DE102017126851B4 - Fuel system control apparatus - Google Patents

Abstract

A fuel system control apparatus (50) adapted to control a heating operation of a heater (110) of a fuel filter (11) which filters fuel supplied to a combustion chamber (1a) in a fuel system (10) of an internal combustion engine (1), wherein the fuel system control apparatus (50) has:a parameter acquisition block (50a; S102, S103, S3101, S4101, S4103, S5101, S5103) set up to obtain a characteristic parameter which indicates a property of the fuel;an average calculation block ( 50a; S104, S2104, S3104, S4104, S5104) for calculating average element numbers of chemical elements constituting the fuel based on the characteristic parameter obtained by the parameter obtaining block (50a; S102, S103, S3101, S4101 , S4103, S5101, S5103); a cloud point estimation block (50a; S105) for estimating a cloud point of the fuel corresponding to the average element numbers determined by the average calculation block (50a; S104, S2104, S3104, S4104, S5104) are calculated, and a heater control block (S107, S108) arranged to control the heater (110) of the fuel filter (10) in the event that a temperature of the fuel drops to the cloud point, which is through the Cloudpoint estimation block (50a, S105) is estimated.

Description

The present invention relates to a fuel system control apparatus.

In a fuel system for an internal combustion engine, a conventional fuel system control apparatus controls heating of a fuel filter that filters fuel supplied to a combustion chamber of the internal combustion engine by a heater to continuously maintain a high filtering efficiency of the fuel filter.

An exemplary fuel system control apparatus included in JP 2014-51920 A is configured to heat a fuel filter through a heating control based on a kinetic viscosity and a temperature of a fuel according to a correlation between a kinetic viscosity and a cloud point of fuel.

However, it has been found that the cloud point of fuel varies from fuel to fuel even in the case where each fuel has the same kinetic viscosity at a temperature. This is because a growth rate of precipitated crystal produced upon solidification varies in accordance with a fuel composition, that is, molecular structures of fuel. For this reason, depending on the fuel composition, the conventional fuel system control apparatus is likely to fail to perform heating even if a present temperature drops to be lower than the cloud point determined by the correlation data relative to the fuel composition kinetic viscosity is defined. As a result, the fuel in the fuel filter solidifies like a wax, ultimately causing clogging of the fuel filter. Once the fuel solidifies like a wax, the precipitated crystal attached to the fuel filter is hardly melted even if it is heated. Solidification thus counteracts the continued maintenance of high filter efficiency of the fuel filter.

JP H06-330 783 A discloses a fuel supply device. A fuel property detection sensor that detects the characteristics of light or heavy fuel, a fuel heat exchanger, and a flow rate control valve serving as a fuel temperature adjusting device are provided on a fuel passage of an injector that supplies fuel under high pressure into an engine injected. An ECU (engine control unit), based on the detection signal of the fuel characteristic detection sensor, provides a heating or cooling command to the fuel heat exchanger and the flow rate control valve to obtain a constant evaporation characteristic of the fuel injected from the injector while the light fuel is cooled and the heavy fuel is heated.

The JP 2011 - 231 659 A discloses a fuel supply system. This fuel supply system includes a heater that heats fuel, a cooler that cools the fuel, a temperature detector that detects the fuel temperature, and a kinematic viscosity detector that detects the kinematic viscosity of the fuel. An ECU is provided to operate the heater and the cooler according to a fuel temperature detection value and a fuel kinematic viscosity detection value. Thereby, when the fuel temperature is low and the fuel kinematic viscosity is high, the heater is turned on to increase the fuel temperature and also reduce the fuel kinematic viscosity. Accordingly, even when a type of fuel having a high kinematic viscosity of the fuel and a low fluidity is used, the fluidity is surely increased and the fuel is sufficiently dispersed and penetrates into the metal ion removing means, thereby removing the metal ions.

From the JP S60- 24 876 U As is known, a heating element is installed in the fuel filter of the engine or on the upstream side thereof, and a part of the fuel pipe is formed of a transparent element so that the light-emitting element and the light-receiving element operated by the light are in contact with each other opposite each other, with the transparent element interposed therebetween, the heating element being connected to a power source when the light from the light-emitting element reaching the light-receiving element decreases.

In the US 2004 / 0 076 413 A1 A fuel heater for a tank and an associated method are disclosed. An elongated element fits through an opening in the tank. The elongated member includes a first tube that defines a fuel passage and terminates with a lower fuel inlet. Fuel can be drawn from the tank and delivered through a supply-side line coupled to the first pipe. A second tube of the elongated member is coupled to a return side line that carries heated fuel back to the tank. A third tube surrounds the first tube substantially coaxially, and a Outlet of the second pipe enters the third pipe. Heat tracing can be used to warm the fuel. Accordingly, the fuel temperature in the tank can be maintained above the cloud point temperature.

The CN 1 03 939 247 A discloses an auxiliary device for heating fuel of a diesel engine. The fuel heating auxiliary device of a diesel engine, which has heating and suction functions, is provided with a control circuit, an electromagnetic gas valve and an exhaust pump device, is installed in front of an oil supply pump of the engine, and is connected to an oil delivery pipe. A small amount of fuel oil is stored in a cup of an electric heating auxiliary device, the temperature of the fuel oil exceeds the clogging point of the cold filter, and the fuel oil is used for low temperature starting and running in the initial stage of the engine. After the engine is started, an oil tank and other oil paths are heated by the residual heat of an antifreeze solution and the tail gas, and therefore stable operation of the engine is achieved. After the engine stops, the fluid level in the auxiliary device cup is restored by the functions of the electromagnetic gas valve and exhaust pump to facilitate the next low temperature start. Due to the technical design, the fuel heating auxiliary device of the diesel engine has the advantages that the preheating time of the engine in the low-temperature starting process is greatly shortened; the load on the accumulator is largely reduced; the diesel engine can use diesel with a high condensation point at low temperature, and oil costs are saved.

