EA041377B1 - METHOD AND SYSTEMS FOR FUEL INJECTION CONTROL IN AN ENGINE WITH A COMMON HIGH PRESSURE RAIL - Google Patents

Description

State of the art

Technical field

Embodiments of the invention described herein relate to methods and systems for controlling a high pressure common rail fuel system in an engine.

Description of the prior art

Vehicles, such as rail vehicles, contain power sources such as diesel engines or dual-fuel engines that use both diesel fuel and another type of fuel, such as natural gas. In some vehicles, diesel fuel is supplied to a diesel or dual-fuel engine using a common rail system. In such a system, the fuel injectors are configured to inject fuel (eg diesel fuel) from a common fuel rail into the engine cylinders for combustion. Some engine systems may use an injector map stored in the controller's memory to determine the output value for firing the fuel injectors. In one example, the output value for starting the fuel injectors may comprise the start time of the injector and/or the amount of time the injectors inject fuel into the engine's cylinders. The injector map may include a table of injector start data, in which each injector start time value corresponds to a fuel rail pressure value and a fuel value or amount of fuel injected per stroke of the fuel injector. Thus, using the injector map, the engine controller outputs the injector start time for the fuel setpoint and the measured fuel rail pressure. Further, the fuel injection can be adjusted based on the determined start time of the injector to supply the required amount of fuel to the engine cylinders.

The essence of the invention

In one embodiment, a computer-readable memory storage medium comprises: fuel injector start data indexed in memory according to two input parameters, instructions for determining a modified fuel injector nozzle orifice pressure difference based on determined pressure values upstream and downstream of said nozzle orifice , engine speed, injection mode, and modified differential pressure function, as well as instructions for generating an output value for firing fuel injectors by interpolating indexed fuel injector firing data using the modified differential pressure value as the first of the two input parameters.

Brief description of the drawings

Fig. 1 is a diagram of a common rail system according to one embodiment of the present invention.

Fig. 2 is a diagram of an exemplary multi-fuel engine cylinder according to one embodiment of the present invention.

Fig. 3 shows tables for fuel injectors according to one embodiment of the present invention.

Fig. 4-9 are graphs of pressures upstream and downstream of the fuel injector nozzle and time or crank angle per cylinder cycle for various engine operating conditions according to one embodiment of the present invention.

Fig. 10 illustrates a method for controlling fuel injection into an engine based on the start time of the injectors according to one embodiment of the present invention.

Detailed description

The following description refers to various embodiments for indexing an injection map and, accordingly, controlling fuel injection into an engine. The amount of fuel injected into the engine cylinder by the fuel injector may be selected based on the pressure in the fuel rail and the start time of the injector (eg, the amount of time the injector injects fuel). In addition, fuel injection data for fuel injection control may be stored in the memory of the engine controller. For example, the fuel injection data may comprise fuel injection start times for various fuel values and fuel rail pressures. In other words, the fuel injection start data can be indexed by the fuel rail pressure and by the fuel value. The fuel injection start time can then be determined by the engine controller by interpolating the injector table data based on the determined fuel rail pressure (eg, measured pressure) and the desired fuel value. Thus, the fuel injectors can be activated based on the received start time to deliver the required amount of fuel at a given fuel rail pressure.

However, indexing the injector table in this way can lead to linear interpolation inaccuracies due to the non-linear relationship between the injector data, which leads to a larger error in determining the start time of the fuel injector. This, in turn, reduces fuel efficiency and results in more uneven emissions.

- 1 041377

By making the relationship between the injector start data more linear, the interpolation error can be reduced and thus the accuracy of the fuel injector start time can be improved. For example, an injector table may be indexed by modified pressure, not just by fuel rail pressure. The modified pressure may be based on a function of the modified pressure and on a determined or measured fuel rail pressure. In this case, using the modified pressure function, it is possible to transform the fuel injector start data stored in the injector table so that the relationship between the data in the cells of said injector table becomes more linear. By interpolating such transformed data, it is possible to reduce the interpolation error compared to the untransformed data, and as a result, obtain more accurate fuel injector start times and provide more accurate engine fuel injection control.

The inventors of the present invention also recognize that the fuel flow model presented in the above injector tables can lead to errors under different engine operating conditions. In particular, the inventors have found that when an injector is installed on an engine (for example, while the engine is running), the pressure values around the injector nozzle change more dynamically and usually do not match the pressure values around the same nozzle hole when the injector is installed on a test bench, using which make up typical injector maps. Thus, the modified pressure function described above can be further modified to account for physical changes in engine operation that introduce errors in the fuel flow model. For example, the modified pressure function (hereinafter the modified pressure difference function) can take into account changes in the supply pressure in the fuel rail, as well as the pressure in the engine cylinder, depending on the injection mode, engine speed, injection duration, amount of fuel and gas in the cylinder (for example, when the engine is a dual-fuel engine for burning both diesel fuel and a secondary fuel such as natural gas), and the like.

Fig. 1 shows an example of a common rail fuel system in an engine such as the engine of FIG. 2. Said system may include injectors for injecting fuel such as diesel fuel. As shown in FIG. 2, the engine may be a diesel-only engine (e.g., injecting only liquid, diesel fuel), or a dual-fuel engine in which both liquid fuel and secondary, gaseous fuel are injected through a common rail fuel system, such as natural gas. The start data for said injectors may be stored in the memory of the engine controller in the form of a map, such as the maps shown in FIG. 3. To take into account errors in the fuel flow model in the injector installed on the engine, during engine operation, data on the start of the injector can be indexed in the injector map using the modified pressure difference function, which is based on the pressure difference in the injector nozzle hole, on the function of injection mode and engine speed, and on a correction factor that takes into account the difference between the pressure in the injector installed on the engine and the pressure in the injector on the test bench (for example, during an injector test outside the engine). The graphs in Fig. 4-9 illustrate pressure changes upstream and downstream of the injector nozzle opening for different injection parameters, including single and multiple injections, different injection modes, different gaseous fuel replacement rates, and the like. In FIG. 10 shows a method for indexing stored fuel injector start data with a modified differential pressure function and then adjusting fuel injection based on an injector start time determined from an injector map containing the indexed fuel injector start data.

Using the modified injector pressure differential functions described herein, a more accurate operation of a dual-fuel engine with a high fuel substitution ratio (for example, a high proportion of natural gas to the total amount of fuel that contains natural gas and diesel fuel) can be provided, as well as precise and efficient subsequent injections in a diesel engine to reduce emissions and fuel consumption.

The approach described herein can be applied to various types of engines and to various engine-driven systems. Some of these systems may be fixed, while others may be placed on semi-movable or mobile platforms. Between working periods, semi-movable platforms, for example, mounted on trailers, can be moved. Mobile platforms contain self-propelled vehicles. Such vehicles may include: road vehicles, mining equipment, marine vessels, rail vehicles and other off-road vehicles. For clarity of illustration, a locomotive is taken as an example of a movable platform supporting the system according to an embodiment of the present invention.

Before proceeding to a detailed description of the proposed approach for indexing the injection map and subsequent control of fuel injection into the engine, an example is first described.

- 2 041377 fuel system for the engine. For example, in FIG. 1 is a block diagram of a common rail fuel system (CRS) 100 for a vehicle engine, such as a rail vehicle. Liquid fuel, such as diesel fuel, enters or is stored in the fuel tank 102. The fuel tank 102 is in fluid communication with the low pressure fuel pump 104. In the embodiment shown in FIG. 1, the fuel pump 104 is located within the fuel tank 102 and can be submerged below the liquid fuel level. In alternative embodiments, a low pressure fuel pump may be attached to the outside of the fuel tank and be capable of pumping fuel with a suction device. The low pressure fuel pump 104 is controlled by the controller 106.

The low pressure fuel pump 104 pumps liquid fuel from the fuel tank 102 to the high pressure fuel pump 108 via conduit 110. Valve 112 is provided in conduit 110 to control the flow of fuel in conduit 110. For example, valve 112 is an inlet metering valve (IMV). An IMV valve 112 is located upstream of the high pressure fuel pump 108 to control the flow of fuel to the high pressure fuel pump 108 and then to the common rail 114 to distribute fuel between the fuel injectors 118 and perform fuel injection. For example, the IMV valve 112 may be a solenoid valve whose opening and closing is controlled by the controller 106. In other words, the controller 106 commands the IMV valve to fully close, fully open, or be between fully closed and fully open to provide controlling the fuel flow to the high pressure fuel pump 108 at a predetermined fuel flow rate. During operation of the vehicle, the IMV valve 112 is controlled to provide fuel metering based on operating conditions, and under at least some conditions, this valve can be at least partially open. It should be understood that this valve is only one example of a fuel metering control device, and any suitable control element may be used within the scope of this invention. For example, the position or state of the IMV valve can be electrically controlled by controlling the electrical current in the valve. In another example, the position or state of said valve may be mechanically controlled by controlling a servomotor to control the operation of said valve.

