Surging sign detection method

Abstract

To provide a surging sign detection method which can detect a sign of surging of a compressor in a supercharger.SOLUTION: A surging sign detection method comprises: a measurement data acquiring step of acquiring measurement data for a plurality of parameters related to an operation state of an engine; an estimation step of estimating a pressure ratio of a compressor of a supercharger and a suction air quantity on the basis of the measurement data for the plurality of parameters; an operation point transition monitoring step of plotting the operation point of the compressor which is determined by the pressure ratio and the suction air quantity estimated by the estimation step on a compressor map with the suction air quantity of the compressor and the pressure ratio being coordinate axes and monitoring a transition of the operation point; and a surging sign detection step of detecting a sign of surging of the compressor by comparing the operation point being monitored at the operation point transition monitoring step and a threshold line which is defined according to a surge line with each other.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to a method for detecting a sign of surging. [Background technology]

[0002] Usually, after the operating point of a turbocharger is confirmed in a matching test between the turbocharger and the engine, the operating point of the turbocharger is not confirmed during operation of the turbocharger. On the other hand, if the operating point changes due to, for example, adhesion of unburned fuel to turbocharger parts, an abnormal event such as surging may occur. If surging occurs, not only the turbocharger but also the engine may be damaged.

[0003] Patent Document 1 describes that when surging occurs in a supercharger, the surging can be quickly eliminated by setting the target EGR rate to zero. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2021-127688 Summary of the Invention [Problem to be solved by the invention]

[0005] Patent Document 1 merely discloses a method for eliminating surging after it has occurred, and is not capable of detecting signs of surging before it occurs.

[0006] In view of the above circumstances, at least one embodiment of the present disclosure has an object to provide a surge sign detection method capable of detecting a sign of compressor surging in a turbocharger. [Means for solving the problem]

[0007] In order to achieve the above object, a surging sign detection method according to at least one embodiment of the present disclosure includes: A surge sign detection method for detecting a sign of compressor surging in a turbocharger, comprising: a measurement data acquisition step of acquiring measurement data of a plurality of parameters related to an operating state of an engine connected to the turbocharger; an estimation step of estimating a pressure ratio and an intake air amount of a compressor of the turbocharger based on measurement data of the plurality of parameters; an operating point transition monitoring step of plotting an operating point of the compressor determined by the pressure ratio and the intake air amount estimated in the estimation step on a compressor map having coordinate axes of the intake air amount and the pressure ratio of the compressor, and monitoring a transition of the operating point; a surge sign detection step of detecting a sign of surging of the compressor by comparing the operating point monitored in the operating point transition monitoring step with a threshold line determined according to a surge line; Equipped with. [Effects of the Invention]

[0008] According to at least one embodiment of the present disclosure, there is provided a surge sign detection method capable of detecting a sign of compressor surging in a turbocharger. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating a configuration of a supercharger to which a surging sign detection method according to an embodiment of the present disclosure is applied; [Figure 2] 1 is a flowchart showing an outline of a surging sign detection method applicable to the above-described turbocharger 3. FIG. [Figure 3] 10 is a diagram showing an example of a compressor map Mp and a transition Lpi of an operating point displayed on a display device 12. FIG. [Figure 4] FIG. 10 is a diagram illustrating an example of a method for estimating an operating point pi. [Figure 5]FIG. 10 is a diagram illustrating another example of a method for estimating an operating point pi. [Figure 6] FIG. 10 is a diagram illustrating another example of a method for estimating an operating point pi. [Figure 7] FIG. 10 is a diagram illustrating another example of a method for estimating an operating point pi. [Figure 8] FIG. 10 is a diagram illustrating another example of a method for estimating an operating point pi. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments of the present disclosure will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of components described as embodiments or shown in the drawings are merely illustrative examples and are not intended to limit the scope of the invention. For example, expressions expressing relative or absolute arrangement such as "in a certain direction," "along a certain direction," "parallel," "orthogonal," "center," "concentric," or "coaxial" not only express such an arrangement exactly, but also express a state in which there is a relative displacement with a tolerance or an angle or distance to the extent that the same function is obtained. For example, expressions such as "identical," "equal," and "homogeneous" that indicate that something is in an equal state not only indicate a state of strict equality, but also indicate a state in which there is a tolerance or a difference to the extent that the same function is obtained. For example, expressions representing shapes such as a square shape or a cylindrical shape not only represent shapes such as a square shape or a cylindrical shape in the strict geometric sense, but also represent shapes including uneven portions, chamfered portions, etc., to the extent that the same effect can be obtained. On the other hand, the expressions "comprise," "include," "have," "includes," or "have" of one element are not exclusive expressions that exclude the presence of other elements.

[0011] 1 is a schematic diagram illustrating the configuration of a turbocharger to which a surging sign detection method according to an embodiment of the present disclosure is applied. The surging sign detection method according to some embodiments of the present disclosure is intended to detect a sign of surging (backflow) of a compressor 32 included in the turbocharger 3. The turbocharger 3 is mounted in an engine system 2 including an engine 5 as shown in FIG. 1.

[0012] (Engine System) 1 , the engine system 2 includes an engine (engine main body) 5 configured to generate power by burning fuel therein, an air supply line 6 for compressing and supplying air to the engine 5, a turbocharger 3 having a compressor impeller 4 provided in the air supply line 6, and an intercooler 7 provided on the air supply line 6 downstream of the compressor impeller 4. The intercooler 7 is a heat exchanger configured to cool the air passing through the intercooler 7.

[0013] In the illustrated embodiment, the engine system 2 further comprises an exhaust gas discharge line 8 for conducting exhaust gases discharged from the engine 5, a fuel injection valve 9 configured to inject fuel into the engine 5, a control device 11, and a display device 12.

[0014] The control device 11 is composed of an engine control unit for controlling the operation of each device (such as the engine 5 and the fuel injection valve 9) in the engine system 2. The control device 11 may be composed of an electric circuit or a computer. When the control device 11 is composed of a computer, it is equipped with a storage device such as a RAM (Random Access Memory) or a ROM (Read Only Memory) and a processor such as a CPU (Central Processing Unit) or a GPU (Graphics Processing Unit), and the processor executes a program stored in the storage device to realize its functions.