From the DE 10 2016 102 529 A1 For example, a machine corresponding to a diesel engine is known, comprising an injector that injects fuel into a combustion chamber. An ECU includes a kinematic viscosity acquisition unit that obtains a kinematic viscosity of the fuel, a density acquisition unit that obtains a density of the fuel, a composition calculation unit that as fuel composition data i) a ratio between a carbon amount and a hydrogen amount, which in the fuel, or ii) calculates a parameter with respect to the amount of carbon and the amount of hydrogen contained in the fuel, wherein the composition calculation unit makes the calculation based on the kinematic viscosity obtained by the kinematic viscosity obtaining unit and of the density obtained by the density obtaining unit, and a control unit that performs a combustion control operation with respect to combustion of the fuel injected into the combustion chamber from the fuel injection valve based on the fuel composition data calculated by the calculation unit.

The present invention addresses the problem described above and has an object of providing a fuel system control apparatus which continuously maintains a high filtering efficiency of a fuel filter.

According to the present invention, a fuel system control apparatus is provided for controlling a heating operation of a heater of a fuel filter that filters fuel supplied to a combustion chamber in a fuel system of an internal combustion engine. The fuel system control apparatus includes a parameter acquisition block, an average calculation block, a cloud point estimation block, and a heater control block. The parameter acquisition block acquires a characteristic parameter indicating a property of the fuel. The average calculation block calculates average element numbers of chemical elements constituting the fuel based on the characteristic parameter obtained by the parameter acquisition block. The cloudpoint estimation block estimates a cloudpoint of the fuel that corresponds to the average element counts calculated by the average calculation block. The heater control block controls the heater of the fuel filter in the event that a temperature of the fuel drops to the cloud point estimated by the cloud point estimation block.

• 1 ein Blockdiagramm, welches ein Kraftstoffsystem einer Maschine mit interner Verbrennung zeigt, bei welcher eine erste Ausführungsform der vorliegenden Erfindung umgesetzt wird.
• 2 ein Flussdiagramm, welches eine Heizsteuerungsverarbeitung zeigt, die bei der ersten Ausführungsform ausgeführt wird.
• 3 einen Graphen, der eine Korrespondenzbeziehung zwischen einer berechneten durchschnittlichen Kohlenstoffanzahl und einer tatsächlichen durchschnittlichen Kohlenstoffanzahl zeigt.
• 4 einen Graphen, der eine Korrespondenzbeziehung zwischen einem berechneten Cloudpoint und einem tatsächlichen Cloudpoint bei der ersten Ausführungsform zeigt.
• 5 ein Flussdiagramm, welches eine Heizsteuerungsverarbeitung zeigt, die bei einer zweiten Ausführungsform der vorliegenden Erfindung ausgeführt wird.
• 6 einen Graphen, der eine Korrespondenzbeziehung zwischen einem kinetischen Viskositäts-Änderungsbetrag und einer vorliegenden kinetischen Viskosität zeigt.
• 7 einen Graphen, der eine Korrespondenzbeziehung zwischen einer geschätzten Dichte und einer vorliegenden Dichte zeigt.
• 8 ein Flussdiagramm, welches eine Heizsteuerungsverarbeitung zeigt, die bei einer dritten Ausführungsform der vorliegenden Erfindung ausgeführt wird.
• 9 ein Flussdiagramm, welches eine Heizsteuerungsverarbeitung zeigt, die bei einer vierten Ausführungsform der vorliegenden Erfindung ausgeführt wird, und
• 10 ein Flussdiagramm, welches eine Heizsteuerungsverarbeitung zeigt, die bei einer fünften Ausführungsform der vorliegenden Erfindung ausgeführt wird.

It shows/shows:

• 1 12 is a block diagram showing a fuel system of an internal combustion engine in which a first embodiment of the present invention is implemented.
• 2 a flowchart showing heating control processing executed in the first embodiment.
• 3 a graph showing a correspondence relationship between a calculated average carbon number and an actual average carbon number.
• 4 a graph showing a correspondence relationship between a computed cloud point and an actual cloud point in the first embodiment.
• 5 is a flowchart showing heating control processing executed in a second embodiment of the present invention.
• 6 a graph showing a correspondence relationship between a kinetic viscosity change amount and an existing kinetic viscosity.
• 7 a graph showing a correspondence relationship between an estimated density and an existing density.
• 8th is a flowchart showing heating control processing carried out in a third embodiment of the present invention.
• 9 a flowchart showing heating control processing executed in a fourth embodiment of the present invention, and
• 10 is a flowchart showing heating control processing carried out in a fifth embodiment of the present invention.

The present invention will be described with reference to various embodiments shown in the drawings. In the following embodiments, corresponding structural parts are denoted by the same reference numerals for ease of description.

First embodiment

With reference to 1 1, an electronic control unit (ECU) 50 is provided as a fuel system control apparatus for a fuel system 10 of an internal combustion engine 1 mounted on a vehicle. The internal combustion engine 1 is a multi-cylinder compression ignition diesel engine for which diesel fuel (light oil) is used as fuel. A fuel composition, i.e. molecular structures of diesel fuel, differ from area to area or country to country worldwide. The ECU 50 is configured to control a heating operation of a heater 110 of a fuel filter 11 that filters fuel supplied to each combustion chamber 1a of the internal combustion engine 1.

More specifically, the fuel system 10 includes a fuel tank 12, a fuel filter 11, a high pressure pump 13, a common rail 14, a temperature sensor 15, a kinetic viscosity sensor 16, a density sensor 17 and the like. The fuel tank 12 stores fuel which is supplied to the combustion chamber 1a.

The fuel filter 11 is formed of a filter element 111 such as a filter paper and a cover 112 in which the filter element 111 is housed. The filter element 111 filters the fuel in a fuel supply path from the fuel tank 12 to the combustion chamber 1a. The filter element 111 filters the fuel by collecting foreign matter in the fuel flowing through the fuel filter 11.

A heating device 110 is provided in the casing 112 of the fuel filter 11. The heater 110 is formed of a heat generating element such as a positive temperature constant (PTC) element. The ECU 50 is configured to control electric power supply to the heater 110, thereby performing heating control of the filter element 111. Thus, with the filter element 111, it is possible to prevent solidification of a fuel that starts at a cloud point before the fuel filter 11 becomes clogged. The cloud point varies with a fuel composition.

The high pressure pump 13 supplies the fuel received from the fuel tank 12 as the fuel supplied to the combustion chamber 1a to the common rail 14 by pressure through the fuel filter 11. The ECU 50 is configured to supply electric power the high pressure pump 13 to thereby perform pressure control of a fuel pressured to the common rail 14. More specifically, the ECU 50 controls the pressure of a fuel supplied to the common rail 14 based on an operating state of the internal combustion engine 1, such as an accelerator pedal position and an engine speed.

