ₂ , the gas equation of state is given by P × V = n × R × T. Therefore, this is expressed as collector pressure P ₂ , collector volume Vc, number of moles of gas n, gas constant R and intake air temperature. If T [absolute temperature: K], then P ₂ × Vc = n × R × T.

The collector pressure change amount ΔP ₂ at a predetermined time Δt, which is the calculation cycle, is ΔP ₂ = Δn × R × T × Δt / Vc. Collector pressure variation [Delta] P ₂ is a value obtained by subtracting the previous collector pressure _{P 2 (n-1)} from the current collector pressure _{P 2.} Δn is a value obtained by subtracting the amount of change in the molar flow rate of air in the collector 11 in the calculation period Δt, that is, the amount of material flow n _in flowing into the collector 11 from the amount of material flow _out n _out flowing into the cylinder 2 (Δn = n _in −n _out ).

Accordingly, when the gas state equation in the calculation period Δt is calculated for P ₂ , P ₂ = P _{2 (n−1)} + (n _in −n _out ) × Δt × R × T / Vc.

In the case where the ideal value is calculated using the measurement target as the collector pressure, the pressure P ₂ [kPa] in the collector 11 may be set as the model measurement value Qm by the model as described above.

When the air flowing through the intake passage 9 is quasi-one-dimensional steady isentropic, the calculated mass flow value n _in [kg / s] is expressed by the following equation, where the opening area of the electric throttle valve 13 is A. It can be calculated by the theoretical formula of fluid dynamics. Since the substance flow rate n _in [mol / s] can be calculated _in a molar equivalent, this may be used as the model measurement value Qm. In this case, when _Pe is a collector pressure and the Mach coefficient M (= u / C) is less than 1 (M <1), the following equation (1a) is obtained, and when the Mach coefficient M is 1 (M = 1): Calculates a mass flow rate calculation value n _in by the following equation (1b).

In the present invention, the ideal value of the collector pressure can be similarly calculated using the collector pressure as the physical quantity to be measured. In this case, while using a collector pressure P ₁ by the boost sensor 25 as a physical quantity measurement value, the collector by fusion means 102 by using the collector pressure P ₂ by the collector model 51 (collector pressure operating unit 52) as a model measured value Qm Calculate the ideal pressure value.

  Next, processing for calculating the ideal value Q of the physical quantity by the physical quantity measuring means 100, the model measured value calculating means 101, and the fusion means 102 will be described with reference to FIG.

  FIG. 7 is a flowchart showing ideal value calculation processing in the present invention. This process is performed every calculation cycle (for example, 4 ms) Δt.

  In step 1 (shown as “S1” in the figure, the same applies hereinafter), the physical quantity is measured. Here, the physical quantity is obtained by measuring the air flow rate Qa flowing through the intake passage 9 with the air flow meter 23.

  In step 2, the model measurement value Qm is calculated. As the model measurement value Qm, a value obtained by calculating the air flow rate flowing through the intake passage 9 by the throttle model 31 based on the throttle opening and the engine speed Ne is used.

  In step 3, the change amount ΔQa of the air flow rate Qa is calculated. The air flow rate change amount ΔQa is a value obtained by subtracting the previously measured air flow rate Qaz from the air flow rate Qa measured in step 1 (ΔQa = Qa−Qaz).

  In step 4, the integral value IntΔQa of the air flow rate change amount ΔQa is calculated. This integral value IntΔQa is calculated by multiplying the air flow rate change integrated value IntΔQaz up to the previous time by a predetermined attenuation constant W and then adding the air flow rate change ΔQ in the calculation period Δt (IntΔQa = IntΔQaz × W + ΔQa). . Details of the attenuation multiplier W will be described later.

  In step 5, a change amount ΔQm of the model measurement value Qm is calculated.

  In step 6, an integral value IntΔQm of the model measurement value change amount ΔQm is calculated. This integrated value IntΔQm is calculated by multiplying the model measured value change integrated value IntΔQmz up to the previous time by a predetermined attenuation constant W and then adding the model measured value change ΔQm in the calculation period Δt (IntΔQm = IntΔQmz × W + ΔQm).

  In step 7, the air flow rate deviation Qe is calculated. The deviation Qe is a value that changes ideally with respect to the ideal value Q, and is calculated by subtracting the air flow rate change integrated value IntΔQa from the model measured value change integrated value IntΔQm (Qe = IntΔQm−IntΔQa). .

  In step 8, the ideal value Q of the air flow rate is calculated. This ideal value Q is calculated by adding the deviation Qe to the air flow rate Qa (Q = Qa + Qe).

  After calculating the ideal value Q as described above, various calculations and various controls are performed based on the ideal value Q to optimize the operation of the engine 1. For example, the ECU 30 performs calculation and control of the fuel injection amount and fuel injection timing of the fuel injection valve 10 and calculation and control of the ignition timing of the spark plug 5 based on the ideal value Q.

