DE102016102820B4 - Fuel property determining device - Google Patents

Abstract

A fuel property determining device (40) for determining a fuel property of a fuel supplied to a cylinder (11a) of an internal combustion engine (10) by a fuel injector (18), the fuel property determining device comprising: a fuel injection control section configured so as to that this a main injection, a first fuel injection before the main injection, the fuel injection amount of which is smaller than that of the main injection, and a second fuel injection after the main injection, the fuel injection amount of which is smaller than that of the main injection, during a combustion cycle of the internal combustion engine; a property determination section which is such is configured to determine the fuel property of the fuel based on a first ignition delay time and a second ignition delay time, the first ignition delay time is a time from the start of the first fuel injection to the ignition of the injected fuel, and the second ignition delay time is a time from the start of the second fuel injection to the ignition of the injected fuel; and a temperature determination section configured to determine whether a temperature in the cylinder after the main injection is higher than a specified temperature, the property determination section configured to determine the fuel property of the fuel based on a first ignition delay time and a second ignition delay time when the temperature determination section determines that the temperature in the cylinder after the main injection is higher than the specified temperature.

Description

Technical area

The present disclosure relates to a fuel property determining device.

background

A for internal combustion engines, such as. B. a diesel engine, the fuel used has different compositions from country to country or from region to region. In a case where a fuel whose composition is different from a supposed composition is supplied to an internal combustion engine, the adequacy of a combustion state is likely to decrease and lead to emission deterioration and the like. In order to avoid such a situation, various fuel property determining devices have been proposed. The patent specification WO 2011/061 851 A1 describes a fuel property determining device that determines a fuel property based on an actual fuel injection amount and an output of an engine.

The rate of combustion of the fuel depends on its composition. For example, if the aromatic component in the fuel increases, the combustibility of the fuel is lower. In addition, the output torque of the machine fluctuates. Thus, it is likely that the fuel property determining device included in FIG WO 2011/061 851 A1 shown cannot determine the fuel property with high accuracy.

The DE 10 2009 052 224 A1 relates to a method for operating an internal combustion engine with at least one working cylinder, in particular a diesel engine, wherein fuel is supplied to the at least one working cylinder and a fuel type and / or a fuel quality of the currently supplied fuel is determined. Here, at least one parameter for supplying the fuel is changed as a function of the specific fuel type and / or fuel quality.

The DE 10 2007 051 254 A1 discloses a method for determining chemical and / or physical properties of a fuel for a diesel internal combustion engine, the internal combustion engine comprising a device for determining the combustion position, with a measure of the chemical and / or physical characteristics from the distance between an injection and a combustion position feature Properties of the fuel, in particular ignitability and / or burn-through speed, is determined.

The DE 10 2014 116 128 A1 relates to a method for determining an ignition delay curve of an internal combustion engine, which represents a time delay between an energy input curve and an energy conversion curve of the internal combustion engine. The method comprises obtaining an energy conversion profile of the internal combustion engine, obtaining an energy input profile of the internal combustion engine and determining the ignition delay profile based on the energy input profile and based on the energy conversion profile.

short version

It is an object of the present disclosure to provide a fuel property determining device which enables a property of a fuel that is supplied to an internal combustion engine to be determined with high precision.

The above object is achieved by the subject matter of claim 1. Advantageous developments of the invention are the subject matter of the subsequent dependent claims.

According to one aspect of the present disclosure, a fuel property determining device includes a fuel injection control portion and a property determining portion. The fuel injection control section performs a main injection, a first fuel injection before the main injection, the fuel amount of which is less than that of the main injection. In addition, the fuel injection control section performs a second fuel injection after the main injection, the fuel injection amount of which is smaller than that of the main injection. The property determining section determines the fuel property based on a first ignition delay time and a second ignition delay time. The first ignition delay time is a period from the start of the first fuel injection to the ignition of the injected fuel. The second ignition delay time is a period from the start of the second fuel injection to the ignition of the injected fuel.

According to such a configuration, a difference in fuel property can be correctly reflected in the difference in ignition delay time. As a result, the fuel property can be determined with high accuracy.