The common rail 14 accumulates therein the fuel which is to be injected individually into the corresponding combustion chamber 1a of the internal combustion engine 1 starting from a fuel injector (injection valve) 1b. The ECU 50 is configured to individually control valve opening and closing of the fuel injector 1b for the combustion chamber 1a. When the fuel injector 1b is driven to open, the fuel accumulated in the common rail 14 is injected into the corresponding combustion chamber 1a and mixed with air sucked into the corresponding combustion chamber 1a. As a result, the mixture of fuel and air passes through a piston the engine 1 is compressed with internal combustion and burned by self-ignition.

A pressure reducing valve 140 is provided in the common rail 14 to limit the fuel pressure from exceeding a withstand pressure or maximum loading pressure of the common rail 14. At the time when the pressure reducing valve 140 is opened, the fuel may be discharged from the common rail 14 to the fuel tank 12 and/or the fuel filter 11 by selecting a return valve 141, as shown in 1 will be shown. Alternatively, the fuel may only be discharged to the fuel tank 12, although this is not shown in detail. The return valve 141 is controlled such that it selects the fuel tank 12 or the fuel filter 11 as a destination for discharging a fuel depending on a fuel temperature by an operation of a thermosensitive element (not shown).

The return valve 141 is not limited to selecting the destination of a fuel discharged from the common rail 14, but may select the destination of a fuel discharged from the high pressure pump 13 or the fuel injector 1b, as shown in FIG 1 will be shown.

The temperature sensor 15, the kinetic viscosity sensor 16 and the density sensor 17 are in the fuel system 10 on (in 1 (not shown) predetermined mounting locations are provided in the fuel supply path, which extends from the fuel tank 12 to the fuel injector 1b of each combustion chamber 1a. The temperature sensor 15 is formed of a sensor element such as a thermistor as a main component. The temperature sensor 15 detects a temperature of the fuel at the predetermined assembly point, which is supplied to the combustion chamber 1a from the fuel tank 12. The kinetic viscosity sensor 16 is formed as a main component of a sensor element, which can measure directly, such as a tuning fork type, an ultrasonic type, or a capillary type, or can measure indirectly, such as a density type. The kinetic viscosity sensor 16 detects a kinetic viscosity of the fuel at the predetermined mounting location as a characteristic parameter indicating a characteristic of the fuel supplied to the combustion chamber 1a from the fuel tank 12. The density sensor 17 is formed of a sensor element such as a characteristic vibration duration measurement type as a main element. The density sensor 17 detects a density of the fuel supplied to the combustion chamber 1a from the fuel tank 12 at its mounting location as a characteristic parameter of the fuel. The density sensor 17 and the kinetic viscosity sensor 16 detect the density and kinetic viscosity at the respective mounting positions where fuel temperatures are assumed to be generally the same.

The ECU 50 is formed of a microcomputer having as main components a processor 50a such as a central processing unit (CPU) and a memory 50b. The ECU 50 is connected not only directly or indirectly to the heater 110, the high-pressure fuel pump 13, the temperature sensor 15, the kinetic viscosity sensor 16, the density sensor 17, the injector 1b and the pressure reducing valve 140, but also through an on-vehicle network other sensors (not shown) of the vehicle are connected. The ECU 50 is configured to, based on vehicle information including detection information of the temperature sensor 15, the kinetic viscosity sensor 16 and the density sensor 17 and an operating state of the internal combustion engine 1, operations of the heater 110, the high pressure fuel pump 13 and of the injector 1b and the pressure reducing valve 140.

More specifically, the ECU 50 is configured to perform steps of heating control processing included in 2 is shown to be operatively carried out by executing by the processor 50a a heating control program which is stored in the memory 50b. The heating control is started when a power switch is turned on as a start command for starting the internal combustion engine 1 by a vehicle operator. The heating control is completed when the power switch is turned off as a stop command for stopping the internal combustion engine 1 by the vehicle operator. In 2 , which shows the heating control processing, “S” indicates a processing step. The memory 50b of the ECU 50, which stores the heating control program, is formed of one or a plurality of storage media such as a semiconductor memory, a magnetic medium, or an optical medium.

With the heating control, which is in 2 As shown, at S101, the processor 50a first obtains, based on detection information of the temperature sensor 15, a present temperature TMp of the fuel at detection positions of the kinetic viscosity and the density of the fuel, that is, at the mounting locations of the kinetic viscosity sensor 16 and the density sensor 16. Sensor 17, as a characteristic parameter of the fuel. In the event that the temperature sensor 15 detects the fuel temperature at or near the mounting locations of the kinetic Viscosity sensor 16 and density sensor 17 are detected, the processor 50a directly obtains the detection temperature of the temperature sensor 15 as the present temperature TMp. In the case that the temperature sensor 15 detects the fuel temperature at locations spaced from the mounting locations of the kinetic viscosity sensor 16 and the density sensor 17, the processor 50a indirectly obtains the present temperature TMp by estimating from the detection temperature of the temperature sensor 15 .

At S102, the processor 50a subsequently obtains a present kinetic viscosity KVp of the fuel at the mounting location of the kinetic viscosity sensor based on the detection information of the kinetic viscosity sensor 16 at a temperature substantially the same as the present temperature TMp obtained at S101 16. At S103, the processor 50a further obtains a present density DDp of the fuel at the mounting location of the density sensor 17 based on the detection information of the density sensor 17 at a substantially same temperature as the present temperature obtained at S101. That is, the present density DDp and the present kinetic viscosity KVp are obtained under the same temperature TMp.

$$\text{NC}=\mathrm{\alpha }\text{t}2\times \text{DDp}+\mathrm{\beta }\text{t}2\times \text{NH}+\mathrm{\gamma }\text{t}2$$

At S104, the processor 50a calculates an average carbon number (average number of carbon atoms C) NC and an average hydrogen number (average number of hydrogen atoms H) NH as average chemical element numbers of a fuel composition including carbon and hydrogen as average molecular structures of fuel. It is noted, as a result of the inventors' research and knowledge, that the present kinetic viscosity KVp and the present density DDp correlate with the average carbon number NC and the average hydrogen number NH, as defined by equations (1) and (2). $$\text{NC}=\mathrm{\alpha }\text{t}1\times \text{KV}+\mathrm{\beta }\text{t}1\times \text{NH}+\mathrm{\gamma }\text{t}1$$

$$\text{NC}=\mathrm{\alpha }\text{t}2\times \text{DDp}+\mathrm{\beta }\text{t}2\times \text{NH}+\mathrm{\gamma }\text{t}2$$

