CN114061962A

CN114061962A - Engine state estimation device, engine state estimation method, and storage medium

Info

Publication number: CN114061962A
Application number: CN202110870668.1A
Authority: CN
Inventors: 川谷圣; 藤原真; 笹岛己喜朗; 福岛圭一郎
Original assignee: Nabtesco Corp
Current assignee: Nabtesco Corp
Priority date: 2020-07-31
Filing date: 2021-07-30
Publication date: 2022-02-18
Also published as: KR20220015990A; JP2022026884A

Abstract

The 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 precision. An engine state estimation device (100) that estimates the state of an engine (200) is provided with: an air density measurement data acquisition unit (110) that acquires measurement data of a parameter relating to the density of air that is taken in by an engine (200) and supplied to a combustion unit; and a state estimation unit (120) that estimates the state of the engine (200) on the basis of the air density measurement data and the fuel supply amount (U) to the combustion unit that is input to an engine model that represents the characteristics of the engine (200).

Description

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

Technical Field

The present invention relates to a state estimation technique for an engine.

Background

Engines are widely used in ships, automobiles, aircrafts, and the like, but awareness of environmental issues is also increasing, and further high efficiency is demanded in recent years, and various technologies have been developed for this purpose.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open publication No. 2005-307800

Patent document 2: japanese patent laid-open publication No. 2015-222074

Patent document 3: japanese patent laid-open publication No. 2015-3658

Disclosure of Invention

Problems to be solved by the invention

As an example of this, a simulation technique of engine parameters as disclosed in patent document 1 is known. Patent document 1 simulates a tuned frequency of a pressure wave in an intake pipe as a parameter of an engine using a predetermined calculation model. However, there are the following problems: the operation and state of the engine change from time to time, and even if the simulation is performed using the same operation model, the accuracy of the simulation varies.

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

Means for solving the problems

In order to solve the above problem, an engine state estimation device according to an aspect of the present invention estimates a state of an engine, the engine including: a combustion unit that combusts air and fuel to generate power; and a supercharger that increases the pressure of the intake air and supplies the air to the combustion unit, the engine state estimation device including: an air density measurement data acquisition unit that acquires air density measurement data that is measurement data of a parameter relating to a density of at least one of air taken in by the supercharger and compressed air supplied to the combustion unit by the supercharger; and a state estimation unit that estimates the state of the engine based on the air density measurement data and the fuel supply amount to the combustion unit, which is input to an engine model indicating the characteristics of the engine.

In this aspect, a parameter relating to the density of at least one of the air taken in by the supercharger and the compressed air supplied to the combustion section after the supercharger has increased the pressure is measured, and the state of the engine is estimated using the parameter. This parameter indicates the density of air used for combustion in the combustion unit, and is a parameter that has a particularly large influence on the operation and state of the engine among a plurality of engine-related parameters. Therefore, if this parameter fluctuates, the state of the engine fluctuates greatly, which causes a large deviation in the accuracy of state estimation. In the present invention, since the parameter having a large influence on the state of the engine can be measured as the air density measurement data and used for the state estimation, the state estimation of the engine can be performed with stable accuracy.

Another aspect of the invention is an engine state estimation method. The method estimates a state of an engine, the engine including: a combustion unit that combusts air and fuel to generate power; and a supercharger that increases the pressure of the intake air and supplies the air to the combustion unit, the engine state estimation method including the steps of: an air density measurement data acquisition step of acquiring air density measurement data, which is measurement data of a parameter relating to a density of at least one of air taken in by the supercharger and compressed air supplied to the combustion section by the supercharger; and a state estimation step of estimating the state of the engine based on the air density measurement data and a fuel supply amount to the combustion portion input to an engine model representing the characteristics of the engine.

In addition, an arbitrary combination of the above-described constituent elements, and a mode in which the expression of the present invention is converted between a method, an apparatus, a system, a recording medium, a computer program, and the like are also effective as modes of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

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

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 graph showing the influence of air density measurement data on the output of the engine.

Fig. 5 is a graph showing the influence of air density measurement data on the fuel efficiency of the engine.