Figure list

• 1 eine schematische Ansicht, die ein Maschinensteuerungssystem zeigt;
• 2 ein Kennfeld, das eine Beziehung zwischen der Maschinenantriebsbedingung und einem Kraftstoffeinspritzmuster zeigt; und
• 3 einen Graphen, der eine Beziehung zwischen der Zylinder-Innentemperatur und einer Zündverzögerungszeit zeigt;
• 4 ein Diagramm, das eine Wärmefreisetzungsrate und eine Zylinder-Innentemperatur zeigt;
• 5 ein Flussdiagramm, das eine Kraftstoffeigenschafts-Bestimmungsverarbeitung zeigt;
• 6 ein Diagramm, das ein Kraftstoffeigenschafts-Bestimmungskennfeld zeigt;
• 7 ein Flussdiagramm, das eine Verarbeitung zum Umschalten auf die zweite Einspritzung zeigt;
• 8 ein Flussdiagramm, das eine Kraftstoffeigenschafts-Bestimmungsverarbeitung gemäß einer weiteren Ausführungsform zeigt; und
• 9 ein Diagramm, das ein Verhältnis zwischen der Leichtkomponente und der Schwerkomponente und einen Bestimmungswert zeigt; und

The above and further aspects, features and advantages of the present disclosure are explained in more detail on the basis of the following detailed description with reference to the accompanying drawings. Show it:

• 1 Fig. 3 is a schematic view showing an engine control system;
• 2 a map showing a relationship between the engine driving condition and a fuel injection pattern; and
• 3 a graph showing a relationship between the cylinder internal temperature and an ignition delay time;
• 4th a graph showing a heat release rate and a cylinder internal temperature;
• 5 Fig. 12 is a flowchart showing fuel property determination processing;
• 6th Fig. 3 is a diagram showing a fuel property determination map;
• 7th Fig. 13 is a flowchart showing processing for switching to the second injection;
• 8th FIG. 13 is a flowchart showing fuel property determination processing according to another embodiment; and
• 9 a diagram showing a relationship between the light component and the heavy component and a determination value; and

Detailed description

An embodiment of the present disclosure will now be described with reference to the accompanying drawings. In the present embodiment, the internal combustion engine is a multi-cylinder diesel engine. An engine control system includes an electronic control unit (ECU) that performs fuel injection control, ignition timing control, and the like.

With reference to 1 becomes a configuration of a machine 10 described. The machine 10 is a diesel engine with four cylinders 11a in a cylinder block 11 . In 1 for the sake of simplicity, only a single cylinder is shown. A piston 12th moves in each cylinder 11a back and forth. A cylinder head 13th is on an upper surface of the cylinder block 11 . A combustion chamber is through the cylinder 11a , the piston 12th and the cylinder head 13th Are defined.

A suction line 14th and an exhaust pipe 15th are with the cylinder block 11 connected. The suction line 14th communicates with each cylinder 11a through an intake manifold and one in the cylinder head 13th defined line 14a . The exhaust pipe 15th communicates with each cylinder 11a through an exhaust manifold and pipe 15a that is in the cylinder head 13th is defined.

An inlet valve 16 is arranged on an inlet duct, and an outlet valve 17th is arranged on an outlet channel. When the inlet valve 16 is opened, a fuel-air mixture is introduced into a combustion chamber. When the exhaust valve 17th is opened, the exhaust gas is in the exhaust pipe 15th discharged.

A fuel injector 18th is on every cylinder 11a arranged. The fuel injector 18th is used to inject light oil directly into the cylinder 11a electromagnetically driven. The fuel injector 18th is with a common rail 20th and a fuel tank (not shown) through a fuel line 19th connected. A high pressure pump (not shown) pumps the fuel into the fuel tank and sets the fuel to the common rail 20th to be fed under pressure. The high pressure fuel that is in the common rail 20th is stored is by the fuel injector 18th injected into the combustion chamber. The fuel injector 18th is with a pressure sensor 33 provided that the fuel pressure in the fuel line between the common rail 20th and an injection port of the fuel injector 18th recorded successively. The fuel tank is equipped with a fuel level sensor 34 provided that detects the amount of fuel in the fuel tank.

The machine 10 is with an exhaust gas recirculation (EGR) device 26th provided for recirculating part of the exhaust gas into the suction line. The EGR device 26th has an EGR line 27 that is the suction line 14th and the exhaust pipe 15th connects, and an EGR valve 28 which adapts a recirculation of the exhaust gas (EGR gas).