[0015] Furthermore, as will be described in detail later, the control device 11 controls the display of the display device 12 to cause the display device 12 to display a compressor map Mp of the compressor 32 of the turbocharger 3, plots the operating point of the compressor 32 on the compressor map Mp, and monitors the transition of the operating point.

[0016] The engine 5 includes at least one cylinder 51 and at least one piston 52 accommodated in the at least one cylinder 51 so as to be able to reciprocate axially. The engine 5 has a combustion chamber 53 defined by the cylinder 51 and the piston 52 therein. The combustion chamber 53 is connected to an air supply line 6 downstream of the intercooler 7 so as to allow gas to flow therethrough. The air supply line 6 is a flow path for guiding compressed air from the compressor 32 to the combustion chamber 53. The combustion chamber 53 is connected to an exhaust gas discharge line 8 so as to allow gas to flow therethrough. The exhaust gas discharge line 8 is a flow path for guiding exhaust gas discharged from the combustion chamber 53 to the turbine 33.

[0017] The fuel injected from the fuel injection valve 9 into the combustion chamber 53 or the air supply line 6 is mixed with air sent to the combustion chamber 53 through the air supply line 6, and then combusted in the combustion chamber 53. The exhaust gas after combustion in the combustion chamber 53 passes through the exhaust gas discharge line 8 and is discharged to the outside of the engine system 2.

[0018] (Turbocharger) In the illustrated embodiment, the turbocharger 3 includes a turbine 33 driven by the energy of exhaust gas (exhaust gas) discharged from the engine 5, a compressor 32 that compresses air to be supplied to the engine 5, and a rotating shaft 31. The compressor 32 includes a compressor impeller 4 provided in the above-mentioned air supply line 6 and a compressor housing 34 that rotatably houses the compressor impeller 4. The compressor impeller 4 is mechanically connected to one side of the rotating shaft 31. The turbine 33 includes turbine blades 35 provided in the above-mentioned exhaust gas discharge line 8 and a turbine housing 36 that rotatably houses the turbine blades 35. The turbine blades 35 are mechanically connected to the other side of the rotating shaft 31.

[0019] The air that has passed through the compressor impeller 4 of the compressor 32 is led through an air supply line 6 to a combustion chamber 53 of the engine 5, and is used for combustion in the combustion chamber 53. Exhaust gas generated by the combustion in the combustion chamber 53 is led through an exhaust gas discharge line 8 to turbine blades 35 of the turbine 33. The turbocharger 3 is configured to rotate the turbine blades 35 using the energy of the exhaust gas discharged from the engine 5. The compressor impeller 4 is mechanically connected to the turbine blades 35 via the rotating shaft 31, and therefore rotates in conjunction with the rotation of the turbine blades 35. The turbocharger 3 is configured to compress the air passing through the compressor impeller 4 by the rotation of the compressor impeller 4, increase the density of the air, and send it to the engine 5.

[0020] (Measuring equipment installed in engine systems) As shown in FIG. 1 , the engine system 2 includes, as devices for measuring a plurality of parameters related to the operating state of the engine 5, an intake air pressure sensor 22 that measures an intake air pressure (scavenging air pressure) Ps of the engine 5, an intake air temperature sensor 24 that measures an intake air temperature Ts of the engine 5, a supercharger rotation speed sensor 25 that measures the rotation speed of the supercharger 3 (hereinafter referred to as supercharger rotation speed Nt), a turbine inlet pressure sensor 26 that measures an inlet pressure of the turbine 33 (hereinafter referred to as turbine inlet pressure P1), and a turbine inlet temperature sensor 27 that measures an inlet pressure of the turbine 33 (hereinafter referred to as turbine inlet pressure P2). The engine 5 includes a turbine inlet temperature sensor 27 that measures the in-cylinder pressure Pc of the engine 5, an in-cylinder temperature sensor 29 that measures the in-cylinder temperature Tc of the engine 5, an engine speed sensor 30 that measures the engine speed (hereinafter referred to as engine speed Ne), a fuel flow rate sensor 38 that measures the fuel consumption F of the engine 5 (the flow rate of fuel supplied to the fuel injection valve 9), and an oxygen concentration sensor 40 that measures the oxygen concentration C1 of the exhaust gas of the engine 5. In the example shown in the figure, the intake air pressure sensor 22 measures the intake air pressure Ps at a position on the air supply line 6 between the intercooler 7 and the engine 5, and the intake air temperature sensor 24 measures the intake air temperature Ts at a position on the air supply line 6 between the intercooler 7 and the engine 5. Note that the oxygen concentration sensor 40 may be an oxygen concentration sensor provided to accurately determine the amount of oxygen in air-fuel ratio control when the engine 5 is a gas engine or a gasoline engine.

[0021] The control device 11 described above receives measurement results from the boost pressure sensor 22, the boost temperature sensor 24, the turbocharger rotation speed sensor 25, the turbine inlet pressure sensor 26, the turbine inlet temperature sensor 27, the in-cylinder pressure sensor 28, the in-cylinder temperature sensor 29, the engine rotation speed sensor 30, the fuel flow sensor 38, and the oxygen concentration sensor 40. That is, the control device 11 is configured to acquire the boost pressure Ps measured by the boost pressure sensor 22, the boost temperature Ts measured by the boost temperature sensor 24, the turbocharger rotation speed Nt measured by the turbocharger rotation speed sensor 25, the turbine inlet pressure P1 measured by the turbine inlet pressure sensor 26, the turbine inlet pressure P1 measured by the turbine inlet temperature sensor 27, the in-cylinder pressure Pc measured by the in-cylinder pressure sensor 28, the in-cylinder temperature Tc measured by the in-cylinder temperature sensor 29, the engine rotation speed Ne measured by the engine rotation speed sensor 30, the fuel consumption F measured by the fuel flow sensor 38, and the oxygen concentration C1 measured by the oxygen concentration sensor 40.

[0022] (Surge precursor detection method) FIG. 2 is a flow chart showing an outline of a surging sign detection method applicable to the turbocharger 3 described above. 2 includes a measurement data acquisition step (S11), an estimation step (S12), an operating point transition monitoring step (S13), and a surging sign detection step (S14). Hereinafter, the measurement data acquisition step, the estimation step, the operating point transition display step, and the surging sign detection step will be referred to as S11, S12, S13, and S14, respectively. In the example shown below, each of S11 to S14 is executed by the above-mentioned control device 11, but any one or more of S11 to S14 may also be executed manually by a person.