The high pressure fuel pump 108 increases the fuel pressure from a lower to a higher pressure. The fuel pump 108 is in fluid communication with the common fuel rail 114. The fuel pump 108 provides fuel to the common fuel rail 114 through the pipeline 116. Fuel injectors 118 are in fluid communication with the common fuel rail 114. Each of these fuel injectors 118 supplies fuel to one from engine cylinders 120 contained in engine 122. In engine cylinders 120, fuel is burned to provide power to the vehicle, such as through an alternator and traction motors. The operation of the fuel injectors 118 is controlled by the controller 106. In the embodiment of FIG. 1 engine 122 contains four fuel injectors and four cylinders. In alternative embodiments, the engine may comprise more or fewer fuel injectors and cylinders.

The fuel pumped by the low pressure fuel pump 104 from the fuel tank 102 to the inlet of the IMV valve 112 can be used at lower fuel pressure or engine fuel pressure. Thus, those components of the CRS 100 that are upstream of the high pressure fuel pump 108 operate in a region of lower fuel pressure or engine fuel pressure. On the other hand, the fuel pump 108 is configured to pump fuel at a lower pressure to provide a higher fuel pressure or fuel rail pressure. Thus, those components of system 100 that are downstream of pump 108 are in the area of system 100 that has a higher fuel pressure or fuel rail pressure.

Fuel pressure in the lower pressure region is measured by a pressure sensor 126 located in conduit 110. Sensor 126 is configured to send a pressure signal to controller 106. In an alternative application, pressure sensor 126 is in fluid communication with the outlet of low pressure fuel pump 104. The temperature of the fuel in the region of lower fuel pressure is measured by a temperature sensor 128 located in the conduit 110. The temperature sensor 128 is configured to send a temperature signal to the controller 106.

Fuel pressure in the higher pressure region is measured by pressure sensor 130 located in conduit 116. Pressure sensor 130 is configured to send a pressure signal to controller 106. In controller 106, this pressure signal is used to determine the pressure of the fuel (eg, FRP) in common fuel rail. Essentially, rail fuel pressure (FRP) data is provided to controller 106 via pressure sensor 130. In an alternative application, sensor 130 is in fluid communication with the outlet of high pressure fuel pump 108. It should be noted that in some applications, different operating parameters may generally

- 3 041377 be determined or obtained indirectly in addition to direct measurements or instead of such measurements.

In addition to the above sensors, controller 106 is configured to receive various signals from engine sensors 134 attached to engine 122 that can be used to evaluate fuel control and related engine operation. For example, controller 106 is configured to receive signals from sensors indicative of an air/fuel ratio, engine speed, engine load, engine temperature, ambient temperature, fuel value, number of cylinders in which fuel is being burned, and the like. In the illustrated embodiment, the controller 106 is a computing device, such as a microcomputer, comprising a processing unit 136, a computer-readable storage medium 138, input/output ports, a memory, and a data bus. The computer-readable medium 138 contained in the controller 106 is capable of being programmed with computer-readable data, which are instructions executable by said processor to implement the control procedures and methods described below, as well as other options not expressly stated herein.

The controller 106 is configured to control various actuators in the CRS system 100 based on various operating parameters received or derived from various signals received from various sensors to dynamically assess the health of said system and control engine operation based on such assessment. For example, in one embodiment, controller 106 is configured to control fuel injection into the engine. In particular, the controller is configured to adjust the fuel injection mode of one or more fuel injectors based on a certain start time of the injectors, which may include controlling a pulse width modulation signal to command said fuel injectors to inject fuel for a certain duration.

The controller 106 is also configured to generate an output signal for firing the fuel injectors, such as fuel injector firing time, based on CRS system operating conditions and stored fuel injector firing data. The fuel injector start data may be stored in the memory of the computer-readable medium of said controller. In one example, fuel injector start data may be stored in an injector table or map, such as first injector table 300 or second injector table 302, as shown in FIG. 3.

Fig. 2 depicts an embodiment of a combustion chamber or cylinder 200 of a multi-cylinder internal combustion engine 202, such as an engine comprising the common rail fuel system described above with reference to FIG. 1. As a cylinder, consider the cylinder head 201 housing the intake and exhaust valves and the liquid fuel injector described later, and the cylinder block 203.

The engine is configured to be controlled at least in part by a control system comprising a controller 106 which, in turn, may be coupled to a vehicle system. As described above, the controller is configured to receive signals from various engine sensors, including, but not limited to, engine speed, engine load, boost pressure, exhaust pressure, turbocharger speed, ambient pressure, CO2 levels, exhaust temperature , NOx emissions, engine coolant temperature (ECT) from a temperature sensor 230 attached to the cooling jacket 228, and so on. Thus, said controller is configured to control the engine device by sending commands to various components such as the alternator, cylinder valves, throttle, fuel injectors, and so on.

A cylinder (eg, a combustion chamber) may include a sleeve 204 containing a piston 206. The piston may be attached to a crankshaft 208 to convert the reciprocating motion of the piston into rotational motion of the crankshaft. The crankshaft may include a speed sensor to output speed data (eg instantaneous speed) of the crankshaft. In some embodiments, the engine may be a four-stroke engine in which each cylinder is ignited in ignition order in two revolutions of the crankshaft. In other embodiments, the engine may be a two-stroke engine in which each cylinder ignites in firing order per revolution of the crankshaft.

The cylinder is configured to receive intake air for combustion from an intake device comprising an intake passage 210. The intake air enters said intake passage through an inlet pipe. For example, in addition to the specified cylinder, the intake port may be in communication with other engine cylinders, or the intake port may be in communication with only the specified cylinder.

Exhaust gas resulting from the combustion of fuel in the engine enters an outlet in which an exhaust passage 212 is formed.

- 4 041377 branch pipe. For example, the exhaust port may also be configured to receive exhaust gases from other engine cylinders in addition to said cylinder.

Each engine cylinder may contain one or more intake valves and one or more exhaust valves. For example, the depicted cylinder includes at least one intake poppet valve 214 and at least one exhaust poppet valve 216 located at the top of the cylinder. In some embodiments, each engine cylinder, including said cylinder, may include at least two intake poppet valves and at least two exhaust poppet valves located on the cylinder head.

The inlet valve is configured to be controlled by the controller via actuator 218. Similarly, the exhaust valve is configured to be controlled by the controller via actuator 220. and exhaust valves. The intake and exhaust valve positions may be determined by respective valve position sensors 222 and 224, respectively, and/or cam position sensors. For example, the valve actuators may be electrically actuated, or cam actuated, or a combination of these types.

The intake and exhaust valves may be controlled jointly, or any of the following may be used: variable mode for the intake cam, variable mode for the exhaust cam, independent variable mode for both cams, or fixed mode for the cams. In other embodiments, the intake and exhaust valves may be controlled by a common valve actuator system or actuator, or a variable valve actuator or actuator. In addition, control of the intake and exhaust valves can be provided so that, by means of the controller, a controlled lift is obtained based on operating conditions.

In other embodiments, a mechanical cam protrusion may be used to open and close the intake and exhaust valves. Additionally, although a four-stroke engine is described above, some embodiments may use a two-stroke engine that does not use intake valves and has ports in the cylinder wall to allow intake air into the cylinder as the piston moves to open said ports. The same applies to exhaust, although exhaust valves may be used in some examples.

In some embodiments, each engine cylinder may include one or more fuel injectors for delivering fuel to said cylinder. As a non-limiting example, FIG. 2 shows a cylinder containing a fuel injector 226. As shown, the fuel injector is attached directly to the cylinder to inject fuel directly into said cylinder. Thus, the fuel injector provides the so-called direct injection of fuel into the combustion cylinder. Fuel may be supplied to the fuel injector from the first liquid fuel system 232, which may include a fuel tank, fuel pumps, and a fuel rail, as described above with reference to FIG. 1. In one example, the fuel is diesel fuel which is combusted in the engine by compression ignition. In other, non-limiting embodiments, the fuel may be gasoline, kerosene, biodiesel, or other petroleum distillates of about the same density that burn by compression ignition (and/or spark ignition). In one example, the controller may be configured to control the amount, duration, mode, and spray pattern of fuel supplied to the cylinder through the fuel injector. As described later, control of fuel supply to the cylinder is provided by a controller configured to actuate a fuel injector based on engine operating conditions and a stored injector table.

In addition, each engine cylinder may be configured to receive a gaseous fuel (eg, natural gas) used instead of or in addition to diesel fuel. The supply of gaseous fuel to the cylinder can be provided through the inlet pipe. As shown in FIG. 2, the inlet may receive gaseous fuel supplied from the second gaseous fuel system 234 through one or more gaseous fuel lines using pumps, pressure regulators, and other components located upstream of said cylinder. In some embodiments, the gaseous fuel system may be located at a distance from the engine, for example, on another vehicle (for example, on a refueling machine), and the supply of gaseous fuel to the engine may be provided through one or more fuel lines passing between separate vehicles. . However, in other embodiments, the gaseous fuel system may be located on the same vehicle as the engine.

Gas inlet valves, such as gas inlet valve 236, may be configured to supply gaseous fuel from the gaseous fuel system to each respective cylinder.