In equations (1) and (2), in accordance with the fuel temperature, the coefficients αt1, βt1, γt1, αt2, βt2 and γt2 are given based on an experimental result or a simulation result of a product design time. In the first embodiment, the processor 50a uses equations (1) and (2) at 5104 by introducing the predetermined coefficients αt1, βt1, γt1, αt2, βt2 and γt2 as model data that correlate the existing kinetics Viscosity KVp and the present density DDp relative to the average carbon number NC and the average hydrogen number NH. More specifically, at S104, the processor 50a selects a set of equations (1) and (2) corresponding to the present temperature TMp obtained at S101 from a set of equations (1) and (2) for which the Coefficients αt1, βt1, γt1, αt2, βt2 and γt2 of each temperature can be used. At the next step S104, the processor 50a introduces the present kinetic viscosity KVp and the present density DDp, obtained at steps S102 and S103, respectively, into the selected set of equations (1) and (2). Further, at S104, the processor calculates the average carbon number NC and the average hydrogen number NH by solving the simultaneous equations (1) and (2) into which the present kinetic viscosity KV and the present density DDp are introduced.

That is, the processor 50a calculates the average carbon number NC and the average hydrogen number NH, which are the present one, based on the equations (1) and (2), which are model data corresponding to the fuel temperature, as described above at S104 correspond to the kinetic viscosity KVp, the existing density DDp and the existing temperature TMp. As in 3 As shown, it is demonstrated that the average carbon number NC calculated as described above is substantially equal to an actual average carbon number NC corresponding to the fuel composition. In the case that, due to limited storage capacity of the memory 50b, discrete values are used as fuel temperatures which are made to correspond to equations (1) and (2), the coefficients αt1, βt1, γt1, αt2, βt2 and γt2 are given by Interpolation calculated and used for equations (1) and (2).

At S105, the processor 50a estimates a cloud point TMc that corresponds to the fuel composition. It is noted as a result of research and knowledge of the inventors that the cloud point TMc is estimated because it has the following correlation (3) with respect to the average carbon number NC and the average hydrogen number NH. $$\text{TMc}=\mathrm{\alpha }3\times \text{NC}+\mathrm{\beta }3\times \text{NH}+\mathrm{\gamma }3$$

The coefficients α3, β3 and γ3 in equation (3) are given based on the experimental result and a simulation result of the product design time. On the first execution form, the processor 50a uses equation (3) at S105 by introducing the predetermined coefficients α3, β3 and γ3 as model data representing the correlation of the cloud point TMc relative to the average carbon number NC and the average hydrogen number NH. At the next step S105, the processor 50a introduces the average carbon number NC and the average hydrogen number NH calculated at S104 into equation (3) to which the coefficients α3, β3 and γ3 are substituted. Thus, the processor 50a calculates the cloud point TMc, which corresponds to the average carbon number NC and the average hydrogen number NH, using equation (3), which includes the average carbon number NC and the average hydrogen number NH. As in 4 As shown, it is demonstrated that the cloud point TMc calculated as described above is approximately estimated with respect to the actual cloud point TMc corresponding to the fuel composition.

At the next step S106, the processor 50a obtains a temperature TMj at the monitoring time based on the detection information of the temperature sensor 15 as the temperature of fuel currently flowing through the filter element 111 of the fuel filter 11. In the case that the temperature sensor 15 detects the fuel temperature at the location spaced from the filter element 111, the processor 50a indirectly obtains the temperature TMj at the monitoring time by estimating from the detection temperature of the temperature sensor 15. In the case that the temperature sensor 15 detects the fuel temperature at the location close to the filter element 111, the processor 50a obtains the detection temperature of the temperature sensor 15 directly as the temperature TMj at the monitoring time. In the case that S106 is executed for the first time immediately following S105, the processor 50a may obtain the temperature TMj at the monitoring time based on the detection information of the temperature sensor 15 acquired at S101.

Subsequently, at S107, the processor 50a determines a relationship of magnitudes of the temperature TMj at the monitoring time and the cloud point TMc by comparing the cloud point TMj at the monitoring time obtained at S106 with the cloud point TMc obtained at S105. In the case of a determination that the temperature TMj at the monitoring time is equal to or lower than the cloud point TMc, the processor 50a executes S108. In the event of a determination that the temperature TMc at the monitoring time exceeds the cloud point TMc, the processor 50a executes S109.

At S108, the processor 50a controls heating of the heater 110 by controlling an electric power supply amount so that the filter element 111 of the fuel filter 11 is appropriately heated. The processor 50a variably controls heating of the filter element 111 to a temperature in accordance with a difference between the values TMj and TMc compared at S107. Alternatively, the processor 50a may control heating of the filter element 111 to a predetermined fixed temperature. At S109, the processor 50a stops heating the filter element 111 of the fuel filter 11 by stopping heating operation of the heater 110 by turning off the power supply to the heater 110. After executing S108 or S109, the processor 50a again repeats the processing of steps S106 to S112 described above.

In the first embodiment described above, a functional part of the ECU 50 that executes S101 corresponds to a temperature acquisition block. A functional part of the ECU 50 that executes steps S102 and S103 corresponds to a parameter acquisition block. Further, a functional part of the ECU 50 that executes S104 corresponds to an average calculation block. A functional part of the ECU 50 that executes S105 corresponds to a Cloudpoint estimation block. Further, a functional part of the ECU 50 that executes steps S107 and S108 corresponds to a heater control block.

Operation and advantage

The first embodiment provides the following operation and advantage.

According to the first embodiment, the cloud point TMc of the fuel is estimated in accordance with the average element number of the fuel composition, which is calculated based on the characteristic parameters of the fuel. Since the cloud point TMc is estimated even in the case that the fuel composition is different, it is possible to prevent fuel from solidifying before the fuel filter 11 becomes clogged by heating the fuel heater when the temperature TMj is equal to or lower at the monitoring time than the Cloudpoint is TMc. It is therefore possible to increase reliability and ensure high filter efficiency.

