Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
  • F02D41/40—Controlling fuel injection of the high pressure type with means for controlling injection timing or duration
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/1409—Introducing closed-loop corrections characterised by the control or regulation method using at least a proportional, integral or derivative controller
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/06—Fuel or fuel supply system parameters
  • F02D2200/0602—Fuel pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/06—Fuel or fuel supply system parameters
  • F02D2200/0602—Fuel pressure
  • F02D2200/0604—Estimation of fuel pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/06—Fuel or fuel supply system parameters
  • F02D2200/0614—Actual fuel mass or fuel injection amount
  • F02D2200/0616—Actual fuel mass or fuel injection amount determined by estimation
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method

Definitions

• the present invention relates to a system, an apparatus and a method for controlling the quantity of fuel injected into the combustion chamber of an internal combustion engine; in particular, the present invention is particularly effective in Diesel-cycle engines.
• the present invention also relates to a computer program comprising a plurality of instructions which, when executed on a computer, will cause said computer to carry out the steps of the method for controlling the quantity of fuel according to the present invention.
• the quantity of fuel delivered into the combustion chamber of the engine must be such as to minimize the presence of residual unbumt hydrocarbons at the end of the combustion process; to this end, according to techniques currently known in the art, it is possible to calculate the optimal quantity of fuel to be injected into the combustion chamber in order to minimize the quantity of unbumt hydrocarbons.
• the fuel injection system must therefore be so designed as to provide accurate control over the fuel injected into the cylinders of the engine.
• Italian patent application IT 102016000008386 discloses a fuel injection system which can control, with a high level of precision, the quantity of fuel delivered by the injector into the internal combustion chamber of the engine.
• such system in order to ensure the utmost injection precision, such system relies on at least two pressure sensors located in the duct that supplies the fuel to the injector.
• the use of two pressure transducers per injector of the engine is a problem in terms of both production cost and system complexity.
• the system disclosed in IT 102016000008386 is exclusively intended for newly designed engines, while it can be hardly implemented on existing engines.
• Italian patent application IT 102017000114678 discloses an injection system comprising a single sensor, wherein the injected fuel quantity is calculated by using the “time frequency analysis” technique.
• the use of a single sensor can partly solve the above- mentioned problems, the calculation precision of such a system has proven to be insufficient to ensure a complete combustion of the fuel injected into the engine cylinders.
• FIG. 1 schematically shows a system for injecting a fuel into a combustion chamber according to the present invention
• FIG. 2 schematically shows a control apparatus according to the present invention
• FIG. 1 shows a graph that illustrates an experimental correlation between the fuel mass Mmj,in entering an injector and the injected fuel mass Mmj.
• reference numeral 100 in Figure 1 designates as a whole a block diagram of the system 100 for injecting a fuel into a combustion chamber of an internal combustion engine.
• the fuel injection system 100 may comprise a tank 101 in fluidic communication with an injection pump 102; according to techniques known in the art, the system 100 may further include, in order to transfer the fuel from the tank 101 to the injection pump 102, a low-pressure pump comprising a fuel filter.
• the injection pump 102 may be configured for raising the fuel pressure up to a predetermined value (e.g. the value of the pressure of the fuel exiting the high-pressure pump 102 may be determined as a function of the type of engine in use).
• a predetermined value e.g. the value of the pressure of the fuel exiting the high-pressure pump 102 may be determined as a function of the type of engine in use.
• the fuel pressure value may be increased up to values of hundreds of bars, whereas for Diesel engines such pressure value at the outlet of the injection pump 102 may reach values of thousands of bars (e.g. 2,000 to 3,000 bar).
• the system 100 further comprises a body 105 comprising an accumulation volume in fluidic communication with said injection pump 102.
• Said body 105 comprising an accumulation volume may either be comprised in the injection pump 102 (e.g. arranged inside the injection pump 102) or be a body separate from the injection pump 102 (e.g. arranged outside the injection pump 102).
