JP2007205339A - State quantity estimation device of turbocharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To estimate the state quantity of a turbocharger using less number of sensors. <P>SOLUTION: This state quantity estimation device of the turbocharger uses a plurality of expressions composed of a compressor model expression, a turbine model expression, an inertia energy expression, loss energy expression, energy balance expression, and mass conservation expression. Specifically, the state quantity estimation device actually measures the predetermined variables among the variables used in these expressions, and estimates, as the state amounts of the turbocharger, the compressor inflow gas state variables, the compressor outflow gas state variables, the turbine inflow gas state variables, the turbine outflow gas state variables, and the actually unmeasured variables of the compressor passing gas flow, the turbocharger rotational speed, and the fuel amount fed into an internal combustion engine. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a state quantity estimating device for a turbocharger that supercharges an internal combustion engine.

Conventionally, a mechanical supercharger is modeled as consisting of two containers on the suction side and discharge side, and the state quantity of the mechanical supercharger is calculated assuming the pressure of each container. There is known a technique for searching for a state where a predetermined condition is satisfied by repeatedly performing while updating the assumed value of each pressure, and estimating a state when the predetermined condition is satisfied as a state quantity of the mechanical supercharger. (See Patent Document 1).
Japanese Patent Laid-Open No. 7-269362

  However, an apparatus for estimating a state quantity of a turbocharger different from that of a mechanical supercharger by a model is not known. Therefore, the conventional apparatus is provided with an extremely large number of sensors in order to acquire the state quantity of the turbocharger.

  One object of the present invention is to provide an apparatus that can estimate the state quantity of a turbocharger using a smaller number of sensors. In order to achieve this object, a turbocharger state quantity estimating apparatus according to the present invention includes a plurality of equations including a compressor model equation, a turbine model equation, an inertia energy equation, a loss energy equation, an energy balance equation, and a mass conservation equation. Is used.

  The compressor model equation is a compressor inflow gas state variable representing the state of gas flowing into the compressor of the turbocharger, a compressor outflow gas state variable representing the state of gas flowing out from the compressor, and a gas flow rate passing through the compressor. It is an equation describing the relationship between the compressor passing gas flow rate, the turbocharger rotation speed that is the rotation speed of the rotation shaft of the turbocharger, and the compressor imparted energy that is the energy that the compressor gives to the gas passing through the compressor.

  The turbine model equation is a turbine inflow gas state variable representing a state of gas flowing into the turbine of the turbocharger, a turbine outflow gas state variable representing a state of gas flowing out from the turbine, and a flow rate of gas passing through the turbine. 6 is an equation describing the relationship between the turbine passing gas flow rate, the turbocharger rotational speed, and the turbine acquired energy, which is the energy that the turbine receives from the gas passing through the turbine.

The inertia energy equation is an equation for obtaining the inertia energy of the turbocharger based on the turbocharger rotation speed.
The loss energy equation is an equation for determining the loss energy of the turbocharger based on the turbocharger rotation speed.

  The turbocharger state quantity estimating apparatus according to the present invention measures a predetermined variable among a plurality of variables used in the plurality of formulas and applies the measured predetermined variable to the plurality of formulas. The compressor inflow gas state variable, the compressor outflow gas state variable, the turbine inflow gas state variable, the turbine outflow gas state variable, the compressor passage gas flow rate, the turbine passage gas flow rate, the turbocharger rotation speed, and the An unmeasured variable of the amount of fuel supplied to the internal combustion engine is estimated as the state quantity of the turbocharger.

  In other words, the turbocharger state quantity estimating device according to the present invention uses the same number and types of equations necessary to identify (finally determine) all variables by solving a plurality of simultaneous equations. The variables to be used are actually measured by a sensor or the like, and the remaining variables that have not been actually measured are estimated by calculation. As a result, the estimated amount of state of the turbocharger can be acquired using a smaller number of sensors. Note that the amount of fuel supplied to the internal combustion engine may be actually measured based on fuel supply instruction data (for example, valve opening time) to a fuel supply means (for example, a fuel injection valve). You may actually measure.

The turbocharger state quantity estimation device is:
A sensor that actually measures one of the estimated variables;
When the variable actually measured by the sensor deviates from the estimated value of one variable by a predetermined value or more (for example, when the absolute value of the difference between these two values is larger than the predetermined value or is estimated Sensor abnormality determination means for determining that the sensor is abnormal, for example, when the ratio of the variable actually measured by the sensor to one variable is not within a predetermined range)
Can be provided.

  According to this, it is possible to easily determine whether the sensor is abnormal (including characteristic deviation).

The turbocharger state quantity estimating device is
At least one of the estimated variables is an assumed value that is sequentially changed until the mass conservation formula is satisfied, and the same mass is maintained even if the assumed value to be changed exceeds a predetermined range. It is preferable to provide a turbocharger abnormality determining unit that determines that the supercharging system including the turbocharger is abnormal when the conservation formula is not established.

Alternatively, the turbocharger state quantity estimating device is:
At least one of the estimated variables is an assumed value that is sequentially changed until the energy balance equation is satisfied, and the same energy even if the assumed value to be changed exceeds a predetermined range. When the balance formula is not established, it is preferable to include a turbocharger abnormality determining unit that determines that the supercharging system including the turbocharger is abnormal.

  According to these, it is possible to easily determine whether or not the supercharging system including the turbocharger is abnormal.

Furthermore, the turbocharger state quantity estimation device is:
When the loss energy used in the energy balance equation when the unmeasured variable is estimated is larger than a threshold value determined based on the compressor imparted energy used in the energy balance equation, the turbocharger It is preferable to include a turbocharger abnormality determination unit that determines that the supercharging system including the abnormality is abnormal.

  If the supercharging system is abnormal, the energy loss is greater than the energy imparted by the compressor. Therefore, as described above, when the loss energy is evaluated with respect to the energy imparted by the compressor, when the loss energy is larger than the assumed range, all of the energy balance formulas and the mass conservation formula are temporarily included. Even if the expression is satisfied, the apparatus is configured to determine that the supercharging system including the turbocharger is abnormal. According to this, the abnormality of the supercharging system can be detected more reliably.

  One of the preferred embodiments of such a turbocharger state quantity estimating device is that one or two of the variables to be estimated are given as assumed values until the energy balance equation and the mass conservation equation are established. The assumed values are sequentially changed, and the values of variables obtained when the energy balance equation and the mass conservation equation are established are output as final turbocharger state quantities.

  Embodiments of a state quantity estimating device for a turbocharger of an internal combustion engine according to the present invention will be described below with reference to the drawings. The turbocharger state quantity estimation device of each embodiment is applied to the four-cylinder diesel engine 10 (hereinafter referred to as “internal combustion engine 10”) shown in FIG.

<First Embodiment>
(Constitution)
The internal combustion engine 10 includes an engine body 20, an intake system 30 for introducing gas into the combustion chamber of each cylinder of the engine body 20, an exhaust system 40 for discharging exhaust gas from the engine body 20, and an electric control device 50. Contains.

  A fuel injection valve 21 is disposed above each cylinder of the engine body 20. Each fuel injection valve 21 is supplied with a boosted fuel from a fuel injection pump connected to a fuel tank (not shown). The fuel injection valve 21 is electrically connected to the electric control device 50 and is opened for a predetermined time by a drive signal from the electric control device 50, thereby injecting the boosted fuel into the combustion chamber of each cylinder. It is supposed to be.