- 5 041377 through the respective inlet ports. For example, it is possible to control the degree and/or duration of opening of the gas inlet valve to control the amount of gaseous fuel supplied to the cylinder. In this case, each respective cylinder can be supplied with gaseous fuel from a separate gas inlet valve, whereby the amount of gaseous fuel supplied to the cylinders can be individually controlled. However, in some embodiments, a single point gassing system may be used in which gaseous fuel is mixed with intake air at one point upstream of the cylinders. In such an arrangement, substantially the same amount of gaseous fuel can be delivered to each cylinder. To control the amount of gaseous fuel provided by the single point gassing system, in some instances a gaseous fuel control valve may be located at the junction of the gaseous fuel supply line and the engine intake air supply line or intake manifold. The degree and/or duration of opening of the gaseous fuel control valve may be adjusted to control the amount of gaseous fuel supplied to the cylinders. In other examples, the single point gassing system is capable of controlling the amount of gaseous fuel entering the cylinders by another mechanism such as controlling a gaseous fuel regulator by controlling a gaseous fuel pump or the like.

As indicated above, the fuel injectors are configured to start in accordance with the output value for starting the fuel injectors, for example, in accordance with the start time of the fuel injectors (for example, the duration of opening), based on the calculated and/or measured operating conditions of the engine and stored data on starting the fuel injector. In one example, fuel injector start data may be stored in a computer-readable medium in the controller, in an injector table, or a card.

In FIG. 3 shows two examples of injection tables. The first injector table 300 contains fuel injector start data indexed in memory by a pressure value, such as fuel rail pressure (FRP). The second injector table 302 contains injector start data indexed in memory by a modified pressure value, which may be a modified injector nozzle pressure difference. As detailed below, the modified differential pressure may be a function of the square root of the difference between rail pressure and peak cylinder pressure, with peak pressure multiplied by a function of engine speed and injection mode, with the differential pressure corrected by a correction coefficient. The second injection table 302 shows an example of another injection table indexing method, which is described in detail below. The first injector table 300 provides an example of a standard way to index an injector table.

As shown in FIG. 3, the first injection table. 300 contains a set of fuel rail pressure (FRP) values along the x-axis (eg, the horizontal axis) or the first row 304 of said table. In one example, a set of fuel rail pressures may range from 600 to 2200 bar. In another example, a set of fuel rail pressures may range from 400 to 2800 bar. In addition, the injector table 300 contains a set of fuel values along the y-axis (eg, vertical axis) or the first column 306 of the table. In one example, a set of fuel values may range from 0 to 3000 mm ³ /stroke. In another example, the set of fuel values may range from 0 to a value in excess of 3000 mm ³ /stroke. The above ranges of fuel rail pressure and fuel values may vary (eg, be more or less) depending on the application of the engine and/or type of injector. The injector table 300 also contains a set of cells 308 containing data on the start of the fuel injector. In one example, the fuel injector start data may be fuel injector start times (eg, the time the injectors open or the amount of time required to start the injectors and inject fuel into the engine cylinders). In this example, each cell contains the start time of the fuel injector, which corresponds to one fuel rail pressure and one fuel value. In another example, the fuel injector start data may be another fuel injection parameter.

The first injection table. 300 may contain a first number of columns and a second number of rows, both of which are greater than 1. The first number and the second number may be the maximum number of rows and the maximum number of columns. In one example, the maximum number of rows and the maximum number of columns may be different. In another example, the maximum number of rows and the maximum number of columns may be less than 50. Thus, a given table may contain a finite number of distinct data values. For example, if the maximum number of rows is 10 and the maximum number of columns is 8, there may be 10 rows and 8 columns of fuel injector start data. In particular, in the first row 304 there may be 8 fuel rail pressures, and in the first column 306 there may be 10 fuel values. Thus, in this example, there are 80 individual fuel injector start data values or fuel injector start time values. In one example, the maximum

- 6 041377 the number of columns and rows may be selected based on the available memory or computer-readable media space in the specified controller. For example, as the number of individual data values or columns and rows increases, the amount of memory used increases. Thus, the number of distinct data values in the injection table may be limited by memory usage requirements.

The controller 106 is configured to generate an output value for starting the fuel injectors, for example, the start time of the fuel injectors, based on the fuel injector table stored in the controller memory, the determined pressure, and the fuel value. In one example, the determined pressure may be measured fuel rail pressure as measured by a CRS pressure sensor (eg, pressure sensor 130 shown in FIG. 1). In another example, the determined pressure may be a fuel rail pressure calculated from pressure sensor data and/or additional engine operating conditions. The fuel value may represent the amount of fuel injected per stroke of the fuel injector (also referred to as fuel charge). In one example, the fuel value may be a setpoint for an engine. Essentially, the fuel value can be stored in the controller. In another example, the fuel value may be selected based on engine operating conditions such as required torque. The controller is configured to inject the required amount of fuel at a given (for example, certain) pressure in the fuel rail by starting the fuel injectors for a certain period of time. Such a period of time or injector start time can be determined from data from the injector start table.

In particular, the controller is configured to find the determined or measured value of the pressure in the fuel rail and the value of the desired fuel value in the injector table. As described above, the injector start table may have a finite number of distinct data values. Since the injector table may have a maximum number of rows and columns, the exact value of the determined fuel rail pressure and the required fuel value may not be contained in the injector table. As a result, in order to determine the start time of the injector by means of the engine controller, it is possible to interpolate individual data values, close to the required values.

In another embodiment, if the determined fuel rail pressure and the desired fuel value are outside the ranges of values specified in the injector table, the controller is provided with the ability to extrapolate the data using the closest data values in the injector table. Thus, methods such as those presented below for injector map interpolation can be used to extrapolate to determine when the injector starts at desired operating modes.

The injection map interpolation may include multi-stage (eg, two-dimensional) linear interpolation. For target fuel values and fuel rail pressure values, four separate data values can be selected in the injector table. In one example, the predetermined (eg, determined) values for the fuel rail pressure and the fuel value may be 1100 bar and 75 mm ³ /stroke, respectively. According to the first injection table 300, both of these values are between the two fuel values and the two fuel rail pressure values indicated in the first injection table 300. As a result, the controller performs a multi-stage linear interpolation between the four closest data values (in cells 314, 316, 318 and 320 in this table), each of which corresponds to a fuel rail pressure value and a fuel value that is greater or less than the specified values.

In another example, a target or desired fuel value may be specified in an injector table, but a specific fuel rail pressure may not be present. In such an example, a one-way linear interpolation can be performed by the controller between the two closest data values that correspond to fuel rail pressure values that are greater than and less than the measured fuel rail pressure at a given fuel value. In particular, such interpolation may include interpolation between the value of the first fuel injection start time, which corresponds to the first fuel rail pressure value and the specified fuel value, and the second fuel injection start time value, which corresponds to the second fuel rail pressure value and the specified fuel value. The first fuel rail pressure may be greater than the determined fuel rail pressure, while the second fuel rail pressure may be less than the determined fuel rail pressure.

However, a linear interpolation between the available fuel rail pressures and the fuel values in the injector map can lead to interpolation errors. In particular, the indexing of the injector map according to the pressure in the fuel rail, as shown in the first injector table. 300 may result in a non-linear relationship between fuel injector start data. Thus, linear interpolation of non-linear data can lead to inaccuracies that increase the error in determining the start time of fuel injectors. This, in turn, leads to a decrease in fuel consumption efficiency and an increase in emissions unevenness.

Alternatively, if mass flow is expressed as the square root of the fuel rail pressure, the resulting mass flow curve becomes more linear. Thus, in a lookup table in which injector start data is indexed by the modified injector nozzle pressure difference for which the square root function is applied, fewer individual data values can be used while still achieving a similar level of accuracy. Storing fewer data values in the lookup table can reduce the amount of memory used on the computer-readable medium in the specified controller.

As the relationship between the selected variables becomes more linear, the accuracy of the linear interpolation increases. Thus, linear interpolation of mass flow versus the square root of the modified injector pressure difference helps to reduce the interpolation error compared to linear interpolation of mass flow versus fuel rail pressure. For these reasons, indexing the injector map to the square root of the modified differential pressure instead of indexing to the fuel rail pressure alone allows for increased accuracy in determining the output variable for firing the fuel injector (eg, fuel injector firing time). This, in turn, reduces the fuel injector start-up time error, thereby improving fuel efficiency and reducing emission fluctuations.