  FIG. 8 is a flowchart for calculating the model measurement value change amount ΔQm in step 5.

  In step 11, it is determined whether or not the previous value Qz of the ideal value Q is equal to or greater than a predetermined lower limit value (Qz ≧ lower limit value). If the previous value Qz is greater than or equal to the lower limit value (Qz ≧ lower limit value), the process proceeds to step 12. This lower limit value is set to substantially zero.

  In step 12, the model measurement value change amount is obtained by multiplying the previous value Qz of the ideal value Q by the model measurement value change rate, that is, the value ΔQm / Qmz obtained by dividing the model measurement value change amount ΔQm by the previous value Qmz of the model measurement value. ΔQm is calculated (ΔQm = Qz × ΔQm / Qmz).

  On the other hand, if the previous value Qz is less than the lower limit value in step 11 (Qz <lower limit value), the process proceeds to step 13.

  In step 13, the previous value Qz of the ideal value Q is set to the model measurement value change amount ΔQm (Qz = ΔQmz), and in step 12, the model measurement value change amount ΔQm is calculated (ΔQm = ΔQmz × ΔQmz / Qmz).

  Note that after the previous value Qz of the ideal value Q is set to the air flow rate change amount ΔQa in step 13 (Qz = ΔQa), the model measurement value change amount ΔQm may be calculated in step 12 (ΔQm = ΔQa × ΔQmz / Qmz).

  After calculating the model measurement value change amount ΔQm as described above, the processing after Step 6 described above is performed.

  Next, derivation of an equation for mathematically determining the ideal value Q of the air flow rate by the fusion means 102 (step 8) will be described.

  As described above, the ideal value Q is calculated by the sum of the air flow rate Qa and the deviation Qe as in the following equation.

  This means that since the measured value Qa by the air flow meter 23 has a temporal response delay, the ideal value Q can be calculated by correcting this delay with the deviation Qe.

  Here, the advantages of the air flow meter 23 and the model, that is, the air flow meter 23 has a high measurement accuracy in a steady state, and the model has a good responsiveness in a state where the air flow rate fluctuates. As a precondition, t = 0, Q = Qa, Qe = 0, as a second precondition, ΔQ / Q = ΔQm / Qm (however, when Q≈0, ΔQ = ΔQm), and as a third precondition, limΔt → 0 Become.

  The first precondition is that when the engine 1 is in a steady (equilibrium) state, the flow rate of air flowing through the intake passage 9 is constant (no deviation), and the measured value Qa by the air flow meter 23 is the model measured value Qm. It means more reliable. The second precondition means that when the air flow rate changes, the change amount (responsiveness) of the air flow rate by the model is reliable compared to the change amount of the air flow rate by the air flow meter 23. The third precondition means that the calculation period Δt is calculated close to 0.

  Also, the ideal value Q at time t is expressed by the following equation when measured by the measured value Qa of the air flow meter 23 and the deviation Qe.

  From the first precondition, in steady state, t = 0, Q = Qa and Qe = 0, and the deviation Qe at time Δt can be expressed by an integral system as shown in the following equation.

  In order to further solve this equation as an ideal value change amount ΔQ, ΔQ (t) is multiplied by Q (t−Δt) / Q (t−Δt) as shown in the following equation.

  Here, from the second precondition, ΔQ / Q = ΔQm / Qm can be expressed by the following equation.

  Substituting equation (5) into equation (4) yields the following equation.

  That is, the deviation Qe can be calculated by a value obtained by subtracting the integral value IntΔQa of the physical quantity measurement value change amount ΔQa from the integral value IntΔQm of the model measurement value change amount ΔQm (Qe = IntΔQm−IntΔQm). Substituting equation (6) into equation (2 ') can be expressed by the following equation.

  When the equation (7) is transformed into a discrete system, the following equation is obtained for the deviation Qe.

  In this equation, the current deviation Qe is a value obtained by adding a difference between the air flow rate change amount (IntΔQm) calculated by the model and the actual air flow rate change amount (IntΔQa) to the previous deviation Qez. It means that. If the current deviation Qe is calculated, the ideal value of the air flow rate flowing through the intake passage 9 can be calculated as Q = Qa + Qe according to the above-described equation (2).

  However, there is a third precondition as a practical problem of equation (2) for calculating the ideal value Q. That is, when the calculation cycle Δt is mathematically brought close to 0, the deviation Qe is always accumulated in the equation (8), so that the accumulated error of the deviation Qe diverges, and when t = ∞, the deviation Qe = ∞. End up.