  The intake system 30 includes an intake manifold 31 connected to the combustion chamber of each cylinder of the engine body 20, a surge tank 32 connected to the intake manifold 31, an intake pipe 33 connected to the surge tank 32, and an intake pipe 33. A throttle valve 34 that is rotatably held, a throttle valve actuator 34a that rotates the throttle valve 34 in response to a drive signal from the electric control device 50, and an intercooler that is interposed in the intake pipe 33 upstream of the throttle valve 34. 35, and a compressor 36a of a turbocharger 36 disposed in the intake pipe 33 upstream of the intercooler 35.

  The exhaust system 40 includes an exhaust manifold 41 connected to each cylinder of the engine body 20, an exhaust pipe 42 connected to a downstream side assembly of the exhaust manifold 41, and a turbine 36 b of a turbocharger 36 disposed in the exhaust pipe 42. Is included.

  The turbocharger 36 includes a turbine shaft (rotary shaft) 36c. The turbine shaft 36c connects the compressor blade 36a1 accommodated in the compressor 36a and the turbine blade 36b1 accommodated in the turbine 36b. The turbocharger 36 is a well-known variable nozzle type turbocharger (see, for example, JP-A-10-47071 and JP-A-2001-173449), and is formed between a plurality of nozzle vanes 36d and the nozzle vanes 36d. And a nozzle vane actuator 36e that drives the nozzle vane 36d in order to make the opening degree (nozzle area) of the turbine nozzle variable.

  In the turbocharger 36, the turbine blade 36b1 is rotated by exhaust. As a result, the compressor blade 36a1 connected to the turbine shaft 36c rotates together with the turbine shaft 36c and performs supercharging to compress intake air. Further, when the turbine nozzle opening is changed by the nozzle vane 36d, the speed of the exhaust gas (exhaust gas) flowing into the turbine 36b is changed. As a result, the supercharging pressure becomes variable.

  The electric control device 50 is a known microcomputer including a CPU, a ROM, a RAM, and the like. The electric control device 50 includes an air flow meter 51, a compressor inflow gas pressure sensor 52, a compressor inflow gas temperature sensor 53, a turbine inflow gas temperature sensor 54, a turbine outflow gas pressure sensor 55, a variable nozzle opening sensor 56, an accelerator pedal operation amount sensor. 57 and an engine speed sensor 58, and signals from these sensors are input. Furthermore, the electric control device 50 is connected to the fuel injection valve 21, the throttle valve actuator 34a, the nozzle vane actuator 36e, and the like, and sends drive signals to these in accordance with instructions from the CPU.

  The air flow meter 51 is disposed in the intake passage upstream of the compressor 36a. The air flow meter 51 measures a compressor passing gas flow rate that is a mass flow rate (air amount per unit time) of air passing through the compressor 36a, and generates a signal Ga representing the compressor passing gas flow rate.

The compressor inflow gas pressure sensor 52 is disposed in the intake passage near the inlet of the compressor 36a. The compressor inflow gas pressure sensor 52 detects the pressure of the gas flowing into the compressor 36a (compressor inflow gas pressure, compressor inlet gas pressure) and generates a signal P0 representing the compressor inflow gas pressure.
The compressor inflow gas temperature sensor 53 is disposed in the intake passage near the inlet of the compressor 36a. The compressor inflow gas temperature sensor 53 detects the temperature of the gas flowing into the compressor 36a (compressor inflow gas temperature, compressor inlet portion gas temperature), and generates a signal T0 representing the compressor inflow gas temperature.

The turbine inflow gas temperature sensor 54 is disposed in the exhaust passage near the inlet of the turbine 36b. The turbine inflow gas temperature sensor 54 detects the temperature of the gas flowing into the turbine 36b (turbine inflow gas temperature, turbine inlet gas temperature), and generates a signal T4 representing the turbine inflow gas temperature.
The turbine outflow gas pressure sensor 55 is disposed in the exhaust passage near the outlet of the turbine 36b. The turbine outflow gas pressure sensor 55 detects the pressure of the gas flowing out from the turbine 36b (turbine outflow gas pressure, turbine outlet gas pressure), and generates a signal P6 representing the turbine outflow gas pressure.

The variable nozzle opening sensor 56 detects the opening of the nozzle vane 36d (hereinafter referred to as “variable nozzle opening”) and generates a signal VN representing the variable nozzle opening.
The accelerator pedal operation amount sensor 57 detects the operation amount of the accelerator pedal AP, and generates a signal Accp representing the accelerator operation amount.
The engine rotation speed sensor 58 detects the rotation speed of the internal combustion engine 10 and generates a signal representing the engine rotation speed NE.

(Estimation principle of turbocharger state quantity estimation device)
Next, the principle of estimation of the turbocharger state quantity by the turbocharger state quantity estimation apparatus configured as described above will be described. As shown in FIG. 2, the turbocharger state quantity estimation apparatus includes an energy balance calculation unit M1, a mass conservation calculation unit M2, a compressor state quantity calculation unit (compressor program 1; compressor model) M3, and a turbine state quantity calculation unit. (Turbine program 1; turbine model) M4, a turbocharger inertial energy calculation unit M5, and a loss energy calculation unit M6 are provided to estimate the state quantity of the turbocharger. The state quantity of the turbocharger is as shown in Table 1. FIG. 3 is a diagram for explaining the state quantity of the turbocharger.

(Energy balance calculator M1)
The energy balance calculation unit M1 uses the energy conservation law regarding the turbocharger 36 expressed by the equation (1). In the equation (1), energy (turbine acquired energy) Lt received by the turbine 36b from the exhaust is energy (compressor imparted energy) Lc that the compressor 36a gives to intake air (gas that passes through the compressor 36a), turbine shaft 36c, and its bearings. Is an equation (energy balance equation) representing an energy balance that is equal to the sum of the loss energy Lm of the turbocharger 36 such as the friction loss between and the turbocharger inertial energy Li.

(Mass conservation calculation part M2)
The mass conservation calculation unit M2 is an equation based on the mass conservation law for the gas passing through the turbocharger 36 expressed by the equation (2). That is, the equation (2) indicates that the gas flow rate (turbine passing gas flow rate) G4 passing through the turbine 36b is the compressor passing gas flow rate Ga and the fuel injection amount (fuel supply amount) given to the internal combustion engine 10 per unit time. It is a formula (mass conservation formula) based on the law of conservation of mass that is equal to the sum of Qinj. In the first embodiment, the value actually measured by the air flow meter 51 is substituted for the compressor passage gas flow rate Ga on the right side of the equation (2), and the fuel injection amount Qinj is assigned to each fuel injection valve 21 from the electric control device 50. A value (measured value) obtained based on the fuel injection amount instructed to be injected is substituted.

  In order to obtain each variable used in the energy balance calculation unit M1 and the mass conservation calculation unit M2, the turbocharger state quantity estimation device includes a compressor state quantity calculation unit M3, a turbine state quantity calculation unit M4, and a turbocharger inertia energy calculation unit. M5 and loss energy calculation unit M6 are used. Hereinafter, each part will be described individually.

(Compressor state quantity calculation unit M3)
The compressor state quantity calculation unit M3 estimates the following output value using the following input value and mathematical expressions represented by the expressions (3) to (10). Equation (3) is a pressure ratio calculation equation, equation (8) is a compressor efficiency calculation equation, equation (9) is a compressor efficiency definition equation, and equation (10) is a compressor energy equation (experimental equation).

