CN114061962B - Engine state estimation device, engine state estimation method and storage medium - Google Patents

Abstract

The present invention provides an engine state estimation device, an engine state estimation method and a storage medium, which can estimate the state of an engine with stable accuracy. The engine state estimation device (100) for estimating the state of an engine (200) comprises: an air density measurement data acquisition unit (110) for acquiring measurement data of a parameter related to the density of air sucked into the engine (200) and supplied to a combustion unit; and a state estimation unit (120) for estimating the state of the engine (200) based on the air density measurement data and the fuel supply amount (U) supplied to the combustion unit input into an engine model representing the characteristics of the engine (200).

Description

Engine state estimation device, engine state estimation method and storage medium

Technical Field

The invention relates to a state estimation technology of an engine.

Background Art

Engines are widely used in ships, automobiles, aircraft, and the like. However, due to increasing awareness of environmental issues, further efficiency improvements have been required in recent years, and various technologies have been developed to meet this need.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2005-307800

Patent Document 2: Japanese Patent Application Publication No. 2015-222074

Patent Document 3: Japanese Patent Application Publication No. 2015-3658

Summary of the invention

Problem that the invention aims to solve

As one example, there is known a simulation technology for engine parameters as disclosed in Patent Document 1. Patent Document 1 uses a predetermined calculation model to simulate the tuning frequency of the pressure wave in the intake pipe as an engine parameter. However, there is a problem that the operation and state of the engine change all the time, and even if the simulation is performed using the same calculation model, the accuracy of the simulation varies.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide an engine state estimation device capable of estimating the state of an engine with stable accuracy.

Solutions for solving problems

In order to solve the above-mentioned problem, an engine state estimation device of one embodiment of the present invention estimates the state of an engine, wherein the engine comprises: a combustion unit that burns air and fuel to generate power; and a supercharger that increases the pressure of the inhaled air and supplies the air to the combustion unit, and the engine state estimation device comprises: an air density measurement data acquisition unit that acquires air density measurement data, wherein the air density measurement data is measurement data of a parameter related to the density of at least one of the air inhaled by the supercharger and the compressed air supplied by the supercharger to the combustion unit; and a state estimation unit that estimates the state of the engine based on the air density measurement data and the amount of fuel supplied to the combustion unit that is input into an engine model representing the characteristics of the engine.

In this method, a parameter related to the density of at least one of the air sucked in by the supercharger and the compressed air supplied to the combustion unit after the supercharger increases the pressure is measured, and the parameter is used to estimate the state of the engine. This parameter represents the density of the air used for combustion in the combustion unit, and is a parameter that has a particularly large impact on the operation and even the state of the engine among multiple engine-related parameters. Therefore, when this parameter changes, the state of the engine changes significantly, which becomes a cause of a large deviation in the accuracy of the state estimation. In the present invention, a parameter that has a large impact on the state of the engine like this can be measured as air density measurement data, and it can be used for state estimation, so that the state of the engine can be estimated with stable accuracy.

Another aspect of the present invention is an engine state estimation method. The method estimates the state of an engine, wherein the engine includes: a combustion unit that generates power by burning air and fuel; and a supercharger that increases the pressure of the inhaled air and supplies the air to the combustion unit, and the engine state estimation method includes the following steps: an air density measurement data acquisition step, in which air density measurement data is obtained, wherein the air density measurement data is measurement data of a parameter related to the density of at least one of the air inhaled by the supercharger and the compressed air supplied by the supercharger to the combustion unit; and a state estimation step, in which the state of the engine is estimated based on the air density measurement data and the amount of fuel supplied to the combustion unit that is input into an engine model representing the characteristics of the engine.

Furthermore, arbitrary combinations of the above-described constituting elements and modes in which the present invention is expressed in the form of methods, apparatuses, systems, recording media, computer programs, and the like are converted into additional modes of the present invention.

Effects of the Invention

According to the present invention, the state of the engine can be estimated with stable accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram showing a configuration of an engine state estimation device according to a first embodiment.

FIG. 2 is a schematic diagram showing the structure of a four-stroke engine.

FIG. 3 is a schematic diagram showing the structure of a two-stroke engine.

FIG. 4 is a diagram showing the influence of air density measurement data on engine output.

FIG. 5 is a diagram showing the influence of air density measurement data on the fuel consumption of the engine.

FIG. 6 is a diagram showing the influence of air density measurement data on the temperature of gas flowing through the engine.

FIG. 7 is a diagram showing the influence of air density measurement data on the pressure of gas flowing through the engine.

FIG. 8 is a schematic diagram showing a configuration of an engine state estimation device according to a second embodiment.

