JP2014047777A - State quantity estimating device of internal combustion engine - Google Patents

Abstract

An object of the present invention is to provide a state quantity estimating device for an internal combustion engine capable of accurately estimating state quantities on the compressor side and turbine side of each stage of a turbocharger in an internal combustion engine equipped with a multistage supercharging system.
In an internal combustion engine (1) equipped with a multi-stage turbocharging system including a high-pressure stage turbocharger (6) and a low-pressure stage turbocharger (5), a state quantity estimation device for estimating a state quantity for each turbocharger (5, 6), An intermediate boost pressure sensor 11 for detecting the pressure between the compressor 6a of the high-pressure stage turbocharger 6 and the compressor 5a of the low-pressure stage turbocharger 5 is provided. Based on the intermediate boost pressure between the compressors detected by the intermediate boost pressure sensor 11 Then, the state quantity on the compressor side is estimated, and the state quantity on the turbine side is estimated using the estimated state quantity on the compressor side (for example, the compressor rotation speed).
[Selection] Figure 1

Description

  The present invention relates to a state quantity estimating device for estimating a state quantity for each turbocharger in an internal combustion engine including a multistage turbocharging system including a high pressure stage turbocharger and a low pressure stage turbocharger.

  When performing vehicle engine control, exhaust gas purification control, or the like, it is important to accurately grasp the state quantities of each part of the engine in order to improve control accuracy. In particular, in the case of an engine equipped with a multistage supercharging system, it is necessary to grasp the state quantity of the turbocharger at each stage. Patent Document 1 discloses that in a two-stage turbocharger, the pressure between the compressors of the high-pressure stage turbocharger and the low-pressure stage turbocharger is detected and the temperature between the compressors is calculated using the intermediate pressure. Yes.

Special table 2010-531412 gazette

  In the multistage turbocharging system, the compressor side and the turbine side are connected in series, and operate while affecting each other. In particular, in the case of transient operation, the total efficiency of the multistage supercharging system varies greatly depending on the operating state of each turbocharger. Therefore, in order to use the multistage turbocharging system in a state where the total efficiency is good, it is necessary to accurately grasp the state quantities on the compressor side and the turbine side of each stage of the turbocharger. However, in patent document 1, only the temperature between compressors is estimated using the intermediate pressure between compressors.

  Accordingly, an object of the present invention is to provide an internal combustion engine state quantity estimation device capable of accurately estimating state quantities on the compressor side and turbine side of each stage turbocharger in an internal combustion engine equipped with a multistage turbocharging system. To do.

  An internal combustion engine state quantity estimation apparatus according to the present invention is a state quantity estimation apparatus that estimates a state quantity for each turbocharger in an internal combustion engine having a multistage turbocharging system including a high-pressure stage turbocharger and a low-pressure stage turbocharger. Intermediate pressure detecting means for detecting the pressure between the compressor of the high-pressure stage turbocharger and the compressor of the low-pressure stage turbocharger or the pressure between the turbine of the high-pressure stage turbocharger and the turbine of the low-pressure stage turbocharger; In the case where the pressure detecting means is a detecting means for detecting the intermediate pressure between the compressors, the state quantity on the compressor side is estimated based on the intermediate pressure between the compressors detected by the intermediate pressure detecting means, and the estimated state quantity on the compressor side is calculated. To estimate the state quantity on the turbine side. In the case of the detection means for detecting the engine, the state quantity on the turbine side is estimated based on the intermediate pressure between the turbines detected by the intermediate pressure detection means, and the state quantity on the compressor side is estimated using the estimated state quantity on the turbine side. And an estimating means.

  In this state quantity estimating device, the pressure between the compressors of the high-pressure stage turbocharger and the low-pressure stage turbocharger is detected by the intermediate pressure detecting means. In the state quantity estimation device, the estimation means estimates the compressor-side state quantity based on the intermediate pressure between the compressors, and estimates the turbine-side state quantity using the compressor-side state quantity. Further, in the state quantity estimating device, the intermediate pressure detecting means detects the pressure between the turbines of the high-pressure stage turbocharger and the low-pressure stage turbocharger. In the state quantity estimation device, the estimation means estimates the turbine-side state quantity based on the intermediate pressure between the turbines, and estimates the compressor-side state quantity using the turbine-side state quantity. When estimating each state quantity, a detection value of a sensor (for example, an intake gas temperature sensor, a flow rate sensor, or a boost pressure sensor) generally provided in an internal combustion engine is used as necessary. As described above, in this state quantity estimating device, only the intermediate pressure detecting means for detecting the intermediate pressure between the compressors or the turbines is added to a general sensor provided in the internal combustion engine, so that each stage of the multistage turbocharging system is The state quantity on the compressor side and turbine side of the turbocharger can be estimated with high accuracy. In this way, the state quantities on the compressor and turbine sides of each stage of the turbocharger can be obtained, so the operating state of each stage of the turbocharger can be ascertained not only from the steady state but also from the transient state. Each turbocharger can be used in an efficient place as a total of the multistage turbocharging system based on the operating state. Furthermore, each of these state quantities can be used for internal combustion engine control (including turbocharger control), exhaust gas purification control, failure detection, etc., and control accuracy can be improved. In the case of a multi-stage turbocharging system with three or more stages, there are multiple combinations of high-pressure turbochargers and low-pressure turbochargers. For each combination, the intermediate pressure between compressors or turbines is detected to estimate the state quantity. To do.