Further, according to the first embodiment, the characteristic parameter having a temperature dependence is determined in accordance with the model data showing the correlation in the average element number for represent any fuel temperature. As a result, the average element value is accurately determined based on the characteristic parameters by further matching the present temperature TMp. Therefore, since the Cloudpoint TMc is estimated by further considering the temperature characteristic of the characteristic parameter even in the case that the fuel composition is different, it is possible to continuously maintain the high filter efficiency by operating the fuel filter 11 at the temperature which is lower as the Cloudpoint TMc, is heated.

Since the fuel composition mainly includes carbon and hydrogen, the average carbon number NC and the average hydrogen number NH are calculated as the average element numbers and prepared to correspond to the estimated value of the cloud point TMc. It is possible to accurately estimate the Cloudpoint TMc. It is possible to maintain the high filter efficiency by heating the fuel filter 11 below the temperature lower than the Cloudpoint TMc.

Furthermore, based on the existing kinetic viscosity KVp and the existing density DDp at the same temperature, the average carbon number NC and the average hydrogen number NH are obtained from the characteristic parameters which have a high correlation with respect to the average carbon number NC and the average hydrogen number NH calculated as the element numbers according to the first embodiment. Thus, even in the case that the fuel composition is different, it is possible to estimate the cloud point TMc in accordance with accurate calculation values of the average carbon number NC and the average hydrogen number NH. It is possible to maintain the high filter efficiency by heating the fuel filter 11 below the temperature lower than the Cloudpoint TMc.

Second embodiment

A second embodiment of the present invention is a modification of the first embodiment. As in 5 As shown, in heating control processing in the second embodiment, instead of S104, the processor 50a executes S2102 following S102, S2103 following S103, and S2104.

At S2102, the processor 50a converts the present kinetic viscosity KVp obtained at S102 from a value at the present temperature TMp obtained at S101 into an estimated kinetic viscosity KVe, which is an estimate at a base temperature TMb. It is noted as a result of the inventors' research and knowledge that a kinetic viscosity change amount ΔKV of the kinetic viscosities KV between the present temperature TMp and the base temperature TMb relative to the present kinetic viscosity KVp has a correlation as shown in 6 is illustrated.

For example, based on the experimental result or the simulation result at the product design time, the correlation of the kinetic viscosity change amount ΔKV relative to the actual kinetic viscosity KVp is set in accordance with an arbitrary temperature. In the second embodiment, the processor 50a executes at S2102 in accordance with the model data shown in 6 are shown, which represent the correlation of the kinetic viscosity change amount ΔKV relative to the existing kinetic viscosity KVp, the conversion. More specifically, at S2102, the processor 50a selects the data corresponding to the present temperature TMp obtained at S101 from the model data corresponding to the fuel temperature of the kinetic viscosity change amount ΔKV relative to the present kinetic viscosity KVp. At S2102, the processor 50a estimates the kinetic viscosity change amount ΔKV between the present temperature TMp and the reference temperature TMb by using the present kinetic viscosity KVp obtained at S102 for the selected model data. Furthermore, at S2102, the processor 50a obtains the estimated kinetic viscosity KVe at the base temperature TMp, which is converted from the present kinetic viscosity KVp at the present temperature TMp by adding the estimated kinetic viscosity change amount ΔKV with respect to the present kinetic viscosity KVp, which was obtained at S102.

The base temperature TMb is set as one of the fuel temperatures prepared to correspond to the model data of equations (4) and (5) described later. A plurality of points in the model data, which are exemplified in 6 are shown indicate experimental values of the kinetic viscosity change amount ΔKV relative to the actual kinetic viscosity KVp corresponding to the fuel composition in each region (country). In the case that, due to limited storage capacity of the memory 50b, discrete values are used as the fuel temperatures, which are made to correspond to the model data exemplified in 6 are shown, the model data at the present temperature TMp, which is between the discrete values of the fuel temperature are corrected by interpolation. Further, the kinetic viscosity change amount ΔKV is defined as a value having a positive or a negative sign by subtracting the kinetic viscosity at the present temperature TMp from the kinetic viscosity at the base temperature TMb. Thus, in the case that the base temperature TMb is higher than the present temperature TMp, the kinetic viscosity change amount ΔKV as a value having the negative sign is added to the present kinetic viscosity KVp, as exemplified in 6 is shown to obtain the estimated kinetic viscosity KVe.

At S2103 in 5 The processor 50a converts the present density DDp, which was obtained at S103, from a value at the present temperature TMp, which was obtained at S101, into an estimated density DDe, which is an estimate at the base temperature TMb. It is noted, as a result of the inventors' research and knowledge, that the estimated density DDe at the base temperature TMb has a correlation with the present density DDp, as exemplified in 7 will be shown.

For example, based on the experimental result or the simulation result at the product design time, the correlation of the estimated density DDe relative to the actual density DDp is given in accordance with an arbitrary temperature. In the second embodiment, the processor 50a performs the conversion at S2103 in accordance with the model data representing the correlation of the estimated density DDe relative to the present density DDp. More specifically, at S2103, the processor 50a selects the data corresponding to the present temperature TMp obtained at S101 from the model data corresponding to the fuel temperature of the estimated density DDe relative to the present density DDp. At S2103, the processor 50a obtains the estimated density DDe at the base temperature TMb, which is converted from the present density DDp at the present temperature TMp by substituting the present density DDp obtained at S103 for the selected model data.