Fig. 6 is a graph showing the influence of air density measurement data on the temperature of the 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 the configuration of an engine state estimation device according to a second embodiment.

Description of the reference numerals

100: an engine state estimating device; 110: an air density measurement data acquisition unit; 120: a state estimation unit; 121: a calculation section; 122: an engine model correction unit; 200: an engine; 210: a combustion section; 220: a gas supply path; 221: an air inlet pipe; 222: a gas supply pipe; 223: a gas supply receiver; 224: a gas supply cooler; 230: an air exhaust path; 231: an exhaust receiver; 232: an exhaust pipe; 233: a turbine outlet duct; 240: a supercharger; 241: a compressor; 242: a 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. The estimation accuracy can be improved by measuring the temperature and pressure of the air for fuel combustion, which has a large influence on the output and fuel consumption of the engine, among the plurality of engine-related parameters and using the measured temperature and pressure for the state estimation.

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

Before describing each part of engine state estimating device 100, engine 200 as a state estimation target will be described with reference to fig. 2 and 3.

Fig. 2 is a schematic diagram showing a so-called four-stroke engine as an example of the engine 200. As will be described later, a four-stroke engine is an engine that performs a single cycle including four strokes of intake, compression, combustion, and exhaust by four vertical movements (two times of ascent and two times of descent) of a piston.

The engine 200 includes a combustion unit 210 that generates power by mixing air and fuel and combusting the air, and a supercharger 240 that increases the pressure of the air taken in 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 gas discharged after combustion in the combustion section 210, and a compressor 241 that is coaxially coupled to the turbine 242 via a shaft 243 to rotate in conjunction therewith.

The compressor 241 is provided at a position on one end side in the air supply passage 220 having one end open to the outside air (atmosphere) and the other end communicating with the combustion portion 210, and sucks in the outside air and compresses the sucked outside air by the rotation of the compressor 241. The air compressed by the compressor 241 and having a high pressure is supplied to the combustion unit 210 through the air supply path 220 so as to be used for combustion of the fuel therein. The gas supply path 220 includes: an intake pipe 221 through which air sucked from one end of the compressor 241, which is open to outside air, flows; an air supply pipe 222 through which compressed air supplied from the compressor 241 to the combustion unit 210 flows; and an air supply receiver 223 as an air supply receiving portion provided at a position close to the combustion portion 210 on the other end side and receiving compressed air. In order to prevent the air compressed by the compressor 241 from expanding due to a temperature rise, an intake air cooler 224, which is a cooler for cooling the compressed air flowing through the air supply pipe 222, is provided in the middle of the air supply pipe 222. Thereby, the temperature of the compressed air cooled while flowing through the air-supply cooler 224 and stored in the air-supply receiver 223 is kept within a fixed range.

The turbine 242 is provided at a position on the other end side in the exhaust passage 230, one end of which communicates with the combustion section 210 and the other end of which is open to the outside air (atmosphere). The gas discharged after combustion in the combustion section 210 rotates the turbine 242 due to its potential, and is then discharged to the outside air from the other end of the exhaust passage 230. The exhaust path 230 includes: an exhaust receiver 231 as an exhaust housing portion, which is provided at a position close to the combustion portion 210 on one end side, and which houses gas discharged after combustion in the combustion portion 210; an exhaust pipe 232 through which exhaust gas flows from the exhaust receiver 231 toward the turbine 242; and a turbine outlet pipe 233 for circulating the exhaust gas after passing through the turbine 242 from the other end thereof until being discharged into the outside air.

The combustion unit 210 includes: a combustion chamber 211 for combustion of fuel caused by air to occur; a fuel supply nozzle 212 for supplying fuel of a quantity specified by a fuel supply quantity U per one combustion into the combustion chamber 211; an intake valve 213 for controlling the supply of air from the air supply receiver 223 to the combustion chamber 211; an exhaust valve 214 for controlling the discharge of gas from the combustion chamber 211 to an exhaust receiver 231; a piston 215 linearly driven in correspondence with combustion of fuel in the combustion chamber 211; a crankshaft 216 serving as a rotation driving unit that is driven to rotate in accordance with the linear motion of the piston 215; and a connecting rod 217 having one end fixed to the piston 215 and the other end fixed to the crankshaft 216, for converting the linear motion of the piston 215 into the rotational motion of the crankshaft 216. Further, although the fuel is directly supplied into the combustion chamber 211 through the fuel supply nozzle 212 in the above description, when fuel having high volatility such as gasoline is used, the fuel may be injected into the air supply receiver 223 or the air supply pipe 222 and supplied into the combustion chamber 211 in a state of being mixed with air.