  In the internal combustion engine state quantity estimating apparatus according to the present invention, the estimating means is based on the intermediate pressure between the compressors detected by the intermediate pressure detecting means when the intermediate pressure detecting means is a detecting means for detecting the intermediate pressure between the compressors. Then, the state quantity of the compressor of the high-pressure stage turbocharger and the state quantity of the compressor of the low-pressure stage turbocharger are estimated, and the high-pressure stage turbocharger is used using the estimated high-speed stage turbocharger compressor state quantity. The turbine state quantity of the low pressure stage turbocharger is estimated using the low speed stage turbocharger rotational speed included in the estimated state quantity of the compressor of the low pressure stage turbocharger. In the case of detection means for detecting the intermediate pressure between The state quantity of the turbine of the high-pressure stage turbocharger and the state quantity of the turbine of the low-pressure stage turbocharger are estimated based on the intermediate pressure between the extracted turbines, and the high-pressure stage turbine included in the estimated state quantity of the turbine of the high-pressure stage turbocharger The state quantity of the compressor of the high-pressure stage turbocharger is estimated using the rotation speed, and the state quantity of the compressor of the low-pressure stage turbocharger is calculated using the low-pressure stage turbine rotation speed included in the estimated state quantity of the turbine of the low-pressure stage turbocharger. It is preferable to estimate.

  In each turbocharger, since the compressor and the turbine rotate coaxially, the compressor speed and the turbine speed are the same. Therefore, when the compressor rotational speed is estimated, the compressor rotational speed can be used as the turbine rotational speed. Alternatively, when the turbine rotational speed is estimated, the turbine rotational speed can be used as the compressor rotational speed. Therefore, in the case where the intermediate pressure detecting means is a detecting means for detecting the intermediate pressure between the compressors, the estimating means determines the state quantity of each part of the compressor of the high-pressure turbocharger based on the intermediate pressure between the compressors detected by the intermediate pressure detecting means. Estimating the state quantity (including compressor speed) of each part of the compressor (including the compressor speed) and the compressor of the low-pressure stage turbocharger, and using the compressor speed of the high-pressure stage turbocharger, each part of the turbine of the high-pressure stage turbocharger The state quantity of each part of the turbine of the low-pressure stage turbocharger can be estimated using the compressor rotation speed of the low-pressure stage turbocharger. On the other hand, when the intermediate pressure detecting means is a detecting means for detecting the intermediate pressure between the turbines, the estimating means determines the state quantity of each part of the turbine of the high-pressure stage turbocharger based on the intermediate pressure between the turbines detected by the intermediate pressure detecting means. The state quantity (including turbine speed) of each part of the turbine of the low-pressure stage turbocharger (including the turbine speed) is estimated, and each part of the compressor of the high-pressure stage turbocharger is estimated using the turbine speed of the high-pressure stage turbocharger. The state quantity of each part of the compressor of the low-pressure stage turbocharger can be estimated using the turbine speed of the low-pressure stage turbocharger.

  In the internal combustion engine state quantity estimating apparatus according to the present invention, it is preferable that the intermediate pressure detecting means is a detecting means for detecting an intermediate pressure between the compressors. The compressor side is the intake side of the internal combustion engine, and the intake side has higher safety in providing pressure detecting means, and is more suitable than the exhaust side.

  According to the present invention, the compressor side of the turbocharger at each stage of the multi-stage turbocharging system can be obtained by adding an intermediate pressure detecting means for detecting an intermediate pressure between compressors or between turbines to a general sensor provided in an internal combustion engine. In addition, the state quantity on the turbine side can be estimated with high accuracy.

It is a schematic block diagram of the engine which concerns on this Embodiment.

  Hereinafter, an embodiment of a state quantity estimating device for an internal combustion engine according to the present invention will be described with reference to the drawings.

  In the present embodiment, the state quantity estimating device for an internal combustion engine according to the present invention is applied to an ECU (Electronic Control Unit) of an engine (internal combustion engine) mounted on a diesel vehicle. The engine according to the present embodiment is equipped with a two-stage turbocharging system and an EGR [Exhaust Gas Recirculation] system of HPL [High Pressure Loop], and the high-pressure turbocharger in the two-stage turbocharging system is a variable capacity type. The low-pressure stage turbocharger is a fixed capacity type. In the engine according to the present embodiment, well-known engine control, turbo variable capacity control, EGR control, exhaust gas purification control, failure diagnosis, and the like are performed by the ECU, and each stage for use in such control is performed. The state quantity of the turbocharger is estimated. In this embodiment, these well-known controls in the ECU are not described, and only the turbocharger state quantity estimation process is described in detail.