[0023] In S11, the control device 11 momentarily acquires, as online data, measurement data of a plurality of parameters related to the operating state of the engine 5 (operation data of the engine system 2). The measurement data of a plurality of parameters related to the operating state of the engine 5 acquired by the control device 11 in S11 may be, for example, measurement data of two or more types of parameters selected from the above-mentioned intake air pressure Ps, intake air temperature Ts, turbocharger rotation speed Nt, turbine inlet pressure P1, turbine inlet temperature T1, in-cylinder pressure Pc, in-cylinder temperature Tc, engine rotation speed Ne, fuel consumption F, and oxygen concentration C1.

[0024] In S12, the control device 11 estimates the pressure ratio R of the compressor 32 and the intake air amount Q of the compressor 32 based on the measurement data of the multiple parameters acquired in S11. Details of the method for estimating the pressure ratio R and the intake air amount Q will be described later.

[0025] In S13, the control device 11 displays a compressor map Mp on the display device 12, with the intake air amount Q and the pressure ratio R of the compressor 32 as coordinate axes, as shown in Fig. 3, and plots the operating points pi of the compressor 32, which are determined by the intake air amount Q and the pressure ratio R estimated in S12, in time series on the compressor map Mp, to monitor the transition Lpi of the operating points pi. In the example shown in Fig. 3, the compressor map Mp displayed on the display device 12 includes a surge line Ls of the compressor 32, two threshold lines Lth1, Lth2 determined according to the surge line Ls, and constant velocity lines (LN1, LN2t, . . . ) which indicate the relationship between the flow rate and the pressure ratio for each rotation speed of the turbocharger 3. In the example shown, each of the two threshold lines Lth1, Lth2 is set parallel or approximately parallel to the surge line Ls, and the intake air volume Q under the same pressure ratio conditions is larger by a predetermined margin for the threshold line Lth2 than for the surge line Ls, and is further larger by a predetermined margin for the threshold line Lth2 than for the threshold line Lth1.

[0026] In S14, the control device 11 detects signs of surging of the compressor 32 by comparing the current operating point pi of the compressor 32 displayed in S13 (the current operating point determined by the pressure ratio R of the compressor 32 estimated in S12 and the amount of intake air Q) with each of the threshold lines Lth1 and Lth2.

[0027] For example, by comparing the current operating point pi with the threshold line Lth1, if the current operating point pi is located on the small flow rate side of the threshold line Lth1, it is possible to detect the occurrence of a sign of surging and cause the display device 12 to display a warning message to warn of the occurrence of a sign of surging, or to cause another alarm device (not shown) to emit a warning sound indicating the occurrence of a sign of surging. Also, if the current operating point pi is not located on the small flow rate side of the threshold line Lth1, no sign of surging has occurred, and therefore the warning message or the like is not displayed.

[0028] Furthermore, when the current operating point pi is located on the smaller flow rate side of the threshold line Lth1, the current operating point pi is further compared with the threshold line Lth2. In this case, when the current operating point pi is located on the smaller flow rate side of the threshold line Lth2, a strong sign of surging is detected, and a warning message warning of the strong sign of surging may be displayed on the display device 12, or a warning sound indicating the strong sign of surging may be generated by an alarm device (not shown). Note that "the current operating point pi is located on the smaller flow rate side of the threshold line" means that the flow rate at the current operating point pi is smaller than the flow rate on the threshold line corresponding to the pressure ratio of the current operating point pi.

[0029] 1 to 3, the operating point pi of the compressor 32 can be estimated based on measurement data of multiple parameters related to the operating state of the engine 5. Therefore, by monitoring the transition Lpi of the operating point and comparing the operating point pi of the compressor 32 with the threshold lines Lth1 and Lth2, it is possible to monitor for signs of surging of the compressor 32 while the engine 5 is running and quickly and accurately detect the signs of surging. This makes it possible to take preventive measures against surging before it actually occurs.

[0030] Next, some specific examples of methods for estimating the operating point pi in the above-mentioned steps S11 and S12 will be described with reference to FIGS.

[0031] FIG. 4 is a diagram showing an example of a method for estimating the operating point pi. In the example shown in FIG. 4, in S11, the control device 11 acquires measurement data of the boost pressure Ps measured by the boost pressure sensor 22 and measurement data of the supercharger rotation speed Nt measured by the supercharger rotation speed sensor 25 as measurement data of a plurality of parameters related to the operating state of the engine 5 (operation data of the engine system 2).

[0032] In the example shown in FIG. 4, S12 includes steps S12a to S12b. In S12a, the control device 11 calculates (estimates) the pressure ratio R of the compressor 32 based on the supply air pressure Ps acquired in S11 and taking into consideration the pressure loss in the economizer 7 (S12a). For example, assuming that the magnitude of the pressure loss in the economizer 7 is ΔP and the inlet pressure of the compressor 32 is atmospheric pressure P0, the pressure ratio R is calculated by the following formula (a). R=(Ps+ΔP) / P0 (a)

[0033] In S12b, the control device 11 estimates the amount of intake air Q of the compressor 32 corresponding to the turbocharger rotation speed Nt acquired in S11 and the pressure ratio R calculated in S12 from the compressor map Mp, based on the turbocharger rotation speed Nt acquired in S11, the pressure ratio R calculated in S12, and the above-mentioned compressor map Mp indicating the relationship between the turbocharger rotation speed, the pressure ratio, and the amount of intake air of the compressor 32. Here, the compressor map Mp may be based on data of a test performed using the turbocharger 3 before shipping the turbocharger 3, for example, or may be created based on past actual values, experimental values, numerical analysis results, etc. other than the test data.

[0034] 4, the pressure ratio R of the compressor 32 can be estimated using the boost pressure of the engine, which is generally measured in an engine system equipped with a turbocharger. Therefore, even if the engine system 2 is not provided with a pressure sensor that measures the outlet pressure of the compressor 32 or a pressure ratio measuring device that measures the pressure ratio of the compressor, the pressure ratio of the compressor 32 can be estimated with high accuracy. In addition, the amount of intake air Q of the compressor 32 can be estimated with high accuracy using the measurement data of the boost pressure Ps, the measurement data of the turbocharger rotation speed Nt, and the compressor map Mp.