The machine 10 is also equipped with a cylinder pressure sensor 31 showing the pressure in the cylinder 11a detected, a fuel density sensor 32 that detects the fuel density, a cylinder temperature sensor 35 showing the temperature in the cylinder 11a detects, a suction pressure sensor (not shown) that the pressure in the suction line 14th detected, and an inlet temperature sensor (not shown), which the temperature in the suction line 14th detected.

The ECU 40 is a microcomputer with a CPU, a ROM, a DRAM and an input / output interface. The ECU 40 receives the detection signals from the above sensors, a crank angle sensor, a coolant temperature sensor and an accelerator pedal position sensor. Based on the above detection signals, the ECU drives 40 various actuators. In a fuel injection control, the fuel injection amount is adjusted so that the fuel combustion condition is optimized on the condition that the reference characteristic fuel is supplied to the cylinder 11a is fed. The ECU 40 controls the fuel injector 18th based on the detected values of the various sensors so that the specified control is carried out.

2 Fig. 13 is a map showing a relationship between the engine driving condition and a fuel injection pattern. In the present embodiment, the fuel injection pattern is in a combustion cycle of the engine 10 defined according to the machine drive condition (machine speed and machine torque). As in particular in 2 As shown, a drive range “Z” represents a drive mode in which fuel economy and emission reduction have priority. A pilot injection and a main injection are carried out in a low-torque range “X”. In a medium-high torque range “Y”, a pilot injection, a main injection and a post injection are carried out. It should be noted that the main injection is the fuel injection, which is used primarily to generate the power that is transferred to an engine output axis. In a multi-stage injection, the largest fuel injection quantity is injected in the main injection. The pilot injection is carried out before the main injection. The post injection is carried out after the main injection. In the pilot injection and the post injection, the fuel injection quantity is small. In 2 a line “L” expresses an output upper limit.

The one for the machine 10 The fuel used varies from country to country and from region to region. A mixing ratio of hydrocarbon components such as a chain type hydrocarbon and a cyclic hydrocarbon (aromatic series, naphthene, etc.) differs from country to country or from region to region. In addition, the rate of combustion of the fuel varies according to a mixing ratio of the hydrocarbon components. In particular, since the mixing ratio of the cyclic hydrocarbon component in the fuel increases more, that is, as the mixing ratio of the heavy component in the fuel increases more, the fuel is less combustible, which may cause emission deterioration or a discharge reduction. On the other hand, in the case where the mixing ratio of the chain-like hydrocarbon is high, that is, the mixing ratio of the light component is high, the fuel is combustible, but less output torque is generated, which may cause a reduction in the output.

In order to prevent the deterioration of engine performance, fuel property determination processing is carried out. An ignition delay time varies according to an ambient temperature at which the fuel is burned. The ignition delay time is a period from the start of fuel injection to the ignition of the injected fuel. In particular, when the fuel is burned under a condition that the cylinder internal temperature is relatively low, the ignition delay time varies according to the composition of the fuel. When the fuel is burned under a condition where the cylinder internal temperature is high enough, the ignition delay time varies according to the composition of the fuel. In view of this, the fuel property determination processing is carried out.

3 Fig. 13 is a graph showing a relationship between the cylinder internal temperature (ambient temperature) and the ignition delay time in the case where three types of fuel “A”, “B” and “C” are in the engine 10 to be burned. 3 shows a standard fuel, a heavy oil and a light oil. As in 3 shown, the difference in ignition delay time between three types of fuel “A”, “B” and “C” is long when the internal cylinder temperature is relatively low. For example, when the cylinder internal temperature is a relatively low temperature "T1o", the ignition delay time of the light oil is the shortest and the ignition delay time of the heavy oil is the longest. As the internal cylinder temperature rises, the difference in ignition delay time decreases. When the internal cylinder temperature has exceeded a specified temperature "Thi", the ignition delay time becomes almost identical regardless of the fuel composition.

The ignition delay time also varies due to deterioration of the cylinder internal pressure sensor 31 or the fuel injector 18th . When the cylinder internal pressure sensor or the fuel injector 18th deteriorate more and more, the ignition delay time is extended further. Such a variation in the ignition delay time due to the deterioration of each part occurs every time the fuel is injected during a combustion cycle of the engine 10 .