  An engine 1 according to the present embodiment will be described with reference to FIG. FIG. 1 is a schematic configuration diagram of an engine according to the present embodiment.

  The engine 1 (especially the state quantity estimation in the ECU 17) is generally mounted in the engine in order to estimate the state quantities (temperature, pressure, rotation speed) of the compressor side and turbine side parts of the turbochargers of each stage. Only a sensor for detecting an intermediate pressure between the compressors (hereinafter referred to as “intermediate boost pressure P2L”) is added to each sensor. In particular, in the state quantity estimation in the ECU 17, the state quantity of each part of the low-pressure stage compressor is estimated using the intermediate boost pressure P2L, and further, the state quantity of each part of the high-pressure stage compressor is estimated, and the rotation speed of the high-pressure stage compressor is used. Then, the state quantity of each part of the high-pressure stage turbine is estimated, and further, the state quantity of each part of the low-pressure stage turbine is estimated using the rotation speed of the low-pressure stage compressor.

  The engine 1 is an in-line 6-cylinder diesel engine in which six cylinders (cylinders) 2a to 2f are arranged in series with an engine body 1a. Each cylinder 2a to 2f is provided with an injector (not shown). In each injector, fuel (light oil) is injected into each cylinder 2a-2f. In the engine body 1a, fuel is injected for each of the cylinders 2a to 2f in a state where the gas in the cylinder (air from the atmosphere + exhaust gas recirculation EGR gas) is adiabatically compressed by a piston (not shown). Combustion is performed.

  An intake manifold 3 is connected to the engine body 1a (cylinders 2a to 2f). In the intake manifold 3, the sucked gas (air + EGR gas) is distributed and supplied to the cylinders 2a to 2f. The intake manifold 3 is provided with an intake manifold temperature sensor 3a. The intake manifold temperature sensor 3 a detects the temperature of the gas in the intake manifold 3 (hereinafter referred to as “intake manifold temperature”), and outputs the detected value to the ECU 17.

  An exhaust manifold 4 is connected to the engine body 1a (cylinders 2a to 2f). In the exhaust manifold 4, exhaust gases exhausted from the cylinders 2 a to 2 f are merged and guided to the turbine 6 b of the high-pressure stage turbocharger 6 and the EGR passage 16 a of the EGR system 16. The exhaust manifold 4 is provided with an exhaust manifold pressure sensor 4a and an exhaust manifold temperature sensor 4b. The exhaust manifold pressure sensor 4 a detects the pressure of the exhaust gas in the exhaust manifold 4 (hereinafter referred to as “exhaust manifold pressure P3H”), and outputs the detected value to the ECU 17. The exhaust manifold temperature sensor 4b detects the temperature of the exhaust gas in the exhaust manifold 4 (hereinafter referred to as “exhaust manifold temperature T3H”), and outputs the detected value to the ECU 17. It should be noted that the state quantity can be estimated even if the exhaust manifold pressure sensor 4a and the exhaust manifold temperature sensor 4b are not provided.

  The engine 1 is equipped with a two-stage supercharging system (a low-pressure stage turbocharger 5 and a high-pressure stage turbocharger 6). The low-pressure stage turbocharger 5 includes a low-pressure stage compressor 5a and a low-pressure stage turbine 5b, and the low-pressure stage compressor 5a and the low-pressure stage turbine 5b rotate coaxially. In the low-pressure stage turbocharger 5, the low-pressure stage turbine 5b rotates with the pressure of the exhaust gas discharged from the high-pressure stage turbine 6b, and the air is compressed and supercharged by the low-pressure stage compressor 5a that rotates coaxially with the low-pressure stage turbine 5b. .

  The high-pressure stage turbocharger 6 includes a high-pressure stage compressor 6a and a high-pressure stage turbine 6b, and the high-pressure stage compressor 6a and the high-pressure stage turbine 6b rotate coaxially. The high-pressure stage compressor 6a is arranged downstream of the low-pressure stage compressor 5a on the intake side, and the high-pressure stage turbine 6b is arranged upstream of the low-pressure stage turbine 5b on the exhaust side. In the high-pressure stage turbocharger 6, the high-pressure stage turbine 6b is rotated by the pressure of the exhaust gas guided from the exhaust manifold 4, and the air is compressed and supercharged by the high-pressure stage compressor 6a that rotates coaxially with the high-pressure stage turbine 6b. The high-pressure turbine 6b is provided with a nozzle vane 6c, and the flow rate of exhaust gas introduced into the high-pressure turbine 6b is controlled by the opening degree of the nozzle vane 6c. The high-pressure stage turbocharger 6 has a smaller capacity than the low-pressure stage turbocharger 5. This is because exhaust energy is once recovered in the high-pressure stage turbocharger 6 and the expanded exhaust gas is handled by the low-pressure stage turbocharger 5.