The base temperature TMb is equal to the value estimated at S2102. A plurality of points in the model data, which are exemplified in 7 shown give experimental values of the estimated density DDe relative to the present density DDp corresponding to the fuel composition in each region (country). In the case that, due to limited storage capacity of the memory 50b, discrete values are used as the fuel temperatures, which are made to correspond to the model data exemplified in 7 are shown, the model data at the present temperature TMp, which lies between the discrete values of the fuel temperature, are corrected by interpolation.

$$\text{NC}=\mathrm{\alpha }2\times \text{DDe}+\mathrm{\beta }2\times \text{NH}+\mathrm{\gamma }2$$

At S2104, the processor calculates the average carbon number NC and the average hydrogen number NH based on the following equations (4) and (5), which are model data at the base temperature TMb, by taking the estimated kinetic viscosity KVe and the estimated density DDe used. $$\text{NC}=\mathrm{\alpha }1\times \text{KVe}+\mathrm{\beta }1\times \text{NH}+\mathrm{\gamma }1$$

$$\text{NC}=\mathrm{\alpha }2\times \text{DDe}+\mathrm{\beta }2\times \text{NH}+\mathrm{\gamma }2$$

The coefficients α1, β1 and γ1 in the equation (4) and the coefficients α2, β2 and γ2 in the equation (5) are set in accordance with the fuel temperature TMb based on the experimental result or simulation result of the product design time. In the second embodiment, the processor 50a uses equations (4) and (5) at S2104 by introducing the predetermined coefficients α1, β1, γ1, α2, β2 and γ2 at the predetermined base temperature TMb as model data showing the correlation of the estimated ones kinetic viscosity KVe and the estimated density DDe relative to the average carbon number NC and the average hydrogen number NH. More specifically, at S2104, the processor 50a introduces the estimated kinetic viscosity KVe and the estimated density DDe, which are obtained at steps S2104 and S2102 as conversion values of the characteristic parameters at the base temperature TMb, into the set of equations (4) and (5 ), for which the coefficients α1, β1, γ1 and the coefficients α2, β2 and γ2 are used. The processor 50a calculates the average carbon number NC and the average hydrogen number NH at the next step S2104 by solving the simultaneous equations (4) and (5) into which the estimated kinetic viscosity KVe and the estimated density DDe are introduced.

In the second embodiment described above, a functional part of the ECU 50 that executes steps S2102 and S2103 corresponds to a parameter conversion block. Further, a functional part of the ECU 50 that executes S2104 corresponds to the average calculation block.

According to the second embodiment described above, the characteristic parameter having the temperature dependence corresponds to the model data at the base temperature indicating the correlation relative to the average element number. It is therefore possible to accurately calculate the average element number based on the characteristic parameters converted from the value at the present temperature to the value at the base temperature. Thus, even in the case that the fuel composition is different, it is possible to estimate the Cloudpoint TMc taking into account the temperature characteristic of the characteristic parameter. It is thus possible to maintain the high filtering efficiency by heating the fuel filter 11 below the temperature lower than the Cloudpoint TMc.

Third embodiment

A third embodiment of the present invention is a modification of the first embodiment. As in 8th As shown, in heating control processing of the third embodiment, the processor 50a executes S3101 following S101 and S3104 instead of S104.

At S3101, the processor 50a checks whether the present temperature TMp obtained at S101 is equal to the base temperature TMb. In this case, the processor 50a may determine that the present temperature TMp is equal to the base temperature TMb as long as both temperatures are generally the same except for a small difference in a predetermined difference range. In the case of a determination at S3101 that the present temperature TMp is not equal to the base temperature TMb (NO), the processor 50a executes S101 again. In the case of a determination at S3101 that the present temperature TMp is equal to the base temperature TMb (YES), the processor 50a executes S102. At steps S102 and S103, the processor 50a obtains the present kinetic viscosity KVp and the present density DDp at substantially the same temperature as the base temperature TMb, which is the present temperature TMp, respectively.

$$\text{NC}=\mathrm{\alpha }2\times \text{DDp}+\mathrm{\beta }2\times \text{NH}+\mathrm{\gamma }2$$

At S3104, the processor 50a calculates the average carbon number NC and the average hydrogen number NH based on the following equations (6) and (7), which are model data at the base temperature TMb, by taking the present kinetic viscosity KVp and the present density DDp used. $$\text{NC}=\mathrm{\alpha }1\times \text{KVp}+\mathrm{\beta }1\times \text{NH}+\mathrm{\gamma }1$$

$$\text{NC}=\mathrm{\alpha }2\times \text{DDp}+\mathrm{\beta }2\times \text{NH}+\mathrm{\gamma }2$$

The coefficients α1, β1 and γ1 in the equation (6) and the coefficients α2, β2 and γ2 in the equation (7) are set in accordance with the fuel temperature TMb based on the experimental result or simulation result of the product design time. In the third embodiment, at S3104, the processor 50a uses equations (6) and (7) by introducing the predetermined coefficients α1, β1, γ1, α2, β2 and γ2 at the predetermined base temperature TMb as the model data showing the correlation of the present kinetic viscosity KVp and the present density DDp relative to the average carbon number NC and the average hydrogen number NH. More specifically, at S3104, the processor 50a introduces the present kinetic viscosity KVp and the present density at the base temperature TMb, which are obtained in steps S102 and S103 as the characteristic parameters, into the set of equations (6) and (7). , for which the coefficients α1, β1, γ1 and the coefficients α2, β2 and γ2 are used. The processor 50a calculates the average carbon number NC and the average hydrogen number NH at S3104 by solving the simultaneous equations (6) and (7) into which the present kinetic viscosity KVp and the present density DDp are introduced.

In the third embodiment described above, a functional part of the ECU 50 that executes steps S3101, S102 and S103 corresponds to the parameter acquisition block. Further, a functional part of the ECU 50 that executes S3104 corresponds to the average calculation block.

According to the third embodiment described above, the characteristic parameter having the temperature dependence corresponds to the model data at the base temperature TMb indicating the correlation relative to the average element number. It is therefore possible to accurately calculate the average element number based on the characteristic parameters obtained at the base temperature TMb. Thus, even in the case that the fuel composition is different, it is possible to estimate the Cloudpoint TMc taking into account the temperature characteristic of the characteristic parameter. It is thus possible to maintain the high filtering efficiency by heating the fuel filter 11 below the temperature lower than the Cloudpoint TMc.

Fourth embodiment

A fourth embodiment of the present invention is a modification of the first embodiment. In a heating control process tion performed in the fourth embodiment as in 9 As shown, the processor 50a executes steps S4100 to 4104 instead of steps S101 to S104.

At S4100, the processor 50a obtains a first present temperature TMp1 of the fuel, similar to the detection of the present temperature TMp in the first embodiment. At S4101, the processor 50a obtains a first present kinetic viscosity KVp1 of the fuel, similar to obtaining the present kinetic viscosity KVp in the first embodiment under substantially the same temperature as the first present temperature TMp1 obtained at S4100.