  Therefore, by multiplying the previous value Qez of the deviation Qe by the attenuation constant W that converges the divergence of the deviation Qe, which is an integral term, as shown in the following equation, the divergence of the accumulated error of the deviation Qe can be prevented even at time t> 0. If the operating state becomes steady, the deviation Qe≈0 in the above-described equation (2), so Q≈Qa. That is, it means that the value of the air flow meter 23 is positively reliable in a steady state.

  The attenuation constant W is a value in the range of 0 to 1 (0 <W <1), and the value of the deviation Qe can be changed by changing the value of W. As a result, the ideal value Q ( = Qa + Qe) can be corrected.

  Here, the step response of the ideal value Q is that the deviation Qe (0) at time t = 0 is 1, the integrated value IntΔQe of the variation ΔQe of the deviation Qe is 0, and the integrated value IntΔQa of the measured value of the air flow rate Qa is 0. From the following expression, the attenuation constant W, time t, and calculation interval Δt are used. That is, the following equation may be used to calculate the time t required for the attenuation factor to approach 1 to 0.

FIG. 9 (a) shows the attenuation rate W ^{t / Δt} with respect to the elapsed time t. Note that the calculation cycle Δt = 4 ms. (I) in the figure is an attenuation rate curve when the attenuation constant W is set to 0.996. Similarly, the attenuation constant W is reduced from 0.994 to 0.002 in steps of (ii) to (vii). The attenuation rate curve when .984 is set is shown. FIG. 9A shows the time x when the attenuation rate is 0.368, that is, a response of 63.2% (when 1-0.632 is set as the time constant τ).

FIG. 9B shows the values corresponding to the attenuation rate W ^{t / Δt} with the time constant τ = 0.368 (63.2% response) in (A) as the attenuation constant W and the time constant τ. The time constant τ is expressed as an exponential function [ms].

For example, as shown in FIG. 9A, when the attenuation rate W ^{t / Δt} is 0.368, the time x [seconds] corresponding to the attenuation curve (iv) when W = 0.990 is obtained. , (B) indicates the same x [ms] shown on the vertical axis.

  For example, when the vehicle is running at a constant speed, the amount of change ΔQm in the model measurement value Qm is constant because the throttle opening and the engine speed are substantially constant when the air flow rate through the intake passage 9 is steady. Becomes smaller.

  In this state, the measured value Qa measured by the air flow meter 23 is more reliable than the model measured value Qm. Therefore, by setting the attenuation constant W to a value smaller than 1 (0 <W <1), the calculation is performed in the equation (9). The deviation Qe is converged to 0 every period Δt. As a result, the ideal value Q converges to the measured value Qa by the air flow meter 23 from the equation (2) (Q = Qa).

  The attenuation constant W is decreased after a state where the change amount ΔQm of the model measurement value Qm is less than a predetermined value continues for a predetermined time. In a state where this condition is satisfied, it can be determined that the flow rate of air flowing through the intake passage 9 is steady, and the measured value Qa by the air flow meter 23 is reliable. The predetermined time is determined based on the calculation period Δt of the ideal value Q and the attenuation constant W.

  On the other hand, when the previous value Qz of the ideal value Q is less than the lower limit value in the above step 11 (Qz <lower limit value), the formulas for calculating the ideal value Q are the formulas (2) and (8) described above. Can be transformed as follows.

  Further, when the previous value Qz of the ideal value Q is multiplied by the attenuation constant W, it can be expressed as the following equation.

  That is, when there is noise such as when the flow rate of air flowing through the intake passage 9 is increasing, when the air is pulsating, or when the measured value Qa by the air flow meter 23 is greatly fluctuating, the fluctuation is large. By making the attenuation constant W closer to 1.0, the deviation Qe (influence by the model measurement value Qm) is increased in the equation (9). Thereby, when calculating the ideal value Q in the equation (2), the amount of correction of the measured value Qa by the air flow meter 23 is increased. That is, when the flow rate of air flowing through the intake passage 9 is fluctuating, the value of the model measurement value Qm is reliable when calculating the ideal value Q. Therefore, the deviation that is the correction amount based on the model measurement value Qm The measured value Qa by the air flow meter 23 is corrected by Qe.

  Next, the result of calculating the ideal value Q by the above-described apparatus will be described with reference to FIG.

  FIG. 10 shows the flow rates of air flowing through the intake passage 9 with respect to the elapsed time [seconds] when the flow rate of air flowing through the intake passage 9 increases by a predetermined amount. In the figure, (1) is the true flow rate Qt, (2) is the flow rate (air flow measurement value) Qa calculated based on the output signal of the air flow meter 23, (3) is the model flow rate (model measurement value) Qm, (4) shows the MSF flow rate (ideal value) Q obtained by the present invention (fusion means 102, step 8).

  Although the air flow rate measurement value Qa has good flow rate calculation accuracy, it takes time to calculate the flow rate by the ECU 30, and therefore has a time delay with respect to the true value Qt.