  On the intake side, air is sucked from the atmosphere through the air cleaner 7 and compressed by the low-pressure compressor 5a. An intake air temperature / intake air amount sensor 9 is provided in the intake air passage 8a between the air cleaner 7 and the low pressure compressor 5a. The intake air temperature / intake air amount sensor 9 detects the temperature of air sucked from the atmosphere (hereinafter referred to as “intake air temperature T1L”) and the amount of air (hereinafter referred to as “intake air amount Ga”). The value is output to the ECU 17. The air compressed by the low-pressure compressor 5 a is cooled by the intercooler 10. The intercooler 10 uses low-temperature cooling water in a separate circuit from the engine body 1a as a refrigerant, and is provided with a refrigerant temperature sensor 10a. The refrigerant temperature sensor 10 a detects the temperature of the refrigerant in the intercooler 10 (hereinafter referred to as “refrigerant temperature Tic”), and outputs the detected value to the ECU 17. An intermediate boost pressure sensor 11 is provided in the intake passage 8b between the low-pressure compressor 5a and the intercooler 10. The intermediate boost pressure sensor 11 detects an intermediate pressure (hereinafter referred to as “intermediate boost pressure P2L”) between the low pressure compressor 5a and the high pressure compressor 6a, and outputs the detected value to the ECU 17. The compressed air cooled by the intercooler 10 is further compressed by the high-pressure compressor 6a. The air compressed by the high-pressure compressor 6 a is cooled by the aftercooler 12 and sucked into the intake manifold 3. A boost pressure sensor 13 is provided in the intake passage 8 c between the aftercooler 12 and the intake manifold 3. The boost pressure sensor 13 detects the pressure in the intake manifold 3 after supercharging by the two-stage turbochargers 5 and 6 (hereinafter referred to as “boost pressure Pim”), and outputs the detected value to the ECU 17. In the present embodiment, the intermediate boost pressure sensor 11 corresponds to the intermediate pressure detection means described in the claims.

  On the exhaust side, the exhaust gas from the exhaust manifold 4 is adjusted in flow rate by the nozzle vane 6c and introduced into the high-pressure turbine 6b, and the high-pressure turbine 6b rotates with the exhaust gas. The exhaust gas emitted from the high-pressure turbine 6b is introduced into the low-pressure turbine 5b, and the low-pressure turbine 5b is rotated by the exhaust gas. The exhaust gas emitted from the low-pressure turbine 5b is guided to an exhaust system (not shown) through the exhaust passage 14, is purified by the exhaust system, and is exhausted from the muffler 15 to the outside of the vehicle.

  The engine 1 is equipped with an EGR system 16. The EGR system 16 includes an EGR passage 16a. The EGR passage 16a is a passage connecting the exhaust manifold 4 and the intake passage 8c, and recirculates exhaust gas from the exhaust manifold 4 to the intake side as EGR gas. The EGR passage 16a is provided with an EGR cooler 16b, and the exhaust gas recirculated by the EGR cooler 16b is cooled. The EGR passage 16a is provided with an EGR valve 16c, and the amount of EGR gas recirculated by the EGR valve 16c is controlled.

  The ECU 17 is an electronic control unit including a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like, and comprehensively controls the engine 1. The ECU 17 loads various programs stored in the ROM into the RAM and executes them by the CPU, thereby controlling the engine main body (for example, injector fuel injection control) and turbo variable capacity control (for example, the opening degree of the nozzle vane 6c). Control), EGR control (for example, opening control of the EGR valve 16c), exhaust gas purification control, failure diagnosis, and other known processes and state quantity estimation processing are performed. In the present embodiment, only the state quantity estimation process will be described in detail for the process performed by the ECU 17. In the present embodiment, the processing in the ECU 17 corresponds to the estimation means described in the claims.

  In the ECU 17, the intake manifold temperature sensor 3a, the exhaust manifold pressure sensor 4a, the exhaust manifold temperature sensor 4b, the intake air temperature / intake air amount sensor 9, the refrigerant temperature sensor 10a, the intermediate boost pressure sensor 11, and the boost pressure sensor 13 are The exhaust manifold pressure P3H, the exhaust manifold temperature T3H, the intake air temperature T1L, the intake air amount Ga, the refrigerant temperature Tic, the intermediate boost pressure P2L, and the boost pressure Pim are acquired. An atmospheric pressure sensor 17 a is provided in the ECU 17. The atmospheric pressure sensor 17a detects the atmospheric pressure P0. The ECU 17 acquires the atmospheric pressure P0 from the atmospheric pressure sensor 17a at regular intervals.