Description of Reference Numerals

100: engine state estimation device; 110: air density measurement data acquisition unit; 120: state estimation unit; 121: calculation unit; 122: engine model correction unit; 200: engine; 210: combustion unit; 220: air supply path; 221: intake pipe; 222: air supply pipe; 223: air supply receiver; 224: air supply cooler; 230: exhaust path; 231: exhaust receiver; 232: exhaust pipe; 233: turbine outlet pipe; 240: supercharger; 241: compressor; 242: turbine.

DETAILED DESCRIPTION

The engine state estimation device of the present embodiment estimates the state of the engine using a mathematical model representing the characteristics of the engine. Among multiple engine-related parameters, the temperature and pressure of the air used for fuel combustion, which have a great influence on the output and fuel consumption of the engine, are measured and used for state estimation, thereby improving the estimation accuracy.

1 is a schematic diagram showing a configuration of an engine state estimation device 100 according to a first embodiment. The engine state estimation device 100 is a device for estimating a state of an engine 200 , and includes an air density measurement data acquisition unit 110 and a state estimation unit 120 .

Before describing each component of the engine state estimation device 100 , an engine 200 as a state estimation target will be described with reference to FIGS. 2 and 3 .

Fig. 2 is a schematic diagram showing a so-called four-stroke engine as an example of an engine 200. As described later, a four-stroke engine is an engine that performs one cycle including four strokes of intake, compression, combustion, and exhaust by four up-and-down movements of a piston (twice up and twice down).

The engine 200 includes a combustion unit 210 that mixes air and fuel and burns them to generate power, and a supercharger 240 that increases the pressure of the sucked air and supplies the air to the combustion unit 210. The supercharger 240 is a so-called turbocharger, and includes a turbine 242 that is rotated by the exhaust gas after combustion in the combustion unit 210, and a compressor 241 that is coaxially coupled to the turbine 242 via a shaft 243 so as to rotate in conjunction.

The compressor 241 is disposed at one end of the air supply path 220, which is open to the outside air (atmosphere) at one end and communicated with the combustion unit 210 at the other end. The compressor 241 rotates to suck in the outside air and compress the sucked outside air. The air compressed by the compressor 241 and having a higher pressure is supplied to the combustion unit 210 through the air supply path 220 to be used for the combustion of the fuel there. The air supply path 220 includes: an air intake pipe 221, through which the air sucked in by the compressor 241 from the one end open to the outside air flows; an air supply pipe 222, through which the compressed air supplied by the compressor 241 to the combustion unit 210 flows; and an air supply receiver 223 as an air supply receiving unit, which is disposed at a position close to the combustion unit 210 at the other end side and receives the compressed air. In addition, in order to prevent the air compressed by the compressor 241 from expanding due to the increase in temperature, a cooler, namely an air supply cooler 224, for cooling the compressed air flowing in the air supply pipe 222 is disposed in the middle of the air supply pipe 222. Thus, the temperature of the compressed air that is cooled while flowing through the supply air cooler 224 and stored in the supply air receiver 223 is maintained within a fixed range.

The turbine 242 is provided at the other end side of the exhaust passage 230, which is connected to the combustion section 210 at one end and is open to the outside air (atmosphere) at the other end. The gas exhausted after combustion in the combustion section 210 rotates the turbine 242 due to its momentum, and then is discharged to the outside air from the other end of the exhaust passage 230. The exhaust passage 230 includes: an exhaust receiver 231 as an exhaust receiving section, which is provided at a position close to the combustion section 210 on one end side and receives the gas exhausted after combustion in the combustion section 210; an exhaust pipe 232, which allows the exhaust gas to flow from the exhaust receiver 231 toward the turbine 242; and a turbine outlet pipe 233, which allows the exhaust gas to flow from the other end after passing through the turbine 242 to before being discharged to the outside air.

The combustion section 210 includes: a combustion chamber 211, which is used to cause combustion of fuel caused by air; a fuel supply nozzle 212, which is used to supply an amount of fuel specified by a fuel supply amount U for each combustion into the combustion chamber 211; an intake valve 213, which is used to control the supply of air from the air supply receiver 223 to the combustion chamber 211; an exhaust valve 214, which is used to control the discharge of gas from the combustion chamber 211 to the exhaust receiver 231; a piston 215, which is linearly driven corresponding to the combustion of the fuel in the combustion chamber 211; a crankshaft 216, which is a rotational drive section driven to rotate along with the linear motion of the piston 215; and a connecting rod 217, one end of which is fixed to the piston 215 and the other end of which is fixed to the crankshaft 216, and is used to convert the linear motion of the piston 215 into the rotational motion of the crankshaft 216. In addition, although the above text sets a structure in which fuel is directly supplied into the combustion chamber 211 through the fuel supply nozzle 212, when using a highly volatile fuel such as gasoline, the fuel can also be injected into the air supply receiver 223 or the air supply pipe 222 and supplied to the combustion chamber 211 in a state mixed with air.