  Equations (3) to (10) are the compressor inflow gas state variables (compressor inflow gas temperature T0 and compressor inflow gas pressure P0) representing the state of gas flowing into the turbocharger compressor, and the state of gas flowing out from the compressor. Compressor outflow gas state variables (compressor outflow gas temperature T3 and compressor outflow gas pressure P3), compressor passing gas flow rate Ga, turbocharger rotation speed Nt, and compressor applied energy Lc that is energy that the compressor 36a gives to the gas passing through the compressor 36a Is a compressor model equation describing the relationship between

(Input value)
Compressor inflow gas pressure P0 (sensor detection value)
Compressor inflow gas temperature T0 (sensor detection value)
Compressor passage gas flow rate Ga (sensor detection value)
Turbocharger rotation speed Nt (assumed value: resulting in an estimated value)
(Output value: Estimated value)
Compressor outflow gas pressure P3
Compressor outflow gas temperature T3
Energy Lc given to intake air by compressor

（３）式の関数ｆ１は、変数Ｇｎ及び変数Ｎ０と、比Ｐ３／Ｐ０と、の関係を定める関数であって、ここでは実験により予め定められた変換テーブル（マップ）として電気制御装置５０のＲＯＭ内に格納されている。

The function f1 in the equation (3) is a function that determines the relationship between the variable Gn and the variable N0 and the ratio P3 / P0. Here, the function f1 is a conversion table (map) determined in advance by experiments. Stored in ROM.

The function f2 in the equation (8) is a function for determining the relationship between the variable Gn and the variable N0 and the compressor efficiency ηc. Here, the ROM of the electric control device 50 is used as a conversion table (map) determined in advance by experiment. Is stored inside.

For the sake of understanding, the following equation (11) is obtained by substituting the equations (4) to (7) into the above equation (3). For the right side of equation (11), the detection value of the air flow meter 51 is substituted as Ga, the detection value of the compressor inflow gas pressure sensor 52 is substituted as P0, and the detection value of the compressor inflow gas temperature sensor 53 is substituted as T0. At the same time, if the turbocharger rotational speed Nt is given as an appropriate assumed value, the compressor outflow gas pressure P3 can be obtained.

  As a result, P3 / P0 on the right side of the equation (9) is obtained, and the compressor efficiency ηc of the equation (9) is obtained from the equations (4), (5), and (8), and the compressor inflow gas Since the temperature T0 is detected by the compressor inflow gas temperature sensor 53, the compressor outflow gas temperature T3 is estimated from the equation (9).

  Further, by substituting the estimated compressor outflow gas temperature T3, the detected compressor inflow gas temperature T0, and the detected compressor passage gas flow rate Ga into the equation (10), the compressor takes in the intake air (passes through the compressor). Energy (compressor imparted energy) Lc given to the gas) is estimated.

(Turbine state quantity calculation unit M4)
The turbine state quantity calculation unit M4 estimates the following output value using the following input value and mathematical expressions represented by the expressions (12) to (17). (12) is a flow rate calculation formula, (15) is a turbine efficiency calculation formula, (16) is a turbine efficiency definition formula, and (17) is a turbine energy formula (experimental formula).

  Equations (12) to (17) are turbine inflow gas state variables (turbine inflow gas temperature T4 and turbine inflow gas pressure P4) representing the state of gas flowing into the turbine 36b of the turbocharger 36, and gas flowing out from the turbine 36b. The turbine effluent gas state variables (turbine effluent gas temperature T6 and turbine effluent gas pressure P6), the turbine passage gas flow rate G4 which is the flow rate of the gas passing through the turbine 36b, the turbocharger rotational speed Nt, the variable nozzle opening It is a turbine model formula describing the relationship between the degree VN and the turbine acquired energy Lt, which is the energy that the turbine 36b receives from the gas passing through the turbine 36b.

(Input value)
Turbine inflow gas temperature T4 (sensor detection value)
Turbine outlet gas pressure P6 (sensor detection value)
Variable nozzle opening VN (sensor detection value)
Turbine inflow gas pressure P4 (assumed value: resulting in an estimated value)
Turbocharger rotation speed Nt (assumed value: resulting in an estimated value)
(Output value: Estimated value)
Turbine passing gas flow rate G4
Turbine effluent gas temperature T6
Energy that turbine receives from exhaust (turbine acquired energy) Lt

（１２）式の関数ｆ３は、変数Ｐ４／Ｐ６，変数Ｎ１及び変数ＶＮと、修正流量Ｑ４と、の関係を定める関数であって、ここでは実験により予め定められた変換テーブル（マップ）として電気制御装置５０のＲＯＭ内に格納されている。

The function f3 in the equation (12) is a function for determining the relationship between the variable P4 / P6, the variable N1 and the variable VN, and the corrected flow rate Q4. Here, the function f3 is an electric conversion table (map) determined in advance by experiments. It is stored in the ROM of the control device 50.

（１５）式の関数ｆ４は、変数Ｐ４／Ｐ６，変数Ｎ１及び変数ＶＮと、タービン効率ηｔと、の関係を定める関数であって、ここでは実験により予め定められた変換テーブル（マップ）として電気制御装置５０のＲＯＭ内に格納されている。

The function f4 in the equation (15) is a function for determining the relationship between the variables P4 / P6, the variable N1, the variable VN, and the turbine efficiency ηt. Here, the function f4 is expressed as a conversion table (map) predetermined by an experiment. It is stored in the ROM of the control device 50.

（１８）式の右辺に対し、Ｐ６としてタービン流出ガス圧力センサ５５の検出値を代入し、Ｔ４としてタービン流入ガス温度センサ５４の検出値を代入し、ＶＮとしてバリアブルノズル開度センサ５６の検出値を代入するとともに、ターボチャージャ回転速度Ｎｔ及びタービン流入ガス圧力Ｐ４を適当な仮定値として与えてやれば、タービン通過ガス流量Ｇ４が推定される。 For the sake of understanding, the following equation (18) is obtained by substituting the equations (12) and (13) into the above equation (14).

For the right side of the equation (18), the detected value of the turbine outflow gas pressure sensor 55 is substituted as P6, the detected value of the turbine inflow gas temperature sensor 54 is substituted as T4, and the detected value of the variable nozzle opening sensor 56 is set as VN. Is substituted, and the turbocharger rotation speed Nt and the turbine inflow gas pressure P4 are given as appropriate assumptions, the turbine passing gas flow rate G4 is estimated.

  On the other hand, P6 is a detected value of the turbine outflow gas pressure sensor 55, and P4 / P6 is obtained because P4 is given an assumed value. Since Nt is an assumed value and T4 is a detected value of the turbine inflow gas temperature sensor 54, the turbine efficiency ηt is obtained from the equations (13) and (15). Accordingly, since P6 / P4 and ηt on the right side of the equation (16) are determined, T6 / T4 is obtained from (16). Further, since T4 is detected by the turbine effluent gas temperature sensor 54, the turbine effluent gas temperature T6 is estimated based on the equation (16). As described above, G4, T4, and T6 are determined, and therefore, the turbine acquisition energy Lt is obtained by the equation (17).

(Turbocharger inertial energy calculation unit M5)
The turbocharger inertial energy calculation unit M5 estimates the turbocharger inertial energy Li based on the equation (19) which is an inertial energy equation. The function funcLi in the equation (19) is a function for obtaining the turbocharger inertial energy Li using the turbocharger rotation speed Nt and the time differential value (dNt / dt) of the turbocharger rotation speed Nt as variables. It is stored in the ROM of the electric control device 50 as a defined conversion table (map). In this specification, when a certain value is acquired using a conversion table as in equation (19), it is expressed as “determining a certain value using an equation”.