  Further, the model measurement value Qm has good responsiveness to a change in the flow rate, but the calculation is performed based on the throttle opening and the engine speed, and thus the flow rate calculation accuracy is poor with respect to the true value Qt.

  On the other hand, the ideal value Q obtained by the present invention is calculated based on the air flow rate measurement value Qa and the model measurement value Qm as described above. Since the fusion is made so as to take advantage of the responsiveness to the flow rate change, it is almost coincident with the true flow rate Qt.

  The ideal value Q is corrected by the deviation Qe by the model measurement value Qm calculated based on the throttle opening and the engine speed Ne that are temporally advanced without being affected by the response delay by the air flow meter 23. This means that it is close to the true value.

  When the air flow rate is increasing, the ideal value Q is calculated by setting the above-described attenuation constant W to a value close to 1.0. Therefore, the effect of improving the responsiveness is exhibited by the model measured value Qm. .

  In the steady state, a value smaller than 1.0 is used for the attenuation constant W, so that the effect of improving accuracy is exhibited by the measured value Qa by the air flow meter 23.

  FIG. 11 shows each flow rate calculation value when the air flow meter 23 fails due to disconnection. In this case, the air flow rate measurement value Qa and the ideal value Q obtained by the present invention change.

  When the air flow rate measurement value Qa is disconnected, the value of the measurement value Qa by the air flow meter 23 fluctuates greatly, so that the above-described attenuation constant W is brought close to 1.0 and the effect of the model measurement value Qm is exerted strongly. Therefore, the ideal value Q is prevented from rapidly decreasing.

  FIG. 12 shows a case where the air flow rate Qa calculated based on the output signal of the air flow meter 23 fluctuates when there is an electrical noise of the air flow meter 23.

  In this case, in the present invention, since the ideal value Q is calculated by considering the variation ΔQa of the air flow rate Qa in the calculation of the deviation Qe (steps 3, 4 and 7), the instantaneous noise caused by the electric noise of the air flow meter 23 is calculated. Tolerate common errors.

  In the present invention, the flow rate of air flowing through the intake passage 9 is set to the value Qa measured by the air flow meter 23 as a physical quantity measurement value. However, the present invention is not limited to this. For example, the pressure (collector pressure) in the intake passage 9 is Similarly, an ideal value can be calculated as a measurement target.

  In addition, if a temporally advanced parameter is used as the physical quantity measurement value, not only the current ideal value but also the predicted future ideal value can be calculated.

  According to the present embodiment, the physical quantity measuring means (step 1, air flow meter 23) for measuring the physical quantity (the air flow rate Qa passing through the intake passage 9), and the physical quantity for integrating the variation ΔQa of the measured value Qa by the physical quantity measuring means. A measured value change amount integrating means (step 4) and a model measured value calculating means (step 2) for calculating a measurement target by the physical quantity measuring means as a model measured value Qm by a model (throttle model 31, cylinder model 41, collector model 51). And a deviation Qe (= IntΔQm) from the model measurement value change amount integration means (step 6) for integrating the change amount ΔQm of the model measurement value Qm, and the model measurement value change amount integration value IntΔQm and the physical quantity measurement value change amount integration value IntΔQa. Deviation calculating means (step 7) for calculating -IntΔQa), and adding the deviation Qe to the physical quantity measurement value Qa Comprises, an ideal value calculating means (step 8) for calculating the ideal value Q (= Qa + Qe) and. Therefore, the air flow meter Qa accurately measures the measurement target air flow rate Qa, suppresses the response delay of the air flow rate based on the model measurement value Qm, and measures the deviation Qe even when the air flow rate fluctuates. Since the ratio of influence of the value Qa or the model measurement value Qm is changed, the ideal value Q of the air flow rate can be calculated while improving the responsiveness and removing the fluctuation component of the measurement value. Further, the ideal value Q can be simply calculated without special setting as compared with the above-mentioned Patent Documents 1 to 4.

  According to the present embodiment, the model measurement value change amount ΔQm is obtained by multiplying the previous value Qz of the ideal value Q by the change rate of the model measurement value Qm (step 12), and the change rate of the model measurement value Qm is The model measurement value change amount ΔQm is divided by the previous value Qmz of the model measurement value Qm (ΔQm / Qmz). On the other hand, the model measurement value change amount ΔQm has a predetermined value (substantially zero) of the previous value Qz of the ideal value Q. ) (Step 11), calculation is performed using either the model measured value change amount ΔQm or the measured value change amount ΔQa (step 13). For this reason, even if the absolute value accuracy of the model measurement value Qm is poor, the accuracy error of the ideal value Q can be reduced. Further, if the previous value Qz of the ideal value Q is substantially zero, the model measurement value change amount ΔQm remains zero even when multiplied by the change rate. Therefore, by using the change amounts ΔQm and ΔQa, the model measurement value change amount It is possible to prevent ΔQm from becoming zero.