  In the ROM of the ECU 17, the corrected rotational speed Ncor = Map (Gcor, πc), the compressor efficiency ηc = Map (Gcor, Ncor), the turbine efficiency ηt = Map (Gcor, Ncor), the turbine expansion ratio πt = Map (Gcor, Gcor, Each map Map such as (Ncor) is held. Each of these maps is a well-known turbo map that is generally known. πc is a pressure ratio. Gcor is the corrected gas flow rate. Gcor and Ncor are “corrected”, but are gas flow rates and rotational speeds standardized by the inlet temperature and inlet pressure. Further, in the ROM of the ECU 17, there is a loss ΔPaf = f (Ga) on the upstream side of the low-pressure compressor 5a including the air cleaner 7 and the like, between the low-pressure compressor 5a including the intercooler 10 and the high-pressure compressor 6a. Each function f such as loss ΔPic = f (Ga), loss ΔPac = f (Ga) downstream of the high-pressure stage compressor 6a including the aftercooler 12 and the like, and intercooler cooling efficiency ηic = f (Ga) is held. Each of these functions is a well-known function that is generally known. Each map may be converted into a function, and each function may be converted into a map.

Each map Map and each function f is obtained by acquiring not the data of the turbocharger alone but the steady data of the use area in the actual engine, and mapping and functioning using the steady data. For example, the compressor efficiency ηc can be obtained by the equation (1) using the compressor input temperature T1, the outlet temperature T2, and the pressure ratio πc, so that the steady-state data at each intake gas flow rate and each compressor speed is used. Compressor efficiency ηc is calculated by equation (1) and mapped. Κ in the formula (1) is a specific heat ratio, and κ = constant pressure specific heat Cp / constant volume specific heat Cv. Further, since the turbine efficiency ηt can be obtained by the equation (2) using the turbine input temperature T3, the outlet temperature T4, and the expansion ratio πt, the steady-state data at each exhaust gas flow rate and each turbine speed is used. Turbine efficiency ηt is calculated according to equation (2) and mapped. Further, the general efficiency ηcool of the cooler (intercooler, etc.) can be obtained by the equation (3) using the cooler input temperature Tin, the outlet temperature Tout, and the refrigerant temperature Tcool. The cooling efficiency ηcool is calculated by the equation (3) using the steady data, and is converted into a function. In the case of a variable capacity type turbocharger (turbine), since the map is unique for each vane opening, a map is prepared for each vane opening at a predetermined interval.

  The state quantity estimation process in the ECU 17 will be described in detail. The ECU 17 uses the detected values of the intermediate boost pressure sensor 11 in addition to the intake air temperature / intake air amount sensor 9, the boost pressure sensor 13, and the atmospheric pressure sensor 17a to determine the state quantity of each part of the low pressure compressor 5a and the high pressure compressor 6a. The state quantity of each part is estimated in order. Further, the ECU 17 estimates the state quantity of each part of the high-pressure stage turbine 6b using the compressor speed of the high-pressure stage compressor 6a, and calculates the state quantity of each part of the low-pressure stage turbine 5b using the compressor speed of the low-pressure stage compressor 5a. Estimate in order.

The estimation of the state quantity of each part of the low-pressure compressor 5a will be described. At regular time intervals, the ECU 17 calculates the loss ΔPaf on the upstream side of the low-pressure compressor 5a including the air cleaner 7 using the intake air amount Ga by the equation (4) based on the function f1. Next, the ECU 17 uses the loss ΔPaf and the atmospheric pressure P0 to calculate the inlet pressure P1L of the low-pressure compressor 5a according to the equation (5). Next, the ECU 17 uses the inlet pressure P1L and the intermediate boost pressure P2L to calculate the pressure ratio πcL of the low-pressure compressor 5a according to the equation (6). Next, the ECU 17 uses the pressure ratio πcL and the corrected flow rate GcorL to search for the corrected rotational speed NcorL of the low-pressure compressor 5a using Map1 shown in Expression (7). The corrected flow rate GcorL is a value obtained by standardizing the intake air amount Ga by the inlet temperature (intake air temperature T1L) and the inlet pressure P1L of the low-pressure compressor 5a. Next, the ECU 17 searches the efficiency ηcL of the low-pressure stage compressor 5a using Map2 shown in Expression (8) using the corrected rotation speed NcorL and the corrected flow rate GcorL. Finally, the ECU 17 uses the efficiency ηcL, the pressure ratio πcL, and the inlet temperature (intake air temperature T1L) to calculate the outlet temperature T2L of the low-pressure compressor 5a according to the equation (9).

The estimation of the state quantity of each part of the high-pressure compressor 6a will be described. The ECU 17 calculates the loss ΔPic between the low-pressure compressor 5a including the intercooler 10 and the high-pressure compressor 6a by using the intake air amount Ga at regular time intervals using the equation (10) based on the function f2. Next, the ECU 17 uses the loss ΔPic and the intermediate boost pressure P2L to calculate the inlet pressure P1H of the high-pressure compressor 6a using Equation (11). Next, the ECU 17 uses the intake air amount Ga to calculate the cooling efficiency ηic of the intercooler 10 by the equation (12) using the function f3. Next, the ECU 17 uses the cooling efficiency ηic, the refrigerant temperature Tic, and the outlet temperature T2L of the low-pressure compressor 5a to calculate the inlet temperature T1H of the high-pressure compressor 6a using Equation (13).