Also, as described above, indexing fuel injector start data by rail pressure only (as shown in Table 200 for fuel injectors) or by differential injector nozzle pressure only (e.g., by fuel rail pressure considering peak pressure in cylinder) can lead to errors under different operating conditions experienced by the engine during its operation. Because the pressure conditions around an injector nozzle on an engine (e.g., while the engine is running) are more dynamic and usually different from the pressure conditions around the same nozzle on the test bench that typical injector charts (e.g., map 300) are generated from, start-up time injectors determined from a normal table indexed by rail pressure only, may result in inaccurate injector start times under current engine operating conditions. As a result, engine performance may be reduced. Thus, fuel injector data may instead be indexed to a modified injector pressure differential, where the modified differential pressure is a function of the square root of the difference between rail pressure and peak in-cylinder pressure, with peak in-cylinder pressure converted to (for example, by multiplying) as a function of engine speed and injection mode, while the pressure difference is corrected using a correction factor. The modified pressure difference function under consideration makes it possible to take into account changes in the supply pressure in the fuel rail, as well as pressure in the engine cylinder, depending on the injection mode, engine speed, injection duration, the amount of combined fuel and gas in the cylinder (for example, when the engine is a dual-fuel engine, in which diesel fuel and secondary fuel such as natural gas are burned), etc.

More specifically, during engine operation, changes in various injection parameters, such as changes in injection mode, cylinder pressure, multiple injections (for example, main and subsequent injections), injection duration and / or intervals between multiple injections, in the replacement fraction (for example, in the amount of natural gas injected from the total amount of gas injected, including natural gas and diesel) and in the amount of diesel fuel lead to pressure changes upstream of the injector nozzle (for example, in one example, calculated/determined from the pressure in the injection accumulator or rail pressure) and pressure downstream of the injector nozzle (e.g. calculated/determined from in-cylinder pressure). Thus, the pressure difference at the injector nozzle opening (eg, the difference between upstream and downstream pressure in the injector nozzle), which results in fuel flow through the nozzle, is replaced by said variable injection parameters.

In FIG. 4-9 illustrate changes in pressure upstream of the injector nozzle (in one example, the pressure in the injector reservoir, which can be calculated from the rail pressure and/or is the rail pressure) and in pressure downstream of the injector nozzle ( in-cylinder pressure) compared to test-bed injector data (as used in conventional injector cards such as the 300 card) and for different injection parameters. In particular, in each of Figs. 4-9 there is a first graph showing the pressure in the injection accumulator (for example, rail pressure) on the y-axis, and the angle of rotation of the crankshaft in degrees (CAD) on the x-axis, and a second graph showing the pressure on the y-axis in the cylinder (which is the outlet pressure of the injector nozzle) and on the x-axis is the angle CAD. Each of the x-axes shows the mode of passage of the top dead center (TDC) in the cycle of the cylinder and additional modes that may represent

- 8 041377 is the time when fuel injection through the injector starts, stops, etc. Referring first to FIG. 4, which shows a graphical display 400 with a first injector pressure plot 402 during injector injection on a test rig (e.g., during pre-installation testing for engine use), a second injector accumulator pressure plot 404 during injection under the condition setting in the engine (e.g., during engine operation in the field), a third graph 406 of the nozzle outlet pressure during injection in the injector on the test bench, and a fourth graph 408 of the nozzle outlet pressure (represented as engine cylinder pressure) during injection into the in case of installation in the engine. The fourth graph 408 shows the total cylinder pressure throughout the entire combustion cycle, and the fifth graph 410 shows the pressure in the cylinder during compression only during injection throughout the combustion cycle. In the fifth plot 410, cylinder pressure with compression alone is shown without taking into account the effect of combustion on cylinder pressure, since combustion may occur some time after fuel injection. As shown in graphs 402 and 404, the actual pressure in the injection accumulator during injection in the injector installed in the engine is reduced by a greater amount than the pressure in the injection accumulator during injection in the injector installed on the test stand. In addition, as shown in graphs 406, 408 and 410, the pressure at the outlet of the nozzle (for example, cylinder pressure) remains relatively constant on the test bench (see graph 406), but in the case of installation in an engine (see graphs 408 and 410 ) increases by a large amount, reaching a peak value (peak cylinder pressure), and then decreases again during injection in the injector. The Peak Cylinder Pressure (PCP) in graph 408 is shown as 412, and the PCP pressure in graph 410 is shown as 414. The PCP pressures 412 and 414 shown are significantly higher than the steady state nozzle outlet pressure observed on the test stand. The injection duration (eg, the amount of time that the injector nozzle is open to inject fuel) for injection is shown between time t1 and time t2 and is denoted as injection duration 416 . Thus, FIG. 4 illustrates the difference between the pressure in the injection accumulator and the pressure at the outlet of the nozzle in the case of installation in the engine and on the test stand. As described in this document, injector start data stored in an injector table compiled from test bench data may not accurately represent the operating conditions observed when an injector is installed in an engine. Thus, using test bench firing data to command the firing modes of fuel injectors installed in the engine during engine operation may result in injection of an amount of fuel that differs from the amount required for current engine operating conditions. thereby reducing engine efficiency and emissions control.

In FIG. 5, a graphical display 500 is shown including a first injector pressure graph 502 during the first injection during engine operation when the injection time is earlier, a second injector pressure graph 504 during the second injection during engine operation when the injection mode is later (for example, later than the first injection mode and/or compared to the standard injection mode), the third cylinder pressure schedule 506 during the first injection in the earlier mode, the fourth second injection schedule 508 in the later mode, and the fifth graph 510 of cylinder pressure only considering compression during the first injection.

The injection duration during the first injection in the earlier mode is indicated as 512 (between the time t1 and the time t3), and the injection duration during the second injection in the later mode is indicated as 514 (between the time t2 and the time t4). The shapes (e.g., amplitude) of the injector pressure plots 502 and 504 are similar, but in the first plot 502, the injector pressure begins to decrease earlier than in the second plot 504 due to the earlier first injection mode. In addition, the peak PCP pressure for in-cylinder pressure during the first injection (plot 506), which occurs just after top dead center TDC, exceeds and occurs before the peak in-cylinder pressure during the second injection (plot 508), which occurs between top dead center dead center TDC and time t3. Thus, changes in the injection mode of the injector affect the pressure upstream and downstream of the injector nozzle, thereby affecting the pressure difference at the injector nozzle opening (and hence the fuel flow through the nozzle). Thus, as described below, the modified differential pressure function used in the injection table may be based at least in part on the injection mode.

In FIG. 6 is a graphical display 600 including a first injector pressure graph 602 during injection while the engine is running, a second in-cylinder pressure graph 604 during injection for a higher cylinder pressure (e.g., higher peak cylinder pressure), a third graph 606 corresponding cylinder pressure only considering compression for higher cylinder pressure, fourth cylinder pressure during injection plot 608 for lower cylinder pressure (e.g., lower peak cylinder pressure), and five

- 9 041377 th graph 610 of the corresponding cylinder pressure only considering compression for lower cylinder pressure. The injection duration is indicated as 612, between the time tl and the time t2. In plots 604 and 608, the peak PCP pressure in both in-cylinder pressure conditions occurs just after the TDC point, but is at different magnitudes. Different cylinder pressures can affect the overall pressure difference at the injector nozzle orifice and hence the flow of fuel through the nozzle. As a result, for the same injector start time (see, for example, duration 612), different amounts of fuel may be injected into the cylinder due to different nozzle pressure differences (due to different cylinder pressures).

Fig. 7 depicts a graphical display 700 showing the difference in injector pressure and in-cylinder pressure between single injection (eg, main injection only) and multiple injections (i.e., having main injection followed by injection). In particular, the graphical display 700 includes a first plot 702 of the injector pressure during the first injection, including only a single injection, a second plot 704 of the pressure in the injector during the second injection, including two injections (main injection and post-injection), the third plot 706 cylinder pressure during the first injection with a single injection, a fourth cylinder pressure plot 708 during the second injection including two injections, and a fifth cylinder pressure plot 710 with only compression for the first injection. The single injection duration for the first injection is indicated as 712. The main injection duration (for example, the duration of the main injection) for the second injection is indicated as 714, and the post injection duration (for example, the duration of the subsequent injection) for the second injection is indicated as 716. the main injection duration 714 and the start of the post injection duration 716 is hereinafter referred to as the post delay time (or duration), which is denoted as 718. In addition, the main main injection mode occurs at time t1, and the subsequent post injection mode occurs at time t3. As shown in graphs 702 and 704, the pressure in the injector reservoir is similar for the main injections in the case of both injections; however, as shown in plot 704, the post-injection results in an additional pressure dip before reaching the centerline level (due to the post-injection). During engine operation, the in-cylinder pressure at one injection (plot 706) and at two injections (plot 708) are similar to each other (eg, have the same peak PCP pressure); however, the post-injection results in a slower reduction in cylinder pressure after peak PCP pressure and a higher overall pressure after the main injection. Thus, different pressure drops across the injector nozzle are also a consequence of the number of injections during an injection event (eg, during an in-cylinder combustion cycle). As a result, the flow of fuel through the injector nozzle may vary depending on the number of injections.