  Further, according to the present embodiment, the physical quantity measurement value change amount integration means multiplies the physical quantity measurement value change amount integration value IntΔQa up to the previous time by the predetermined attenuation constant W, and then adds the current physical quantity measurement value change amount ΔQa. (Step 4). Therefore, divergence can be prevented by gradually converging the physical quantity measured value variation integrated value IntΔQa up to the previous time with the attenuation constant W to zero.

  Further, according to the present embodiment, the model measurement value change amount integration means multiplies the model measurement value change amount integration value IntΔQm up to the previous time by the predetermined attenuation constant W and then adds the current model measurement value change amount ΔQm. (Step 6). For this reason, divergence can be prevented by gradually converging the model measurement value change amount integrated value IntΔQm up to the previous time to zero by the attenuation constant W.

  Further, according to the present embodiment, the attenuation constant W uses a value smaller than 1.0 as the model measurement value change amount ΔQm is smaller. For this reason, the smaller the model measurement value change amount ΔQm is, the closer the air flow rate through the intake passage 9 is to a constant value. By reducing the attenuation constant W, the measurement value Qa by the air flow meter 23 is reduced to the ideal value Q. As a result, the accuracy can be improved.

  Further, according to the present embodiment, the attenuation constant W is decreased after the state in which the model measurement value change amount ΔQm has decreased for a predetermined time, and the predetermined time is reduced by the calculation period Δt of the ideal value Q and the attenuation constant W. Time determined based on the above. For this reason, the attenuation constant W can be reduced after the air flow rate is stabilized at a substantially constant value.

  Further, according to the present embodiment, the attenuation constant W approaches 1.0 as the noise of the physical quantity measurement value Qa increases, such as when the fluctuation of the measurement value Qa by the physical quantity measurement means is large. For this reason, when the measured value Qa measured by the air flow meter 23 is unreliable, such as when the air flowing through the intake passage 9 is pulsating, the effect of eliminating fluctuations due to the model measured value Qm can be exhibited to improve the calculation accuracy of the ideal value Q. .

  Further, according to the present embodiment, since the measurement target by the model measurement value calculation means (step 6) is the air flow rate Qm flowing through the intake passage 9 of the internal combustion engine 1, the ideal value Q is calculated based on this flow rate Qm. It can be carried out.

  Further, according to the present embodiment, the air flow rate Qm is a value calculated using a plurality of parameters including at least one of the throttle opening degree and the engine speed of the internal combustion engine 1 (step 2). For this reason, even if pulsation occurs in the air flowing through the intake passage 9, it is not affected by this, and a stable value Qm can be calculated. In addition, a parameter that precedes the air flow meter 23 can be used, and the response of the ideal value Q can be improved.

  Further, according to the present embodiment, the physical quantity measuring means (step 1) is a hot-wire flow meter (air flow meter 23) attached to the intake system of the internal combustion engine 1, so that the flow rate can be accurately measured in a steady state. .

According to the present embodiment, the measurement target by the model measured value calculating means (step 6) are the gas pressure P ₂ in the intake passage 9 of the engine 1, the pressure P ₂ as a model measurement Qm, The ideal gas pressure value can be calculated in the same manner as when calculating the ideal value of the air flow rate flowing through the intake passage 9.

According to the present embodiment, the physical quantity measuring means (step 1) are the pressure sensor mounted in the intake system of an internal combustion engine 1 (boost sensor 25), the ideal value Q based on the pressure P ₁ of the intake system Can be performed.

  Next, a second embodiment of the present invention will be described.

  In the present embodiment, when there is an abnormality in the physical quantity measuring means such as disconnection of the air flow meter 23 while calculating the ideal value Q, this is detected and the ideal value Q is set as the model measured value Qm. A failure-tolerant system that suppresses the influence on the ideal value Q due to an abnormality in the air flow meter 23 is provided.

  FIG. 13 is a flowchart showing a process of making a failure determination (abnormality determination) of the air flow meter 23 based on the deviation increase determination flag and shifting the ideal value Q to the model calculation value Qm when there is a failure. This process is performed every predetermined calculation interval Δt (for example, 4 ms).

  In step 21, the deviation increase determination flag of the air flow meter 23 is calculated in FIG. This flag indicates 1 when the deviation increase is large.

  In step 22, it is determined whether or not the deviation increase determination flag is 1. If the determination flag is 1, the process proceeds to step 23 where the counter value is incremented. On the other hand, if the determination flag is 0 (determination flag ≠ 1), the counter value is reset in step 24 (counter value = 0).