• Figure 1 shows a system 100 according to the present invention, wherein said body 105 comprising an accumulation volume is arranged outside said injection pump 102.
• the injection pump 102 may be put in fluidic communication with the body 105 via a fuel duct 103; moreover, as schematically shown in Figure 1, the body 105 may comprise an injection rail.
• the system 100 further comprises an injector 112 (also referred to as electro-injector in the present description) adapted to inject the fuel into the combustion chamber of the engine; as is known in the art, the injector 112 comprises at least one inlet 111, configured for receiving the fuel, and an outlet, configured for permitting the injection of the fuel into the engine.
• the injector 112 can be activated or deactivated to allow or inhibit the flow of fuel from the injector 112 to the combustion chamber.
• the activation of the injector 112 will indicate, in general, a configuration of the injector 112 according to which the fuel is injected into the combustion chamber of the engine; conversely, the deactivation of the injector 112 will indicate, in general, a configuration according to which the flow of fuel into the combustion chamber is interrupted.
• the injector 112 may comprise a solenoid valve capable of closing and opening upon request. When the injector 112 is in the active configuration, the solenoid valve is open to permit the flow of fuel; conversely, when the injector 112 is in the inactive configuration, the solenoid valve is closed to prevent the fuel from flowing into the combustion chamber.
• the inlet 111 of the injector 112 is configured to be in fluidic communication with said body 105; to this end, the system 100 comprises a high-pressure duct 109 in fluidic communication with both the body 105 and the injector 112.
• the high-pressure duct 109 is put in fluidic communication with the body 105 by means of a fluid-dynamic coupling element 108; such fluid-dynamic coupling element is configured to allow the fuel to flow from the body 105 to the high-pressure duct 109.
• the fluid-dynamic coupling element 108 may be so configured as to comprise a fuel passage cross-section which is smaller than the cross-section of the high-pressure duct 109.
• the fluid-dynamic coupling element may comprise a restriction (e.g. a restriction directly formed in the high-pressure duct 109 near the body 105) or a calibrated orifice with a passage cross-section smaller than the cross-section of the high-pressure duct.
• the fluid-dynamic coupling element 108 can be implemented in many different ways.
• the fluid-dynamic coupling element 108 may be such as to provide both a fluid-dynamic coupling and a mechanical coupling between the body 105 and the high-pressure duct 109.
• the coupling element 108 may be comprised in the body 105 or in the high-pressure duct 109, or, alternatively, it may comprise an element which is independent of both the body 105 and the high-pressure duct 109.
• the fluid-dynamic coupling element may be a connector which is independent of both the body 105 and the high-pressure duct 109, or it may be comprised in at least one of them.
• the body 105, the high-pressure duct 109 and the fluid-dynamic coupling 108 may be produced jointly and be comprised in a single body.
• the system 100 further comprises a first sensor 110 (e.g. a pressure sensor, preferably a piezoelectric or pi ezoresi stive one) capable of detecting a first flow property paown of the fuel (e g. its static or dynamic pressure) at a first measurement point along said high-pressure duct 109; according to one embodiment of the present invention, the first measurement point may be so located as to permit detecting said first flow property paownat the inlet 111 of the injector 112.
• a first sensor 110 e.g. a pressure sensor, preferably a piezoelectric or pi ezoresi stive one
• the first measurement point may be so located as to permit detecting said first flow property paownat the inlet 111 of the injector 112.
• the system 100 further comprises a second sensor 104 adapted to detect at least one second flow property p ra ii of the fuel within the accumulation volume of the body 105; preferably, the system 100 may comprise a pressure control valve (PCV) 106 comprised in the body 105, configured to put the body 105 in fluidic communication with a fuel recovery duct 107 (wherein the pressure is similar to that in the tank 101) when the pressure within the body 105 reaches or exceeds a predetermined pressure threshold.
• PCV pressure control valve
• the system 100 further comprises a control apparatus 113 configured for controlling the operations executed by the injector 112; for example, the control apparatus 113 may be configured for activating or deactivating the injector 112 for the purpose of accurately controlling the quantity of fuel injected into the combustion chamber of the engine.
• FIG. 2 shows a block diagram representing the control apparatus 113 as a whole, which comprises:
• a processing unit 201 e.g. one or more CPUs
• a memory 202 e.g. a random access memory RAM and/or a Flash memory and/or another type of memory operatively connected to said processing unit 113 and configured for storing at least the instructions necessary for controlling the injector 112;