As shown in FIG. 8, the fuel flow at the nozzle and the total amount of fuel injected can also be affected by the duration of the main injection and the post-injection for the main/post-injection event. In particular, FIG. 8 depicts a graphical display 800 including a first injector pressure plot 802 and a third in-cylinder pressure plot 806 for a first injection event having a shorter main injection 812 and a longer delay time 816 (compared to the second injection event, described later). Plotting 800 also includes a second injector pressure plot 804 and a fourth in-cylinder pressure plot 808 for a second injection event with a longer main injection 818 and a shorter delay time 822. Both the post injection for the first injection event (denoted 814) and the post injection for the second injection event (denoted 820) occur between time t4 and time t5, after the end of the respective delay time. The graphical display 800 also includes a fifth compression-only pressure plot 812 for the second injection event. As shown in FIG. 8, the injector reservoir pressure remains lower and slower to build up to centerline after the main injection for the second injection event having a longer main injection 818 (plot 804) than the first injection event (plot 802). In addition, the cylinder pressure is slightly greater at the second injection event (plot 808) than at the first injection event (plot 806) after the main injection 808 for the second injection event is completed. Thus, the duration of the main injection and the subsequent injection, as well as the modes of these injections, including the delay time, affect the pressure difference in the injector nozzle. As a result, these injection parameters can also affect the flow of fuel through the nozzle during injection while the engine is running. As noted above, in some embodiments, the engine may be a dual-fuel engine configured to inject both liquid fuel (eg, diesel) and gaseous fuel (eg, natural gas) through a fuel system comprising an injector. The proportion of gaseous fuel substitution to total fuel volume (eg, the ratio of injected natural gas to total injected gas, including natural gas and diesel fuel) can be adjusted during engine operation based on engine operating conditions.

- 10 041377

However, as shown in FIG. 9, the displacement ratio can affect the flow of fuel through the injector nozzle and the total amount of fuel (eg, diesel fuel) injected into the cylinder. In particular, in FIG. 9 is a graphical display 900 including a first reservoir pressure graph 902, a second cylinder pressure graph 906, and a third compression-only cylinder pressure graph 908 for an injection event (e.g., a diesel fuel injection event) during engine operation with the first, less substitution (for example, with diesel only and/or with more diesel than gaseous fuel). The graphical display 900 also includes a fourth injector pressure graph 904, a fifth in-cylinder pressure graph 910, and a sixth compression-only cylinder pressure graph 912 for an injection event (e.g., a diesel fuel injection event) during engine operation with a second, larger share. substitution (for example, with a smaller amount of diesel fuel compared to gaseous fuel). The duration 914 of the low displacement injection event is longer than the duration 916 of the high displacement injection event because the amount of diesel fuel is larger for the low displacement injection event (and therefore more fuel will require a longer injection start time to inject more fuel). ). Due to the longer injection duration 914 and the greater amount of diesel fuel injected in the injection event with the first, lower displacement fraction, the pressure in the injection accumulator is reduced by a larger amount and for a longer period (pass time t3, as shown in plot 902), and the pressure in-cylinder has a higher peak PCP pressure (plot 906) than for an injection event with a second, higher replacement rate. Thus, the displacement fraction can affect the pressure difference at the injector nozzle and hence the flow of fuel entering the engine cylinder.

The pressure difference in the nozzle hole of the injector can be modified based on the dependencies described above with reference to Figs. 4-9 to take into account injection parameters under various engine operating conditions. As a result, it is possible to reduce errors in the fuel flow model, while a more accurate injection start time used to start the fuel injectors can be determined for the current operating conditions. As a result, the required amount of fuel can be injected into the engine cylinders, and the engine efficiency can be improved.

Returning to FIG. 3, it depicts an example of a second injector table 302 that contains injector start data indexed in the controller memory by a modified injector orifice pressure difference. In one example, the modified pressure difference is a function containing the square root of the pressure difference at the injector nozzle orifice, wherein the orifice outlet pressure is converted by a factor containing a function of engine speed and injection mode, and a correction factor is subtracted from said pressure difference (e.g., correction). As described below, the orifice pressure difference may be calculated based on the difference between the rail pressure (eg, orifice inlet pressure) and peak cylinder pressure (PCP) (eg, orifice outlet pressure). In one example, the PCP pressure may be the pressure during fuel injection. In some examples, fuel injection occurs within 20° of top dead center in the engine cycle. As such, the in-cylinder ignition pressure when fuel is injected into an engine cylinder may represent the peak in-cylinder ignition pressure. In another example, the peak in-cylinder pressure may be the peak pressure only experienced during compression. The modified differential pressure may be a specific value that is continuously updated based on engine operating conditions. For example, a modified differential pressure may be determined based on current measured or calculated engine operating parameters, as detailed below.

The second injection tab. 302 may be generated and/or stored in the memory of the controller by converting the first injector table 300 as a function of the modified differential pressure. In one example, the modified pressure difference function comprises a square root approximation of the rail pressure difference and peak cylinder pressure, a function of engine speed and injection mode, and a correction factor. In particular, in one example, the modified pressure difference function can be determined by the following formula:

MP = JRP - PCP * fl(eng speed, injtiming) - f2(x) (Equation 1) where RP is the fuel rail pressure measured and/or calculated from the output of a pressure sensor located in the fuel rail of the fuel system ( for example, the sensor 130 shown in Fig. 1). As described above, said pressure RP may be the same or similar to the pressure in the injector reservoir shown in FIG. 4-9. RP is the inlet pressure of the fuel injector nozzle, with any additional pressure drops between the nozzle orifice and the injector delivery means (eg, in the fuel rail) taken into account in the values in the injector table. The second term of equation 1, which contains the coefficient or f1,

- 11 041377 is converted by Peak Cylinder Pressure (PCP), which can be modeled in one example by assuming that fuel is typically injected at about the same time (for example, at a similar crank angle) that PCP pressure is observed on the engine (as shown in Fig. 49). The PCP pressure may be modeled based on additional engine operating parameters, including one or more of the following: intake manifold pressure, engine speed, inlet oxygen ratio, main injection mode, intake manifold temperature, cylinder gas mass fraction (for a dual-fuel engine ) and/or fuel rail pressure. In one example, PCP pressure may be modeled based on measured intake manifold pressure, engine speed, inlet oxygen ratio, main injection mode, and fuel rail pressure. In a second example related to a multi-fuel engine, PCP pressure can be modeled based on intake manifold pressure, engine speed, intake manifold temperature, cylinder gas mass fraction (mg/stroke), main injection mode, and fuel rail pressure. The PCP pressure may be the outlet pressure of the injector nozzle. The PCP in Equation 1 is further corrected by a factor f1 that depends on engine speed and diesel injection mode, since these engine operating parameters can be further refined when fuel injection is observed on the cylinder pressure curve (based on crank angle). The f1 term is for adjusting the pressure downstream of the nozzle. The f2 term may be a constant value or a function of one or more other parameters (as detailed below) and is intended to correct for cylinder pressure differences (to correct for pressure downstream of a specified port) and the actual ramp accumulator difference on the rig (e.g. , test data) compared to the engine setting (to correct the pressure upstream of the specified port).

In one embodiment, the engine is configured to operate with at least one main injection per cylinder cycle (eg, per in-cylinder combustion cycle). The engine is also configured to operate while providing multiple injections in the same cylinder, such as a main injection and a post-injection (as shown in the examples in FIGS. 7 and 8). In this embodiment, the modified pressure equation according to equation 1 can be converted into equation 2 (for the main injection) and equation 3 (for the subsequent injection and any additional injections performed after the first, main injection):

MP _main = ^- speed, main timing) - f2Q (Equation 2),

MP _post = J{RP + MD * Cl + PD * 672} - PCP * fl(eng speed, pos timing) - f2Q (Equation 3).

In Equation 2 for liquid (e.g. diesel) fuel main injection, the PCP pressure is the PCP pressure for a complete cylinder cycle (not just during compression), with the multiplier in the second term (PCP term) being a function of (f1) of engine speed and command-set mode of the main injection of diesel fuel. The commanded mode of the main diesel fuel injection may be the time or angle of rotation of the crankshaft in the cylinder cycle corresponding to the beginning of the main injection of diesel fuel (for example, the angle of rotation of the crankshaft before top dead center, at which the injector is started to open it and inject diesel fuel into cylinder). In one embodiment, the multiplier f1 (engine speed, main mode) may be determined based on a lookup table stored in the memory of the engine controller. For example, the lookup table may contain the value of the current engine speed and the main injection mode for diesel fuel injection as input and the factor f1 as output. The correction value f2 is a constant value that can be used to correct for cylinder pressure drops and the actual pressure difference in the rail accumulator on the bench compared to the engine installation. Thus, the correction value f2 can be predetermined and stored in the controller's memory.

In Equation 3 relating to post-injection of liquid (eg, diesel) fuel, the multiplier in the second term is a function of f1 of engine speed and the commanded start of diesel post-injection mode. The commanded start of the diesel post-injection mode may be the time or crank angle in the cylinder cycle that corresponds to the start of the specified post-injection (for example, the crank angle before top dead center at which the injector is started to open and inject diesel fuel into the cylinder for subsequent injection). In one embodiment, the multiplier f1 (engine speed, subsequent mode) may be determined from a lookup table stored in the memory of the engine controller. For example, the lookup table might contain the current engine speed and post-injection mode for diesel injection.