(Loss energy calculation part M6)
The loss energy calculation unit M6 estimates other loss energy Lm based on the equation (20) which is a loss energy equation. The function funcLm in the equation (20) is a function for obtaining other loss energy Lm using the turbocharger rotational speed Nt as a variable, and here, in the ROM of the electric control device 50 as a conversion table (map) determined in advance by experiment. Stored in The function funcLm may be a function expressed by a mathematical expression such as funcLm = km · Nt ⁿ (km and n are constants).

  The turbocharger state quantity estimating apparatus of the present embodiment sequentially changes the values of the turbocharger rotation speed Nt and the turbine inflow gas pressure P4 until the expressions (1) and (2) are satisfied, Each value (P3, T3, P4, T6, G4, Nt) when the expression (2) is satisfied is estimated as a turbocharger state quantity.

(common belief)
By the way, in the first embodiment, a value of (Nt, P4) is assumed, and the detected values (Nt, P4) and detected values (P0, T0, T4, P6, Ga, Qinj, VN) ( (Actually measured value) is input as an input value to each of the above calculation units to determine the final value of (Nt, P4), and when the final value is obtained (P3, T3, P4, T6, G4, Nt ) Is estimated as the turbocharger state quantity. From this, it is easily understood that the remaining variables can be estimated even if at least one of (Nt, P4) is detected by the sensor.

  Further, as is apparent from the above equations, other values can be used as input values and the remaining values can be used as output values. In order to be able to calculate the output value, the following condition is selected from 13 variables of (P0, T0, P3, T3, P4, T4, P6, T6, VN, Ga, G4, Qinj, Nt). A combination of seven variables satisfying the above may be used as an input.

Condition 1: Any two or more of P0, T0, P3, and T3 are selected.
Condition 2: Any three or more of P4, T4, P6, T6, and VN are selected.
Condition 3: The four variables selected in condition 1 and condition 2 must not be pressure or temperature.
Condition 4: Any two or more of Ga, G4, Qinj, and Nt are selected.

Therefore, there are 348 combinations that can be calculated as shown in equation (21). A typical example of such combinations is shown in Table 2. Case 1 corresponds to the first embodiment. In Table 2, since the assumed value is a value estimated as a result, it is described as an output value.

(Actual operation)
Next, the actual operation of the turbocharger state quantity estimating apparatus according to the first embodiment will be described with reference to FIGS.

  When estimating the turbocharger state quantity, the CPU of the electric control device 50 starts processing from step 400 of the program shown in the flowchart of FIG. 4 and proceeds to step 405 to initially set the turbocharger rotational speed Nt, which is an assumed value. Set the value Ntint. Note that the initial value Ntint is selected to be a value slightly smaller than the minimum value that the turbocharger rotational speed Nt that is finally estimated can assume. Next, the CPU proceeds to step 410 and proceeds to step 500 of the compressor program 1 shown by the flowchart of FIG. 5 and then executes each step described below.

Step 505: The compressor inflow gas pressure P0, the compressor inflow gas temperature T0, and the compressor passage gas flow rate Ga are acquired from the compressor inflow gas pressure sensor 52, the compressor inflow gas temperature sensor 53, and the air flow meter 51, respectively.
Step 510: Calculate the value θ0 and the value δ0 according to the equations (6) and (7).
Step 515: The value N0 is obtained according to the equation (5).
Step 520: A value Gn is obtained according to the equation (4).
Step 525: The compressor outflow gas pressure P3 is obtained according to the equation (3).
Step 530: Determine the compressor efficiency ηc according to equation (8).
Step 535: The compressor outflow gas temperature T3 is obtained according to the equation (9).
Step 540: Determine the compressor imparted energy Lc according to the equation (10).
Step 545: The compressor outflow gas pressure P3, the compressor outflow gas temperature T3, and the compressor applied energy Lc calculated as described above are stored in a predetermined area of the RAM. The CPU also stores other values used or calculated in the above steps in a predetermined area of the RAM.

  Next, the CPU returns to step 415 in FIG. 4 via step 595, and sets an initial value P4int to the turbine inflow gas pressure P4, which is an assumed value. The initial value P4int is selected to be a value slightly smaller than the minimum value that the predicted value of the finally estimated turbine inflow gas pressure P4 can take. Thereafter, the CPU proceeds to step 420 and proceeds to step 600 of the turbine program 1 shown by the flowchart of FIG. 6 and then executes each step described below.

Step 605: The turbine inflow gas temperature T4, the turbine outflow gas pressure P6, and the variable nozzle opening degree VN are acquired from the turbine inflow gas temperature sensor 54, the turbine outflow gas pressure sensor 55, and the variable nozzle opening degree sensor 56, respectively.
Step 610: The value N1 is obtained according to the equation (13).
Step 615: The value Q4 is obtained according to the equation (12).
Step 620: A turbine passing gas flow rate G4 is obtained according to the equation (14).
Step 625: The turbine efficiency ηt is obtained according to the equation (15).
Step 630: The turbine outlet gas temperature T6 is obtained according to the equation (16).
Step 635: The energy (turbine acquired energy) Lt that the turbine receives from the exhaust gas is obtained according to the equation (17).
Step 640: The turbine passage gas flow rate G4, the turbine outflow gas temperature T6, and the turbine acquired energy Lt calculated as described above are stored in a predetermined area of the RAM. The CPU also stores other values used or calculated in the above steps in a predetermined area of the RAM.

  Next, the CPU returns to step 425 in FIG. 4 via step 695, and per unit time determined based on the signal Accp indicating the accelerator operation amount and the engine speed NE by a known fuel injection amount calculation program (not shown). The fuel injection amount Qinj is input.

  Next, the CPU proceeds to step 430, where the turbine passage gas flow rate G4 obtained by the previous turbine program 1 (step 420), the compressor passage gas flow rate Ga actually measured by the air flow meter 51, and the fuel injection input at step 425 are obtained. It is determined whether or not the quantity Qinj satisfies the expression based on the mass conservation law of the expression (2) (that is, whether or not the expression (2) is satisfied).

  At this time, if the equation based on the law of conservation of mass of equation (2) is not satisfied, the CPU makes a “No” determination at step 430 to proceed to step 435, and sets the turbine inflow gas pressure P4 to a predetermined minute value. Increases by α. Thereafter, the CPU returns to step 420 and executes the turbine program 1 to calculate the turbine passage gas flow rate G4 again. Next, the CPU executes the processing of step 425 and step 430. Such processing (step 420 to step 435) is repeated until it is determined in step 430 that the formula based on the law of conservation of mass is established.

  Therefore, when the turbine inflow gas pressure P4 becomes an appropriate value with respect to the turbocharger rotation speed Nt assumed at that time, the equation based on the law of conservation of mass is established. The determination proceeds to step 440, where turbocharger inertial energy Li is determined based on equation (19), and other loss energy Lm is determined based on equation (20).

  Next, the CPU proceeds to step 445, where the compressor imparted energy Lc obtained by the previous compressor program 1 (step 410), the turbine acquired energy Lt obtained by the turbine program 1 (step 420), and obtained by step 440. Whether the turbocharger inertial energy Li and other loss energy Lm satisfy the energy balance formula (formula based on the law of conservation of energy) of formula (1) (that is, whether formula (1) is met) ).