• an acquisition interface 203 e.g. a CAN-BUS interface or another type of interface operatively connected to the processing unit 201 and configured for acquiring the first flow property paown and the second flow property praii;
• actuating means 204 e.g. an injector drive circuit
• said processing unit 201 configured for activating or deactivating the injector 112 (e.g. capable of generating an electric current suitable for causing a solenoid valve comprised in the injector 112 to open or close);
• a communication bus 207 configured for operatively connecting the processing unit 201, the memory 202, the acquisition interface 203, the actuating means 204 and the input/output means 205.
• the control apparatus 113 is operatively connected to the first sensor 110, the second sensor 104 and the injector 112.
• the control apparatus 113 is configured for providing feedback control over the injector 112 based on an estimate of the fuel mass Minj injected into the combustion chamber.
• the control apparatus 113 is configured for activating or deactivating said injector 112 as a function of an estimate of the injected fuel mass Minj; in other words, the control apparatus 113 is configured for calculating, at every engine cycle, the energization timeET of the injector 112 (i.e. the time interval during which the injector 112 is active in each engine cycle) as a function of the estimated fuel mass Minj injected into the combustion chamber.
• control apparatus 113 may be configured for making a comparison between the estimated value of the fuel mass Minj injected into the engine during a given engine cycle and a target value M inj (e.g. this comparison may comprise a difference between such quantities); based on such comparison, the control apparatus 113 may be configured for determining the energization time ET of the injector 112 in the next engine cycle. For example, if the estimated value of the fuel mass Minj injected during a given engine cycle turns out to be greater than a target value M inj (i.e. the injected fuel quantity is greater than desired), then the control apparatus 113 may be configured for decreasing the energization time ET in the next engine cycle.
• the control apparatus 113 may be configured for increasing the energization time ET in the next engine cycle.
• feedback control may comprise a Proportional-Integral-Derivative system.
• Figure 3 shows a graph that illustrates an example of an experimental correlation between the fuel mass Minj, in entering the injector 112 and the fuel mass actually injected into the combustion chamber (i.e. the fuel mass exiting the injector).
• this relation can be directly obtained, for example, through an experimental process comprising a plurality of preliminary measurements taken on the injection system 100 (i.e. before it is mounted to the engine), to be carried out by means of a hydraulic bench configured for measuring the fuel flow rates in and out of the injector 112. Based on such relation it is thus possible to make an accurate assessment of the fuel mass Mmj injected at every engine cycle during the operating phases of the engine as a function of the fuel mass Minj.in entering the injector 112.
• the relation between the injected fuel quantity and the fuel mass Minj,in entering the injector 112 can be expressed in a more complex and accurate way by taking into account additional variables such as, for example, the pressure in the accumulation chamber of the body 105.
• the present invention is by no means limited to the use of the relation illustrated in Figure 3; on the contrary, any relation capable of accurately expressing the correlation between the injected fuel quantity and the fuel mass Minj.in entering the injector 112 may be used, without nevertheless departing from the basic inventive idea.
• control apparatus 113 is configured for determining the fuel mass Mmj,in entering the injector; to this end, the control apparatus 113 is also configured for determining a third flow property p up of said fuel at a second measurement point along said high-pressure duct 109.
• the letter L will designate the distance between the first measurement point and the second measurement point, both of which are located along the high-pressure duct 109; according to one embodiment of the present invention, the first measurement point may be located at the inlet of the injector 112, while the second measurement point may be located at the fluid-dynamic coupling element 108 (in this case, the distance L between the first and second measurement points will approximately coincide with the length of the high-pressure duct 109). More generally, it is sufficient that the second measurement point is located along the high- pressure duct 109 between said fluid-dynamic coupling element and said first measurement point.
• the letter A will designate the cross-section of the high-pressure duct 109; the letter Cd, will designate the outflow coefficient of the fluid-dynamic coupling element 108, and the letter A res will designate the restricted cross-section of the fluid-dynamic coupling element 108.