In the above configuration, the engine 200 is driven in the following cycle. Here, it is assumed that the engine 200 is in an operating state by driving before the previous cycle or driving by combustion of multiple cylinders, and the piston 215 repeatedly ascends and descends in accordance with the operation of the crankshaft 216 that continues to rotate.

(1) Air intake: intake valve 213 is opened, exhaust valve 214 is closed, and piston 215 is lowered, thereby supplying air from air supply receiver 223 to combustion chamber 211.

(2) Compression: the intake valve 213 is closed and the piston 215 is raised, whereby the air in the combustion chamber 211 is compressed.

(3) And (3) combustion: the fuel supply amount U per one combustion is supplied from the fuel supply nozzle 212 into the combustion chamber 211, and the fuel is combusted in the compressed air. Thereby generating power and lowering the piston 215.

(4) Exhausting: exhaust valve 214 opens and piston 215 moves upward, thereby discharging combusted gas from combustion chamber 211 to 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 (components corresponding to those in fig. 2 are given the same reference numerals and description thereof is omitted as appropriate). Unlike the four-stroke engine of fig. 2, which completes one cycle with four upward and downward movements of the piston, in the two-stroke engine, one cycle is completed by a total of two upward and downward movements by one upward and one downward movements of the piston.

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

In the illustrated state in which the piston 215 is lowered, gas can flow through a path passing through the crankcase 218, the scavenging passage 219, the combustion chamber 211, and the exhaust passage 230, and fresh air in the crankcase 218 flows into the combustion chamber 211 through the scavenging passage 219, and the combusted gas is discharged (scavenged) to the exhaust passage 230 by the momentum thereof.

When the piston 215 moves up, the scavenging passage 219 and the exhaust passage 230 are closed, and the combustion chamber 211 is sealed and the pressure thereof increases. Then, fuel is supplied from the fuel supply nozzle 212 into the combustion chamber 211 having a high pressure to cause combustion, and power for lowering the piston 215 again is generated. On the other hand, when the piston 215 moves up, the crankcase 218 communicates with the air supply passage 220, and fresh air flows into the crankcase 218 from the air supply passage 220. As described above, when the piston 215 moves upward, combustion in the combustion chamber 211 and air supply to the crankcase 218 are performed simultaneously.

As described above, in the two-stroke engine, one cycle is completed by two strokes of 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 intake air to the crankcase 218 when the piston 215 is raised and the pressure of the scavenging air to the combustion chamber 211 when the piston 215 is lowered can be increased.

Further, as the two-stroke engine, a configuration as disclosed in patent document 2 may be used. In this two-stroke engine, similarly to the above description regarding fig. 3, in a state where the piston (41: reference numeral (the same shall apply hereinafter) in patent document 2) is lowered, gas can flow through a path passing through the scavenging receiver (2) corresponding to the intake receiver 223, the scavenging port (17) corresponding to the crankcase 218 and the scavenging passage 219, the cylinder (1) corresponding to the combustion chamber 211, and the exhaust duct (6) corresponding to the exhaust passage 230, and fresh air in the scavenging receiver flows into the cylinder through the scavenging port, and a scavenging operation of discharging the burned gas to the exhaust duct is performed by the momentum thereof. In addition, when the supercharger 240 is used in such a structure, the pressure of scavenging in the scavenging receiver can be increased.