According to the present embodiment, the fuel property is determined based on the ignition delay time (first ignition delay time “Tpi”) of a pilot injection and the ignition delay time (second ignition delay time “Taf”) a post-injection determined. The pilot injection is carried out before the internal cylinder temperature becomes high enough. The post injection is carried out under a condition where the cylinder internal temperature is high enough. In particular, the fuel property is based on a difference ΔT from the first ignition delay time “Tpi” and that of the second ignition delay time “Taf” (= Taf-Tpi). That is, by calculating the difference ΔT, a component of the ignition delay time due to the fuel property is extracted. The fuel property is determined based on the extracted component of the ignition delay time. It should be noted that the pilot injection corresponds to a “first injection” and that the post-injection corresponds to a “second injection”.

4th Fig. 13 is a graph showing a fuel command pulse, a heat release rate [J / deg.], and a cylinder internal temperature. It should be noted that the heat release rate represents the amount of heat generated per unit crank angle. 4th FIG. 13 shows a case where the pilot injection, the main injection and the post injection are in one combustion cycle of the engine 10 are executed. “TDC” refers to a compression top dead center.

The internal cylinder temperature varies before and after the main injection. As in particular in 4th is shown, before the main injection, the cylinder internal temperature is lower than the temperature “Thi”. After the main injection, the internal cylinder temperature is higher than the “Thi” temperature. In this case, the first ignition delay time “Tpi” of the pilot injection includes components due to the fuel property. The second ignition delay time “Taf” of the post injection includes no component or a small component due to the fuel property. The components due to deterioration of respective parts are generated equally between the pilot injection and the post injection. The difference ΔT between the first ignition delay time “Tpi” and the second ignition delay time “Taf” corresponds to the ignition delay time due to the fuel property.

Referring to an in 5 As shown in the flowchart, the processing of fuel property determination will be described below. This processing is performed in a specified cycle by the ECU 40 executed.

In S101 the computer determines whether the fuel property determination request is generated. Specifically, when at least one of the following two conditions is met, the computer determines that the fuel property determination request is generated. This means that it takes place immediately after refueling. Alternatively, a specified time has elapsed since the fuel property determination was previously carried out. Based on the amount of fuel received by the fuel amount sensor 34 is detected, the computer determines that it will immediately follow a refueling. The above conditions may include that the vehicle has traveled a specified distance.

If the answer is in S101 If YES, the procedure will be followed S102 continued where the current machine drive condition is obtained. The engine driving condition corresponds to an engine speed, an engine load, a cylinder internal temperature, a cylinder internal pressure, and the like. In S103 the computer determines whether an execution condition for executing the fuel property determination has been established.

In the present embodiment, the execution condition includes the following conditions. That is, the cylinder internal temperature after the main injection is higher than a determination temperature “Tth”, and the current engine driving condition is a driving condition (area “Y”) in which the post injection is carried out after the main injection. When the above two conditions are satisfied, it is determined that the execution condition has been established.

The determination temperature “Tth” corresponds to a lower limit temperature of a temperature range in which a variation in an ignition delay time due to the fuel property difference is less than or equal to a specified value. In the present embodiment, the determination temperature “Tth” is set based on the specified temperature “Thi”. The determination temperature "Tth" is e.g. 1000K.

When the answer is NO in S103, the process is ended. When the answer is YES, the process advances to S104, where the first ignition delay time “Tpi” is obtained. In particular, when the pilot injection is carried out, the in-cylinder pressure is obtained from the in-cylinder pressure sensor 31 receive. Based on the obtained cylinder internal pressure, the heat release rate of the fuel is calculated. 4 (b) Fig. 13 shows a waveform of the heat release rate. The rate of heat release is increased rapidly near the pilot injection. This timing is defined as a pilot injection time "θρ2". Then the first ignition delay time "Tpi" is calculated based on the difference between a pilot injection start time "θρ1" and the pilot injection time "θp2" calculated. In S104 the first ignition delay time "Tpi" is obtained as described above.

In S105 the computer receives the second ignition delay time “Taf”. Particularly when the post injection is carried out, the cylinder internal pressure is obtained from the cylinder internal pressure sensor 31 receive. Based on the obtained cylinder internal pressure, the heat release rate of the fuel is calculated. As in 4 (b) as shown, the rate of heat release is rapidly increased near the post injection. This time control is defined as a post-injection time "θρ2". Then, the second ignition delay time “Taf” is calculated based on the difference between a post injection start time “θa1” and the post injection time “θρ2”. In S105 the second ignition delay time "Taf" is obtained as described above.