  In step 25, it is determined whether or not the counter value exceeds the failure determination count. If the counter value exceeds the failure determination count (counter value> failure determination count), it is determined that the air flow meter 23 is defective. On the other hand, if the counter value is less than or equal to the failure determination number (counter value ≦ failure determination number), it is determined that the air flow meter 23 is in a normal state and the process is terminated. As a result, it is possible to reliably detect a state in which the air flow meter 23 has failed after a predetermined time has elapsed, and to eliminate the case where the deviation Qe has increased due to an instantaneous error.

  In step 26, since the calculated value (physical quantity measured value) Qa based on the output signal of the air flow meter 23 is not reliable, the ideal value Q is shifted to the model measured value Qm calculated by the model.

  In order to shift the ideal value Q to the model measurement value Qm, the equation for calculating the ideal value Q in the above-described step 8 is replaced with an equation (Q = Qm + Qe) obtained by the sum of the model measurement value Qm and the deviation Qe. For the calculation of the deviation Qe, a value (Qm−Qa) obtained by subtracting the measured value Qa from the air flow meter 23 from the model measured value Qm once is used. After the next calculation, the previous value Qez of the deviation Qe and the attenuation constant A value obtained by multiplying W by Q is substituted (Qe = W × Qez), and calculation of IntΔQm and IntΔQa, which are integral terms in the above-described equation (9), is stopped, whereby a calculation value Qa based on the output signal of the air flow meter 23 is obtained. To suppress the effects of

  That is, when a failure of the air flow meter 23 is detected, the value of Qm−Qa is held as the deviation Qe, and the ideal value Q is gradually shifted to the model measurement value Qm at every calculation interval Δt. Since the attenuation constant W is a value in the range of 0 to 1, from the equation Qe = W × Qez for obtaining the deviation, the deviation Qe gradually approaches 0 every calculation period Δt. As a result, the ideal value Q is a model. It approaches the measured value Qm.

  FIG. 14 is a block diagram for outputting the presence / absence of a deviation increase determination flag used for determining the failure of the air flow meter 23.

  The physical quantity measuring means 61 measures the air flow rate Qa [kg / s] passing through the intake passage 9 by using a mass flow rate measurement table corresponding to the output signal (voltage) of the air flow meter 23.

  The deviation calculating means 62 calculates the deviation Qe [kg / s] based on the air flow rate Qa and the model measurement value Qm [kg / s]. The next deviation Qe uses an integrated value of deviation.

  The division means 63 divides the model measurement value Qm from the deviation Qe to obtain an error ratio (Qe / Qm).

  The adding means 64 calculates the net ratio (= 1−Qe / Qm) by subtracting the error ratio Qe / Qm from 1. The deviation Qe becomes 0 when the air flow is steady, but the deviation Qe becomes large at the time of failure, and the value of the error ratio Qe / Qm may exceed 1.

  For this reason, the absolute value calculating means 65 takes the absolute value | x | of the net ratio.

  The deviation increase determination means 66 determines whether or not the absolute value | x | exceeds a predetermined determination threshold value. Here, the determination threshold is set to 0.2. If the absolute value exceeds the determination threshold (| x |> 0.2), it is determined that the increase in the deviation Qe is large, and the deviation increase determination flag is set to 1.

  Note that the value calculated by the dividing means 64 may be an error rate [%]. In this case, the above-described error ratio is set to% and the same processing is performed.

  FIG. 15 shows a case where the ideal value Q is shifted to the model measurement value Qm after the failure of the air flow meter 23 is detected.

  When the air flow meter 23 fails due to disconnection, the ideal value Q is shifted to the model measurement value Qm after a predetermined time has elapsed from the occurrence of the failure based on the above-described deviation increase determination flag. In the figure, the time point at which the ideal value Q is shifted to the model measurement value Qm is indicated by t1, and the ideal value Q thereafter changes so as to follow the model measurement value Qm.

  Thereby, when the air flow meter 23 breaks down, the minimum calculation accuracy can be secured by the model measurement value Qm.

  According to the present embodiment, the abnormality detection means (step 25) for detecting an abnormality of the physical quantity measurement means (air flow meter 23, step 1), and the ideal value Q is changed to the model measurement value Qm when the abnormality detection means detects the abnormality. Ideal value shifting means (step 26) for shifting. For this reason, when a failure occurs in the air flow meter 23, the driving state of the vehicle can be stabilized without being affected by the measurement value Qa by the air flow meter 23.

  Further, according to the present embodiment, the abnormality detection means is configured to determine the ratio (Qe / Qm) between the deviation Qe and the model measurement value Qm or the deviation Qe and the model measurement value Qm based on the deviation Qe and the model measurement value Qm. When any one of the ratios (Qe / qm [%]) is out of the predetermined range or when the state has elapsed for a predetermined time, the physical quantity measuring means determines that it is abnormal (deviation increase determining means 66, step 21, step 21). 25). For this reason, even when the air flow meter 23 momentarily causes a measurement error, it can be determined whether or not there is a failure.