The present embodiment is applicable to various types of engines 200 as described above, but is particularly suitable for use in marine engines having a rated rotation speed of 1000 rpm or less, without being limited to marine, vehicle, aircraft, and other applications. In general, a marine engine can be driven at a lower rated rotation speed than a vehicle engine as described above. In particular, in a large ship, since it takes time until power generated by the engine is reflected in an actual operation of the ship, accurate engine driving is required. As described above, in the engine for the ship, it is highly required to estimate the state of the engine with high accuracy and to perform accurate driving, and it is preferable to use the engine state estimation device 100 of the present embodiment.

Further, as a ship, the engine 200 of the present embodiment can be used in addition to the structure disclosed in patent document 3, for example. That is, the engine 200 of the present embodiment is used as a main power unit (10: reference numeral in patent document 3 (the same applies hereinafter)) for generating the propulsive force of the ship, and the power generated therein is transmitted to the propeller (14) via the drive shaft, whereby the propeller (14) is rotated to generate the propulsive force of the ship.

In the engine 200 configured as described above, the gas used for combustion of the fuel flows through the following path. External air → an intake duct 221 → a compressor 241 → an intake duct 222 → an intake air receiver 223 → a combustion portion 210 (combustion chamber 211) → an exhaust air receiver 231 → an exhaust duct 232 → a turbine 242 → a turbine outlet duct 233 → external air.

In the present embodiment, sensors for measuring parameters related to the density of air, specifically, parameters such as pressure and temperature, may be provided at various positions in the gas flow path. As shown in the drawing, the installation positions of the sensors are classified into three positions S0 to S2 below.

S0: in the air inlet pipe 221

S1: in the gas supply pipe 222

S2: in the air supply receiver 223

Sensors for measuring the pressure, temperature, and flow rate of the outside air sucked by the compressor 241 may be provided at a sensor installation position S0 in the intake pipe 221. The sensor installation position S0 in the intake pipe 221 is preferably a position spaced apart from the open end of the intake pipe 221 that opens to the outside air and the inlet of the compressor 241 by a predetermined distance, so that stable measurement can be performed. When the open end opened to the outside air is excessively close, the measurement data is easily influenced by a sudden change in the outside air, and when the open end is excessively 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 pressure of the compressor 241 is increased can be provided at a sensor installation position S1 in the air supply pipe 222. The temperature may be measured directly or indirectly by measuring the temperature of the compressed air, or by measuring the cooling temperature of the supply air cooler 224 for cooling the compressed air, that is, the temperature of a refrigerant such as cooling water. In the case where the cooling temperature of the supply air cooler 224 is fixed and the temperature of the compressed air in the air supply pipe 222 can be regarded as fixed, it is preferable to measure the pressure because the importance of measuring the temperature at the sensor installation position S1 is low.

The sensor installation position S1 in the air supply pipe 222 is preferably a position away from the outlet of the compressor 241 by a predetermined distance, so that stable measurement can be performed. More preferably, if the position is set to a position after the compressed air is sufficiently cooled in the subsequent stage of the charge air cooler 224, more stable measurement can be performed. In particular, when the cooling temperature of the charge air cooler 224 can be regarded as constant, the temperature of the compressed air can be regarded as constant, and therefore 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 provided at a sensor installation position S2 in the air supply receiver 223. Similarly to the air supply pipe 222 described above, when the cooling temperature of the supply air cooler 224 is fixed and the temperature of the compressed air in the supply air receiver 223 can be regarded as fixed, it is preferable to measure the pressure because the importance of measuring the temperature at the sensor installation position S2 is low.

It is preferable that the sensor installation position S2 in the air supply receiver 223 is a position spaced apart 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 by a predetermined distance, so that stable measurement can be performed. This makes it possible to perform stable measurement while avoiding the influence of abnormal air flow that may occur at these locations. Further, even when the cooling temperature of the supply air cooler 224 can be regarded as constant, the temperature of the compressed air in the supply air receiver 223 can be regarded as constant, and therefore the state of the compressed air in the supply air receiver 223 can be accurately grasped by measuring only the pressure.