In the above structure, the engine 200 is driven in the following cycle. Here, the engine 200 is in an operating state due to the drive before the last cycle or the drive caused by the combustion of multiple cylinders, and the piston 215 is repeatedly raised and lowered in accordance with the action of the crankshaft 216 that continuously rotates.

(1) Intake: The intake valve 213 opens, the exhaust valve 214 closes, and the piston 215 descends, thereby supplying air from the air supply receiver 223 to the combustion chamber 211.

(2) Compression: The intake valve 213 is closed and the piston 215 rises, thereby compressing the air in the combustion chamber 211.

(3) Combustion: A fuel supply nozzle 212 supplies a fuel in an amount specified by a fuel supply amount U per combustion into the combustion chamber 211, and the fuel burns in the compressed air. This generates power, and the piston 215 moves downward.

(4) Exhaust: The exhaust valve 214 opens and the piston 215 rises, thereby exhausting the combusted gas from the combustion chamber 211 to the exhaust receiver 231.

Fig. 3 is a schematic diagram showing a combustion unit of a so-called two-stroke engine as another example of the engine 200 (the same reference numerals are given to the components corresponding to those in Fig. 2 and the description thereof is omitted as appropriate). Unlike the four-stroke engine of Fig. 2 in which one cycle is completed by four up-and-down movements of the piston, in the two-stroke engine, one cycle is completed by two up-and-down movements of the piston, i.e. one ascent and one descent.

Similar to the above-mentioned four-stroke engine, the combustion section 210 of the two-stroke engine drives the piston 215 linearly by the combustion of the fuel in the combustion chamber 211, and converts the drive into the rotational power of the crankshaft 216. In both types of engines, the main structure is almost the same, but there is a difference in the two-stroke engine: the combustion section 210 is provided with a scavenging path 219 for connecting the crankcase 218 accommodating the crankshaft 216 and the combustion chamber 211.

In the illustrated state where the piston 215 is descending, the gas is able to flow through the crankcase 218, the scavenging passage 219, the combustion chamber 211 and the exhaust passage 230. The new air in the crankcase 218 flows into the combustion chamber 211 through the scavenging passage 219, and uses its momentum to discharge the burned gas into the exhaust passage 230 (scavenging).

Next, when the piston 215 rises, the scavenging passage 219 and the exhaust passage 230 are closed, the combustion chamber 211 is sealed and its pressure rises. Then, by supplying fuel from the fuel supply nozzle 212 to the high-pressure combustion chamber 211, combustion is caused, and power is generated to move the piston 215 down again. On the other hand, when the piston 215 rises, the crankcase 218 is connected to the air supply passage 220, and new air flows into the crankcase 218 from the air supply passage 220. In this way, when the piston 215 rises, combustion in the combustion chamber 211 and air supply to the crankcase 218 are simultaneously performed.

As described above, in a two-stroke engine, one cycle is completed by two strokes, namely, one descent and one ascent of the piston 215. In such a two-stroke engine, when the supercharger 240 shown in FIG. 2 is used, the pressure of the air supply to the crankcase 218 when the piston 215 rises and the pressure of the scavenging air to the combustion chamber 211 when the piston 215 descends can be increased.

In addition, as a two-stroke engine, a structure as disclosed in Patent Document 2 may also be used. In this two-stroke engine, as in the above description regarding FIG. 3, in the state where the piston (41: the reference numeral in Patent Document 2 (hereinafter the same)) is lowered, the gas can flow through the path of the scavenging receiver (2) corresponding to the air supply receiver 223, the scavenging port (17) corresponding to the crankcase 218 and the scavenging path 219, the cylinder (1) corresponding to the combustion chamber 211, and the exhaust pipe (6) corresponding to the exhaust path 230, and the new air in the scavenging receiver flows into the cylinder through the scavenging port, and the momentum thereof is used to perform a scavenging action of discharging the combusted gas to the exhaust pipe. In addition, when a supercharger 240 is used in such a structure, the pressure of the scavenging air in the scavenging receiver can be increased.

The present embodiment is not limited to uses such as ships, vehicles, and aircraft, and can be applied to various types of engines 200 as described above, but is particularly suitable for use in ship engines having a rated speed of less than 1000 revolutions per minute. Generally, ship engines can be driven at a lower rated speed than vehicle engines as described above. Moreover, in large ships in particular, accurate engine driving is required because it takes time until the power generated by the engine is reflected as the actual movement of the ship. As such, in ship engines, there is a high demand for accurately estimating the state of the engine for accurate driving, and it is preferred to use the engine state estimation device 100 of the present embodiment.

In addition, as a ship, the engine 200 of this embodiment can be used on the basis of the structure disclosed in Patent Document 3, for example. That is, the engine 200 of this embodiment is used as a main power device (10: the reference numeral in Patent Document 3 (the same below)) for generating propulsion force for the ship, and the power generated here is transmitted to the propeller (14) via the drive shaft, thereby rotating the propeller (14) to generate propulsion force for the ship.