In S106 the computer calculates a ratio α between the light component and the heavy component based on the first ignition delay time “Tpi” and the second ignition delay time “Taf”. The ratio α is a parameter indicating a component deviation from the standard fuel. The ratio α is a ratio of “light oil / heavy oil”. In the present embodiment, the standard fuel has a reference ratio αo (eg 1). In the event that the fuel is heavier than the standard fuel, the ratio α of the fuel is larger than the reference ratio αo. In the event that the fuel is lighter than the standard fuel, the ratio α of the fuel is smaller than the reference ratio αo. In addition, in the present embodiment, a relationship between the difference ΔT and the ratio α is stored as a property determination map. In S106 the ratio α is calculated with respect to the property determination map.

6th shows an example of the property determination map. As in 6th as shown, the difference ΔT varies linearly with respect to the ratio α. In particular, when the fuel is heavier relative to the standard fuel, the difference ΔT becomes larger. As the fuel is lighter relative to the standard fuel, the difference ΔT becomes smaller. When the difference .DELTA.T is a value .DELTA.T1 larger than the reference value .DELTA.To, the fuel supplied to the cylinder 11a is supplied heavier than the reference fuel, and the ratio α corresponds to the ratio α1, which is higher than the reference ratio αo (eg1).

It should be noted that the ratio α with respect to a cylinder can be calculated during a combustion cycle. Alternatively, the ratio α can be calculated over several combustion cycles. In this case, an average value of the difference ΔT is calculated, and the ratio α is calculated based on the average value of the difference ΔT.

In the present embodiment, various controls of the machine 10 corrected based on the above ratio α. Based on the ratio α, high pressure injection control is carried out so that the injection pressure of the fuel injector 18th is corrected to a higher value when, based on the ratio α, it is determined that the fuel supplied to the cylinder 11a is heavier than the reference fuel. Alternatively, the lower EGR control is carried out so that the EGR amount is corrected to decrease, or a frequency of the EGR control is reduced. Thus, an emission amount of particulate matter (PM) can be reduced.

When it is determined that the cylinder 11a supplied fuel is lighter than the reference fuel, fuel injection is performed so that fuel penetration is decreased in a low-load drive range. In particular, the number of injections in the case of multiple fuel injection is increased, or the injection pressure of the fuel injector is increased 18th is corrected to be less. Since the torque is less obtained by the light oil, the fuel injection period is lengthened so that the fuel can easily spread. In this case, there is a likelihood that hydrocarbon (HC) or carbon monoxide (CO) can easily be formed, causing emission deterioration. In view of the above, when the fuel is lighter than the reference fuel, the fuel penetration is decreased so that the emission deterioration is prevented.

According to the present embodiment, the following advantages can be obtained.

The fuel property is determined based on the ignition delay time of the first injection and the ignition delay time of the second injection. According to such a configuration, a difference in fuel property can be correctly reflected in the difference in ignition delay time. As a result, the fuel property can be determined with high accuracy.

When it is determined that the cylinder internal temperature is higher than the determination temperature “Tth” after the main injection, the fuel property is determined based on the first ignition delay time “Tpi” and the second ignition delay time “Taf”. With such a configuration, a calculation error of the Ignition delay time can be reduced, and the fuel property can be determined with high accuracy because the fuel property is determined after actually determining that the cylinder internal temperature is higher than the determination temperature “Tth”.

The second injection is the post injection, and the fuel property is determined based on the ignition delay time of the pilot injection and the ignition delay time of the post injection. Since the fuel property can be determined using the post injection, no additional fuel injection is necessary after the main injection.

The fuel property is determined based on the difference ΔT between the first ignition delay time “Tpi” and the second ignition delay time “Taf”. The first ignition delay time “Tpi includes a component due to the deterioration of the sensor and the fuel injector 18th , and a component due to fuel property. The second ignition delay time “Taf” includes only the component due to the deterioration of the sensor and the fuel injector 18th . In view of the above, the fuel property can be determined by the simple control.

[Other embodiment]

The present invention is not limited to the embodiments described above, but can, for. B. be carried out as follows.

A test injection for determining the fuel property only is carried out as the second injection. The fuel property can be determined based on the ignition delay time of the pilot injection and the ignition delay time of the test injection. According to such a configuration, the fuel property determining process can be carried out even in a drive region in which no post injection is carried out after the main injection.