  At this time, if the expression (1) is not satisfied, the CPU makes a “No” determination at step 445 to proceed to step 450 to increase the turbocharger rotation speed Nt by a predetermined minute value β. Thereafter, the CPU returns to step 410 and executes the processing from step 410 to step 440 again. Thereby, each value including the energy Lt, Lc, Li, and Lm is updated. Such processing (steps 410 to 450) is repeated until the expression (1) (energy balance expression) is established in step 445.

  Accordingly, when the turbine inflow gas pressure P4 and the turbocharger rotational speed Nt become appropriate values, the values including the energy Lt, Lc, Li, and Lm become appropriate values, and therefore the formula (1) based on the energy conservation law is established. To do. As a result, when the CPU proceeds to step 445, the CPU makes a “Yes” determination at step 445 to proceed to step 455, where the compressor outflow gas pressure P3, the compressor outflow gas temperature T3, and the turbine inflow calculated at that time are calculated. The gas pressure P4, turbine outflow gas temperature T6, turbocharger rotation speed Nt, and turbine passage gas flow rate G4 are output as estimated values of the turbocharger state quantity. Thereafter, the CPU proceeds to step 495 to end the present routine tentatively. The above is the operation of the turbocharger state quantity estimation device according to the first embodiment.

  As described above, the turbocharger state quantity estimation device according to the first embodiment includes a plurality of equations including a compressor model equation, a turbine model equation, an inertia energy equation, a loss energy equation, an energy balance equation, and a mass conservation equation. Then, some of the turbocharger state quantities (P0, T0, T4, P6, Ga, Qinj, VN) included as variables in those equations are measured, and the measured values are applied to these equations to Turbocharger state quantities (P3, T3, P4, T6, G4, Nt) are estimated. Therefore, a value representing the turbocharger state quantity can be acquired using a smaller number of sensors.

  The turbocharger state quantity estimating apparatus sequentially changes one or two of the variables to be estimated (in this example, two of Nt and P4) as assumed values, and these values are energy balance equations. The calculation is repeated until the mass conservation equation is satisfied. And the variable calculated | required by said each formula when these values satisfy | fill the energy balance type | formula and mass conservation type | formula is estimated (output) as a turbocharger state quantity. Therefore, a value representing the turbocharger state quantity can be obtained by using a smaller number of sensors (a smaller number of assumed variables).

Second Embodiment
Next, a turbocharger state quantity estimating device according to a second embodiment of the present invention will be described. This device is mainly different from the turbocharger state quantity estimating device of the first embodiment in that the CPU of the electric control device 50 executes the program shown in the flowcharts of FIGS. 7 to 10 instead of FIGS. 4 to 6. Yes. Therefore, this difference will be mainly described below.

  The estimation apparatus according to the first embodiment detects (actually measures) predetermined variables (P0, T0, T4, P6, Ga, Qinj, VN) from each sensor and uses them as input values, as well as turbine inflow gas pressure. (P3, T3, P4, T6, G4, Nt) were estimated by sequentially changing P4 and the turbocharger rotation speed Nt. In contrast, the estimation device according to the second embodiment includes a turbine inflow gas pressure sensor that detects the turbine inflow gas pressure P4 in the vicinity of the inlet of the turbine 36b, and the turbine inflow gas pressure P4 is detected by the turbine inflow gas pressure sensor. Then, the value is used as an input value instead of the compressor passing gas flow rate Ga, and the compressor passing gas flow rate Ga is estimated.

  That is, the estimation apparatus according to the second embodiment detects predetermined variables (P0, T0, P4, T4, P6, Qinj, VN) from each sensor, uses them as input values, and sets the turbocharger rotational speed Nt. Are sequentially estimated (P3, T3, T6, Ga, G4, Nt) (see case 11 in Table 2).

(Actual operation)
When estimating the turbocharger state quantity, the CPU of the electric control device according to the second embodiment starts processing from step 700 in FIG. 7 and proceeds to step 705 to set the initial value Ntint to the turbocharger rotational speed Nt. Set. Next, the CPU proceeds to step 710 and proceeds to step 800 of the turbine program 2 shown by the flowchart of FIG. Then, the CPU proceeds to Step 805 to set the turbine inflow gas pressure P4, the turbine inflow gas temperature T4, the turbine outflow gas pressure P6, and the variable nozzle opening VN to the turbine inflow gas pressure sensor, the turbine inflow gas temperature sensor 54, the turbine outflow gas. Obtained from the pressure sensor 55 and the variable nozzle opening sensor 56, respectively.

  Next, the CPU performs processing from step 810 to step 840. Since Steps 810 to 840 are the same steps as Steps 610 to 640 described above, description thereof will be omitted. However, the turbine inflow gas pressure P4 is not an assumed value as in the first embodiment but an actual measurement value. Thus, the turbine passing gas flow rate G4, the turbine outflow gas temperature T6, and the turbine acquired energy Lt are obtained and stored in a predetermined area of the RAM.

  Next, the CPU returns to step 715 of FIG. 7 via step 895, and the fuel injection amount determined based on the signal Accp representing the accelerator operation amount and the engine speed NE by a known fuel injection amount calculation program (not shown). Enter Qinj. Thereafter, the CPU proceeds to step 720, and obtains the compressor passage gas flow rate Ga based on the turbine passage gas flow rate G4 obtained in step 710, the fuel injection amount Qinj obtained in step 715, and the equation (2). Thereby, the formula based on the mass conservation law of formula (2) is reflected in the calculation result.

  Next, the CPU proceeds to step 725 and proceeds to step 900 of the compressor program 2 shown by the flowchart of FIG. Then, the CPU proceeds to step 905 to acquire the compressor inflow gas pressure P0 and the compressor inflow gas temperature T0 from the compressor inflow gas pressure sensor 52 and the compressor inflow gas temperature sensor 53, respectively.

  Next, the CPU performs processing from step 910 to step 945. Steps 910 to 945 are the same steps as steps 510 to 545 described above, and thus description thereof is omitted. As described above, the compressor outflow gas pressure P3, the compressor outflow gas temperature T3, and the compressor imparted energy Lc are stored in a predetermined area of the RAM.

  Next, the CPU returns to step 730 in FIG. 7 via step 995, and in step 730, the turbocharger inertia energy Li is obtained based on the equation (19), and other loss energy Lm is obtained based on the equation (20). Ask. Thereafter, the CPU proceeds to step 735, where the turbine acquisition energy Lt obtained by the previous turbine program 2 (step 710), the compressor applied energy Lc obtained by the compressor program 2 (step 725), and the step 730 obtained. It is determined whether the turbocharger inertial energy Li and other loss energy Lm satisfy the energy balance equation (1).

  At this time, if the energy balance equation (1) is not satisfied, the CPU makes a “No” determination at step 735 to proceed to step 740 to increase the turbocharger rotation speed Nt by a predetermined minute value β. To do. Thereafter, the CPU returns to step 710 and executes the processing from step 710 to step 730 again. Thereby, each value including the energy Lt, Lc, Li, and Lm is updated. Such processing (steps 710 to 740) is repeated until it is determined in step 735 that the energy balance equation (1) is established.