In the engine 200 having the above-described structure, the gas used for the combustion of the fuel flows through the following path: external air → intake pipe 221 → compressor 241 → air supply pipe 222 → air supply receiver 223 → combustion section 210 (combustion chamber 211) → exhaust receiver 231 → exhaust pipe 232 → turbine 242 → turbine outlet pipe 233 → external air.

In this embodiment, sensors for measuring parameters related to air density, specifically, pressure, temperature, etc., can be installed at various locations in the gas flow path. As shown in the figure, the installation positions of the sensors are classified into the following three locations S0 to S2.

S0: In the intake pipe 221

S1: In the air supply pipe 222

S2: In the gas supply receiver 223

A sensor for measuring the pressure, temperature, and flow rate of the external air sucked by the compressor 241 can be installed at the sensor installation position S0 in the intake pipe 221. The sensor installation position S0 in the intake pipe 221 is preferably set to a position at a predetermined distance from the open end of the intake pipe 221 open to the outside air and the inlet of the compressor 241 so that stable measurement can be performed. When it is too close to the open end open to the outside air, the measurement data is easily affected by the sudden change of the outside air. In addition, when it is too close to the inlet of the compressor 241, there is a possibility that the measurement environment is unstable due to the influence of the airflow generated by the rotating compressor 241.

A sensor for measuring the pressure and temperature of the compressed air supplied to the combustion unit 210 after the compressor 241 increases the pressure can be installed at the sensor installation position S1 in the air supply pipe 222. As for the temperature, the temperature of the compressed air can be directly measured, or the cooling temperature of the air supply cooler 224 for cooling the compressed air, that is, the temperature of a refrigerant such as cooling water, can be indirectly measured. In addition, when the cooling temperature of the air supply cooler 224 is fixed and the temperature of the compressed air in the air supply pipe 222 can be regarded as fixed, the importance of measuring the temperature at the sensor installation position S1 is low, and therefore it is preferred to measure the pressure.

In addition, the sensor installation position S1 in the air supply pipe 222 is preferably set to a position at a predetermined distance from the outlet of the compressor 241 so that stable measurement can be performed. More preferably, if it is set to a position after the compressed air is sufficiently cooled in the post-stage of the air supply cooler 224, more stable measurement can be performed. In particular, when the cooling temperature of the air supply cooler 224 can be regarded as fixed, the temperature of the compressed air can also be regarded as fixed, so that the state of the compressed air in the air supply pipe 222 can be grasped with high accuracy by measuring only the pressure.

A sensor for measuring the pressure and temperature of the compressed air supplied to the combustion unit 210 can be installed at the sensor installation position S2 in the air supply receiver 223. Similar to the air supply pipe 222 described above, when the cooling temperature of the air supply cooler 224 is fixed and the temperature of the compressed air in the air supply receiver 223 can be regarded as fixed, the importance of measuring the temperature at the sensor installation position S2 is low, so it is preferred to measure the pressure.

In addition, the sensor installation position S2 in the air supply receiver 223 is preferably set to a position at a predetermined distance from the inlet of the compressed air from the air supply pipe 222 and the outlet of the compressed air to the combustion unit 210, so that stable measurement can be performed. Thus, stable measurement can be performed while avoiding the influence of abnormal airflow that may occur in these parts. In addition, when the cooling temperature of the air supply cooler 224 can be regarded as fixed, the temperature of the compressed air in the air supply receiver 223 can also be regarded as fixed, so the state of the compressed air in the air supply receiver 223 can be grasped with high accuracy by measuring only the pressure.

The parameters that can be measured at the three sensor installation positions S0 to S2 described above represent the density of the air used for combustion in the combustion unit 210, and are used to estimate the state of the engine 200 by the engine state estimation device 100 as described later. Here, it is not necessary to install sensors at all three sensor installation positions S0 to S2, and the state of the engine 200 can be estimated by installing a sensor at at least one sensor installation position. On the other hand, when sensors are installed at multiple sensor installation positions among S0 to S2, or when multiple sensors of different types are installed at one sensor position, the accuracy of the state estimation of the engine 200 can be improved based on the multiple measurement data obtained thereby.

Returning to FIG. 1 , each unit (the air density measurement data acquisition unit 110 and the state estimation unit 120 ) of the engine state estimation device 100 that estimates the state of the engine 200 will be described.

The air density measurement data acquisition unit 110 acquires various air density measurement data measured at the sensor installation positions S0 to S2. Specifically, the measurement data of the external air sucked in by the compressor 241 is acquired from the sensor installation position S0 (in the intake pipe 221), and the measurement data of the air supplied to the combustion unit 210 after the compressor 241 increases the pressure is acquired from the sensor installation positions S1 (in the air supply pipe 222) and S2 (in the air supply receiver 223).

