Fuel supply system and method for controlling a fuel pump of a fuel supply system of an internal combustion engine

Abstract

The subject matter described herein relates to a method, a controller and a computer program product for controlling a fuel pump of an internal combustion engine fuel supply system, and an internal combustion engine fuel supply system. The problem to be solved is that no efficient fuel supply system is provided that is capable of supplying various types of fuel without forming bubbles under different environmental conditions. The method comprises the steps of: measuring, by a first measuring device, a pressure of the fuel in the fuel supply system; measuring, by a second measuring device, a temperature of the fuel; measuring, by a third measuring device, a physical parameter of the fuel; determining, by a control unit, a fuel type based on the measured physical parameter of the fuel, a vapor pressure of the fuel based on the determined fuel type and the measured temperature, and a pressure amplitude of the measured pressure; calculating, by the control unit, a first target pressure value as a sum of the determined vapor pressure, the determined pressure amplitude and a predetermined pressure margin, and a pressure difference between the first target pressure value and a predetermined second target pressure value; and adjusting, by the control unit, a control value for controlling an operating point of the fuel pump based on the calculated pressure difference, if the calculated pressure difference is greater than zero.

Description

Technical Field

[0001] The subject matter described herein relates to a method, controller, and computer program product for controlling a fuel pump in an internal combustion engine fuel supply system, as well as an internal combustion engine fuel supply system. Background Technology

[0002] To mitigate global climate change, CO2 emissions from industry and transportation must be drastically reduced. While electric drive is increasingly used, vehicles will still require internal combustion engines to cover greater distances.

[0003] To achieve the required CO2 emission reductions, biofuels and so-called electric fuels for internal combustion engines play a crucial role. Biofuels (such as ethanol) have proven their importance as a gasoline alternative. Currently, the production of second-generation ethanol (e.g., which can be obtained from cellulose) is becoming increasingly important. Electric fuels are synthetic fuels produced through the reaction of hydrogen from renewable energy sources with carbon dioxide. Examples of liquid electric fuels for gasoline engines include methanol and dimethyl carbonate (DMC). These synthetic fuels are expected to be available at gas stations in their pure form and blended with conventional fuels in the future.

[0004] However, when handling different types of fuel in the fuel supply system of an internal combustion engine, the different fuel characteristics must be considered. In particular, the vapor pressure of the fuel used must be taken into account to avoid the formation of bubbles in the fuel supply system. Bubbles can obstruct fuel injection and damage fuel-carrying components. Bubbles formed in the fuel supply system (low-pressure side of a gasoline direct injection system) may be transported to the high-pressure side, where they are compressed and imploded. If these bubbles implode on the surface of the injection components, it can lead to cavitation corrosion, causing serious damage to the components.

[0005] Therefore, regardless of the type of fuel used, a fuel supply system is required to ensure that the fuel pressure in the system is always higher than the steam pressure. Reference List Patent documents

[0006] Patent Document 1: US 6,742,479 B2 Summary of the Invention Technical issues

[0007] Patent Document 1 describes a fuel supply system for a dimethyl ether (DME) engine, wherein DME is supplied from a fuel tank to a high-pressure fuel pump via a pressure feed pump, and is simultaneously boosted to saturated vapor pressure or above. The fuel supply system includes a DME detection device for detecting the state of the DME from the pressure feed pump, and an electronic control unit for driving the high-pressure fuel pump when the DME in the fuel line leading to the high-pressure fuel pump is in a liquid state.

[0008] However, the fuel supply system disclosed in Patent Document 1 is specifically designed to work with dimethyl ether, thus making it unable to handle different types of fuel.

[0009] The purpose of the subject matter described herein is to provide an efficient fuel supply system capable of supplying various types of fuel under different environmental conditions without forming bubbles. This problem is solved by the subject matter according to the independent claim. The dependent claims describe further preferred developments. Problem Solution

[0010] This document describes a method for controlling a fuel pump in a fuel supply system for an internal combustion engine. The method includes steps of measuring the pressure of fuel in the fuel supply system using a first measuring device, measuring the temperature of fuel using a second measuring device, and measuring the physical parameters of the fuel using a third measuring device.

[0011] Subsequently, the control unit determines the fuel type based on the measured physical parameters of the fuel, and determines the fuel vapor pressure based on the determined fuel type and the measured temperature. Preferably, the physical parameters of the fuel measured / detected by the third measuring device may be the dielectric constant, density, and / or kinematic viscosity of the fuel in the fuel supply system.

[0012] Table 1 below shows examples of the physical parameters of various fuels. It is evident, in particular, that the dielectric constants of the various fuels differ significantly. Therefore, fuel type can be reliably determined by measuring the dielectric constant. Table 1

[0013] To improve the accuracy of the test, other physical parameters such as the density and kinematic viscosity of the fuel in the fuel supply system can also be measured.

[0014] When a fuel type is identified, its vapor pressure is determined based on the identified fuel type and the measured temperature. Vapor pressure is defined as the pressure exerted by vapor and its condensed phase (solid or liquid) in a closed system at a given temperature when they are in thermodynamic equilibrium. In a fuel supply system, this means that if the fuel pressure is lower than the vapor pressure, bubbles will form. Vapor pressure is a function of temperature (higher temperatures result in higher vapor pressure) and varies between different fuels. In particular, methanol and ethanol, which play important roles as alternative fuels, have higher vapor pressures than gasoline. Therefore, to handle different fuels in a fuel supply system, it is necessary to determine the vapor pressure of the fuel used to avoid bubble formation. By specifically determining the vapor pressure of the fuel used at the current fuel temperature, the fuel pressure in the fuel supply system can be precisely adjusted to the current state.