• the symbol pdown will designate the value of the first flow property, measured at the first measurement point (e.g.
• the symbol p ra ii will designate the value of the second flow property measured within the accumulation volume of the body 105; the symbol p up will designate the value of a third flow property, computed as a function of the first and second flow properties, pdown and p ra n, at the second measurement point (e g. at the outlet of the fluid-dynamic coupling element 108).
• the control apparatus 113 is configured for solving a system of equations comprising a first equation and a second equation, both of which comprise a first unknown and a second unknown; in particular, the first unknown corresponds to the fuel mass flow rate G through said fluid-dynamic coupling element 108, and the second unknown corresponds to the third flow property p up .
• the fuel flow rate is assumed to be positive when the fuel flows in the direction from the body 105 towards the high-pressure duct 109.
• the fuel mass flow rate G through said fluid-dynamic coupling element 108 can be assessed by means of the following first equation, wherein the two formulae must be selected as a function of the time histories of p up e p ra u, and wherein the flow rate is assumed to have a positive sign when the fuel flows from the body 105 towards the injector 112 (i.e. when PraiA Pup): • 12 • (p U p — Prail)p If Pup > Pra.il
• the second equation can be expressed by combining the mass conservation equation with the motion quantity equation as follows:
• wall friction is not considered, in that it has been experimentally verified that its effect is negligible.
• the difference pup(tj)-p ra ii(tj) is greater or smaller than zero, and then the correct relation is chosen in the equation (1), which is subsequently solved jointly with the equation (4).
• the algorithm will provide new values of p up (tj) and G(tj); if such values meet the relations under examination, then such two values will be those actually required, otherwise the procedure will be restarted using these very values as second-attempt values (the procedure will generally reach convergence after just a few iterations); c) by repeating the procedure described at b) for every time instant, it is possible to determine the time histories p up (t) and G(t).
• the control apparatus 113 After having determined the time history of the pressure p U p(t) (i.e. the third flow property p up ), this is used in order to calculate the flow rate through the duct (i.e. the flow rate entering the injector 112).
• the flow rate Ginjjn through the duct can thus be determined by the control apparatus 113 as follows: where (Ap) represents the time average of Ap.
• control apparatus may be configured for explicitly computing the mass
• the control apparatus 113 is therefore configured for determining, as a function of the first flow property paown (measured, for example, at the inlet of the injector 112) and the second flow property p ra ii, the value of the third flow property p up of said fuel at the second measurement point along said high-pressure duct 109 (e.g. at the outlet of the fluid-dynamic coupling element 108). After having determined the value of the third flow property p up , the control apparatus 113 is configured for determining, as a function of the first flow property Pdown and third flow property p up , the flow rate Ginj,in and/or the mass Mmj.ui of fuel entering said injector 112.
• control apparatus 113 is configured for either activating or deactivating said injector 112.
• the present invention further provides a computer program, configured for being stored in the memory 202 of the control apparatus 113, which comprises instructions adapted to control the injector 112 as described above.
• this invention is also applicable to, in addition to Diesel-cycle engines, any other engine types (e.g. Otto-cycle engines, Atkinson-cycle engines or other engine types) using fuel injectors, which usually do not include the solenoid valve.
• Diesel-cycle engines any other engine types (e.g. Otto-cycle engines, Atkinson-cycle engines or other engine types) using fuel injectors, which usually do not include the solenoid valve.

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• Engineering & Computer Science (AREA)
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• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Consolidation Of Soil By Introduction Of Solidifying Substances Into Soil (AREA)
• Paper (AREA)
• Control Of Non-Electrical Variables (AREA)
• Fuel-Injection Apparatus (AREA)

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Publications (1)

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Citations (4)

Family Cites Families (2)

• 2021
  • 2021-10-11 IT IT102021000026006A patent/IT202100026006A1/it unknown
• 2022
  • 2022-10-10 WO PCT/IB2022/059696 patent/WO2023062508A1/en active Application Filing

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