The state estimation unit 120 for estimating the state of the engine 200 includes a calculation unit 121, which calculates state variables as parameters related to the state of the engine 200 based on an engine model representing the characteristics of the engine 200. The engine model of the calculation unit 121 mathematically models various characteristics of the engine 200, such as thermal efficiency, power transmission efficiency, dynamic characteristics, supercharger efficiency, and disturbance influence, and performs calculations using the fuel supply amount U supplied to the combustion unit 210 for each combustion, the measured data Ne of the rotation speed of the crankshaft 216 that generates the rotational power in the combustion unit 210, and the like as input data, and outputs estimated values of various state variables of the engine 200 as engine state estimation results. As described later, in this embodiment, not only the fuel supply amount U and the rotation speed Ne are input to the engine model, but also the air density measurement data acquired by the air density measurement data acquisition unit 110 is input to the engine model, thereby enabling the state of the engine 200 to be estimated with high accuracy. In addition, a variety of methods can be thought of to construct the engine model, but as a simple example, it can be constructed as a table that associates the fuel supply amount U, speed Ne, air density measurement data, etc. as inputs with the estimated values of each state variable of the engine 200 as outputs.

Examples of the state variables of the engine 200 that can be estimated by the state estimation unit 120 include the following variables.

Parameters related to the operation of the combustion unit 210:

The rotation speed of the crankshaft 216 (the rotation speed Ne of the combustion unit 210)

Parameters related to the operation of the supercharger 240:

The rotation speeds of the compressor 241, the turbine 242, and the shaft 243 (the rotation speed Ntc of the supercharger 240)

In addition, in the present embodiment, the rotation speed Ne is acquired as measurement data, and therefore it is not necessary to estimate it by the state estimation unit 120 .

The following are variables that can be acquired as measurement data by the air density measurement data acquisition unit 110 among the state variables of the engine 200. In the present embodiment, the state variables acquired as measurement data in this manner do not need to be estimated by the state estimation unit 120.

Parameters related to the external air sucked by the compressor 241 (which can be measured at S0 in the intake pipe 221):

·Outside air pressure (outside air pressure Pa)

·Outside air temperature (outside air temperature Ta)

Parameters related to the compressed air (air supply) supplied to the combustion unit 210 after the compressor 241 increases the pressure (can be measured at S1 in the air supply pipe 222 and S2 in the air supply receiver 223):

Supply air pressure (supply air pressure Pb/also referred to as scavenging air pressure Ps in a two-stroke engine that performs scavenging)

Supply air temperature (supply air temperature Tb/also referred to as scavenging air temperature Ts in a two-stroke engine that performs scavenging)

The temperature of the cooling water of the supply air cooler 224 (cooling water temperature Tw)

In addition to the above, parameters related to the gas flowing through each part in the engine 200 are:

·Flow rate in the air inlet pipe 221, air supply pipe 222, and air supply receiver 223

The pressure, temperature, and flow rate in the exhaust receiver 231, the exhaust pipe 232, and the turbine outlet pipe 233 can be used to calculate various performances of the engine 200 using the above parameters through the engine model:

Performance related to the power generated by the engine 200 (torque, output, etc.)

Performance related to the fuel consumption of the engine 200 (fuel consumption per unit time (hereinafter referred to as fuel consumption), fuel consumption rate per unit time and per unit output, travel distance per unit volume of fuel, etc.)

Each of the above-mentioned state variables can be measured by installing appropriate sensors, but it is not realistic to measure all state variables due to cost and installation limitations in the actual engine 200. Therefore, in this embodiment, a structure is set as follows: only the rotation speed Ne and a part of the air density measurement data used to improve the estimation accuracy of the state estimation unit 120 are measured, and the state estimation unit 120 calculates the estimated values of the other state variables.

Furthermore, the fuel supply amount U per combustion, which is the driving input to the engine 200, is set based on the measured data of the rotation speed Ne of the combustion unit 210. That is, when the target rotation speed of the combustion unit 210 is set to Ne0, the difference between Ne, which is the measured value, and Ne0, which is the target value, is calculated, and the fuel supply amount U per combustion is set based on a predetermined table or algorithm so that the difference is small.

Next, the technique for improving the state estimation accuracy by using the air density measurement data discovered by the inventor through experiments will be described. FIG. 4 to FIG. 7 show the results of experiments on the influence of the outside air temperature Ta, the outside air pressure Pa, and the cooling water temperature Tw, which are the air density measurement data, on various state variables of the engine 200. Specifically, FIG. 4 shows the influence on the output, FIG. 5 shows the influence on the fuel consumption, FIG. 6 shows the influence on the temperature near the outlet of the compressor 241 in the air supply pipe 222 (compressor outlet temperature Tc), the scavenging air temperature Ts in the air supply receiver 223, and the exhaust gas temperature Tex in the exhaust receiver 231, respectively, and FIG. 7 shows the influence on the scavenging air pressure Ps in the air supply receiver 223, the exhaust pressure Pex in the exhaust receiver 231, and the pressure in the turbine outlet pipe 233 (turbine outlet pressure P0), respectively. In each experiment, the load of the engine 200 was changed while the measurement was performed, and the results when the load of the engine 200 was 50%, 75%, 85%, and 100% of the maximum load were shown in each figure.