  Next, a third embodiment of the present invention will be described.

  In this embodiment, when the air flow meter 23 is normal, a standard is determined in advance, and when the measured value Qa is changed due to an abnormality of the air flow meter 23, the abnormality is detected by comparing with the standard. To do.

  FIG. 16 shows a block diagram of the abnormality detection system in the present embodiment.

  The abnormality detection system includes a reference physical quantity calculation means 71, a reference deviation calculation means 72, a normal deviation calculation means 73, and an abnormality detection means 74 in addition to the physical quantity measurement means 100 and the model measurement value calculation means 101 described above. Yes.

  The reference physical quantity calculating means 71 is a model for calculating the reference physical quantity, and calculates the reference physical quantity Qas of the air flow rate Q flowing through the intake passage 9 based on the model measured value Qm and the measured value Qa when the air flow meter 23 is normal. To do. For example, when the air flow meter 23 is normal and in a steady state, the measurement value Qa of the air flow meter 23 with respect to the model measurement value Qm is tabulated as a reference physical quantity Qas.

  The normative deviation calculating means 72 calculates the normative deviation Qes based on the normative physical quantity Qas and the model measurement value Qm.

  The normal deviation calculating means 73 calculates the normal deviation Qe by performing the same processing as in the above-described step 7 based on the air flow rate Qa calculated based on the output signal of the air flow meter 23 and the model measured value Qm.

  The abnormality detection unit 74 performs abnormality detection based on the standard deviation Qes and the normal deviation Qe. For example, the normal deviation Qa is subtracted from the standard deviation Qes (Qes−Qe), and when this value exceeds a predetermined threshold value, it is detected that the air flow meter 23 is abnormal. Thus, when the air flow meter 23 fails, the current measured value Qa by the air flow meter 23 shows a value different from the normal value, so that the deviation Qe is different from the normal value, and an abnormality can be detected.

  Note that when there is an abnormality in the physical quantity measuring means such as a failure due to disconnection of the air flow meter 23 while the ideal value Q is being calculated by the abnormality detecting means 74, as described in the second embodiment. Further, by setting the ideal value Q as the model measurement value Qm, the influence on the ideal value Q due to the failure of the air flow meter 23 is suppressed.

  According to the present embodiment, the abnormality detection means 74 calculates the reference value Qas of the physical quantity measurement value Qa based on the model measurement value Qm and the physical quantity measurement value Qa when the physical quantity measurement means (air flow meter 23) 100 is normal. Physical quantity normative value calculating means 71, deviation normative value calculating means 72 for calculating a deviation normative value Qes based on the physical quantity normative value Qas and the model measured value Qm, and the model measured value Qm and the physical quantity measuring means 100 A normal deviation value calculating means 73 for calculating a normal deviation value Qe based on the physical quantity measurement value Qa, and detecting the abnormality of the physical quantity measuring means 100 by comparing the deviation reference value Qes and the normal deviation value Qe. For this reason, a reference value can be set based on the measured value Qa when the air flow meter 23 is normal, and when there is an abnormality in the air flow meter 23, the abnormality can be detected accurately and quickly based on the output.

The system block diagram of the control apparatus of the engine 1 in 1st Embodiment. The block diagram which shows the ideal value calculation of this invention Block diagram showing calculation by model measurement value calculation means Block diagram showing the throttle model Block diagram showing the cylinder model Block diagram showing the collector model Flow chart showing ideal value calculation processing Flowchart for calculating model measurement value variation Diagram showing attenuation rate Diagram showing the calculation result of the ideal value The figure which shows each flow calculation value when the air flow meter breaks down due to disconnection Figure showing each flow rate calculation value when electrical noise is large Diagram showing failure determination and processing for shifting ideal values to model calculation values Block diagram to output the presence / absence of deviation increase judgment flag Diagram showing a case where an ideal value is transferred to a model measurement value after a failure is detected Block diagram showing the case where abnormality detection is performed based on the standard deviation

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Cylinder 5 Spark plug 9 Intake passage 10 Fuel injection valve 11 Collector 13 Electric throttle valve 23 Air flow meter 24 Throttle opening sensor 25 Boost sensor 26 Temperature sensor 27 Crank angle sensor 28 Atmospheric pressure sensor 30 ECU
31 Throttle model 41 Cylinder model 51 Collector model 100 Physical quantity measurement means 101 Model measurement value calculation means 102 Fusion means

Claims (23)