The machine is in particular immediately after refueling 10 in a state in which it should be started and in which the engine speed and the engine torque are low. Therefore, fuel injection cannot be carried out after the main injection for a specified period of time after a determination request is generated. According to the present embodiment, the test injection is carried out after the main injection, and the fuel property is determined based on the ignition delay time of the pilot injection and the ignition delay time of the test injection. This means that the fuel properties can be determined immediately after refueling. As a result, the machine control can be executed immediately according to the ratio α.

When the test injection is carried out, the test injection corresponds to the second injection. Alternatively, the second injection is switched between the post-injection and the test injection according to the engine drive condition.

7th Fig. 13 is a flowchart showing processing for switching the second injection. This processing is performed in a specified cycle by the ECU 40 executed. In S201 the computer determines whether the engine driving condition is the driving condition area “Y” in which the post injection is carried out after the main injection. When the answer is YES in S201, the flow advances to S202 where the second injection is the post injection. In this case the ECU determines 40 the fuel property based on the ignition delay time "Tpi" of the pilot injection and the ignition delay time "Taf" of the post-injection. When the answer is NO in S201, the flow advances to S203, where the test injection is carried out after the main injection as the second injection. Specifically, it becomes one of four cylinders 11a selected as a test injection cylinder. Only a small amount of fuel is injected into the test injection cylinder. The injection time for a test injection is after the main injection. In the present embodiment, the test injection is carried out immediately after the main injection in the power stroke. The ECU 40 determines the fuel properties based on the ignition delay time "Tpi" of the pilot injection and the ignition delay time "Tex" of the test injection.

In the above embodiment, the computer determines whether the current engine driving condition is the driving condition area “Y” in which the post injection is carried out. If YES, the fuel property is determined based on the first ignition delay time “Tpi” and the second ignition delay time “Taf”. When the current engine driving condition is not the driving condition area “Y”, the injection pattern is changed so that the post injection is carried out. The fuel property is determined based on the ignition delay time "Tpi" of the pilot injection and the ignition delay time "Taf" of the post injection. The fuel property can thus be appropriately determined.

In the above embodiment, the first injection is the pilot injection. However, the first injection can be the test injection. The test injection is carried out so that the ignition delay time is obtained.

The ignition delay time due to the deterioration of the parts may vary according to the fuel combustion environments such as B. the cylinder internal pressure and the vortex intensity vary. In view of the foregoing, the actual ignition delay time of the second injection may be corrected according to parameters related to the fuel combustion environment. The fuel property can be determined based on the corrected ignition delay time. In particular, the actual ignition delay time of the second injection is corrected based on the cylinder internal pressure obtained by the cylinder internal pressure sensor 31 is captured. The fuel property is determined based on the corrected ignition delay time. In addition, the vortex intensity is recorded so that the actual ignition delay time of the second injection is corrected. The fuel property is determined based on the corrected ignition delay time.

In the above embodiment, the fuel property is determined based on the difference ΔT of the first ignition delay time “Tpi” and the second ignition delay time “Taf”. The first ignition delay time "Tpi" is corrected based on the difference between the standard ignition delay time "Tbs" and the second ignition delay time "Taf". The fuel property can be determined based on the corrected first ignition delay time "Tpi".

8th Fig. 13 is a flowchart showing fuel property determination using the standard ignition delay time “Tbs”. 8th FIG. 13 is a flowchart showing processing other than the processing in S104 to S106 shown in FIG 5 are shown. In S301 a correction amount "KT" is calculated based on the second ignition delay time "Taf" and the standard ignition delay time "Tbs". The correction amount "KT" is a difference between the second ignition delay time "Taf" and the standard ignition delay time "Tbs" (= Taf-Tbs). In S302 the first ignition delay time "Tpi" is corrected using the correction quantity "KT". The correction amount "KT" is z. B. subtracted from the first ignition delay time "Tpi". In S303 The computer calculates the ratio α based on the first ignition delay time Tpi ". The relationship between the ratio α and the first ignition delay time" Tpi "has been stored in advance as a map. With regard to the map, the ratio α in Received reference to the current first ignition delay time "Tpi".