In each of the figures, the ratio of the change of the state variable as the object in each figure when the outside air temperature Ta, the outside air pressure Pa, and the cooling water temperature Tw change within the range of variation of the assumed environmental conditions is shown as a curve graph. For example, from the outside air temperature Ta of Figure 4, which is the object of the output, there is an influence of about -1.2% at a load of 100%, which means that the output when the outside air temperature Ta is the upper limit of the assumed range is reduced by about 1.2% relative to the output when the outside air temperature Ta is the lower limit of the assumed range. Similarly, from the outside air temperature Ta of Figure 5, which is the object of the fuel consumption, there is an influence of about 1.5% at a load of 50%, which means that the fuel consumption when the outside air temperature Ta is the upper limit of the assumed range is increased by about 1.5% relative to the fuel consumption when the outside air temperature Ta is the lower limit of the assumed range.

According to FIG. 4 and FIG. 5 related to the output and fuel consumption, which are important indicators of the engine 200, among the three air density measurement data, the influence of the outside air temperature Ta on the output and fuel consumption is obviously large. Therefore, the outside air temperature Ta is measured at the sensor installation position S0, and the outside air temperature Ta is supplied to the state estimation unit 120 via the air density measurement data acquisition unit 110, so that the state estimation unit 120 can estimate the output and fuel consumption with high accuracy.

According to Figure 6 which is related to the temperature of the gas circulating in the engine 200, it can be seen that the external air temperature Ta has the greatest impact on the compressor outlet temperature Tc (followed by the cooling water temperature Tw), the cooling water temperature Tw has the greatest impact on the scavenging temperature Ts, and the external air temperature Ta has the greatest impact on the exhaust temperature Tex (followed by the cooling water temperature Tw).

In addition, according to Figure 7 which is related to the pressure of the gas flowing in the engine 200, it can be seen that the external air temperature Ta has the greatest impact on the scavenging pressure Ps (followed by the cooling water temperature Tw), the external air temperature Ta has the greatest impact on the exhaust pressure Pex (followed by the cooling water temperature Tw), and the external air pressure Pa has the greatest impact on the turbine outlet pressure P0.

Therefore, by respectively measuring the external air temperature Ta (sensor installation position S0), the external air pressure Pa (sensor installation position S0), and the cooling water temperature Tw (sensor installation position S1), and supplying them to the state estimation unit 120 via the air density measurement data acquisition unit 110, the state estimation unit 120 can estimate the state variables with a large influence caused by each air density measurement data with high accuracy.

In the above, the experiment was conducted on three air density measurement data, but the inspiration obtained here can also be applied to other air density measurement data as follows.

As shown in Fig. 4 and Fig. 5, the external air temperature Ta has the greatest influence on the output and fuel consumption, and it is considered that this is because the state of the external air directly affects the basic operation of the engine 200, that is, the combustion of fuel and the generation of power in the combustion unit 210. That is, since the external air is sucked in by the compressor 241 and supplied to the combustion unit 210, it can be understood that the state of the external air has a great influence on the output and fuel consumption of the engine 200.

On the other hand, in Figures 4 and 5, the influence of the outside air pressure Pa, another parameter indicating the state of the outside air, on the output and fuel consumption is hardly observed. This is probably because within the assumed range of fluctuation of the outside air pressure Pa, there is almost no influence on the output and fuel consumption.

When the external air is sucked in by the compressor 241 and compressed and then enters the air supply pipe 222 and the air supply receiver 223 as described above, it is considered that the pressure, namely the air supply pressure Pb and the scavenging pressure Ps, are the main parameters that affect the output and fuel consumption. This is because the air supply temperature Tb and the scavenging temperature Ts are cooled within a fixed range by the air supply cooler 224 provided in the middle of the air supply pipe 222, so the density of the air supplied to the combustion unit 210 is mainly determined by the pressure. Therefore, in the engine 200 provided with the air supply cooler 224, the air supply pressure Pb and the scavenging pressure Ps of the cooled air are measured as air density measurement data, and are supplied to the state estimation unit 120 via the air density measurement data acquisition unit 110, thereby the state estimation unit 120 can estimate the output and fuel consumption with high accuracy. On the other hand, in the engine 200 without the supply air cooler 224, it is considered that the supply air temperature Tb and the scavenging air temperature Ts continue to have a significant influence on the output and fuel consumption like the outside air temperature Ta. Therefore, by measuring the supply air temperature Tb and the scavenging air temperature Ts, the output and fuel consumption can be estimated with high accuracy.

As described above, in order to improve the estimation accuracy of the output and fuel consumption which are important indicators of the engine 200, it is preferable to use the following air density measurement data.