The parameters measurable at the three sensor installation positions S0 to S2 described above indicate the density of air used for combustion in the combustion section 210, and are used by the engine state estimation device 100 to estimate the state of the engine 200 as described later. Here, the state of the engine 200 can be estimated by providing a sensor at least one sensor installation position without providing a sensor at each of the three sensor installation positions S0 to S2. On the other hand, when sensors are provided at a plurality of sensor positions in S0 to S2, or when a plurality of sensors of different types are provided at one sensor position, the accuracy of the state estimation of engine 200 can be improved based on the plurality of measurement data obtained thereby.

Referring back to fig. 1, the respective units (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, measurement data of the outside air taken in by the compressor 241 is acquired from the sensor installation position S0 (in the intake pipe 221), and measurement data of the air supplied to the combustion unit 210 after the pressure of the compressor 241 is increased is acquired from the sensor installation position S1 (in the air supply pipe 222) and S2 (in the air supply receiver 223).

The state estimating unit 120 that estimates the state of the engine 200 includes a calculating unit 121, and the calculating unit 121 calculates a state variable that is a parameter 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 the characteristics of the engine 200 such as the thermal efficiency, the power transmission efficiency, the dynamic characteristics, the supercharger efficiency, and the influence of disturbance, calculates the fuel supply amount U per combustion supplied to the combustion unit 210, the measurement data Ne of the rotation speed of the crankshaft 216 generating the rotational power in the combustion unit 210, and the like as input data, and outputs the estimated values of the state variables of the engine 200 as the engine state estimation result. As will be described later, in the present embodiment, the state of the engine 200 can be estimated with high accuracy by inputting not only the fuel supply amount U and the rotation speed Ne to the engine model but also the air density measurement data acquired by the air density measurement data acquisition unit 110 to the engine model. Further, although various methods of constructing the engine model can be conceived, as a simple example, the method can be constructed as a table in which the fuel supply amount U, the rotation speed Ne, the air density measurement data, and the like, which are input, are associated with the estimated values of the respective state variables of the engine 200, which are output.

The state variables of engine 200 that can be estimated by state estimation unit 120 include, for example, the following variables.

Parameters related to the operation of the combustion unit 210:

rotational speed of crankshaft 216 (rotational speed Ne of combustion unit 210)

Parameters related to the operation of the supercharger 240:

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

In the present embodiment, since the rotation speed Ne is acquired as measurement data, it is not necessary to estimate the rotation speed Ne by the state estimating unit 120.

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

Parameters relating to the outside air taken in by the compressor 241 (which can be measured at S0 within the intake pipe 221):

pressure of outside air (outside air pressure Pa)

Temperature of outside air (outside air temperature Ta)

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

pressure of intake air (intake air pressure Pb/scavenging pressure Ps in the two-stroke engine performing the scavenging operation)

Temperature of intake air (intake air temperature Tb/scavenging temperature Ts in the case of a two-stroke engine performing a scavenging operation)

Temperature of cooling water of the charge air cooler 224 (cooling water temperature Tw)

In addition to the above, parameters relating to the gas flowing through each portion in the engine 200:

flow rates in the intake pipe 221, the air supply pipe 222, and the air supply receiver 223

The pressure, temperature, and flow rate in the exhaust receiver 231, exhaust pipe 232, and turbine outlet pipe 233 can be calculated by the engine model using the above parameters:

performance (torque, output, etc.) relating to the power generated by the engine 200

Performances related to fuel consumption of engine 200 (fuel consumption per unit time (hereinafter simply referred to as "fuel consumption"), fuel consumption rate per unit time and unit output, travel distance per unit volume of fuel, and the like)

Each of the above state variables can be measured by providing an appropriate sensor, but in the actual engine 200, it is not practical to measure all the state variables due to limitations in cost and installation. Therefore, in the present embodiment, the following configuration is adopted: only the rotation speed Ne and a part of the air density measurement data used for improving the estimation accuracy of the state estimating unit 120 are measured, and the state estimating unit 120 calculates the estimated values of the other state variables.

Further, fuel supply amount U per one combustion as a drive input to engine 200 is set based on measurement data of rotation speed Ne of combustion unit 210. That is, assuming that Ne0 is the target rotation speed of combustion unit 210, the difference between Ne as the measurement value and Ne0 as the target value is calculated, and fuel supply amount U per combustion is set such that the difference is small, based on a predetermined table or algorithm.