In the above embodiment, when it is determined that the in-cylinder temperature is higher than the determination temperature Tth after the main injection, the fuel property is determined based on the first ignition delay time “Tpi” and the second ignition delay time “Taf”. However, the fuel property can be determined based on the first ignition delay time “Tpi” and the second ignition delay time “Taf” without determining whether the cylinder internal temperature after the main injection is higher than the determination temperature Tth.

wobei „V“ ein internes Volumen eines Zylinders darstellt, „Wg“ eine Zylinder-Innengasmenge darstellt, und „R“ eine Gaskonstante darstellt.In the above embodiment, the cylinder inside temperature is determined by the cylinder inside temperature sensor 35 detected. However, the cylinder inside temperature can be calculated so that it can be compared with the determination temperature Tth. With the help of the internal cylinder pressure P generated by the internal cylinder pressure sensor 31 is detected, and an intake pressure detected by the intake pressure sensor, the in-cylinder temperature T is calculated as the estimated in-cylinder temperature according to the following formula (1): $$\text{T}=\text{P}\ast \text{V /}\left(\text{Wg}\ast \text{R.}\right)-\left(1\right)$$

where “V” represents an internal volume of a cylinder, “Wg” represents a cylinder internal gas amount, and “R” represents a gas constant.

The internal volume “V” is geometrically obtained according to the crank angle. The cylinder internal gas amount “Wg” is an estimated value based on the intake pressure, the intake temperature, and an internal volume of the cylinder when the intake valve is closed 16 is appreciated. According to such a configuration, the cylinder internal temperature sensor is 35 for determining whether the cylinder internal temperature is higher than the determination temperature is not necessary, which can reduce the manufacturing cost.

According to a comparison result between the ratio α and the determination value, it can be determined whether the various controls of the engine are in use 10 can be corrected based on the ratio α. As in particular in 9 (a) shown are the various controls of the machine 10 is corrected based on the ratio α when it is determined that the ratio α is on a heavier side with respect to the determination value αth. In 9 (a) the detected value α1 is on a heavier side with respect to the determination value αth, and correction is made based on the ratio α.

If, as in 9 (b) is alternatively determined that the ratio α is on a lighter side than the first determination value αth1, or when it is determined that the ratio α is on a heavier side than the second determination value αth2, the various controls of the machine 10 corrected based on the ratio α. In 9 (b) the detected value α1 lies between the first determination value αth1 and the second determination value αth2. In this case, no correction is made based on the ratio α.

In a case where the present disclosure is applied to an HC-SCR system, catalyst performance improvement control can be carried out based on the ratio α between the light component and the heavy component. In particular, when the fuel is heavier, the catalyst temperature is increased.

The present disclosure can be applied to a system in which ozone is supplied to the exhaust pipe. In this case, the amount of ozone added is determined based on the ratio α between the light component and the heavy component. The amount of ozone added is determined based on the ratio α. As the fuel is lighter, the amount of ozone added is increased more.

In the above embodiment, the pilot injection, the main injection and the post injection are carried out according to the engine driving condition. In addition, the pilot injection and a post injection can be carried out.

Claims (5)

A fuel property determining device (40) for determining a fuel property of a fuel supplied to a cylinder (11a) of an internal combustion engine (10) by a fuel injector (18), the fuel property determining device comprising: a fuel injection control section configured to include a main injection, a first fuel injection before the main injection, the fuel injection amount of which is smaller than that of the main injection, and a second fuel injection after the main injection, the fuel injection amount of which is smaller than that of the main injection, during a Executes combustion cycle of the internal combustion engine; a property determining section configured to determine the fuel property of the fuel based on a first ignition delay time and a second ignition delay time, the first ignition delay time being a period from the start of the first fuel injection to the ignition of the injected fuel, and the second ignition delay time being a Is the period from the start of the second fuel injection to the ignition of the injected fuel; and a temperature determination section configured to determine whether a temperature in the cylinder after the main injection is higher than a specified temperature, wherein the property determination section is configured to determine the fuel property of the fuel based on a first ignition delay time and a second ignition delay time when the temperature determination section determines that the temperature in the cylinder after the main injection is higher than the specified temperature. Fuel property determining device according to Claim 1 wherein the fuel injection control section is configured to carry out a test injection as the second injection. Fuel property determining device according to Claim 1 or 2 wherein the fuel injection control section is configured to perform a test injection as the second injection for determining the fuel property after the main injection. Fuel property determining device according to one of Claims 1 to 3 wherein the property determining section is configured to determine the fuel property of the fuel based on a difference between the first ignition delay time and the second ignition delay time. Fuel property determining device according to one of Claims 1 to 3 , wherein the property determination section is configured to correct the first ignition delay time using a difference between a predetermined standard ignition delay time and the first ignition delay time, and the property determination section is configured to determine the fuel property based on the corrected first ignition delay time.

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