Outside air temperature Ta

Supply air pressure Pb and scavenging air pressure Ps

Supply air temperature Tb and scavenging air temperature Ts (when the supply air cooler 224 is not provided)

It is preferable to pre-incorporate the above-mentioned insights obtained from FIGS. 4 to 7 as information indicating the relationship between each air density measurement data and each state variable into the engine model of the calculation unit 121. According to such an engine model, it is possible to calculate each state variable with high accuracy based on each measured air density measurement data, taking into account the influence shown in FIGS. 4 to 7.

In addition, it can be seen from FIGS. 4 to 7 that when the load of the engine 200 is low, such as 50% of the maximum load, the gas density measurement data tends to have a greater influence on each state variable. This is considered to be because when the engine 200 is operating at a low load, it is easily affected by various changes inside and outside the engine 200. Therefore, it is preferred that the state estimation unit 120 estimates the state of the engine 200 using the gas density measurement data when the engine 200 is operating at a low load, for example, when the engine 200 is operating at a load of less than 50% of the maximum load. On the other hand, when the engine 200 is operating at a high load in which the influence caused by the gas density measurement data is relatively small, for example, when the engine 200 is operating at a load higher than 50% of the maximum load, the gas density measurement data may not be used for state estimation, and the frequency of state estimation itself may be reduced.

The engine state estimation result output by the engine state estimation device 100 as described above can be used for the following purposes, for example.

The engine state estimation result can be used for various controls of the engine 200. According to the present embodiment, the state estimation accuracy of the engine 200 can be improved, and accordingly, the control accuracy can also be improved.

The engine state estimation result can be used for monitoring and deterioration diagnosis of the engine 200. An abnormality of the engine can be reliably identified and a prompt response can be taken.

Fig. 8 is a schematic diagram showing the structure of the engine state estimation device 100 according to the second embodiment. Compared with the engine state estimation device 100 according to the first embodiment shown in Fig. 1 , only the structure of the state estimation unit 120 is different. The state estimation unit 120 includes a calculation unit 121 and an engine model correction unit 122.

The calculation unit 121 uses the fuel supply amount U and the rotation speed Ne as input data, calculates the estimated value of the state variable of the engine 200 based on the engine model representing the characteristics of the engine 200, and outputs the estimated value as the engine state estimation result. In this embodiment, unlike the first embodiment, the air density measurement data is not input to the engine model of the calculation unit 121, but is supplied to the subsequent engine model correction unit 122. Instead, the calculation unit 121 calculates the estimated value of the gas density measurement data, that is, the air density estimation data, during the calculation process based on the above-mentioned engine model. As described in the first embodiment, the measurement data that affects the air density, such as the external air pressure Pa, the external air temperature Ta, the supply pressure Pb/scavenging pressure Ps, the supply temperature Tb/scavenging temperature Ts, and the cooling water temperature Tw, are all state variables of the engine 200, so the calculation unit 121 can obtain the gas estimation data in the usual calculation for obtaining the engine state estimation result.

The engine model correction unit 122 corrects the engine model in the calculation unit 121 in such a way that the difference between the air density estimation data supplied from the calculation unit 121 and the air density measurement data supplied from the air density measurement data acquisition unit 110 becomes smaller. Here, when there is a difference between the estimated value, i.e., the air density estimation data, and the actual measured value, i.e., the air density measurement data, the engine model that is the basis for calculating the estimated value deviates from the characteristics of the actual engine 200, and therefore the engine model is corrected by the engine model correction unit 122 so as to be close to the characteristics of the actual engine 200. If the difference between the air density estimation data and the air density measurement data is always ideally zero, the engine model accurately represents the characteristics of the actual engine 200. By such correction, the engine model becomes a model that better reflects the characteristics of the actual engine 200, and thus the accuracy of the engine state estimation can be improved. In particular, in the present embodiment, by using the air density measurement data that has a large influence on each state variable such as the output and fuel consumption of the engine 200, the engine model can be effectively corrected.

The present invention has been described above based on the embodiments. It should be understood by those skilled in the art that the embodiments are illustrative only and that various modifications may be produced by combinations of their constituent elements and processing steps, and that such modifications are also within the scope of the present invention.

In the embodiment, temperature or pressure is exemplified as air density measurement data, but other parameters related to air density may be measured, such as gas concentration, density, and component amount.

In addition, the functional structure of each device described in the embodiment can be realized by hardware resources or software resources or the cooperation of hardware resources and software resources. As hardware resources, processors, ROM, RAM, and other LSIs can be used. As software resources, programs such as operating systems and applications can be used.

In the embodiments disclosed in this specification, the embodiments in which multiple functions are dispersedly arranged may also be arranged in a centralized manner with part or all of the multiple functions. Conversely, the embodiments in which multiple functions are centralized may be arranged in a manner in which part or all of the multiple functions are dispersed. Whether the functions are centralized or dispersed, as long as the configuration is such that the purpose of the invention can be achieved.