  Therefore, when the turbocharger rotational speed Nt becomes an appropriate value, each value including the energy Lt, Lc, Li, and Lm becomes an appropriate value, so that the energy balance expression (1) is established. As a result, when the CPU proceeds to step 735, the CPU makes a “Yes” determination at step 735 to proceed to step 745, where the compressor outflow gas pressure P3, the compressor outflow gas temperature T3, the turbine outflow are calculated. The gas temperature T6, the turbocharger rotation speed Nt, the turbine passing gas flow rate G4, and the compressor passing gas flow rate Ga are output as estimated values of the turbocharger state quantity. Thereafter, the CPU proceeds to step 795 to end the present routine tentatively. The above is the operation of the turbocharger state quantity estimating device according to the second embodiment.

  As described above, the turbocharger state quantity estimation device according to the second embodiment includes a plurality of formulas including a compressor model formula, a turbine model formula, an inertia energy formula, a loss energy formula, an energy balance formula, and a mass conservation formula. Then, some of the turbocharger state quantities (P0, T0, P4, T4, P6, Qinj, VN) included as variables in those equations are measured, and the measured values are applied to these equations to Turbocharger state quantities (P3, T3, T6, Ga, G4, Nt) are estimated. Therefore, a value representing the turbocharger state quantity can be acquired using a smaller number of sensors.

<Third Embodiment>
Next, a turbocharger state quantity estimating apparatus according to a third embodiment of the present invention will be described. This estimation apparatus estimates the turbocharger rotational speed Nt as the estimated value Ntcal, similarly to the estimation apparatus of the first embodiment described above. On the other hand, this estimation apparatus includes a turbocharger rotation speed detection sensor that detects (actually measures) the turbocharger rotation speed Nt in the vicinity of the turbine shaft 36c, and inputs the detected turbocharger rotation speed as an actual measurement value Ntact. Then, the estimation device compares the estimated value Ntcal and the actually measured value Ntact, and determines whether or not the turbocharger rotation speed detection sensor is abnormal based on the comparison result.

(Actual operation)
More specifically, the estimation device is an estimation device according to the first embodiment in that the CPU of the electric control device 50 executes the program shown in the flowchart of FIG. 10 in addition to FIGS. 4 to 6. Is different. Therefore, this difference will be mainly described below.

  When the processing of step 455 in FIG. 4 ends, the CPU proceeds to step 1010 in FIG. 10 and inputs the turbocharger rotation speed detected by the turbocharger rotation speed sensor as the actual measurement value Ntact. Next, the CPU proceeds to step 1020 to input the turbocharger rotational speed Nt estimated (finally obtained) by the program shown in FIGS. 4 to 6 as the estimated value Ntcal, and in step 1030, the estimated value Ntcal Whether or not the absolute value of the difference between the measured value Ntact and the measured value Ntact is smaller than a threshold value (abnormality determination value) err is determined.

  If the absolute value of the difference between the estimated value Ntcal and the measured value Ntact is smaller than the threshold err, the CPU makes a “Yes” determination at step 1030 to proceed to step 1040, where the turbocharger rotation speed sensor is normal. As shown, the value of the abnormality flag XDNt is set to “0”. On the other hand, if the absolute value of the difference between the estimated value Ntcal and the measured value Ntact is greater than or equal to the threshold err, the CPU makes a “No” determination at step 1030 to proceed to step 1050, where the turbocharger rotation speed sensor is abnormal. The value of the abnormality flag XDNt is set to “1” so as to indicate that it is. Thereafter, the CPU proceeds to step 495 in FIG.

(Modification of the third embodiment)
The estimation apparatus according to the third embodiment described above determines whether or not the turbocharger rotation speed sensor is abnormal. According to the present invention, it is determined whether or not other sensors are abnormal. It can also be determined. The program shown in the flowchart of FIG. 11 is an example for performing such processing.

  According to this program, in step 1110, the CPU detects the value detected by the Y sensor from the “sensor that determines whether there is an abnormality (referred to as a“ Y sensor ”for convenience)”. Enter as. In this case, the actual measurement value detected by the “Y sensor” should not be the actual measurement value of the sensor used as the input value for turbocharger state quantity estimation, and the turbocharger state quantity estimation device It is necessary that the value corresponds to the value estimated by.

  Next, the CPU proceeds to step 1120 and inputs, for example, a value Y estimated by the program shown in FIGS. 4 to 6 and corresponding to the measured value Yact as the estimated value Ycal. Next, in step 1030, the CPU determines whether or not the absolute value of the difference between the estimated value Ycal and the actually measured value Yact is smaller than a threshold value (abnormality determination value) errY.

  If the absolute value of the difference between the estimated value Ycal and the measured value Yact is smaller than the threshold errY, the CPU makes a “Yes” determination at step 1130 to proceed to step 1140 to indicate that the Y sensor is normal. As described above, the value of the abnormality flag XY is set to “0”. On the other hand, if the absolute value of the difference between the estimated value Ycal and the measured value Yact is greater than or equal to the threshold value errY, the CPU makes a “No” determination at step 1130 to proceed to step 1150 to indicate that the Y sensor is abnormal. As shown, the value of the abnormality flag XY is set to “1”. Thereafter, the CPU proceeds to step 1195 to end the program once.

  As described above, the turbocharger estimation device according to the third embodiment and the modification thereof is an estimated variable (estimated state quantity) and a variable of the same type as the estimated variable and measured by the sensor. When the (measured state quantity) deviates from a predetermined value or more, it is determined that the sensor is abnormal. Therefore, it is possible to easily detect the presence or absence of abnormality of a sensor that actually measures the same type of state quantity as the estimated state quantity.

  In the above example, when the absolute value of the difference between the measured state quantity and the estimated state quantity is larger than a predetermined value, it is determined that the sensor that measured the measured state quantity is abnormal. On the other hand, for example, when the ratio of the measured state quantity to the estimated state quantity is not within a predetermined range, it may be determined that the sensor that measured the measured state quantity is abnormal.

<Fourth embodiment>
Next, a turbocharger state quantity estimating apparatus according to a fourth embodiment of the present invention will be described. This estimation device is a device having a function of determining whether or not the turbocharger 36 is abnormal by using the turbocharger state quantity estimation device according to the first embodiment. Specifically, in the estimation device of the fourth embodiment, the turbocharger rotation speed Nt exceeds a predetermined range when the turbine inflow gas pressure P4 exceeds a predetermined range during or after estimation of the turbocharger state quantity. Or when “other energy loss Lm” (for example, the ratio R = Lm / Lc thereof) exceeds a threshold value (abnormality determination value) when “compressor energy Lc” is used as a reference. When this occurs, it is determined that the turbocharger 36 is abnormal.

(Actual operation)
More specifically, the estimation device is different from the estimation device of the first embodiment in that the CPU of the electric control device 50 executes the program shown in the flowchart of FIG. 12 instead of FIG. . Therefore, this difference will be mainly described below. In FIG. 12, the same steps as those in FIG. 4 are denoted by the same reference numerals, and detailed description thereof is omitted.

  In order to estimate the turbocharger state quantity and determine whether or not the turbocharger 36 is abnormal, the CPU starts processing from step 1200 in FIG. 12 and proceeds to step 405 to set an initial value to the turbocharger rotation speed Nt that is an assumed value. Set Ntint. Next, the CPU proceeds to step 410 to execute the compressor program 1 shown in FIG. As a result, the compressor outflow gas pressure P3, the compressor outflow gas temperature T3, and the compressor imparted energy Lc are obtained.