- 12 041377 fuel as input and multiplier fl as output. The correction value f2 may be the same as the correction value in Equation 2 as described above. In addition, in Equation 3, the modified post-injection differential pressure converts the actual rail pressure RP to account for the observed decrease in fuel rail pressure (e.g., delivery pressure) based on how long the last main injection lasts (referred to herein as pressure drop). ), and how long the command was given to start the post-injection after the main injection (referred to in this document as pressure build-up or post-injection delay time). Thus, the first term calculates what the actual rail pressure is at the beginning of the next injection, since the initial conditions for subsequent injections depend on how much fuel was consumed by the accumulator during the previous main injection. Thus, in equation 3, in the first term of this equation, the main injection duration, denoted as MD, is added to the rail pressure RP, which is multiplied by the first constant C1, and the delay time before the subsequent injection is added (for example, the time between the end of the main injection duration and the start of after injection) multiplied by the second constant C2. The first constant C1 is to calculate how much the intake pressure has dropped during the main injection, and the second constant C2 is to calculate how much the intake pressure has recovered during the delay between the main and subsequent injections.

If the engine performs more than two injections in one cylinder cycle, equation 3 can be used for all subsequent injections, considering the post-mode time for the current post-injection.

In another embodiment, the engine may be a multi-fuel engine configured to burn at least two fuels, including liquid fuels (eg, diesel fuel) and gaseous fuels (eg, natural gas). Diesel fuel may be injected through an injector using the equations and injection maps described herein, and gaseous fuel may be injected through another injector or gas inlet valve. As described above, during engine operation, the replacement ratio (SR) of gaseous fuel to the total amount of fuel (liquid + gaseous fuel) can be adjusted based on engine operating conditions. In some embodiments, the maximum possible amount of gaseous fuel can be used while still providing efficient operation of the engine. Under other engine operating conditions, only diesel fuel can be injected (no gaseous fuel). In this embodiment of a multi-fuel (e.g., dual-fuel) engine, the modified pressure equation based on Equation 1 can be converted to Equation 4 (for the main injection, which may be liquid-fuel-only injection in a cylinder cycle):

MP _mainiDF = y/RP- PCP _co * flieng speed, diesel timing) - f2(CGQ, CDQ) (equation

4).

In the equation above, PCPco is the addition of the above simulated PCP pressure in compression only. In one embodiment, the PCP model may include a compression-only term in addition to a summing term for the case where combustion results in an increase in PCP pressure greater than the compression-only term (e.g., the pressure in a compression-only cylinder can be modeled separately based on the additional combustion pressure in the cylinder). Thus, the PCPco pressure can be obtained from the term considering only the compression of the simulated PCP pressure. As described above with reference to Equation 2, the PCP term is corrected by a function f1 of the engine speed and the (primary) diesel injection mode. As explained above, the term f1 can be determined from a lookup table stored in the controller memory using the engine speed and the diesel injection command mode (eg, crankshaft angle in degrees before the TDC point) as input. The correction value f2 is not a constant value in Equation 4 and is a function of the fuel gas command amount, CGQ, (eg, in mg/stroke) and the diesel fuel command amount, CDQ, (eg, in mm ³ /stroke). In one embodiment, during engine operation, the correction term f2 can be found by the controller in a lookup table stored in the controller's memory using the CGQ and CDQ values as input. The f2 term is intended to correct for the difference in values upstream and downstream of the nozzle port for the stand and for the engine mounting option. Upstream, the effect is that a high replacement rate leads to a reduction in the amount of diesel fuel and, as a result, to smaller pressure drops caused by the accumulator, compared to data for injectors on the test bench. The downstream effect is that different proportions of gas replacement (for example, with a combination of different amounts of gas and/or diesel fuel) affect the combustion parameters and the rate of heat removal at a certain crankshaft angle. For example, the pressure parameters in the cylinder during dual-fuel combustion may differ from the pressure parameters in

- 13 041377 cylinder when burning only diesel fuel. Thus, the pressure downstream of the orifice must be compensated appropriately, as shown in Equation 4. In some embodiments, the f2 term in Equations 2 and 3 may not be a constant value, but a function of the amount of diesel fuel.

Returning to FIG. 3, on it the pressure values in the fuel rail, indicated in the first line 304 of the first injector table. 300 may be entered into a modified differential pressure function (eg, one of Equations 1-4 above) to determine a set of modified differential pressure values. These values, which may represent the output values of one of the equations 1-4, are indicated in the first line 310 of the second injector table. 302. As such, the first line 310 contains a set of modified differential pressure values corresponding to a set of fuel rail pressure values. In the first line 310, F denotes the remaining terms of the modified differential pressure equation (eg, in addition to the pressure RP). As described above, in one example, the fuel rail pressure range may vary from 600 to 2200 bar. The second injection table 302 indicates the same injector start data at the same fuel values as the first injection table 300. For example, the first column 312 of the second injection table 312 indicates the same set of fuel values as described above. However, in the second injector table 302, the injector start data is indexed by the modified differential pressure and not just by the fuel rail pressure.

As explained above, adjusting the data in the table for fuel injectors by the terms of the modified differential pressure function(s) described herein allows the difference between predetermined injector start data and actual engine operating conditions to be corrected. For example, an injector table (such as the first injector table 300) may be generated during bench testing using a test bench instead of an actual engine that uses an injector table. As such, the test bench may not have the same pressure drop across the fuel injector nozzle as a running engine. In addition, the test stand may not have the same back pressure or cylinder pressure (eg, peak cylinder pressure) as a running engine. Thus, the terms of the modified differential pressure equation (described above with reference to Equations 1-4) can compensate for any pressure-related deviations in values for the running engine and for the equipment used to create the injection table. This adjustment based on engine operation allows the same injection map to be used for many different engines. In addition, the correction factor can be changed based on the current operating conditions of the engine, thereby improving the accuracy of the injection table in a given engine as the engine system variables change.

Due to the transformation in the injector table by indexing with the square root function, the fuel injector start data stored in the second injector table. 302 are more linear than the fuel injector start data stored in the first injector table 300. Thus, the linear interpolation of the data in the second injector table. 302 may result in less error in the resulting fuel injector start output (eg, fuel injector start time). Since the accuracy of the linear interpolation can be improved by indexing the fuel injector start data with a modified differential pressure, fewer data values can be obtained with the same degree of accuracy. As such, the size of the injector table stored in the controller's memory can be reduced, thereby reducing the amount of memory used.

When indexing an injector table by a modified differential pressure, the input data for the injector table must also be converted using a modified differential pressure function. Thus, in Equations 1-4 above, the RP pressure may be the specific fuel rail pressure. In one example, the determined fuel rail pressure may be measured by a pressure sensor, such as pressure sensor 130 shown in FIG. 1, which is installed upstream of the fuel injectors. Essentially, the modified differential pressure is determined by entering into the modified pressure function a certain fuel rail pressure value and additionally required engine operating parameters. The determined modified pressure and additional engine operating parameters (e.g., engine speed, injection mode, etc.) can then be used as input to the indexed injector table to interpolate from the nearest indexed fuel injector start data to determine the output value to start. fuel injector, such as the start time of the fuel injector.

As described above, the fuel injector start output may be used to control fuel injection in a propulsion system. Thus, the technical result of the indexing and interpolation method described above (and detailed below with reference to Fig. 5) is to increase the accuracy of fuel injector control. In particular, by indexing the injector start table with a modified differential pressure

- 14 041377 by means of the controller, it is possible to determine a more accurate fuel injection start time for a certain pressure in the fuel rail and the required fuel value. As such, the injection mode can be adjusted based on a certain start time of the fuel injectors to deliver the desired amount of fuel. Delivering the exact amount of fuel can improve the fuel efficiency of the engine while reducing engine emission fluctuations. In addition, for multi-fuel engines, by using the modified differential pressure equation (Equation 4) to control the injectors, it is possible to use large proportions of natural gas substitution while maintaining efficient and reliable engine operation. Thus, the approach described above and in more detail below can reduce design time and increase cost savings.

In some embodiments, computer-readable medium 138 has a memory with one or more sets of instructions and/or data stored therein, and when accessed and executed by an electronic device (eg, processing unit 136), the electronic device performs various actions. In particular, the computer-readable storage medium may include fuel injector start data indexed in the memory with an input parameter, instructions for determining a modified differential pressure value based on a determined pressure, current engine operating conditions, a modified differential pressure function, and instructions for generating an output value for firing the fuel injectors by interpolating the indexed fuel injector firing data using the modified differential pressure value as an input. In one example, the determined pressure is a measured fuel rail pressure that is measured upstream of the fuel injector, where the modified difference function includes a square root approximation.

In one embodiment, fuel injector start data may be stored in an injector table, the injector table having a first number of columns and a second number of rows, said first and second numbers being greater than one. The first row of the second number of rows contains a set of modified differential pressure values, which corresponds to a set of fuel rail pressure values, and the first column of the first number of columns contains a set of fuel values, which includes a set of values of the amount of fuel injected by one fuel injector. In addition, each cell in the injector table contains a fuel injector start time value corresponding to one of the modified pressure values in the corresponding set and one of the fuel values in the corresponding set.