Next, a technique which is found by the present inventors through experiments to improve the state estimation accuracy using air density measurement data will be described. Fig. 4 to 7 show results obtained by experiments on the influence of the outside air temperature Ta, the outside air pressure Pa, and the cooling water temperature Tw, which are 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 influences on the temperature (compressor outlet temperature Tc) in the vicinity of the outlet of the compressor 241 in the air supply pipe 222, the scavenging temperature Ts in the air supply receiver 223, and the exhaust gas temperature Tex in the exhaust gas receiver 231, respectively, and fig. 7 shows the influences on the scavenging pressure Ps in the air supply receiver 223, the exhaust gas pressure Pex in the exhaust gas 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 measured while varying, and the results of the cases where the load of the engine 200 was 50%, 75%, 85%, and 100% of the maximum load are shown in the respective drawings.

In each drawing, the ratios of changes in the state variables that are the objects of the respective drawings when the outside air temperature Ta, the outside air pressure Pa, and the cooling water temperature Tw each change within the range of fluctuation of the assumed environmental conditions are shown as graphs. For example, the influence of about-1.2% at the load of 100% is exhibited from the outside air temperature Ta of fig. 4, which is the target of the output, which means that the output when the outside air temperature Ta is the upper limit in the assumed range becomes smaller by about 1.2% than the output when the outside air temperature Ta is the lower limit in the assumed range. Similarly, the outside air temperature Ta of fig. 5, which is the target of the fuel economy, has an influence of about 1.5% at the load of 50%, which means that the fuel economy when the outside air temperature Ta is the upper limit of the assumed range becomes larger by about 1.5% than the fuel economy when the outside air temperature Ta is the lower limit of the assumed range.

As is clear from fig. 4 and 5 relating to the output and the fuel consumption, which are important indexes of the engine 200, in the above experimental results, the influence of the outside air temperature Ta on the output and the fuel consumption is significantly large among the three air density measurement data. Therefore, the outside air temperature Ta is measured at the sensor installation position S0 and supplied to the state estimating unit 120 via the air density measurement data acquiring unit 110, whereby the state estimating unit 120 can estimate the output and the fuel consumption with high accuracy.

As is apparent from fig. 6 relating to the temperature of the gas flowing through the engine 200, the influence of the outside air temperature Ta on the compressor outlet temperature Tc is the greatest (the cooling water temperature Tw, the cooling water temperature Tw on the scavenging temperature Ts, and the influence of the outside air temperature Ta on the exhaust gas temperature Tex is the greatest (the cooling water temperature Tw, the following).

As is apparent from fig. 7 relating to the pressure of the gas flowing through the engine 200, the influence of the outside air temperature Ta on the scavenging pressure Ps is the greatest (the cooling water temperature Tw, the following), the influence of the outside air temperature Ta on the exhaust pressure Pex is the greatest (the following cooling water temperature Tw), and the influence of the outside air pressure Pa on the turbine outlet pressure P0 is the greatest.

Therefore, by measuring the outside air temperature Ta (sensor installation position S0), the outside air pressure Pa (sensor installation position S0), and the cooling water temperature Tw (sensor installation position S1), respectively, and supplying the measured air density data to the state estimating unit 120 via the measured air density data acquiring unit 110, the state estimating unit 120 can estimate the state variable having a large influence on each measured air density data with high accuracy.

In addition, although experiments were performed on three air density measurement data in the above description, the teaching obtained here can be applied to other air density measurement data as follows.

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

On the other hand, in fig. 4 and 5, the influence of the outside air pressure Pa, which is another parameter indicating the state of the outside air, on the output and the fuel consumption is hardly observed. This is considered to be because the output and the fuel consumption are hardly affected within the range of the assumed fluctuation of the external air pressure Pa.