  Next, the CPU sets an initial value P4int to the turbine inflow gas pressure P4, which is an assumed value, in step 415, and proceeds to step 420 to execute the turbine program 1 shown in FIG. As a result, the turbine passing gas flow rate G4, the turbine outflow gas temperature T6, and the turbine acquired energy Lt are obtained.

  Thereafter, the CPU inputs the fuel injection amount Qinj per unit time at step 425, and is measured by the turbine flow gas flow rate G4 obtained by the previous turbine program 1 (step 420) and the air flow meter 51 at the subsequent step 430. It is determined whether the compressor passing gas flow rate Ga and the fuel injection amount Qinj input in step 425 satisfy the equation based on the mass conservation law of equation (2). At this time, if the equation based on the law of conservation of mass of equation (2) is not satisfied, the CPU makes a “No” determination at step 430 to proceed to step 435, and sets the turbine inflow gas pressure P4 to a predetermined minute value. Increases by α.

  Next, the CPU proceeds to step 1205 to determine whether or not the turbine inflow gas pressure P4 updated at step 435 is within a predetermined range (Pmin to Pmax). If the turbine inflow gas pressure P4 is within a predetermined range (Pmin to Pmax), the CPU makes a “Yes” determination at step 1205 to return to step 420.

  On the other hand, if the turbine inflow gas pressure P4 is not within the predetermined range (Pmin to Pmax), the CPU makes a “No” determination at step 1205 to proceed to step 1210 to indicate that the turbocharger 36 is abnormal. (Turbocharger abnormality flag) The value of XTC is set to “1”, and the process proceeds to step 1295 to end the program once.

  While the turbine inflow gas pressure P4 is sequentially increased (changed) by the above procedure, it is determined in step 430 whether or not an equation based on the law of conservation of mass is established, and the turbine inflow gas pressure P4 is within a predetermined range. When (Pmin to Pmax) is exceeded, it is determined that the turbocharger 36 (supercharging system including the turbocharger 36) is abnormal. That is, in this apparatus, the turbine inflow gas pressure P4, which is at least one of the estimated variables (turbocharger state quantity), is an assumed value and is sequentially changed until the mass conservation formula is satisfied. Turbocharger abnormality determination means is provided that determines that the supercharging system including the turbocharger is abnormal when the same mass conservation equation is not satisfied even if the assumed value to be changed exceeds a predetermined range.

  Now, it is assumed that the formula based on the law of conservation of mass is established in step 430 before the turbine inflow gas pressure P4 exceeds a predetermined range (Pmin to Pmax). In this case, the CPU makes a “Yes” determination at step 430 to proceed to step 440 to obtain the turbocharger inertial energy Li and other loss energy Lm. Thereafter, in step 445, the CPU obtains the compressor imparted energy Lc obtained by the previous compressor program 1 (step 410), the turbine acquired energy Lt obtained by the turbine program 1 (step 420), and obtained in step 440. It is determined whether the turbocharger inertial energy Li and other loss energy Lm satisfy the energy balance equation (1).

  At this time, if the energy balance equation (1) is not established, the CPU makes a “No” determination at step 445 to proceed to step 450 to increase the turbocharger rotational speed Nt by a predetermined minute value β. To do.

  Next, the CPU proceeds to step 1215 to determine whether or not the turbocharger rotational speed Nt updated at step 450 is within a predetermined range (Ntmin to Ntmax). If the turbocharger rotational speed Nt is within a predetermined range (Ntmin to Ntmax), the CPU makes a “Yes” determination at step 1215 to return to step 410.

  On the other hand, if the turbocharger rotational speed Nt is not within the predetermined range (Ntmin to Ntmax), the CPU makes a “No” determination at step 1215 to proceed to step 1220 to set the value of the turbocharger abnormality flag XTC to “1”. And the program proceeds to step 1295 to end the program once.

  According to the above procedure, while the turbocharger rotation speed Nt is sequentially increased (changed), it is determined in step 445 whether or not an expression based on the energy conservation law is established, and before the expression based on the energy conservation law is established. When the turbocharger rotational speed Nt exceeds a predetermined range (Ntmin to Ntmax) at the time of, it is determined that the turbocharger 36 (supercharging system including the turbocharger) is abnormal.

  That is, in this apparatus, the turbocharger rotational speed Nt, which is at least one of the estimated variables (turbocharger state quantity), is an assumed value and is sequentially changed until the energy balance equation is satisfied. Turbocharger abnormality determination means is provided for determining that the supercharging system including the turbocharger is abnormal when the energy balance equation is not satisfied even if the assumed value to be changed exceeds a predetermined range.

  Now, the turbine inflow gas pressure P4 does not exceed the predetermined range (Pmin to Pmax) and the turbocharger rotational speed Nt does not exceed the predetermined range (Ntmin to Ntmax). Assuming that the energy balance equation is established, the CPU makes a “Yes” determination at step 445 to proceed to step 1225 to execute a step for “compressor imparted energy Lc” obtained by the previous compressor program 1 (step 410). It is determined whether the ratio R (R = Lm / Lc) of “other energy loss Lm” obtained at 440 is greater than a threshold value (abnormality determination value) Rth.

  If there is no abnormality in the turbocharger 36 (a turbocharging system including a turbocharger), the ratio R does not become larger than the threshold value Rth. Therefore, when the ratio R is larger than the threshold value Rth, the CPU determines that the turbocharger 36 is abnormal, proceeds from step 1225 to step 1220, and sets the value of the turbocharger abnormality flag XTC to “1”. Proceeding to step 1295, the program is temporarily terminated.

  On the other hand, if the ratio R (Lm / Lc) is equal to or smaller than the threshold value Rth in step 1225, the CPU determines the turbocharger state quantities (P3, T3, P4, T6, Nt, G4) as estimated values in step 455. In step 1230, the value of the turbocharger abnormality flag XTC is set to “0”, and the process proceeds to step 1295 to end the program once. The above is the operation of the fourth embodiment.

  Thus, in the turbocharger state quantity estimation device according to the fourth embodiment, when both the energy balance equation and the mass conservation equation are established, the loss energy Lm used in the energy balance equation is the same energy. Turbocharger abnormality determining means for determining that the supercharging system including the turbocharger is abnormal when it is larger than a threshold value (Rth · Lc) determined based on the compressor imparted energy Lc used in the balance equation.

  According to this, even when both the energy balance type and the mass conservation type are satisfied, it is possible to more reliably detect that the supercharging system including the turbocharger is abnormal.

In the fourth embodiment, it is also preferable to configure the program so as to proceed directly to step 420 after the processing of step 435 in FIG. 12, and to arrange step 1205 and step 1210 between step 445 and step 1225. is there.
Similarly, it is also preferable to configure the program to proceed directly to step 410 after the processing of step 450 in FIG. 12 and to arrange step 1215 and step 1220 between step 445 and step 1225.

  As mentioned above, although the embodiment of the turbocharger state quantity estimating device according to the present invention has been described, the present invention is not limited to the above-described embodiments, and various modifications may be adopted within the scope of the present invention. it can. For example, in each embodiment, the turbocharger rotational speed Nt is gradually increased from the initial value Ntint until an equation based on the law of conservation of energy is satisfied. The calculation is performed with the initial value Ntint + γ, then the calculation is performed with the initial value Ntint−γ, and then the initial value Ntint + 2 · γ, the initial value Ntint−2 · γ, the initial value Ntint + 3 · γ, and the initial value Ntint− You may carry out by increasing / decreasing like 3 * (gamma). Alternatively, the maximum value assumed as the assumed turbocharger rotation speed Nt may be given as an initial value, and gradually decreased from the initial value Ntint during estimation. What has been described above is similarly applied to the assumed value (variable) changed for estimating the turbocharger state quantity in addition to the turbine inflow gas pressure P4.