[0035] This makes it possible to monitor the operating point pi of the compressor 32, which is determined by the estimated pressure ratio R and the intake air amount Q, and quickly and accurately detect signs of surging of the compressor 32.

[0036] FIG. 5 is a diagram showing another example of a method for estimating the operating point pi. In the example shown in FIG. 5, in S11, the control device 11 acquires measurement data of a plurality of parameters related to the operating state of the engine 5 (operating data of the engine system 2), including measurement data of the boost pressure Ps measured by the boost pressure sensor 22, measurement data of the turbine inlet pressure P1 measured by the turbine inlet pressure sensor 26, and measurement data of the turbine inlet temperature T1 measured by the turbine inlet temperature sensor 27.

[0037] In the example shown in FIG. 5, S12 includes S12a and S12c to S12e. In S12a, the control device 11 calculates (estimates) the pressure ratio R of the compressor 32 based on the supply air pressure Ps acquired in S11, taking into account the pressure loss in the intercooler 7, by the same method as the method described with reference to FIG. 4 (for example, the method using the above formula (a)).

[0038] In S12c, the control device 11 calculates (estimates) the turbine flow rate G, which is the mass flow rate of the turbine, based on the turbine inlet pressure P1 and turbine inlet temperature T1 acquired in S11 and the turbine corrected flow rate K, which is a predetermined constant K. Here, the corrected turbine flow rate K is expressed by K=(G√T) / P, and therefore the turbine flow rate G is calculated using the following formula (b). G=K·(P1) / √(T1) (b) Here, the turbine corrected flow rate K may be based on data of a test conducted using the turbocharger 3 before shipping of the turbocharger 3, or may be created based on past performance values, experimental values, numerical analysis results, etc. other than the test data.

[0039] In S12d, the control device 11 calculates the compressor flow rate J, which is the mass flow rate of the compressor 32, based on the turbine flow rate G calculated in S12c. Then, in S12e, the control device 11 converts the compressor flow rate J calculated in S12d into the intake air amount Q, which is the volumetric flow rate of the compressor 32. Here, the compressor flow rate J may be calculated, for example, as the sum of the turbine flow rate G and the fuel consumption rate F of the engine 5, or if the fuel consumption rate F of the engine 5 is negligibly small compared to the turbine flow rate G, the same value as the turbine flow rate G may be used as the compressor flow rate J approximately.

[0040] 5, the pressure ratio R of the compressor 32 can be estimated using the engine boost pressure, which is generally measured in an engine system equipped with a turbocharger. Also, the intake air amount Q of the compressor 32 can be estimated with high accuracy based on the measurement data of the inlet pressure P1 and inlet temperature T1 of the turbine 33 and the turbine corrected flow rate K.

[0041] This makes it possible to monitor the operating point pi of the compressor 32, which is determined by the estimated pressure ratio R and the intake air amount Q, and quickly and accurately detect signs of surging of the compressor 32.

[0042] FIG. 6 is a diagram showing another example of a method for estimating the operating point pi. 6 , in S11, the control device 11 acquires measurement data of a plurality of parameters related to the operating state of the engine 5 (operational data of the engine system 2), such as measurement data of the boost pressure Ps measured by the boost pressure sensor 22 and measurement data of the boost temperature Ts measured by the boost temperature sensor 24. For example, in addition to the measurement data of the boost pressure Ps and the boost temperature Ts, the control device 11 acquires measurement data of the in-cylinder pressure Pc measured by the in-cylinder pressure sensor 28, measurement data of the in-cylinder temperature Tc measured by the in-cylinder temperature sensor 29, measurement data of the engine speed Ne measured by the engine speed sensor 30, and measurement data of the back pressure P1 (turbine inlet pressure) of the engine 5 measured by the turbine inlet pressure sensor 26.

[0043] In the example shown in FIG. 6, S12 includes S12a and S12f to S12i. In S12a, the control device 11 calculates (estimates) the pressure ratio R of the compressor 32 based on the supply air pressure Ps acquired in S11, taking into account the pressure loss in the intercooler 7, by the same method as the method described with reference to FIG. 4 (for example, the method using the above formula (a)).

[0044] In S12f, the charging efficiency η1 and the scavenging efficiency η2 of the engine 5 are calculated based on the intake pressure Ps, the intake temperature Ts, etc. (for example, the intake pressure Ps, the intake temperature Ts, the in-cylinder pressure Pc, the in-cylinder temperature Tc, the engine speed Ne, and the back pressure P1) acquired in S11, as well as the intake timing (scavenging timing) and the exhaust timing of the engine 5. For example, the charging efficiency η1 and the scavenging efficiency η2 of the engine 5 may be calculated (estimated) based on the intake pressure Ps, the intake temperature Ts, etc. acquired in S11 and correlation information H indicating the relationship between these parameters and the charging efficiency and scavenging efficiency of the engine 5.

[0045] In S12g, a planned value TSVp of the total stroke volume of the engine 5 is calculated based on the specifications of the engine 5 (for example, the engine's bore diameter, stroke, and number of cylinders). In S12h, an actual value TSVa of the total stroke volume of the engine 5 is calculated (estimated) based on the charging efficiency η1 and scavenging efficiency η2 of the engine 5 calculated in S12f and the planned value TSVp of the total stroke volume of the engine 5 calculated in S12g. In S12i, the amount of intake air Q of the compressor 32 is calculated based on the actual value TSVa of the total stroke volume of the engine 5 calculated in S12h.

[0046] 6, the pressure ratio R of the compressor 32 can be estimated using the engine boost pressure, which is generally measured in an engine system equipped with a turbocharger. Also, the intake air amount Q of the compressor 32 can be estimated with high accuracy based on measurement data such as the boost pressure Ps and the boost air temperature Ts, as well as the specifications of the engine 5.

[0047] This makes it possible to monitor the operating point pi of the compressor 32, which is determined by the estimated pressure ratio R and the intake air amount Q, and quickly and accurately detect signs of surging of the compressor 32.

[0048] FIG. 7 is a diagram showing another example of a method for estimating the operating point pi. In the example shown in FIG. 7, in S11, the control device 11 acquires measurement data of a plurality of parameters related to the operating state of the engine 5 (operating data of the engine system 2), including measurement data of the intake air pressure Ps measured by the intake air pressure sensor 22, measurement data of the fuel consumption F measured by the fuel flow rate sensor 38, and measurement data of the oxygen concentration C1 measured by the oxygen concentration sensor 40.

[0049] In S12a, the control device 11 calculates (estimates) the pressure ratio R of the compressor 32 based on the supply air pressure Ps acquired in S11, taking into account the pressure loss in the intercooler 7, by the same method as the method described with reference to FIG. 4 (for example, the method using the above formula (a)).

[0050] In S12j, the control device 11 calculates the air consumption amount V of the engine 5 by multiplying the fuel consumption amount F measured by the fuel flow rate sensor 38 by the theoretical air amount. In S12k, the control device 11 calculates the excess air ratio m of the engine 5 based on the oxygen concentration C1 measured by the oxygen concentration sensor . In S12l, the control device 11 calculates (estimates) the amount of intake air Q of the compressor 32 by multiplying the air consumption amount V calculated in S12j by the excess air ratio m calculated in S12k.

[0051] 7, the pressure ratio R of the compressor 32 can be estimated using the engine boost pressure, which is generally measured in an engine system equipped with a turbocharger. Also, the intake air amount Q of the compressor 32 can be estimated with high accuracy based on the measurement data of the fuel consumption amount F of the engine 5 and the measurement data of the oxygen concentration C1 in the exhaust gas of the engine 5.

[0052] This makes it possible to monitor the operating point pi of the compressor 32, which is determined by the estimated pressure ratio R and the intake air amount Q, and quickly and accurately detect signs of surging of the compressor 32.

[0053] The present disclosure is not limited to the above-described embodiments, but also includes modifications to the above-described embodiments and appropriate combinations of these modifications.

[0054] For example, in some of the above-described embodiments, the pressure ratio R is calculated based on the boost pressure Ps, but in some of the embodiments shown in Figures 5 to 7, for example, instead of acquiring the boost pressure Ps in S11, the supercharger rotation speed Nt may be acquired, and based on the acquired supercharger rotation speed Nt, the intake air amount Q calculated by any of the methods described using Figures 5 to 7, and the above-described compressor map Mp, the pressure ratio R of the compressor 32 corresponding to the acquired supercharger rotation speed Nt and the estimated intake air amount Q may be estimated from the compressor map Mp (see Figure 8). By such a method, the operating point pi determined by the intake air amount Q and the pressure ratio R of the compressor 32 can also be estimated.

[0055] In the example shown in FIG. 3, two threshold lines Lth1 and Lth2 are set, but the number of threshold lines is not limited, and may be one or more.

[0056] In addition, the surging sign detection method according to some embodiments may include a step of confirming whether there is any difference between the intake air volume Q of the compressor 32 estimated in any one of the estimation steps (S12) in Figures 4 to 8 and the intake air volume Q of the compressor 32 estimated in any other estimation step (S12).

[0057] That is, a step of confirming whether there is a difference between the amount of intake air Q of the compressor 32 estimated in any one of the following estimation steps (1) to (4) and the amount of intake air Q of the compressor 32 estimated in any other estimation step may be provided. This can improve the reliability of the estimated value of the amount of intake air Q of the compressor 32. (1) The measurement data of the multiple parameters acquired in the measurement data acquisition step includes measurement data of the intake air pressure Ps and measurement data of the turbocharger rotation speed Nt, and in the estimation step, the intake air amount Q of the compressor 32 is estimated based on the pressure ratio R of the compressor 32 estimated based on the intake air pressure Ps, the turbocharger rotation speed Nt acquired in the measurement data acquisition step, and a compressor map Mp indicating the correlation between the turbocharger rotation speed Nt, the pressure ratio R, and the intake air amount Q of the compressor 32. (2) The measurement data of multiple parameters acquired in the measurement data acquisition step includes measurement data of the inlet pressure P1 and inlet temperature T1 of the turbine 33 in the turbocharger 3, and in the estimation step, the intake air volume Q of the compressor 32 is estimated based on the inlet pressure P1 and inlet temperature T1 of the turbine 33 and the turbine corrected flow rate K acquired in the measurement data acquisition step. (3) The measurement data of the multiple parameters acquired in the measurement data acquisition step includes measurement data of the intake air temperature Ts and intake air pressure Ps of the engine 5, and in the estimation step, the intake air volume Q of the compressor 32 is estimated based on the intake air temperature Ts and intake air pressure Ps acquired in the measurement data acquisition step and the specifications of the engine 5. (4) The measurement data of multiple parameters acquired in the measurement data acquisition step includes the fuel consumption F of the engine 5 and the oxygen concentration C1 of the exhaust of the engine 5, and in the estimation step, the intake air volume of the compressor is estimated based on the fuel consumption F and oxygen concentration C1 acquired in the measurement data acquisition step and the theoretical air volume of the fuel used by the engine 5.

[0058] Furthermore, in some embodiments, a sign of surging of the compressor 32 may be detected by comparing an operating point determined using an average value of the intake air volume Q of the compressor 32 estimated in any one of the estimation steps (1) to (4) above and the intake air volume Q of the compressor 32 estimated in any other estimation step with a threshold line. This makes it possible to accurately estimate the operating point of the compressor 32 and quickly and accurately detect a sign of surging of the compressor 32.

[0059] The contents described in each of the above embodiments can be understood, for example, as follows.

[0060] [1] A method for detecting a sign of surging according to at least one embodiment of the present disclosure includes: A surging sign detection method for detecting a sign of surging of a compressor (e.g., the above-mentioned compressor 32) in a turbocharger (e.g., the above-mentioned turbocharger 3), a measurement data acquisition step of acquiring measurement data of a plurality of parameters (e.g., two or more appropriate parameters selected from the above-mentioned intake pressure Ps, intake temperature Ts, turbocharger rotation speed Nt, turbine inlet pressure P1, turbine inlet pressure P1, in-cylinder pressure Pc, in-cylinder temperature Tc, engine rotation speed Ne, fuel consumption F, and oxygen concentration C1) related to the operating state of an engine (e.g., the above-mentioned engine 5) connected to the turbocharger; an estimation step of estimating a pressure ratio (e.g., the above-mentioned pressure ratio R) and an intake air amount (e.g., the above-mentioned intake air amount Q) of the compressor based on measurement data of the plurality of parameters; an operating point transition monitoring step of plotting an operating point of the compressor (for example, the above-mentioned operating point pi) determined by the pressure ratio and the intake air amount estimated in the estimation step on a compressor map (for example, the above-mentioned compressor map Mp) having coordinate axes of the intake air amount and the pressure ratio of the compressor, and monitoring a transition of the operating point (for example, the above-mentioned transition Lpi of the operating point); a surge sign detection step of detecting a sign of surging of the compressor by comparing the operating point monitored in the operating point transition monitoring step with a threshold line (e.g., the above-mentioned Lth1 and / or Lth2) determined according to a surge line; Equipped with.

[0061] According to the surging sign detection method described in [1] above, the operating point of the compressor (combination of pressure ratio and intake air volume) can be estimated based on measurement data of multiple parameters related to the operating state of the engine, and by monitoring the transition of the operating point and comparing the operating point of the compressor with a threshold line, signs of compressor surging can be monitored during engine operation and detected promptly and accurately. This makes it possible to take preventive measures against surging before it actually occurs.

[0062] [2] In some embodiments, in the surge sign detection method described in [1] above, the measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of an intake pressure of the engine (for example, the above-mentioned intake pressure Ps), In the estimating step, a pressure ratio of the compressor is estimated based on the supply air pressure acquired in the measurement data acquiring step.

[0063] According to the surging sign detection method described in [2] above, the compressor pressure ratio can be estimated using the engine intake pressure, which is generally measured in an engine system equipped with a turbocharger. Furthermore, even if the engine system is not provided with a pressure sensor for measuring the compressor outlet pressure or a pressure ratio measuring device for measuring the compressor pressure ratio, the compressor pressure ratio can be accurately estimated and a sign of compressor surging can be quickly and accurately detected.

[0064] [3] In some embodiments, in the surge sign detection method described in [2] above, The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the rotation speed of the supercharger (for example, the above-mentioned supercharger rotation speed Nt), In the estimating step, the amount of intake air of the compressor is estimated based on the pressure ratio of the compressor estimated based on the air supply pressure, the rotation speed of the turbocharger acquired in the measurement data acquiring step, and intake air amount correlation information (for example, the above-mentioned compressor map Mp) indicating a correlation between the rotation speed of the turbocharger, the pressure ratio, and the amount of intake air of the compressor.

[0065] According to the surging sign detection method described in [3] above, the amount of intake air of the compressor can be estimated with high accuracy using measurement data of the engine intake pressure and measurement data of the turbocharger rotation speed. As a result, the operating point of the compressor can be monitored using the estimated amount of intake air, and signs of compressor surging can be detected quickly and accurately.

[0066] [4] In some embodiments, in the surge sign detection method described in [1] above, the measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of an inlet pressure (e.g., the above-mentioned turbine inlet pressure P1) and an inlet temperature (e.g., the above-mentioned turbine inlet temperature T1) of a turbine in the turbocharger, In the estimation step, the intake air amount of the compressor is estimated based on the turbine inlet pressure and the turbine corrected flow rate (for example, the above-mentioned turbine corrected flow rate K) acquired in the measurement data acquisition step.

[0067] According to the method for detecting a sign of surging described in [4] above, the amount of intake air of the compressor can be estimated with high accuracy using measurement data of the turbine inlet pressure and inlet temperature. As a result, the estimated amount of intake air can be used to monitor the operating point of the compressor, and signs of compressor surging can be detected quickly and accurately.

[0068] [5] In some embodiments, in the surge sign detection method described in [1] above, the measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of an intake air temperature (e.g., the above-mentioned intake air temperature Ts) and an intake air pressure (e.g., the above-mentioned intake air pressure Ps) of the engine, In the estimation step, the intake air volume of the compressor is estimated based on the intake air temperature and the intake air pressure acquired in the measurement data acquisition step and the engine specifications (e.g., the bore diameter, stroke, and number of cylinders of the engine 5 described above).

[0069] According to the surging sign detection method described in [5] above, the intake air volume of the compressor can be estimated with high accuracy using measurement data of the intake air temperature and intake air pressure of the engine. As a result, the estimated intake air volume can be used to monitor the operating point of the compressor, and signs of compressor surging can be detected quickly and accurately.

[0070] [6] In some embodiments, in the surge sign detection method described in [1] above, the measurement data of the plurality of parameters acquired in the measurement data acquisition step includes a fuel consumption amount of the engine and an oxygen concentration of exhaust gas from the engine (for example, the above-mentioned oxygen concentration C1); In the estimation step, the amount of intake air of the compressor is estimated based on the fuel consumption amount and the oxygen concentration acquired in the measurement data acquisition step, and a theoretical air amount of the fuel used by the engine.

[0071] According to the surging sign detection method described in [6] above, the amount of intake air of the compressor can be estimated with high accuracy using measurement data of the engine's fuel consumption and measurement data of the oxygen concentration in the engine's exhaust. As a result, the estimated amount of intake air can be used to monitor the operating point of the compressor, and signs of compressor surging can be detected quickly and accurately.

[0072] [7] In some embodiments, in the surge sign detection method described in [1] above, 2. The surge precursor detection method according to claim 1, further comprising a step of confirming whether there is any difference between the amount of intake air of the compressor estimated in any one of the following estimation steps (1) to (4) and the amount of intake air of the compressor estimated in any other estimation step: (1) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the intake pressure of the engine (for example, the above-mentioned intake pressure Ps) and measurement data of the rotational speed of the turbocharger (for example, the above-mentioned turbocharger rotational speed Nt), and in the estimation step, the intake air amount of the compressor is estimated based on the pressure ratio of the compressor (for example, the above-mentioned pressure ratio R) estimated based on the intake pressure of the engine, the rotational speed of the turbocharger acquired in the measurement data acquisition step, and intake air amount correlation information (for example, the above-mentioned compressor map Mp) indicating a correlation between the rotational speed of the turbocharger, the pressure ratio, and the intake air amount of the compressor. (2) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the inlet pressure (e.g., the turbine inlet pressure P1 described above) and inlet temperature (e.g., the turbine inlet temperature T1 described above) of the turbine in the turbocharger, and in the estimation step, the intake air volume of the compressor is estimated based on the inlet pressure and inlet temperature of the turbine and the corrected turbine flow rate (e.g., the corrected turbine flow rate K described above) acquired in the measurement data acquisition step. (3) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the intake air temperature (e.g., the above-mentioned intake air temperature Ts) and intake air pressure (e.g., the above-mentioned intake air pressure Ps) of the engine, and in the estimation step, the intake air amount of the compressor is estimated based on the intake air temperature and the intake air pressure acquired in the measurement data acquisition step and the specifications of the engine. (4) The measurement data of the multiple parameters acquired in the measurement data acquisition step includes the fuel consumption of the engine (e.g., the above-mentioned fuel consumption F) and the oxygen concentration of the exhaust of the engine (e.g., the above-mentioned oxygen concentration C1), and in the estimation step, the intake air volume of the compressor is estimated based on the fuel consumption and the oxygen concentration acquired in the measurement data acquisition step and the theoretical air volume of the fuel used by the engine.

[0073] According to the method for detecting signs of surging described in [7] above, by checking whether there is any difference between the amount of intake air of the compressor estimated in any one of the estimation steps (1) to (4) above and the amount of intake air of the compressor estimated in any other estimation step, the reliability of the estimated value of the amount of intake air of the compressor can be improved.

[0074] [8] In some embodiments, in the surge sign detection method described in [1] above, 2. The method for detecting signs of surging according to claim 1, wherein a sign of surging of the compressor is detected by comparing an operating point of the compressor determined using an average value of the intake air volume of the compressor estimated in any one of the following estimation steps (1) to (4) and the intake air volume of the compressor estimated in any other estimation step with the threshold line. (1) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the intake pressure of the engine (for example, the above-mentioned intake pressure Ps) and measurement data of the rotational speed of the turbocharger (for example, the above-mentioned turbocharger rotational speed Nt), and in the estimation step, the intake air amount of the compressor is estimated based on the pressure ratio of the compressor (for example, the above-mentioned pressure ratio R) estimated based on the intake pressure of the engine, the rotational speed of the turbocharger acquired in the measurement data acquisition step, and intake air amount correlation information (for example, the above-mentioned compressor map Mp) indicating a correlation between the rotational speed of the turbocharger, the pressure ratio, and the intake air amount of the compressor. (2) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the inlet pressure (e.g., the turbine inlet pressure P1 described above) and inlet temperature (e.g., the turbine inlet temperature T1 described above) of the turbine in the turbocharger, and in the estimation step, the intake air volume of the compressor is estimated based on the inlet pressure and inlet temperature of the turbine and the corrected turbine flow rate (e.g., the corrected turbine flow rate K described above) acquired in the measurement data acquisition step. (3) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the intake air temperature (e.g., the above-mentioned intake air temperature Ts) and intake air pressure (e.g., the above-mentioned intake air pressure Ps) of the engine, and in the estimation step, the intake air amount of the compressor is estimated based on the intake air temperature and the intake air pressure acquired in the measurement data acquisition step and the specifications of the engine. (4) The measurement data of the multiple parameters acquired in the measurement data acquisition step includes the fuel consumption of the engine (e.g., the above-mentioned fuel consumption F) and the oxygen concentration of the exhaust of the engine (e.g., the above-mentioned oxygen concentration C1), and in the estimation step, the intake air volume of the compressor is estimated based on the fuel consumption and the oxygen concentration acquired in the measurement data acquisition step and the theoretical air volume of the fuel used by the engine.

[0075] According to the method for detecting signs of surging described in [8] above, the operating point of the compressor is estimated using the average value of the intake air volume of the compressor estimated in any one of the estimation steps (1) to (4) above and the intake air volume of the compressor estimated in any other estimation step, so that the operating point of the compressor can be accurately estimated and signs of compressor surging can be detected quickly and accurately. [Explanation of symbols]

[0076] 2 Engine System 3. Turbocharger 4 Compressor impeller 5 Engine 6 Air supply line 7 Intercooler 8 Exhaust gas discharge line 9 Fuel injection valve 11 Control device 12 Display device 22 Air intake pressure sensor 24 Intake air temperature sensor 25 Turbocharger speed sensor 26 Turbine inlet pressure sensor 27 Turbine inlet temperature sensor 28 Cylinder pressure sensor 29 Cylinder temperature sensor 30 Engine RPM Sensor 31 Rotating shaft 32 Compressor 33 Turbine 34 Compressor housing 35 Turbine blades 36 Turbine housing 38 Fuel flow sensor 40 Oxygen concentration sensor 51 cylinders 52 Piston 53 Combustion chamber C1 Oxygen concentration F Fuel consumption G Turbine flow rate H correlation information J Compressor flow rate K Turbine corrected flow rate Lpi transition Ls surge line Lth1, Lth2 threshold lines Mp Compressor map (intake air volume correlation information) Ne Engine RPM Nt Turbocharger rotation speed P1 Turbine inlet pressure (back pressure) Pc Cylinder pressure Ps Supply pressure Q Intake air volume R pressure ratio T1 Turbine inlet temperature TSVa Actual Total Stroke Volume TSVp Planned total stroke volume Tc Cylinder temperature Ts Intake air temperature V Air consumption m excess air ratio pi operating point

Claims

1. A surge sign detection method for detecting a sign of compressor surging in a turbocharger using a computer, a measurement data acquisition step of executing a process of acquiring measurement data of a plurality of parameters related to an operating state of an engine connected to the turbocharger by the computer; an estimation step of executing a process of estimating a pressure ratio and an intake air amount of a compressor of the turbocharger based on measurement data of the plurality of parameters by the computer; an operating point transition monitoring step of plotting an operating point of the compressor determined by the pressure ratio and the intake air amount estimated in the estimation step on a compressor map having coordinate axes of the intake air amount and the pressure ratio of the compressor by the computer, and executing a process of monitoring a transition of the operating point; a surge sign detection step in which the computer executes a process of detecting a sign of surging of the compressor by comparing the operating point monitored in the operating point transition monitoring step with a threshold line that is determined to have a predetermined margin with respect to a surge line; Equipped with the measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of an inlet pressure and an inlet temperature of a turbine in the turbocharger, In the estimation step, an intake air amount of the compressor is estimated based on the inlet pressure and inlet temperature of the turbine and the turbine corrected flow rate acquired in the measurement data acquisition step. A method for detecting signs of surging.

2. A method for detecting a sign of surging of a compressor in a turbocharger using a computer, comprising: a measurement data acquisition step of executing a process of acquiring measurement data of a plurality of parameters related to an operating state of an engine connected to the turbocharger by the computer; an estimation step of executing a process of estimating a pressure ratio and an intake air amount of a compressor of the turbocharger based on measurement data of the plurality of parameters by the computer; an operating point transition monitoring step of plotting an operating point of the compressor determined by the pressure ratio and the intake air amount estimated in the estimation step on a compressor map having coordinate axes of the intake air amount and the pressure ratio of the compressor by the computer, and executing a process of monitoring a transition of the operating point; a surge sign detection step in which the computer executes a process of detecting a sign of surging of the compressor by comparing the operating point monitored in the operating point transition monitoring step with a threshold line that is determined to have a predetermined margin with respect to a surge line; Equipped with the measurement data of the plurality of parameters acquired in the measurement data acquisition step includes a fuel consumption amount of the engine and an oxygen concentration in exhaust gas from the engine; In the estimation step, the intake air amount of the compressor is estimated based on the theoretical air amount of the fuel used by the engine, the fuel consumption amount acquired in the measurement data acquisition step, and an excess air ratio calculated based on the oxygen concentration. A method for detecting signs of surging.

3. A method for detecting a sign of surging of a compressor in a turbocharger using a computer, comprising: a measurement data acquisition step of executing a process of acquiring measurement data of a plurality of parameters related to an operating state of an engine connected to the turbocharger by the computer; an estimation step of executing a process of estimating a pressure ratio and an intake air amount of a compressor of the turbocharger based on measurement data of the plurality of parameters by the computer; an operating point transition monitoring step of plotting an operating point of the compressor determined by the pressure ratio and the intake air amount estimated in the estimation step on a compressor map having coordinate axes of the intake air amount and the pressure ratio of the compressor by the computer, and executing a process of monitoring a transition of the operating point; a surge sign detection step in which the computer executes a process of detecting a sign of surging of the compressor by comparing the operating point monitored in the operating point transition monitoring step with a threshold line that is determined to have a predetermined margin with respect to a surge line; Equipped with A method for detecting signs of surging, which increases the reliability of an estimated value of the intake air volume of the compressor by performing a step of confirming whether there is any difference between the intake air volume of the compressor estimated in any one of the following estimation steps (1) to (4) and the intake air volume of the compressor estimated in any other estimation step. (1) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the boost pressure of the engine and measurement data of the rotation speed of the turbocharger, and in the estimation step, the intake air amount of the compressor is estimated based on a pressure ratio of the compressor estimated with the boost pressure of the engine as the outlet pressure of the compressor and atmospheric pressure as the inlet pressure of the compressor, the rotation speed of the turbocharger acquired in the measurement data acquisition step, and intake air amount correlation information indicating a correlation between the rotation speed of the turbocharger, the pressure ratio, and the intake air amount of the compressor. (2) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the inlet pressure and inlet temperature of the turbine in the turbocharger, and in the estimation step, the intake air volume of the compressor is estimated based on the inlet pressure and inlet temperature of the turbine and the corrected turbine flow rate acquired in the measurement data acquisition step. (3) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the intake air temperature and intake air pressure of the engine, and in the estimation step, the intake air amount of the compressor is estimated based on the charging efficiency and scavenging efficiency of the engine calculated based on the intake air temperature and the intake air pressure acquired in the measurement data acquisition step and on the total stroke volume of the engine. (4) The measurement data of the multiple parameters acquired in the measurement data acquisition step includes the fuel consumption of the engine and the oxygen concentration of the exhaust of the engine, and in the estimation step, the amount of air suctioned into the compressor is estimated based on the fuel consumption acquired in the measurement data acquisition step, the air excess ratio calculated based on the oxygen concentration, and the theoretical air amount of the fuel used by the engine.

4. A method for detecting a sign of surging of a compressor in a turbocharger using a computer, comprising: a measurement data acquisition step of executing a process of acquiring measurement data of a plurality of parameters related to an operating state of an engine connected to the turbocharger by the computer; an estimation step of executing a process of estimating a pressure ratio and an intake air amount of a compressor of the turbocharger based on measurement data of the plurality of parameters by the computer; an operating point transition monitoring step of plotting an operating point of the compressor determined by the pressure ratio and the intake air amount estimated in the estimation step on a compressor map having coordinate axes of the intake air amount and the pressure ratio of the compressor by the computer, and executing a process of monitoring a transition of the operating point; a surge sign detection step in which the computer executes a process of detecting a sign of surging of the compressor by comparing the operating point monitored in the operating point transition monitoring step with a threshold line that is determined to have a predetermined margin with respect to a surge line; Equipped with A method for detecting a sign of surging, which detects a sign of surging in the compressor by comparing an operating point of the compressor, which is determined by the pressure ratio and an average value of the intake air volume of the compressor estimated in any one of the following estimation steps (1) to (4) and the intake air volume of the compressor estimated in any other estimation step, with the threshold line. (1) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the boost pressure of the engine and measurement data of the rotation speed of the turbocharger, and in the estimation step, the intake air amount of the compressor is estimated based on a pressure ratio of the compressor estimated with the boost pressure of the engine as the outlet pressure of the compressor and atmospheric pressure as the inlet pressure of the compressor, the rotation speed of the turbocharger acquired in the measurement data acquisition step, and intake air amount correlation information indicating a correlation between the rotation speed of the turbocharger, the pressure ratio, and the intake air amount of the compressor. (2) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the inlet pressure and inlet temperature of the turbine in the turbocharger, and in the estimation step, the intake air volume of the compressor is estimated based on the inlet pressure and inlet temperature of the turbine and the corrected turbine flow rate acquired in the measurement data acquisition step. (3) The measurement data of the plurality of parameters acquired in the measurement data acquisition step includes measurement data of the intake air temperature and intake air pressure of the engine, and in the estimation step, the intake air amount of the compressor is estimated based on the charging efficiency and scavenging efficiency of the engine calculated based on the intake air temperature and the intake air pressure acquired in the measurement data acquisition step and on the total stroke volume of the engine. (4) The measurement data of the multiple parameters acquired in the measurement data acquisition step includes the fuel consumption of the engine and the oxygen concentration of the exhaust of the engine, and in the estimation step, the amount of air suctioned into the compressor is estimated based on the fuel consumption acquired in the measurement data acquisition step, the air excess ratio calculated based on the oxygen concentration, and the theoretical air amount of the fuel used by the engine.

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