When the external air is sucked and compressed by the compressor 241 into the air supply pipe 222 and the air supply receiver 223 as described above, the pressures thereof, i.e., the supply air pressure Pb and the scavenging air pressure Ps, are considered to be the main parameters that affect the output and the fuel consumption this time. This is because the intake air temperature Tb and the scavenging temperature Ts are cooled within a fixed range by the intake air cooler 224 provided in the middle of the intake pipe 222, and therefore the density of the air supplied to the combustion portion 210 is mainly determined by the pressure. Therefore, in the engine 200 provided with the charge air cooler 224, the charge air pressure Pb and the scavenging air pressure Ps of the cooled air are measured as the air density measurement data, and are supplied to the state estimating unit 120 via the air density measurement data acquiring unit 110, whereby the state estimating unit 120 can estimate the output and the fuel consumption with high accuracy. On the other hand, in the engine 200 not provided with the intake air cooler 224, since it is considered that the intake air temperature Tb and the scavenging temperature Ts continue to have a large influence on the output and the fuel consumption like the outside air temperature Ta, the output and the fuel consumption can be estimated with high accuracy by measuring the intake air temperature Tb and the scavenging temperature Ts.

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

Outside air temperature Ta

Supply pressure Pb and scavenging pressure Ps

Feed air temperature Tb and scavenging air temperature Ts (in the case where the feed air cooler 224 is not provided)

The above-described findings obtained from fig. 4 to 7 are preferably incorporated in advance in the engine model of the calculation unit 121 as information indicating the relationship between each air density measurement data and each state variable. According to such an engine model, the state variables can be calculated with high accuracy by taking into consideration the degrees of influence shown in fig. 4 to 7 from the measured air density measurement data.

As is clear from fig. 4 to 7, when the load on the engine 200 is low, such as 50% of the maximum load, the gas density measurement data tends to have a large influence on the state variables. This is considered to be because engine 200 is susceptible to various changes inside and outside engine 200 when operating at a low load. Therefore, it is preferable that the state estimating unit 120 estimate 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 is operating at a load of 50% or less of the maximum load. On the other hand, when a high-load operation is performed in which the influence of the gas density measurement data is relatively small, for example, when the operation is performed at a load higher than 50% of the maximum load, the state estimation may be performed without using the gas density measurement data, or the frequency of the 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 applications, for example.

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

The engine state estimation result can be used for monitoring and degradation diagnosis of the engine 200. It is possible to reliably identify an abnormality of the engine and to quickly respond thereto.

Fig. 8 is a schematic diagram showing the configuration of the engine state estimation device 100 according to the second embodiment. Only the configuration of the state estimating unit 120 is different from the engine state estimating apparatus 100 according to the first embodiment shown in fig. 1. The state estimating unit 120 includes a calculating unit 121 and an engine model correcting unit 122.

The calculation unit 121 calculates an estimated value of a state variable of the engine 200 based on an engine model indicating the characteristics of the engine 200 using the fuel supply amount U and the rotation speed Ne as input data, and outputs the estimated value as an engine state estimation result. In the present 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 engine model correction unit 122 at the subsequent stage. Instead, the calculation unit 121 calculates air density estimation data, which is an estimation value of the gas density measurement data, in a calculation process based on the engine model. As described in the first embodiment, since the measurement data affecting the air density, such as the outside air pressure Pa, the outside air temperature Ta, the intake air pressure Pb/scavenging pressure Ps, the intake air temperature Tb/scavenging temperature Ts, and the cooling water temperature Tw, are all state variables of the engine 200, the calculation unit 121 can determine the gas estimation data in the normal calculation for determining the engine state estimation result.

The engine model correction unit 122 corrects the engine model in the calculation unit 121 so 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 air density estimation data that is the estimated value and the air density measurement data that is the actual measurement value, the engine model that is the basis of calculation of the estimated value deviates from the actual characteristics of engine 200, and therefore, engine model correction unit 122 corrects the engine model so as to approach the actual characteristics of engine 200. If ideally the difference between the air density estimation data and the air density measurement data is always zero, the engine model accurately represents the actual engine 200 characteristics. By such correction, the engine model is a model that better reflects the characteristics of the actual engine 200, and therefore the accuracy of the engine state estimation can be improved. In particular, in the present embodiment, by using air density measurement data having a large influence on each state variable such as the output and the fuel consumption of the engine 200, the engine model can be efficiently corrected.