  Furthermore, since the turbocharger whose state quantity is estimated in each of the above embodiments is a variable nozzle type turbocharger, the variable nozzle opening VN is one of the turbocharger state quantities. In contrast, the present invention is naturally applicable to a turbocharger that does not include a variable nozzle variable mechanism (not a variable nozzle type). In this case, for example, in the formulas (12) and (15), if the variable nozzle opening VN is set to a constant value, the state quantity of the turbocharger can be obtained using the plurality of formulas as they are.

1 is a schematic configuration diagram of a turbocharger state quantity estimation device and an internal combustion engine to which the estimation device according to a first embodiment of the present invention is applied. FIG. 2 is a functional block diagram of the turbocharger state quantity estimating device shown in FIG. 1. It is a figure which shows the variable which the turbocharger state quantity estimation apparatus shown in FIG. 1 handles as a turbocharger state quantity. It is the flowchart which showed the program which CPU of the turbocharger state quantity estimation apparatus shown in FIG. 1 performs. It is the flowchart which showed the program (compressor program 1) which CPU of the turbocharger state quantity estimation apparatus shown in FIG. 1 performs. It is the flowchart which showed the program (turbine program 1) which CPU of the turbocharger state quantity estimation apparatus shown in FIG. 1 performs. It is the flowchart which showed the program which CPU of the turbocharger state quantity estimation apparatus which concerns on 2nd Embodiment of this invention runs. It is the flowchart which showed the program (turbine program 2) which CPU of the turbocharger state quantity estimation apparatus which concerns on 2nd Embodiment of this invention performs. It is the flowchart which showed the program (compressor program 2) which CPU of the turbocharger state quantity estimation apparatus which concerns on 2nd Embodiment of this invention performs. It is the flowchart which showed the program which CPU of the turbocharger state quantity estimation apparatus which concerns on 3rd Embodiment of this invention performs additionally for the abnormality detection of a turbocharger rotational speed detection sensor. The CPU of the turbocharger state quantity estimation device according to the third embodiment of the present invention shows a program that is additionally executed to determine whether other sensors other than the turbocharger rotation speed detection sensor are abnormal. It is a flowchart. It is the flowchart which showed the program which CPU of the turbocharger state quantity estimation apparatus which concerns on 4th Embodiment of this invention runs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Multi-cylinder diesel engine (internal combustion engine), 20 ... Engine main body, 21 ... Fuel injection valve, 30 ... Intake system, 31 ... Intake manifold, 32 ... Surge tank, 33 ... Intake pipe, 34 ... Throttle valve, 34a ... Throttle Valve actuator, 35 ... intercooler, 36 ... turbocharger, 36a ... compressor, 36a1 ... compressor blade, 36b ... turbine, 36b1 ... turbine blade, 36c ... turbine shaft, 36d ... nozzle vane, 36e ... nozzle vane actuator, 40 ... exhaust system, 41 DESCRIPTION OF SYMBOLS ... Exhaust manifold, 42 ... Exhaust pipe, 50 ... Electric control device, 51 ... Air flow meter, 52 ... Compressor inflow gas pressure sensor, 53 ... Compressor inflow gas temperature sensor, 54 ... Turbine inflow gas temperature sensor, 55 ... Turbine outflow Scan the pressure sensor, 56 ... variable nozzle opening degree sensor, 57 ... accelerator pedal operation amount sensor, 58 ... engine rotational speed sensor.

Claims (6)

A turbocharger state quantity estimating device for supercharging an internal combustion engine,
A compressor inflow gas state variable representing a state of gas flowing into the compressor of the turbocharger, a compressor outflow gas state variable representing a state of gas flowing out from the compressor, a compressor passing gas flow rate being a flow rate of gas passing through the compressor, Compressor model equation describing the relationship between the turbocharger rotation speed, which is the rotation speed of the rotating shaft of the turbocharger, and the compressor applied energy, which is the energy that the compressor gives to the gas passing through the compressor,
A turbine inflow gas state variable representing a state of gas flowing into the turbine of the turbocharger, a turbine outflow gas state variable representing a state of gas flowing out from the turbine, a turbine passing gas flow rate being a flow rate of gas passing through the turbine, A turbine model equation describing the relationship between the turbocharger rotational speed and turbine acquired energy, which is the energy the turbine receives from the gas passing through the turbine,
An inertial energy equation for determining the inertial energy of the turbocharger based on the turbocharger rotation speed;
Loss energy formula for determining the loss energy of the turbocharger based on the turbocharger rotation speed,
An energy balance formula that the sum of compressor imparted energy, turbocharger inertial energy, and turbocharger loss energy is equal to turbine acquired energy, and
A mass conservation type in which the sum of the compressor passing gas flow rate and the amount of fuel supplied to the internal combustion engine is equal to the turbine passing gas flow rate,
And measuring the predetermined variable of the plurality of variables used in the plurality of equations, and applying the measured predetermined variable to the plurality of equations, so that the compressor inflow gas state variable, the compressor outflow Of the gas state variable, the turbine inflow gas state variable, the turbine outflow gas state variable, the compressor passing gas flow rate, the turbine passing gas flow rate, the turbocharger rotational speed, and the amount of fuel supplied to the internal combustion engine. A turbocharger state quantity estimating apparatus that estimates a variable that is not present as a state quantity of the turbocharger. The turbocharger state quantity estimating device according to claim 1,
A sensor that actually measures one of the estimated variables;
Sensor abnormality determination means for determining that the sensor is abnormal when a variable actually measured by the sensor and a value of the one estimated variable deviate by a predetermined value or more;
A turbocharger state quantity estimating device. The turbocharger state quantity estimating device according to claim 1,
At least one of the estimated variables is an assumed value that is sequentially changed until the mass conservation formula is satisfied, and the same mass is maintained even if the assumed value to be changed exceeds a predetermined range. A turbocharger state quantity estimation device comprising turbocharger abnormality determining means for determining that the supercharging system including the turbocharger is abnormal when the conservation formula is not satisfied. The turbocharger state quantity estimating device according to claim 1,
At least one of the estimated variables is an assumed value that is sequentially changed until the energy balance equation is satisfied, and the same energy even if the assumed value to be changed exceeds a predetermined range. A turbocharger state quantity estimating device comprising turbocharger abnormality determining means for determining that the supercharging system including the turbocharger is abnormal when the balance formula is not established. The turbocharger state quantity estimating device according to claim 1,
When the loss energy used in the energy balance equation when the unmeasured variable is estimated is larger than a threshold value determined based on the compressor imparted energy used in the energy balance equation, the turbocharger A turbocharger state quantity estimation device comprising turbocharger abnormality determination means for determining that the supercharging system including the abnormality is abnormal. In the turbocharger state quantity estimating device according to any one of claims 1 to 5,
The compressor inflow gas state variables are the temperature and pressure of the gas flowing into the turbocharger compressor,
The compressor effluent gas state variables are the temperature and pressure of the gas leaving the turbocharger compressor,
The turbine inflow gas state variables are the temperature and pressure of the gas flowing into the turbocharger turbine,
The turbine effluent gas state variables are the temperature and pressure of gas exiting the turbocharger turbine,
Turbocharger state quantity estimation device.

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