At S4102, the processor 50a obtains a fuel temperature different from the first present temperature TMp1 obtained at S4100 as a second present temperature TMp2, similar to obtaining the present temperature TMp in the first embodiment. At S4103, the processor 50a obtains a second present kinetic viscosity KVp2 of the fuel, similar to obtaining the present kinetic viscosity KVp in the first embodiment under substantially the same temperature as the second present temperature TMp2 obtained at S4102.

The processor 50a calculates the average carbon number NC and the average hydrogen number NH at S4104 based on the first kinetic viscosity KVp1 and the second kinetic viscosity KVp2 by using equation (1), which is the model data corresponding to the fuel temperature correspond to that described in the first embodiment. More specifically, at S4104, the processor 50a selects the set of equations (1) corresponding to the first present temperature TMp1 and the second present temperature TMp2 obtained at steps S4100 and S4102, respectively, and for which the coefficients αt1, βt1 and γt1 can be used. Further, at S4104, the processor 50a substitutes the first present kinetic viscosity KVp1 obtained at S4101 for the present kinetic viscosity KVp in the equation (1), which is selected in accordance with the first present temperature TMp1. Similarly, at S4104, the processor 50a substitutes the second present kinetic viscosity KVp2 obtained at S4103 for the present kinetic viscosity KVp in equation (1), which is selected in accordance with the second present temperature TMp2. Thus, at S4104, the processor 50a calculates the average carbon number NC and the average hydrogen number NH by solving the set of simultaneous equations (1) for which the first kinetic viscosity KVp1 and the second kinetic viscosity KVp2 are substituted.

In the fourth embodiment described above, a functional part of the ECU 50 that executes steps S4100 and S4102 corresponds to the temperature acquisition block. A functional part of the ECU 50 that executes steps S4101 and S4103 corresponds to the parameter acquisition block. Further, a functional part of the ECU 50 that executes S4104 corresponds to the average calculation block.

According to the fourth embodiment described above, the present kinetic viscosities KVp1 and KVp2 at the plurality of temperatures TMp1 and TMp2 are characteristic parameters which have a high correlation with the average carbon number NC and the average hydrogen number NH as the average element number. It is therefore possible to calculate the average carbon number NC and the average hydrogen number NH based on such kinetic viscosities KVp1 and KVp2. Thus, even in the case that the fuel composition is different, it is possible to estimate the cloud point TMc in accordance with the calculation values of the average carbon number NC and the average hydrogen number NH. It is thus possible to maintain the high filtering efficiency by heating the fuel filter 11 below the temperature lower than the Cloudpoint TMc. In the fourth embodiment, the ECU 50 does not need the detection information of the density sensor 17 or the density sensor 17 itself.

Fifth embodiment

A fifth embodiment of the present invention is a modification of the fourth embodiment. In the heating control processing of the fifth embodiment, the processor 50a executes steps S5101, S5103 and S5104 instead of steps S4101, S4103 and S4104 as shown in 10 will be shown.

At S5101, the processor 50a obtains a first present density DDp1 at substantially the same temperature as the first present temperature TMp1 obtained at S4100, similar to obtaining the present density DDp in the first embodiment. At S5103, the processor 50a obtains a second present density DDp2 at substantially the same temperature as the second present temperature TMp2 obtained at S4101, similar as in obtaining the present density DDp in the first embodiment.

The processor 50a calculates the average carbon number NC and the average hydrogen number NH at S5104 based on the first present density DDp1 and the second present density DDp2 by using equation (2), which is the model data corresponding to the fuel temperature correspond to that described in the first embodiment. More specifically, at S5104, the processor 50a selects the set of equations (2) corresponding to the first present temperature TMp1 and the second present temperature TMp2 obtained at steps S4100 and S4102, respectively, and for which the coefficients αt2, βt2 and γt2 can be used. Further, at S5104, the processor 50a substitutes the first present density DDp1 obtained at S5101 for the present density DDp in the equation (2), which is selected in accordance with the first present temperature TMp1. Similarly, at S5104, the processor 50a substitutes the second present density DDp2 obtained at S5103 for the present density DDp in equation (2), which is selected in accordance with the second present temperature TMp2. Thus, at S5104, the processor 50a calculates the average carbon number NC and the average hydrogen number NH by solving the set of simultaneous equations (2) for which the first present density DDp1 and the second present density DDp2 are substituted.

In the fifth embodiment described above, a functional part of the ECU 50 that executes steps S5101 and S5103 corresponds to the parameter acquisition block. A functional part of the ECU 50 that executes S5104 corresponds to the average calculation block.

According to the fifth embodiment described above, the present densities DDp1 and DDp2 at the plurality of temperatures TMp1 and TMp2 are characteristic parameters which have a high correlation with the average carbon number NC and the average hydrogen number NH as the average element number. It is therefore possible to accurately calculate the average carbon number NC and the average hydrogen number NH based on such existing densities DDp1 and DDp2. Thus, even in the case that the fuel composition is different, it is possible to estimate the cloud point TMc in accordance with the calculation values of the average carbon number NC and the average hydrogen number NH. It is thus possible to maintain the high filtering efficiency by heating the fuel filter 11 below the temperature lower than the Cloudpoint TMc. In the fifth embodiment, the ECU 50 does not need the detection information of the density sensor 17 or the density sensor 17 itself.

Other embodiment

The present invention is not limited to the embodiments described above but may be variously implemented as explained below.

More specifically, as a first modification in the first to fifth embodiments, the present temperature TMp, TMp1, TMp2 and a temperature TMj at monitoring time can be obtained by estimation based on an operating state of the internal combustion engine 1. According to the first modification, the detection information of the temperature sensor 15 and the temperature sensor 15 itself need not be provided. Further, according to the first modification, a frequently used condition such as a low pressure condition or a medium pressure condition of fuel after a complete warm-up of the internal combustion engine 1 may be used as the operating condition for estimating the present temperature TMp, TMp1 and TMp2 and the temperature TMj be used at monitoring time.

As a second modification, in the fourth embodiment, by a second kinetic viscosity sensor, the second present kinetic viscosity KVp2, which is substantially of the same type but from the viscosity sensor 16 at a different mounting position in the fuel supply path in the Fuel system 1 is provided. In the second modification, the second present temperature TMp2 at the mounting position of the second kinetic viscosity sensor is obtained in accordance with the present temperature TMp in the first embodiment.