Next, the ECU 17 calculates the loss ΔPac on the downstream side of the high-pressure compressor 6a including the aftercooler 12 by using the intake air amount Ga by the equation (14) based on the function f4. Next, the ECU 17 uses the loss ΔPac and the boost pressure Pim to calculate the outlet pressure P2H of the high-pressure compressor 6a using Equation (15). Next, the ECU 17 uses the outlet pressure P2H and the inlet pressure P1H to calculate the pressure ratio πcH of the high-pressure compressor 6a according to the equation (16). Next, the ECU 17 uses the pressure ratio πcH and the corrected flow rate GcorH to search for the corrected rotation speed NcorH of the high-pressure compressor 6a using Map3 shown in Expression (17). The corrected flow rate GcorH is a value obtained by standardizing the intake air amount Ga by the inlet temperature T1H and the inlet pressure P1H of the high-pressure compressor 6a. Next, the ECU 17 searches the efficiency ηcH of the high-pressure compressor 6a by Map4 shown in Expression (18) using the corrected rotation speed NcorH and the corrected flow rate GcorH. Finally, the ECU 17 uses the efficiency ηcH, the pressure ratio πcH, and the inlet temperature T1H to calculate the outlet temperature T2H of the high-pressure compressor 6a using Equation (19).

The estimation of the state quantity of each part of the high-pressure turbine 6b will be described. At regular intervals, the ECU 17 searches for the expansion ratio πtH of the high-pressure turbine 6b using Map5 shown in Equation (20) using the corrected rotation speed NcorH and the corrected flow rate GcorH delivered from the high-pressure compressor 6a side. The corrected flow rate GcorH is a value obtained by standardizing the exhaust gas flow rate (intake air amount Ga + fuel flow rate) based on the inlet temperature (exhaust manifold temperature T3H) and the inlet pressure (exhaust manifold pressure P3H) of the high-pressure turbine 6b. The fuel flow rate can be obtained from the indicated fuel injection amount from the ECU 17 by adjusting the fuel injection amount instructed to each injector from the ECU 17 and the actual fuel injection amount. Next, the ECU 17 uses the expansion ratio πtH and the inlet pressure (exhaust manifold pressure P3H) to calculate the outlet pressure P4H of the high-pressure turbine 6b according to the equation (21). Next, the ECU 17 searches the efficiency ηtH of the high-pressure turbine 6b by Map6 shown in Expression (22) using the corrected rotation speed NcorH and the corrected flow rate GcorH delivered from the high-pressure compressor 6a side. Finally, the ECU 17 uses the efficiency ηtH, the expansion ratio πtH, and the inlet temperature T3H to calculate the outlet temperature T4H of the high-pressure turbine 6b using Equation (23). In the case of a variable capacity type turbocharger (turbine), the map is unique for each vane opening as described above. Therefore, each value is calculated for each vane opening by the above formula, and the current vane opening is calculated. The value interpolated in is used as the current state quantity.

  The inlet pressure P3H is detected by the exhaust manifold pressure sensor 4a, but may be obtained by estimation using an intake manifold pressure (boost pressure Pim), a vane opening degree, or the like. The inlet temperature T3H is detected by the exhaust manifold temperature sensor 4b. However, the inlet temperature T3H may be obtained by estimation in consideration of damage to the turbine when the sensor breaks. When the inlet pressure P3H and the inlet temperature T3H are obtained by these estimations, the sensor in the exhaust manifold 4 is not necessary.

The estimation of the state quantity of each part of the low-pressure stage turbine 5b will be described. At regular intervals, the ECU 17 sets the outlet pressure P4H of the high-pressure turbine 6b as the inlet pressure P3L of the low-pressure turbine 5b as shown in the equation (24). Next, the ECU 17 sets the outlet temperature T4H of the high-pressure turbine 6b as the inlet temperature T3L of the low-pressure turbine 5b as shown in the equation (25). Next, the ECU 17 searches for the expansion ratio πtL of the low-pressure turbine 5b using Map7 shown in Expression (26) using the corrected rotation speed NcorL and the corrected flow rate GcorL delivered from the low-pressure compressor 5a side. The corrected flow rate GcorL is a value obtained by standardizing the exhaust gas flow rate (intake amount Ga + fuel flow rate) by the inlet temperature T3L and the inlet pressure P3L of the low-pressure turbine 5b. Next, the ECU 17 uses the expansion ratio πtL and the inlet pressure P3L to calculate the outlet pressure P4L of the low-pressure turbine 5b according to the equation (27). Next, the ECU 17 searches the efficiency ηtL of the low-pressure stage turbine 5b using Map8 shown in Expression (28) using the corrected rotation speed NcorL and the corrected flow rate GcorL delivered from the low-pressure stage compressor 5a side. Finally, the ECU 17 uses the efficiency ηtL, the expansion ratio πtL, and the inlet temperature T3L to calculate the outlet temperature T4L of the low-pressure turbine 5b according to the equation (29).

  Then, the ECU 17 estimates each state quantity of the low-pressure stage compressor 5a (inlet pressure P1L, outlet temperature T2L, corrected rotational speed NcorL, etc.), and each state quantity of the high-pressure stage compressor 6a (inlet pressure P1H, inlet temperature T1H, outlet Pressure P2H, outlet temperature T2H, corrected rotational speed NcorH, etc.), each state quantity of the high pressure turbine 6b (exit pressure P4H, outlet temperature T4H, etc.), each state quantity of the low pressure turbine 5b (inlet pressure P3L, inlet temperature T3L, The outlet pressure P4L and the outlet temperature T4L) are used for engine body control, turbo variable capacity control, EGR control, exhaust gas purification control, failure diagnosis, and the like. At this time, since the respective state quantities of the compressors 5a, 6a and the turbines 5b, 6b of each stage are obtained in the steady operation state and the transient operation state, the operation states of the turbochargers 5, 6 of each stage are obtained from these state quantities. The turbochargers 5 and 6 can be used where the total efficiency of the two-stage turbocharging system is high based on each operating state. Since each calculated state quantity is an instantaneous value, for each state quantity, first-order lag correction is performed for each state quantity using a time-series instantaneous value, and an annealing value is calculated. May be used.

  According to the engine 1 (particularly, the state quantity estimation processing in the ECU 17 using the intermediate boost pressure sensor 11), in addition to the general sensors (intake air temperature / intake air quantity sensor 9, boost pressure sensor 13, etc.) provided in the engine. By adding only the intermediate boost pressure sensor 11 for detecting the intermediate pressure between the compressors 5a and 6a, the state quantities of the compressor side and turbine side parts of the turbochargers 5 and 6 of each stage of the two-stage turbocharging system can be obtained. It can be estimated with high accuracy. As described above, since the state quantities of the compressor side and the turbine side of the turbochargers 5 and 6 of each stage can be obtained, the efficiency of the two-stage turbocharging system as a whole is good not only in the steady operation state but also in the transient operation state. By the way, turbochargers 5 and 6 can be used. Furthermore, each of these state quantities can be used for engine control (including turbo control and EGR control), exhaust gas purification control, failure detection, and the like, and the control accuracy not only in the steady operation state but also in the transient operation state can be improved.

  Further, according to the engine 1, since the intermediate boost pressure sensor 11 for detecting the intermediate pressure is provided on the compressor side (intake side) of the turbochargers 5 and 6, the environment is better than the exhaust side and the safety is high. .

  As mentioned above, although embodiment which concerns on this invention was described, this invention is implemented in various forms, without being limited to the said embodiment.

  For example, in the present embodiment, the state quantity estimation device is incorporated as one function of the engine ECU. However, the state quantity estimation device may be incorporated in other ECUs or configured as a state quantity estimation device alone. You may comprise in the form of.

  In the present embodiment, the internal combustion engine is a diesel engine, which is applied to a variable displacement turbocharger, a fixed displacement turbocharger, and an EGR system. However, other internal combustion engines such as a gasoline engine are also used. Applicable, even without an EGR system, applicable to turbochargers regardless of fixed capacity type / variable capacity type, and EGR systems applicable to EPL systems of LPL . Further, it is also possible to use a device without an intermediate cooler (intercooler), and the cooling method of the intermediate cooler may be another cooling method such as air cooling.

  Moreover, although applied to the two-stage supercharging system in the present embodiment, the present invention can also be applied to other multistage supercharging systems such as a three-stage supercharging system. For example, in the case of a three-stage turbocharging system, between the compressors (or between the turbines) of the first-stage turbocharger and the second-stage turbocharger, and between the compressors of the second-stage turbocharger and the third-stage turbocharger Provide an intermediate boost pressure sensor (or between turbines) to obtain the state quantity of each part on the compressor (or turbine) side using the intermediate boost pressure for each combination, and use the compressor speed (or turbine speed) The state quantity of each part on the turbine (or compressor) side is obtained.

  In the present embodiment, since the intercooler (intercooler) is a cooler that uses low-temperature cooling water in a separate circuit from the engine main body as a refrigerant, a refrigerant temperature sensor (water temperature sensor) is provided. In the case of the cooler using the coolant in the same circuit as the refrigerant, the refrigerant temperature sensor is not necessary in the case of other configurations such as an air-cooled cooler.

  In this embodiment, the intermediate boost pressure sensor (intermediate pressure detection means) is provided between the intercooler and the low-pressure compressor, but the intermediate boost pressure sensor may be provided between the low-pressure compressor and the high-pressure compressor. Therefore, it may be provided between the intercooler and the high-pressure stage compressor.

  Further, in the present embodiment, an intermediate pressure sensor is provided between the compressors, the intermediate pressure between the compressors is detected, and the state quantity of the high-pressure stage compressor and the state quantity of the low-pressure stage compressor are estimated using the intermediate pressure. The state quantity of the high-pressure stage turbine is estimated using the high-pressure stage compressor rotational speed and the state quantity of the low-pressure stage turbine is estimated using the low-pressure stage compressor rotational speed. The intermediate pressure is detected, the state quantity of the high-pressure turbine and the state quantity of the low-pressure turbine are estimated using the intermediate pressure, and the high-pressure stage compressor state quantity is estimated using the estimated high-pressure turbine speed. It is good also as a structure which estimates the state quantity of a low pressure stage compressor using a low pressure stage turbine rotation speed.

  In the present embodiment, the turbine-side state quantity is estimated using the compressor rotation speed as the compressor-side state quantity. However, the turbine-side state quantity is estimated using another compressor-side state quantity. It is good also as a structure.

  DESCRIPTION OF SYMBOLS 1 ... Engine, 1a ... Engine main body, 2a, 2b, 2c, 2d, 2e, 2f ... Cylinder, 3 ... Intake manifold, 3a ... Intake manifold temperature sensor, 4 ... Exhaust manifold, 4a ... Exhaust manifold pressure sensor, 4b ... Exhaust manifold temperature sensor DESCRIPTION OF SYMBOLS 5 ... Low pressure stage turbocharger, 5a ... Low pressure stage compressor, 5b ... Low pressure stage turbine, 6 ... High pressure stage turbocharger, 6a ... High pressure stage compressor, 6b ... High pressure stage turbine, 6c ... Nozzle vane, 7 ... Air cleaner, 8a, 8b , 8c ... Intake passage, 9 ... Intake temperature / intake amount sensor, 10 ... Intercooler, 10a ... Refrigerant temperature sensor, 11 ... Intermediate boost pressure sensor, 12 ... After cooler, 13 ... Boost pressure sensor, 14 ... Exhaust passage, 15 ... Muffler 16 ... EGR system, 16a ... EGR passage, 16b ... EGR La, 16c ... EGR valve, 17 ... ECU, 17a ... atmospheric pressure sensor.

Claims (3)

In an internal combustion engine equipped with a multi-stage turbocharging system including a high-pressure stage turbocharger and a low-pressure stage turbocharger, a state quantity estimation device that estimates a state quantity for each turbocharger,
Intermediate pressure detecting means for detecting the pressure between the compressor of the high-pressure stage turbocharger and the compressor of the low-pressure stage turbocharger or the pressure between the turbine of the high-pressure stage turbocharger and the turbine of the low-pressure stage turbocharger;
When the intermediate pressure detecting means is a detecting means for detecting an intermediate pressure between the compressors, a state quantity on the compressor side is estimated based on the intermediate pressure between the compressors detected by the intermediate pressure detecting means, and the estimated compressor side In the case where the intermediate pressure detection means is a detection means for detecting the intermediate pressure between the turbines, it is based on the intermediate pressure between the turbines detected by the intermediate pressure detection means. Estimating the state quantity on the turbine side, and estimating means for estimating the state quantity on the compressor side using the estimated state quantity on the turbine side,
A state quantity estimating device for an internal combustion engine, comprising:   In the case where the intermediate pressure detecting means is a detecting means for detecting the intermediate pressure between the compressors, the estimating means is based on the intermediate pressure between the compressors detected by the intermediate pressure detecting means, and the state of the compressor of the high pressure turbocharger And the state quantity of the compressor of the low-pressure stage turbocharger, and the state quantity of the turbine of the high-pressure stage turbocharger using the high-pressure stage compressor rotation speed included in the estimated state quantity of the compressor of the high-pressure stage turbocharger. And estimating the turbine state quantity of the low-pressure stage turbocharger using the low-pressure stage compressor rotational speed included in the estimated state quantity of the compressor of the low-pressure stage turbocharger, and the intermediate pressure detecting means In the case of detection means for detecting pressure, the intermediate pressure detection means The state quantity of the turbine of the high-pressure stage turbocharger and the state quantity of the turbine of the low-pressure stage turbocharger are estimated based on the detected intermediate pressure between the turbines, and are included in the estimated state quantity of the turbine of the high-pressure stage turbocharger. The compressor state quantity of the high-pressure stage turbocharger is estimated using the high-pressure stage turbine speed, and the low-pressure stage turbocharger is estimated using the low-pressure stage turbine speed included in the estimated turbine state quantity of the low-pressure stage turbocharger. The state quantity estimating device for an internal combustion engine according to claim 1, wherein the state quantity of the compressor is estimated.   The internal combustion engine state quantity estimating apparatus according to claim 1 or 2, wherein the intermediate pressure detecting means is a detecting means for detecting an intermediate pressure between the compressors.

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