A physical quantity measuring means for measuring the physical quantity;
Physical quantity measurement value change amount integration means for integrating the change amount of the measurement value by the physical quantity measurement means;
Model measurement value calculation means for calculating a measurement target by the physical quantity measurement means as a model measurement value by a model;
Model measurement value change amount integration means for integrating the change amount of the model measurement value;
Deviation calculating means for calculating a deviation from the model measured value change integrated value and the physical quantity measured value integrated integrated value;
Ideal value calculating means for calculating an ideal value by adding the deviation to the physical quantity measurement value;
An ideal value calculation device comprising:   2. The ideal value calculation device according to claim 1, wherein the model measurement value change amount is obtained by multiplying a previous value of the ideal value by a change rate of the model measurement value.   The ideal value calculation device according to claim 2, wherein the rate of change of the model measurement value is a value obtained by dividing the amount of change in the model measurement value by the previous value of the model measurement value.   The model measured value change amount is calculated using either the model measured value change amount or the measured value change amount when the previous value of the ideal value is less than a predetermined value. Alternatively, the ideal value calculation device according to claim 3.   The ideal value calculation device according to claim 4, wherein the predetermined value is substantially zero.   The physical quantity measurement value change amount integration means adds the current physical quantity measurement value change amount after multiplying the physical quantity measurement value change amount integration value up to the previous time by a predetermined attenuation constant. Item 6. The ideal value calculation device according to any one of Items 5 above.   The model measured value change amount integration means adds the current model measured value change amount after multiplying the model measured value change amount integrated value up to the previous time by a predetermined attenuation constant. Item 7. The ideal value calculation device according to any one of Items 6 above.   8. The ideal value calculation device according to claim 6, wherein the attenuation constant uses a value smaller than 1.0 as the amount of change in the model measurement value decreases.   The ideal value calculation device according to any one of claims 6 to 8, wherein the attenuation constant is decreased after a state in which the amount of change in the model measurement value is reduced continues for a predetermined time.   The ideal value calculation according to claim 9, wherein the predetermined time is a time determined based on a calculation period of the ideal value and the attenuation constant.   The ideal value calculation apparatus according to claim 6 or 7, wherein the attenuation constant approaches 1.0 as noise of the physical quantity measurement value increases.   12. The ideal value calculation device according to claim 11, wherein the noise of the physical quantity measurement value is large when the fluctuation of the measurement value by the physical quantity measurement means is large. An abnormality detecting means for detecting an abnormality of the physical quantity measuring means;
Ideal value transfer means for transferring the ideal value to the model measurement value when the abnormality detection means detects an abnormality;
The ideal value arithmetic unit according to claim 1, comprising:   The ideal value calculation device according to claim 13, wherein the abnormality detection unit detects an abnormality of the physical quantity measurement unit based on the deviation and the model measurement value.   The abnormality detecting means determines that the physical quantity measuring means is abnormal when one of a ratio between the deviation and the model measured value or a ratio between the deviation and the model measured value is out of a predetermined range. The ideal value calculation apparatus according to claim 14.   The anomaly detecting means is the physical quantity measuring means when a predetermined time elapses when either the ratio between the deviation and the model measured value or the ratio between the deviation and the model measured value is outside a predetermined range. The ideal value calculation device according to claim 14, wherein the ideal value calculation device is determined as abnormal. The abnormality detection means is
Physical quantity reference value calculation means for calculating a reference value of the physical quantity measurement value based on the model measurement value and the physical quantity measurement value when the physical quantity measurement means is normal;
Deviation normative value calculating means for calculating a normative value of deviation based on the physical quantity normative value and the model measurement value;
Normal deviation value calculating means for calculating a normal deviation value based on the model measured value and the current physical quantity measured value by the physical quantity measuring means,
14. The ideal value calculation device according to claim 13, wherein an abnormality of the physical quantity measuring means is detected by comparing the deviation reference value with the normal deviation value.   The ideal value transition means switches the ideal value to an equation that is calculated by adding the model measurement value and the deviation, while the deviation is a value obtained by subtracting the physical quantity measurement value from the model measurement value only once. The calculation of the ideal value according to any one of claims 13 to 17, wherein the calculation of the model measured value change integrated value and the physical measured value integrated change value is stopped thereafter. apparatus.   The ideal value calculation apparatus according to any one of claims 1 to 18, wherein a measurement target by the model measurement value calculation means is an air flow rate flowing through an intake passage of an internal combustion engine.   The ideal value calculation device according to claim 19, wherein the air flow rate is a value calculated using a plurality of parameters including at least one of a throttle opening degree and an engine speed of an internal combustion engine.   The ideal value calculation device according to any one of claims 1 to 20, wherein the physical quantity measuring means is a hot-wire flow meter attached to an intake system of an internal combustion engine.   The ideal value calculation apparatus according to any one of claims 1 to 18, wherein a measurement target by the model measurement value calculation means is a gas pressure in an intake passage of an internal combustion engine.   The ideal value calculation device according to any one of claims 1 to 18, wherein the physical quantity measuring means is a pressure sensor attached to an intake system of an internal combustion engine.

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