As a third modification, in the fourth embodiment, kinetic viscosity values at a first base temperature and a second base temperature obtained by converting the first kinetic viscosity KVp1 at the first present temperature TMp1 and the second kinetic viscosity KVp2 at the second present temperature TMp2 are separately used for the set of equations (1) corresponding to each base temperature, thereby calculating the average carbon number NC and the average hydrogen number NH in the similar manner to the second embodiment.

As a fourth modification, in the fourth embodiment, the first kinetic viscosity KVp1 and the second kinetic viscosity KVp2 at the first present temperature TMp1 and the second present temperature TMp2, which are the first base temperature and the second base temperature, respectively, may be separately for the set of equations (1), which correspond to each base temperature, are used to thereby calculate the average carbon number NC and the average hydrogen number NH in the similar manner to the third embodiment.

As a fifth modification, in the fifth embodiment, a second present density DDp2, which is substantially of the same type but from the density sensor 17 at a different mounting position in the fuel supply path in the fuel system 1, can be obtained by a second density sensor is provided. In the fifth modification, a second present temperature TMp2 is acquired at a mounting position of the second density sensor in accordance with the present temperature TMp in the first embodiment.

As a sixth modification, in the fifth embodiment, density values at a first base temperature and a second base temperature obtained by converting the first density DDp1 at the first present temperature TMp1 and the second density DDp2 at the second present temperature TMp2 may be separately for the Set of equations (2) corresponding to each base temperature are used to thereby calculate the average carbon number NC and the average hydrogen number NH in the similar manner to the second embodiment.

As a seventh modification, in the fifth embodiment, the first present density DDp1 and the second present density DDp2 at the first present temperature TMp1 and the second present temperature TMp2, which are the first base temperature and the second base temperature, respectively, may be separately for the set of equations (2) corresponding to each base temperature are employed, thereby calculating the average carbon number NC and the average hydrogen number NH in the similar manner to the third embodiment.

As an eighth modification, in the first to fifth embodiments, at least part of the heating control processing may be performed by hardware of one or a plurality of integrated circuits instead of software control by the processor 50a.

Claims (8)

A fuel system control apparatus (50) adapted to control a heating operation of a heater (110) of a fuel filter (11) which filters fuel supplied to a combustion chamber (1a) in a fuel system (10) of an internal combustion engine (1), wherein the fuel system control apparatus (50) has: a parameter acquisition block (50a; S102, S103, S3101, S4101, S4103, S5101, S5103) arranged to obtain a characteristic parameter indicating a property of the fuel; an average calculation block (50a; S104, S2104, S3104, S4104, S5104) configured to calculate average element numbers of chemical elements constituting the fuel based on the characteristic parameter obtained by the parameter acquisition block (50a; S102, S103, S3101, S4101, S4103, S5101, S5103) was obtained; a cloud point estimation block (50a; S105) arranged to estimate a cloud point of the fuel corresponding to the average element numbers calculated by the average calculation block (50a; S104, S2104, S3104, S4104, S5104), and a heater control block (S107, S108) configured to control the heater (110) of the fuel filter (10) in the event that a temperature of the fuel drops to the cloud point estimated by the cloud point estimation block (50a, S105). Fuel system control apparatus (50) according to Claim 1 , further comprising: a temperature acquisition block (50a; S101, S4100, S4102) set up to obtain an existing temperature of the fuel, wherein the parameter acquisition block (50a; S102, S103, S4101, S4103, S5101, S5103) contains the characteristic curve parameter at the present temperature obtained by the temperature obtaining block (50a; S101, S4100, S4102), and the average calculation block (50a; S104, S4104, S5104) based on the characteristic parameter obtained by the parameter acquisition block (50a; S102, S103, S3101, S4101, S4103, S5101, S5103) was acquired, and the present temperature acquired by the temperature acquisition block (50a; S101, S4100, S4102) in accordance with model data, which is set as data indicating a correlation of the characteristic parameter regarding the average element numbers in accordance with the temperature of the fuel, the average element numbers are calculated. Fuel system control apparatus (50) according to Claim 1 , further comprising: a temperature obtaining block (50a; S101) arranged to obtain a present temperature of the fuel; and a parameter conversion block (50a; S2102, S2103) arranged to convert the characteristic parameter obtained by the parameter acquisition block (50a; S102, S103) from values at the present temperature obtained by the temperature acquisition block ( 50a; S101) to values at a base temperature, wherein the average calculation block (50a; S2104) in accordance with model data of the base temperature set as data indicating the correlation of the characteristic parameter with respect to the average element number Based on the characteristic parameter converted by the parameter conversion block (50a; S2102, S2103), the average element number is calculated from the value obtained by the temperature acquisition block (50a; S101). Fuel system control apparatus (50) according to Claim 1 , wherein: the parameter acquisition block (50a; S102, S103, S3101) acquires the characteristic parameter at a base temperature; and the average calculation block (50a; S3104), in accordance with model data of the base temperature set as data indicating the correlation of the characteristic parameter with respect to the average element number, calculates the average element number from the characteristic parameter determined by the Parameter acquisition block (50a; S102, S103, S3101) was obtained. Fuel system control apparatus (50) according to one of Claims 1 until 4 , where: the average calculation block (50a; S104, S2104, S3104, S4104, S5104) an average carbon number, which is the average element number of carbon atoms constituting the fuel, and an average hydrogen number, which is the average element number of hydrogen atoms, which constitute the fuel, and the cloud point estimation block (50a; S105) calculates the cloud point based on the average carbon number and the average hydrogen number calculated by the average calculation block (50a; S104, S2104, S3104, S4104, S5104). , estimates. Fuel system control apparatus (50) according to one of Claims 1 until 5 , wherein: the parameter obtaining block (50a; S102, S103, S3101) obtains a kinetic viscosity and a density of the fuel at a same temperature as the characteristic parameter. Fuel system control apparatus (50) according to one of Claims 1 until 5 , wherein: the parameter obtaining block (50a; S4101, S4103) obtains kinetic viscosities of the fuel at a plurality of temperatures as the characteristic parameter. Fuel system control apparatus (50) according to one of Claims 1 until 5 , wherein: the parameter acquisition block (50a; S5101, S5103) obtains densities of the fuel at a plurality of temperatures as the characteristic parameter.

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