Claims (14)

1. An engine state estimation device for estimating a state of an engine, the engine comprising: a combustion unit that generates power by burning air and fuel; and a supercharger that increases the pressure of inhaled air and supplies the air to the combustion unit, the engine state estimation device comprising: an air density measurement data acquisition unit that acquires air density measurement data, the air density measurement data being measurement data of a parameter related to density of at least one of air sucked into the supercharger and compressed air supplied by the supercharger to the combustion unit; and a state estimation unit that estimates the state of the engine based on the air density measurement data and the amount of fuel supplied to the combustion unit input into an engine model representing the characteristics of the engine, Wherein, the state estimation unit comprises: a calculation unit that calculates air density estimation data that is an estimated value of the air density measurement data based on the fuel supply amount input into the engine model and measurement data of the rotation speed of a rotary drive unit that generates rotary power in the combustion unit; and An engine model correction unit corrects the engine model so as to reduce a difference between the air density estimation data and the air density measurement data. 2. The engine state estimation device according to claim 1, characterized in that: The engine is a ship engine having a rated speed of 1000 revolutions per minute or less. 3. The engine state estimation device according to claim 1 or 2, characterized in that: The state estimation unit estimates the state of the engine by inputting the air density measurement data into the engine model. 4. The engine state estimation device according to claim 1, characterized in that: The device for measuring the air density measurement data is provided in an intake pipe through which the air sucked by the supercharger flows. 5. The engine state estimation device according to claim 1, characterized in that: The measuring device for measuring the air density data is provided in an air supply housing portion for housing the compressed air. 6. The engine state estimation device according to claim 1, characterized in that: The air density measurement data is measurement data of at least one of the temperature and the pressure of the air sucked into the supercharger and the compressed air. 7. The engine state estimation device according to claim 6, characterized in that: The air density measurement data is measurement data of the temperature of the air sucked into the supercharger. 8. The engine state estimation device according to claim 6 or 7, characterized in that: The engine includes a cooler for cooling the compressed air. The air density measurement data is measurement data of the pressure of the compressed air cooled by the cooler. 9. The engine state estimation device according to claim 1, characterized in that: The engine includes a cooler for cooling the compressed air. The air density measurement data is measurement data of the temperature of the cooling refrigerant of the cooler. 10. The engine state estimation device according to claim 1, characterized in that: The state estimation unit estimates the state of the engine based on measurement data of a rotation speed of a rotary drive unit that generates rotary power in the combustion unit. 11. The engine state estimation device according to claim 1, characterized in that: The state estimation unit estimates the state of the engine when the load of the engine is 50% or less of the maximum load of the engine. 12. An engine state estimation method, estimating the state of an engine, the engine comprising: a combustion unit that burns air and fuel to generate power; and a supercharger that increases the pressure of inhaled air and supplies the air to the combustion unit, the engine state estimation method comprising the following steps: an air density measurement data acquisition step of acquiring air density measurement data, wherein the air density measurement data is measurement data of a parameter related to the density of at least one of the air sucked by the supercharger and the compressed air supplied by the supercharger to the combustion unit; and a state estimating step of estimating a state of the engine based on the air density measurement data and the amount of fuel supplied to the combustion unit input into an engine model representing characteristics of the engine, Wherein, the state estimation step comprises: a calculation step of calculating air density estimation data which is an estimated value of the air density measurement data based on the fuel supply amount input into the engine model and the measurement data of the rotation speed of the rotary drive unit which generates the rotary power in the combustion unit; and The engine model correction step is to correct the engine model so as to reduce the difference between the air density estimation data and the air density measurement data. 13. A computer-readable storage medium storing an engine state estimation program for estimating the state of an engine, the engine comprising: a combustion unit that burns air and fuel to generate power; and a supercharger that increases the pressure of inhaled air and supplies the air to the combustion unit, the engine state estimation program causing a computer to execute the following steps: an air density measurement data acquisition step of acquiring air density measurement data, wherein the air density measurement data is measurement data of a parameter related to the density of at least one of the air sucked by the supercharger and the compressed air supplied by the supercharger to the combustion unit; and a state estimating step of estimating a state of the engine based on the air density measurement data and the amount of fuel supplied to the combustion unit input into an engine model representing characteristics of the engine, Wherein, the state estimation step comprises: a calculation step of calculating air density estimation data which is an estimated value of the air density measurement data based on the fuel supply amount input into the engine model and the measurement data of the rotation speed of the rotary drive unit which generates the rotary power in the combustion unit; and The engine model correction step is to correct the engine model so as to reduce the difference between the air density estimation data and the air density measurement data. 14. A computer program product comprising a computer program, wherein the computer program implements the engine state estimation method according to claim 12 when being executed by a processor.