The present invention has been described above based on embodiments. It will be understood by those skilled in the art that the embodiments are illustrative, and various modifications can be made by combining the respective constituent elements and the respective processing steps, and such modifications are also within the scope of the present invention.

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

The functional configuration of each device described in the embodiments can be realized by hardware resources, software resources, or cooperation of hardware resources and software resources. As the hardware resources, a processor, ROM, RAM, or other LSI can be used. As the software resource, a program such as an operating system or an application can be used.

In the embodiments disclosed in the present specification, in which a plurality of functions are provided in a distributed manner, some or all of the plurality of functions may be provided in a concentrated manner, and conversely, in the embodiments in which a plurality of functions are provided in a concentrated manner, some or all of the plurality of functions may be provided in a distributed manner. The functions may be integrated or distributed, and the functions may be configured to achieve the object of the invention.

Claims

1. An engine state estimation device that estimates a state of an engine, the engine comprising: a combustion unit that combusts air and fuel to generate power; and a supercharger that increases the pressure of the intake air and supplies the air to the combustion unit, the engine state estimation device including:

an air density measurement data acquisition unit that acquires air density measurement data that is measurement data of a parameter relating to a density of at least one of air taken in by the supercharger and compressed air supplied to the combustion unit by the supercharger; and

a state estimating unit that estimates a state of the engine based on the air density measurement data and a fuel supply amount to the combustion unit, which is input to an engine model representing characteristics of the engine.

2. The engine state estimation device according to claim 1,

the engine is a marine engine having a rated rotation speed of 1000 rpm or less.

3. The engine state estimation device according to claim 1 or 2,

the state estimating unit inputs the air density measurement data to the engine model to estimate the state of the engine.

4. The engine state estimation device according to claim 1 or 2,

the state estimation unit includes:

a calculation unit that calculates air density estimation data, which is an estimation value of the air density measurement data, based on the engine model; and

an engine model correction unit that corrects the engine model so that a difference between the air density estimation data and the air density measurement data is reduced.

5. The engine state estimation device according to claim 1,

the air density measuring data measuring device is arranged in an air inlet pipe for the air sucked by the supercharger to circulate.

6. The engine state estimation device according to claim 1,

the air density measuring data measuring device is arranged in an air supply accommodating part for accommodating the compressed air.

7. The engine state estimation device according to claim 1,

the air density measurement data is measurement data of at least one of a temperature and a pressure of air taken in by the supercharger and the compressed air.

8. The engine state estimation device according to claim 7,

the air density measurement data is measurement data of a temperature of air taken in by the supercharger.

9. The engine state estimation device according to claim 7 or 8,

the engine is provided with 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.

10. The engine state estimation device according to claim 1,

the engine is provided with a cooler for cooling the compressed air,

the air density measurement data is measurement data of a temperature of the cooling refrigerant of the cooler.

11. The engine state estimation device according to claim 1,

the state estimating unit estimates the state of the engine based on measurement data of the rotation speed of a rotation driving unit that generates rotational power in the combustion unit.

12. The engine state estimation device according to claim 1,

the state estimating unit estimates a state of the engine when a load of the engine is 50% or less of a maximum load of the engine.

13. An engine state estimation method that estimates a state of an engine, the engine comprising: a combustion unit that combusts air and fuel to generate power; and a supercharger that increases a pressure of intake air and supplies the air to the combustion portion, the engine state estimation method including:

an air density measurement data acquisition step of acquiring air density measurement data, which is measurement data of a parameter relating to a density of at least one of air taken in by the supercharger and compressed air supplied to the combustion section by the supercharger; and

a state estimation step of estimating a state of the engine based on the air density measurement data and a fuel supply amount to the combustion portion input to an engine model representing characteristics of the engine.

14. A computer-readable storage medium storing an engine state estimation program that estimates a state of an engine, the engine comprising: a combustion unit that combusts air and fuel to generate power; and a supercharger that increases the pressure of the intake air and supplies the air to the combustion unit, wherein the engine state estimation program causes the computer to execute: