GB2502366A - Method of biodiesel blending detection in an i.c. engine - Google Patents

Abstract

A method of biodiesel blending detection in an internal combustion engine comprises the following steps: determining a value of a parameter representative of a NOx concentration in the exhaust line, eg using NOx sensor in a steady state condition; comparing the determined value with a reference value thereof; calculating a biodiesel blending ratio as a function of the difference between the determined value and the reference value.

Description

METHOD OF BIODIESEL BLENDING DETECTION

TECHNICAL FIELD

The present disclosure relates to a method of biodiesel blending detection.

BACKGROUND -

Biodiesel can be used in pure form or may be blended with petroleum diesel at any concentration in modern diesel engines.

It may be foreseen that use of biodiesel will increase in the future especially due to the advantages of such type of fuel and by effect of government legislations.

In particular the use of biodiesel may have the effect of a particulate reduction up to 80%.

Furthermore, biodiesel gives the possibility of recalibrating the Soot-NOr trade-off in order to eliminate increase of NO.

Also it gives the possibility of reducing the regeneration frequency of the antiparticulate filter.

However, the use of biodiesel is not without problems; for example with biodiesel cold start of the motor may be more difficult, especially at low temperatures, with respect to conventional petrodiesel.

A further problem is given by increased oil dilution due to the inferior evaporability of biodiesel.

Moreover use of biodiesel may have the effect of reducing the power of the motor by 7-10%.

Furthermore use of biodiesel may lead to an increase of nitrogen oxides emission up to 60% due to its oxygen content and that is particularly evident at high load were Exhaust Gas Recirculation (EGR) is not used.

In order to be compliant with emission levels legislation, Diesel engines will be equipped with a dedicated aftertreatment system for NO reduction (i.e. Lean NOx Trap (LNT), Selective Catalytic Reduction (5CR)). Those NO dedicated aftertreatment systems are generally equipped with a NO sensor to ensure the required level of efficiency.

A biodiesel blending detection system may determine a percentage of biodiesel with respect to petrodiesel, whereby such percentage may vary from 0% to 100% and is indicated with symbols from BC to B100 in the following description.

An object of the present invention is to enable the detection of biodiesel in a vehicle tank as well as to provide an estimate of the percentage volume of biodiesel as accurate as possible.

Another object is to provide an estimate of the percentage volume of biodiesel without using dedicated devices and by taking advantage from the computational* capabilities of the Electronic Control Unit (ECU) of the vehicle.

Another object of the present disclosure is to meet these goals by means of a simple, rational and inexpensive solution.

These objects are achieved by a method, by an engine, by an apparatus, by an automotive system, by a computer program and a computer program product, and by an electromagnetic signal having the features recited in the independent claims.

The dependent claims delineate preferred and/or especially advantageous aspects.

SUMMARY

An embodiment of the invention provides a method of biodiesel blending detection in an Iritemal Combustion Engine, the Internal Combustion Engine being equipped with an exhaust line, the method comprising the following steps: -determining a value of a parameter representative of a NO concentration in the exhaust line; -comparing the determined value with a reference value thereof; -calculating a biodiesel blending ratio as a function of the difference between the determined value and the reference value.

An advantage of this embodiment of the invention is that detecting the biodiesel blending level allows the engine to mitigate emission and performance drift due to different fuel properties.

This detection allows to make diesel engine functionalities completely independent from fuel type without adding any cost.

In particular, with blending ratio information, oil life monitoring can be tailored to actual engine fuelling, taking into account the fact that biodiesel requires shorter oil drain interva Is.

Furthermore known soot accumulation statistical models can be tailored to actual engine fuelling, since biodiesel could enable longer intervals between Diesel Particulate Fuel (DPF) regeneration events.

According to an embodiment of the invention, the value of the parameter is measured by a NO sensor in the exhaust line.

An advantage of this embodiment is that it does not use any additional sensor with respect to current diesel engine configurations.

According to an embodiment of the invention, the measurement of the NOx sensor is taken when the Internal Combustion Engine is operating in a steady state condition.

An advantage of this embodiment is that it allows to take a reliable measurement of the NOx concentration in the exhaust gas that is not affected by transitory changes in engine speed and engine load.

According to an embodiment of the invention, the biodiesel blending ratio is calculated by means of the following equation: Bxx ( 0.30 * ([NOxj -[NOx]80) ). 100 [NOx]530 -[NOx}50 where B represents a generic (x%) percentage of blending, [NO]80 and [NO]830 respectively represents the value of NC emissions at 0% blending value and at a 30% blending value and [NOJ(]Bc, represents the value of the NO concentration in the exhaust line.

An advantage of this embodiment is that it allows the calculation of the blending ratio employing a linear relationship between the value of the NO concentration in the exhaust line and the blending ratio.

Another embodiment of the invention provides an apparatus for biodiesel blending detection in an Internal Combustion Engine, the Internal Combustion Engine being equipped with an exhaust line, the apparatus comprising: -means for determining a value of a parameter representative of a NO concentration in the exhaust line; -means for comparing the determined value with a reference value thereof; -means for calculating a biodiesel blending ratio as a function of the difference between the determined value and the reference value.

Another embodiment of the invention provides an automotive system comprising an Internal Combustion Engine equipped with an exhaust line and managed by. an Electronic Control Unit configured to: -determine a value of a parameter representative of a NO concentration in the exhaust line; -compare the determined value with a reference value thereof; -calculate a biodiesel blending ratio as a function of the difference between the determined value and the reference value.

These last two embodiments have substantially the same advantages of the various embodiments of the method of the invention.

The method according to one of its aspects can be carried out with the help of a computer program comprising a program-code for carrying out all the steps of the method described above, and in the form of computer program product comprising the computer program.

The computer program product can be embodied as a control apparatus for an internal combustion engine, comprising an Electronic Control Unit (ECU), a data carrier associated to the ECU, and the computer program stored in a data carrier, so that the control apparatus defines the embodiments described in the same way as the method. In this case, when the control apparatus executes the computer program all the steps of the method described above are carried out.

The method according to a further aspect can be also embodied as an electromagnetic signal, said signal being modulated to carry a sequence of data bits which represents a computer program to carry out all steps of the method.

A still further aspect of the disclosure provides an intemal combustion engine specially arranged for carrying out the method claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The various embodiments will now be described, by way of example, with reference to the accompanying drawings, wherein like numerals denote like elements, and in which: Figure 1 shows an automotive system; Figure 2 is a cross-section of an internal combustion engine belonging to the automotive system of figure 1; Figure 3 represents schematically a portion of an aftertreatment system of the automotive system of figures 1-2; Figure 4 represents an alternative aftertreatment system that may be associated with the engine of the automotive system of fig 1-2; Figure 5 represents a graph of the increase of NJOX emissions due to an increase of the air to fuel ratio; Figure 6 represents a graph of the increase of NO emissions due to an increase in the blending ratio of fuel; and Figure 7 represents a graph of a relationship between NO emissions due to different blending ratio and the blending ratio itself, and Figure 8 is a flowchart representing an embodiment of the method of the invention.

DETAILED DESCRIPTION

Exemplary embodiments will now be described with reference to the enclosed drawings without intent to limit application and uses.

Some embodiments may include an automotive system 100, as shown in Figures 1 and 2, that includes an internal combustion engine (ICE) 110 having an engine block 120 defining at least one cylinder 125 having a piston 140 coupled to rotate a crankshaft 145.

A cylinder head 130 cooperates with the piston 140 to define a combustion chamber 150.

A fuel and air mixture (not shown) is disposed in the combustion chamber 150 and ignited, resulting in hot expanding exhaust gasses causing reciprocal movement of the piston 140. The fuel is provided by at least one fuel injector 160 and the air through at least one intake port 210. The fuel is provided at high pressure to the fuel injector 160 from a fuel rail 170 in fluid communication with a high pressure fuel pump 180 that increase the pressure of the fuel received from a fuel source 190. Each of the cylinders 125 has at least two valves 215, actuated by a camshaft 135 rotating in time with the crankshaft 145. The valves 215 selectively allow air into the combustion chamber 150 from the port 210 and alternately allow exhaust gases to exit through a port 220. In some examples, a cam phaser 155 may selectively vary the timing between the camshaft 135 and the crankshaft 145.

The air may be distributed to the air intake port(s) 210 through an intake manifold 200. An air intake duct 205 may provide air from the ambient environment to the intake manifold 200. In other embodiments, a throttle body 330 may be provided to regulate the flow of air into the manifold 200. In still other embodiments, a forced air system such as a turbocharger 230, having a compressor 240 rotationally coupled to a turbine 250, may be provided. Rotation of the compressor 240 increases the pressure and temperature of the air in the duct 205 and manifold 200. An intercooler 260 disposed in the duct 205 may reduce the temperature of the air. The turbine 250 rotates by receiving exhaust gases from an exhaust manifold 225 that directs exhaust gases from the exhaust ports 220 and through a series of vanes prior to expansion through the turbine 250. The exhaust gases exit the turbine 250 and are directed into an exhaust system 270. This example shows a variable geometry turbine (VGT) with a VGT actuator 290 arranged to move the vanes to alter the flow of the exhaust gases through the turbine 250. In other embodiments, the turbocharger 230 may be fixed geometry and/or include a waste gate.

The exhaust system 270 may include an exhaust pipe 275 having one or more exhaust aftertreatment devices 280. The aftertreatment devices may be any device configured to change the composition of the exhaust gases. Some examples of aftertreatment devices 280 include, but are not limited to, catalytic converters (two and three way), oxidation catalysts, lean NO traps, hydrocarbon adsorbers, selective catalytic reduction (SCR) systems, and particulate filters.

More specifically, as also better detailed in Figure 3, the exhaust line 275 is equipped with a Diesel Oxidation Catalyst (DOC) 280, for oxidizing hydrocarbon (HC) and carbon monoxides (CO) into carbon dioxide (C02) and water (1-120), and a Diesel Particulate Filter (DPF) 285, located in the exhaust line downstream the DOC 280, for removing diesel particulate matter or soot from the exhaust gas.

Furthermore, downstream of the DPF 285, a SCR Selective Catalytic Reduction device (5CR) 287 is provided.

Other embodiments may include an exhaust gas recirculation (EGR) system 300 coupled between the exhaust manifold 225 and the intake manifold 200. The EGR system 300 may include an EGR cooler 310 to reduce the temperature of the exhaust gases in the EGR system 300. An EGR valve 320 regulates a flow of exhaust gases in the EGR system 300.

The automotive system 100 may further include an electronic control unit (ECU) 450 in communication with one or more sensors and/or devices associated with the ICE 110.

The ECU 450 may receive input signals from various sensors configured to generate the signals in proportion to various physical parameters associated with the ICE 110. The sensors include, but are not limited to, a mass airflow and temperature sensor 340, a manifold pressure and temperature sensor 350, a combustion pressure sensor 360, coolant and oil temperature and level sensors 380, a fuel rail pressure sensor 400, a cam position sensor 410, a crank position sensor 420, exhaust pressure and temperature sensors 430, an EGR temperature sensor 440, and an accelerator pedal position sensor 445. Furthermore, the ECU 450 may generate output signals to various control devices that are arranged to control the operation of the ICE 110, including, but not limited to, the fuel injectors 160, the throttle body 330, the EGR Valve 320, the VGT actuator 290, and the cam phaser 155. Note, dashed lines are used to indicate communication between the ECU 450 and the various sensors and devices, but some are omitted for clarity.

Turning now to the ECU 450, this apparatus may include a digital central processing unit (CPU) in communication with. a memory system, or data carrier 460, and an interface bus. The CPU is configured to execute instructions stored as a program in the memory system, and send and receive signalé toffrom the interface bus. The memory system may include various storage types including optical storage, magnetic storage, solid state storage, and other non-volatile memory. The interface bus may be configured to send, receive, and modulate analog and/or digital signals to/from the various sensors and control devices. The program may embody the methods disclosed herein, allowing the CPU to carry out the steps of such methods and control the ICE 110.

More specifically, Figure 3 shows a schematic illustration of a portion of an aftertreatment system of the automotive system of figures 1-2.

As seen in Fig. 3, the exhaust line 275 of the Internal Combustion engine 110 is equipped with a Diesel Oxidation Catalyst (DOC) 280, and with a Diesel Particulate Filter (DPF) 285, located in the exhaust line downstream the DOC 280. Furthermore1 downstream of the DPF 285, a SCR Selective Catalytic Reduction device (SCR) 287 is provided.

The SCR catalyst 287 can be fed with a Diesel Exhaust Fluid (DEF), for example urea, that is stored in a DEF tank 720, in order to reduce the nitrogen oxides (NOr) contained in the exhaust into diatonic nitrogen (N2) and water (ftc). The DEE is provided to a DEF injector 700 by means of a DEF pump 710 that receives the DEF from the DEF tank 720. The DEF injector 700 can be controlled by the ECU 450 of the automotive system 100.

A NO sensor 500 is provided upstream of DOC and is connected to the ECU 450.

Figure 4 represents an alternative aftertreatrnent system that may be associated with.the engine of the automotive system of fig 1-2.

In this case a Lean NOx Trap (LNT) 269 is provided upstream of the Diesel Particulate Filter (DPF) 285, located in the exhaust line. A NOx sensor 500 is provided upstream of the LNT 289 and is connected to the ECU 450.

Figure 5 represents a graph of the increase of NO emission due to an increase of the air to fuel ratio.

The graph is realized by performing experimental measures and shows that, at very high combustion temperature typical of an engine full load operation NO emissions increase linearly (curve A) as air to fuel ratio, or lambda, increases. Lambda may be defined as the ratio of the actual air to fuel ratio to stoichiometric air to fuel ratio.

In general, in the present description, BO to 8100 indicate corresponding percentages of biodiesel with respect to petrodiesel from 0% to 100%.

Indicating with Bxx a generic (x%) percentage of biodiesel with respect to petrodiesel, it can be observed that, from BC to 8100, for the same air mass flow, the lambda increases about 12%, which leads to a NO emission increase of about 45%.

With a typical NO sensor error of about 3-4 [ppm] a ±0.1% accuracy should be guaranteed.

Figure 6 represents a graph of the increase of NO emission due to an increase in the blending ratio of fuel.

The data available show that the NO emissions increase is well described by an exponential function across the entire operating range (curve B) but, in an area of practical interest, namely from 60 to B30, the data can be interpolated with a linear interpolation in a very precise way (curve C).

Figure 7 represents a graph of a linear relationship between NO emissions due to different blending ratio and the blending ratio itself.

Since in the range of BO to B30 biodiesel to petrodiesel blending ratio NO emission increase in a substantially linear fashion with the increase of biodiesel blending level, the biodiesel blending ratio can be calculated with the following methodology.

After a fuel refill once the engine is working in a steady state condition (almost constant engine speed, load, coolant temperature) at high load point, a measure of the NO concentration is triggered. The measured value is then compared with a reference value measured at a known blending ratio and, finally, the actual blending ratio is calculated with the following equation: Bxx=( 0.30.(INOr]8 -[NOx}80) ).ioo (1) [NOx]B30 -[NOx]80 where Bxx represents a generic percentage of blending, [N0J90 and LNOB3O respectively represents the value of NOx concentration in the exhaust line 275 at 0% blending value and at a 30% blending value and [NOx]Bxx represents the value of the NOx concentration in the exhaust line 275.

Equation (1) can be calibrated for any specific automotive system.

Figure 8 is a flowchart representing an embodiment of the method of the invention.

In the illustrated embodiment, until the engine 110 is not working in a steady state condition, no operations of the method are performed (block 600). If the engine 110 is working in a steady state condition, a measurement of the NO concentration in the exhaust line 275 is taken by the NOx sensor 500 (block 610).

The measured value of the NO concentration [NOYJBXX is then fed to the ECU 450 that manages the Internal Combustion Engine 110 and the blending value Bxx is calculated using equation (1) (block 620).

A steady state condition of the engine 110 for the various embodiments of the method may be defined as characterized by almost constant engine speed, load and coolant temperature at high load point, whereby at high load point no Exhaust Gas Recirculation (EGR) is used.

While at least one exemplary embodiment has been presented in the foregoing summary and detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration in any way. Rather, the foregoing summary and detailed description will provide those skilled in the art with a convenient road map for implementing at least one exemplary embodiment, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope as set forth in the appended claims and their legal equivalents.

REFERENCE NUMBERS

automotive system internal combustion engine (ICE) engine block 125 cylinder cylinder head camshaft piston crankshaft 150 combustion chamber cam phaser fuel injector fuel rail fuel pump 190 fuel source intake manifold 205 air intake duct 210 intake airport 215 valves of the cylinder 220 exhaustgas port 225 exhaust manifold 230 turbocharger 240 compressor 250 turbine 260 intercooler 270 exhaust system 275 exhaust line 280 DOC 285 DPF 287 SCR 289 LNT 290 VGT actuator 300 EGR system 31Ô EGS cooler 320 EGR valve 330 throttle body 340 mass airflow and temperature sensor 350 manifold pressure and temperature sensor 360 combustion pressure sensor 380 coolant and oil temperature and level sensors 400 fuel rail pressure sensor 410 cam position sensor 420 crank position sensor 430 exhaust pressure and temperature sensor 445 accelerator pedal position sensor 450 electronic control unit (ECU) 13 460 data carrier 500 NO sensor 600 block 610 block 620 block