Modified differential pressure values may be determined based on one or more equations or one or more tables stored in the controller's memory. For example, modified differential pressure values may be calculated by the controller according to a stored modified differential pressure function (eg, one of Equations 1-4) and measured and/or calculated engine operating conditions. In another example, modified differential pressure values may be retrieved from the controller's memory using one or more stored lookup tables that contain operating parameters used as input to the modified differential pressure equation.

With the modified pressure function, it is possible to convert the fuel injector start data stored in the injector table to make the data in the cells of said injector table more linear. The computer-readable medium also contains instructions for performing a multi-stage linear interpolation of the indexed fuel injector start data contained in the injector table to determine the fuel injector start time at a certain pressure difference and fuel value. Further, the computer-readable storage medium includes instructions for outputting the determined fuel injector start time and adjusting fuel injection based on the determined fuel injector start time. In one example, fuel injection control includes control of the injector opening time.

In addition, the system shown in Fig. 1 comprises a fuel rail system comprising a common fuel rail, fuel injectors configured to inject fuel from a common fuel rail into engine cylinders, an injector table stored in computer memory, and a controller configured to control fuel injection into the cylinders based on time. starting the fuel injectors, which is determined by indexing the injector data stored in the injector table using a modified differential pressure function that contains the square root of the rail pressure, taking into account the peak pressure in the cylinders, multiplied by a function of engine speed and injection mode, and taking into account a correction term that corrects the pressure difference between the injector data on the engine and on the bench, both upstream and downstream of the injector nozzle, and also by interpolating indexed injector data based on a certain pressure in the fuels ramp, the amount of fuel injected per stroke of the fuel injector, and additional

- 15 041377 engine operating conditions. In one example, a determined fuel rail pressure is measured based on one or more pressure signals sent to the controller by at least one pressure sensor located upstream of the common fuel rail.

In another embodiment of the present invention, the system of FIG. 1 contains a fuel rail system containing a common fuel rail, fuel injectors configured to inject fuel from a common fuel rail into the engine cylinders, a computer-readable storage medium with memory, and an injector table is stored in the memory containing data about injectors indexed using a modified differential pressures, and a controller configured to control the fuel injectors based on the start time of the fuel injectors, wherein the controller is configured to determine the start time of the fuel injectors by interpolating indexed injector data based on the determined fuel rail pressure and the amount of fuel injected per stroke. fuel injector. The modified pressure function includes the square root of the pressure in the fuel rail, taking into account the peak pressure in the cylinders, and an additional correction term containing a constant value or a function of the amount of liquid and gaseous fuel injected into the engine. In addition, the determined fuel rail pressure may be measured based on one or more pressure signals sent to the controller by at least one pressure sensor located upstream of the common fuel rail.

In one embodiment, the line of engines may contain different engines and/or engines of different types. All engines in a given line may contain the same fuel injectors. In addition, in each engine, the same fuel injector start data may be stored in a table for fuel injectors in the memory of the computer-readable medium. In fact, each of these engines can use a common table for fuel injectors. However, the engines in said line may have different peak cylinder pressures, different injection patterns, and/or gaseous fuel displacement fractions. As described above, the data stored in the common table for fuel injectors can be indexed using a modified differential pressure function, which contains the square root of the rail pressure, taking into account the peak pressure in the cylinder, converted using a function of engine speed and injection mode, and also taking into account the correction factor for the pressure upstream and downstream of the injector nozzle. The peak cylinder pressure for each engine may be separately stored in the memory of the respective engine and/or determined based on a peak cylinder pressure model specific to the particular engine. In essence, after indexing the data in the general table for fuel injectors by the engine controller, it is possible to enter the stored or simulated value of peak cylinder pressure, as well as additional engine operating conditions, into the modified pressure function for subsequent indexing of the stored fuel injector start data. Thus, the same fuel injector start table can be stored in a plurality of engines and/or engines of different types and can be used to determine the start time of the fuel injectors with improved accuracy. In some embodiments, the modified differential pressure functions may be used in different functions while still using the same fuel injector trigger table. For example, the modified differential pressure equation of Equation 4 above may be used in a multi-fuel engine, and the modified differential pressure equations of Equations 2 and 3 may be used in an engine that runs on liquid fuel only and provides multiple injections per cylinder cycle.

In one example, said engine line may comprise a first engine and a second engine, both engines containing the same fuel injectors. The first engine may include a first injection table stored in a first computer memory and the second engine may include a second fuel injector table stored in a second computer memory, the first and second injection tables being the same. In addition, the first engine may have a first peak in-cylinder pressure, and the second engine may have a second peak in-cylinder pressure, said first pressure being different from said second pressure. The first controller in the first engine can then index the injector data stored in the first injector table with a modified differential pressure function that contains the square root of the fuel rail pressure given the first peak cylinder pressure converted by a factor , which is a function of engine speed and injection mode, and contains a correction factor. Similarly, the second controller in the second engine is configured to index the injector data stored in the second injector table with the same modified differential pressure function, but with the second peak cylinder pressure converted by a multiplier that is a function of speed. engine and injection mode, as well as taking into account the correction factor.

Next, consider Fig. 10, which shows an embodiment of a method 1000 for determining

- 16 041377 an output value for starting the fuel injectors, for example, the start time of the fuel injectors, and adjusting fuel injection into the engine based on the determined output value for starting the fuel injectors. In one example, method 1000 is performed using controller 106 shown in FIG. 1, according to the instructions stored in the controller's memory. In particular, the controller 106 is configured to repeatedly execute the method 1000 during engine operation to determine when to start the injectors.

Method 1000 begins at 1002 including calculating and/or measuring engine operating parameters. Engine operating parameters may include engine speed and load, fuel rail system pressure, engine cylinder pressure, required torque, boost pressure, injection mode for injector(s), gaseous fuel replacement to total fuel quantity, commanded liquid fuel, a commanded amount of gaseous fuel, or the like. In particular, the calculation and/or measurement of engine operating parameters at 1002 may include determining the pressure in the fuel rail. As described above, in one example, fuel rail pressure may be determined based on the output of a pressure sensor (e.g., pressure sensor 130 in FIG. 1) installed in the fuel rail system upstream of the fuel injector and/or common rail. Calculating and/or measuring engine performance at 1002 may include determining a commanded injection mode, engine speed, and a commanded amount of diesel and/or gaseous fuel. For example, the method at 1002 may include determining engine operating conditions (eg, parameters) using a modified differential pressure function according to one or more of Equations 1-4 above.

At 1004, the method includes obtaining a fuel value. In one example, the fuel value for all engine operating points may be stored in a controller memory. In another example, the fuel value may be calculated based on engine operating conditions, such as required torque. At 1006, the method includes determining a desired modified differential pressure function for indexing fuel injector firing data. In one example, the desired modified differential pressure function may be predetermined and stored in the controller based on engine type (e.g., multi-fuel or single-fuel type) and/or based on the presence or absence of multiple injections (e.g., main and post injections) during one cycle. cylinder. For example, one or more of Equations 1-4 above may be stored in the memory of the controller, which is configured to select the desired equation or combination of equations to use as a function of the modified differential pressure based on engine type and/or injection types or fuels. used in the engine.

The method then proceeds to step 1008 where the determined fuel rail pressure and additional engine operating conditions are substituted into a selected (or predetermined) modified pressure difference function to determine a modified pressure difference value. In particular, at step 1008, the controller provides input to the modified differential pressure function of a certain pressure in the fuel rail and additional engine operating conditions (for example, engine speed, injection mode, time between several injections and / or a commanded amount of liquid and / or gaseous fuel). In one example, the modified differential pressure function is one or more of the functions represented as Equations 1-4. As explained above, the modified pressure difference function may be a square root approximation. In alternative examples, the modified pressure function may be another function close to the specified function using the square root. For example, as a function of the modified differential pressure, the fuel rail pressure minus the PCP pressure and the f2 term can be raised to the power of 0.45 rather than 0.5.

After the modified differential pressure value is determined by the controller in step 1008, the method proceeds to step 1010 where the fuel injector start data is indexed as a function of the modified differential pressure function. As described above, fuel injector start data may be stored in an injector table, such as injector table 300 shown in FIG. 3. The injector table may also be stored on a computer-readable storage medium for long-term data storage. As such, when determining fuel injection command values, the data in the stored injector table can be actively indexed using the modified differential pressure function while the engine is running. In one example, the modified differential pressure function for indexing fuel injector start data is the same as the modified differential pressure function used in step 1006 to determine the modified differential pressure. Thus, the final output value obtained by indexing the stored fuel injector start data during engine operation may be a modified injector table, the values in which are indexed by a modified pressure difference (and not just by fuel rail pressure or based on pressure difference in the nozzle hole of the injector). An example of a modified injection table is the second injection table 302 shown in FIG. 3. In one example, a modified injector table may be stored in memory. This method then continues to step 1012 where the fuel value (obtained in step 1004) and the modified differential pressure are found in the modified injector table.

In step 1014, the controller interpolates the indexed injector start data from the modified injector table to determine the injector start time according to the determined modified differential pressure and fuel value. The method at 1014 may include determining, from the injector table, individual injector start values that are near a modified differential pressure and fuel value setpoint. For example, the controller can find a first modified pressure difference value that is greater than the determined modified pressure difference value and a second modified pressure difference value that is less than the determined modified pressure difference value. The first and second values of the modified pressure difference are two values of the modified pressure difference from the group of corresponding values indicated in the first row of the injector table (for example, in the first row 310 of the second table 302). The controller can then find a first fuel value that is greater than the selected fuel value and a second fuel value that is less than the selected fuel value. The first and second fuel values are two fuel values from the group of fuel values specified in the first column of the injector table (eg, in the first column 312 of the second table 302). Then, in the injector table (containing data on the start of the injectors or the time of their start), cells are selected whose values correspond to the first and second values of the modified pressure difference and the first and second fuel values. The controller then interpolates the selected individual data values to determine the start time of the fuel injectors according to the determined modified differential pressure and fuel value.

In step 1016, a specific start time for the injectors is obtained from the output controller. Then, at 1018, the controller controls the fuel injection based on the determined start time of the injectors. As described above, fuel injection control may include adjusting the fuel injection mode of one or more fuel injectors. In particular, in one example, the controller adjusts the pulse width modulation signal to command the fuel injectors to inject fuel with a certain duration. This duration may be selected based on the start time of the fuel injectors. As such, the start time of the fuel injectors may be the time during which the fuel injectors are open and inject fuel into the engine cylinders.

Thus, with the controller in the engine, the fuel injector firing data in the computer memory is indexed as a function by the modified differential pressure function, the indexed injector firing data is linearly interpolated to determine the firing time of the injectors at a certain fuel rail pressure based on functions of the modified pressure difference and regulate the fuel injection in the engine based on the start time of the injectors. In one example, fuel injection control includes adjusting the pulse width of one or more fuel injectors, with the pulse duration increasing as the injector firing time increases. In addition, the controller is configured to inject fuel within a range of 20° from top dead center at in-cylinder pressure. In one example, indexing fuel injector firing data includes indexing stored fuel injector firing data by calculating the square root of a modified fuel injector nozzle pressure difference, wherein the stored fuel injector firing data is stored in the computer memory of said multiple engines using the same fuel injectors. The Modified Differential Pressure function allows the output pressure at the nozzle outlet to be converted as a function of engine speed and injection mode, while the pressure difference is corrected with an additional correction factor that corrects the difference between the actual pressure values when installed on the engine and the pressure values observed during testing the injector on the stand (outside the engine). In alternative embodiments, the additional correction factor may be a function of the amount of liquid fuel (eg, diesel fuel) and the amount of gaseous fuel injected into a multi-fuel engine. In addition, the controller is configured to linearly interpolate the first indexed fuel injector start time and the second indexed injector start time based on the fuel value and the modified pressure difference, the modified pressure difference being the square root of the pressure difference at the injector nozzle hole minus an additional correction factor and outlet pressure multiplied by a function of engine speed and injection mode. As explained above, indexing the injector table with a modified differential pressure (e.g., based on a modified differential pressure function) allows the fuel injector start data stored in the injector table to be converted to make the data in the cells of the injector table more linear and take into account the pressure difference in when mounted on the engine under different engine operating conditions. As a result, the interpolation error can be reduced, thereby improving the accuracy of the start time value of the fuel injectors at the output of the controller. In addition, for the current operating conditions of the engine, more accurate values for the start time of the injectors can be determined. Thus, the control accuracy of the fuel injectors can be improved, thereby improving the fuel consumption efficiency of the engine while reducing engine emission fluctuations.

In one embodiment, a system is provided comprising an engine, a fuel injector, and a controller comprising one or more processors. The controller is configured to determine the value of the modified pressure difference in the fuel injector nozzle opening based on the determined pressure values upstream and downstream of the nozzle opening, engine speed, injection mode, and the modified pressure difference function. The controller is also configured to generate an output value for starting the fuel injectors by interpolating the indexed fuel injector start data using the modified pressure difference value as the first input parameter, wherein the fuel injector start data is indexed in accordance with the first and second input parameters. For example, in accordance with one aspect, the second input parameter may be a fuel value, where the fuel value is the amount of fuel injected per stroke of the fuel injector.

In one embodiment, a system is provided comprising an engine, a fuel injector, and a controller comprising one or more processors. The controller is configured to control fuel injection by starting the injector at a certain time. The controller is configured to determine the start time based on the commanded fuel value and the function of the modified pressure difference in the injector nozzle hole. The modified pressure difference is derived from the difference between rail pressure and peak cylinder pressure, which is converted as a function of engine speed and injection mode, with the pressure difference corrected using a correction factor.

It should be understood that in this document, the designation of an element or step in the singular should be construed without excluding the possibility of using several such elements or steps, unless expressly stated otherwise. In addition, references to one embodiment of the present invention do not exclude the existence of additional embodiments that also contain these features. Moreover, unless expressly stated otherwise, embodiments containing, including, or having an element or elements having a certain feature, may contain such additional elements that do not have the specified feature. The words including and in which are used as simplified equivalents of the corresponding words containing and in which. In addition, the words first, second, third, etc. are used solely as a guide and do not imply numerical requirements or a specific order of the location of such objects.

The control methods and algorithms disclosed herein may be stored as executable instructions in long-term memory and may be implemented by a control system comprising a controller in combination with various sensors, actuators, and other engine hardware. The particular algorithms described herein may represent at least one of any number of processing strategies, such as event driven, interrupt, multitasking, multithreading strategies, and the like. As such, the various acts, operations, and/or functions described herein may be performed in sequence, in parallel, or, in some cases, may be omitted. Likewise, the processing order indicated is not necessarily intended to provide the features and benefits of the exemplary embodiments described herein, as such order is provided to facilitate illustration and description of the invention. One (a) or more of the described actions, operations and/or functions can be performed repeatedly depending on the use of a particular strategy. In addition, the described actions, operations and/or functions can be graphically expressed in the form of a code embedded in the long-term memory of a computer-readable medium used in the engine management system, and the described actions are performed by executing instructions in a system containing various technical engine components in combination with electronic controller.

In this description, examples are used to disclose the present invention, including the preferred embodiment, as well as to enable a person skilled in the relevant field of technology to practice this invention, including its manufacture and use of any devices or systems, as well as to carry out any methods included in this invention. The patentable scope of this invention is defined by the claims and may contain other examples that can be carried out by experts in this field of technology. Other examples cited include

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Claims (5)

within the scope of the claims if they contain structural elements that correspond to the elements in the claims according to its literal interpretation, or if such examples contain equivalent structural elements with minor differences from the elements in the claims according to its literal interpretation. CLAIM 1. A computer-readable storage medium containing: fuel injector start-up data ordered in computer-readable storage medium space according to two input parameters, instructions for determining the value of the converted fuel injector nozzle pressure difference based on the obtained pressure values upstream and downstream of the specified nozzle hole, engine speed, mode injection and a converted pressure difference function, and instructions for generating an output value for firing the fuel injector by interpolating the ordered fuel injector firing data using said converted pressure difference value as the first of said two inputs. 2. The carrier of claim 1, wherein said determined pressures upstream and downstream of said nozzle include a measured fuel rail pressure measured upstream of said fuel injector and a simulated in-cylinder peak pressure, wherein said measured the fuel rail pressure is preferably the rail pressure for liquid fuel injected into the engine through said fuel injector. 3. The carrier of claim 1, wherein said converted pressure difference function is the square root approximation of the difference between the upstream pressure and the downstream pressure of said nozzle port, corrected by a correction factor, wherein the pressure downstream of said nozzle port orifice is converted as a function of engine speed and injection mode, whereby the square root approximation linearizes fuel injector start data stored in a single injector map recorded on a computer-readable medium. 4. An engine operation method, wherein the engine controller determines an engine fuel injector start time using data and instructions stored in the computer-readable storage medium space of claim 1, said start time being determined based on a commanded fuel value and a function of the converted pressure difference in the injector nozzle opening, wherein said converted difference is obtained based on the difference between rail pressure and peak cylinder pressure, wherein peak pressure is converted using a function of engine speed and injection mode, wherein said pressure difference is corrected using a correction factor, and performing fuel injection by firing the fuel injector at the determined start time. 5. The fuel rail system, containing a common fuel rail, fuel injectors configured to inject liquid fuel from a common fuel rail into the engine cylinders, a computer-readable storage medium according to claim 1, in the space of which one injector table is stored, which contains data about the injectors, ordered by a converted pressure difference function that provides a more linear relationship between the injector data in said single injection table, where the converted pressure difference function is a function of the nozzle pressure difference for each of said fuel injectors, engine speed, and mode injection, and a controller configured to control said fuel injectors based on the start time of the fuel injectors, wherein said controller is configured to determine the start time of the fuel injectors by interpolating ordered inject data ore from the specified one injector table based on the determined pressure in the fuel rail and the amount of fuel injected per stroke of the fuel injector. -