[0015] Additionally, the control unit determines the pressure amplitude of the measured pressure. The average pressure in the fuel supply system is typically caused by pressure fluctuations / pulsations, such as those caused by the vibrating piston movement of a high-pressure pump. These pressure pulsations must be taken into account to ensure that the lowest pressure occurring in the fuel supply system does not fall below the vapor pressure. By determining the average pressure and the lowest measured pressure over a predetermined time interval, and then calculating the difference between the average and lowest pressures, the pressure amplitude can be determined based on the measured pressure signal. For example, the predetermined time interval can be in the range of 0.2 to 2 seconds. This process can be repeated continuously during the operation of the fuel supply system.

[0016] Furthermore, the control unit calculates the first target pressure value as the sum of a determined steam pressure, a determined pressure range, and a predetermined pressure margin. The predetermined pressure margin can be a safety margin ensuring that the first target pressure is always higher than the steam pressure. The predetermined pressure margin can vary with the fuel pump's temperature and / or operating point to ensure that the fuel pump does not exceed its optimized operating range. For example, the predetermined pressure margin can be in the range of 0.2 bar to 1 bar.

[0017] The current effective target pressure for ensuring that the fuel pressure in the fuel supply system is maintained above the steam pressure is specified by calculating the first target pressure value as the sum of a determined steam pressure, a determined pressure range, and a predetermined pressure margin.

[0018] To provide control values ​​for controlling the operating point of the fuel pump, the control unit calculates the pressure difference between a first target pressure value and a predetermined second target pressure value. When the calculated pressure difference is greater than zero, the control unit adjusts the control values ​​for controlling the fuel pump's operating point based on the calculated pressure difference. In other words, the control unit compares the determined first target pressure value with the predetermined second target pressure value and adjusts the control values ​​for controlling the fuel pump's operating point so that fuel is delivered at a higher pressure when the first target pressure value is greater than the predetermined second target pressure.

[0019] The above method prevents fuel injection failures caused by fuel vapor lock and minimizes the risk of cavitation corrosion on the high-pressure side of the high-pressure pump inlet valve and injection system. Furthermore, by measuring fuel pressure and determining the associated vapor pressure, the method avoids unnecessarily increasing the target pressure, thereby achieving efficient operation of the fuel pump.

[0020] According to one aspect, a predetermined second target pressure value is stored in the control unit as a function of fuel temperature. The predetermined second target pressure can be understood as a basic target pressure value, which is generally valid across the entire engine characteristic curve, but can be adjusted at certain engine operating points and / or under certain environmental conditions.

[0021] For example, the second target pressure value can be stored in the characteristic curve as a function of fuel temperature, thus outputting a higher target pressure at higher fuel temperatures. Alternatively, the second target pressure value can be stored in the characteristic curve as a function of fuel temperature and engine speed, so that the target pressure is increased at high engine speeds to maintain the delivery rate of the high-pressure pump. Multiple characteristic curves or characteristic graphs can also be provided in the control unit, storing second target pressure values ​​for different fuels.

[0022] This means that the vapor pressure of the fuel used has been taken into account to some extent in the second target pressure value, so that the control value of the fuel pump will only be adjusted when the first target pressure value determined from the current measurement exceeds the second target pressure value.

[0023] According to one approach, the control value used to control the operating point of the fuel pump can first be adjusted by converting the calculated pressure difference into a control value difference using a PID controller. In other words, the PID controller is used to convert the pressure difference into a value suitable for controlling the operation of the fuel pump. The PID controller can amplify the control value difference in response to a currently detected large pressure difference. The control value difference can then be added to an existing control value, preferably based on a predetermined second target pressure value. Preferably, the existing control value can be determined from the characteristic curve of the fuel pump, which can be stored in the control unit or a separate unit of the fuel pump. For example, if the fuel pump is a positive displacement pump driven by a DC motor, the characteristic curve can indicate the control voltage and / or control current required to achieve a specific fuel flow rate at a specific fuel pressure. The fuel pump characteristic curve can also include one or more characteristic graphs to provide the control value.

[0024] Alternatively, the control value used to control the operating point of the fuel pump can be adjusted by calculating a third target pressure value, which is the sum of the calculated pressure difference and a predetermined second pressure value. Then, the third target pressure value can be converted into a control value using the characteristic curve of the fuel pump, as described above. In this case, when generating the control value for controlling the operating point of the fuel pump, the pressure difference between the currently determined first and second target pressure values ​​can be considered.

[0025] According to one aspect, the fuel type is determined by the control unit based on measured physical parameters of the fuel, using a first set of reference data stored in the control unit as a function of fuel temperature. This means that the first set of reference data includes characteristic curves or characteristic graphs of multiple different fuels, each fuel including one or more physical parameters as a function of fuel temperature that can be used to identify the fuel type. This is necessary because physical parameters vary at different fuel temperatures. For example, dielectric constant, density, and viscosity decrease as temperature increases. Therefore, it is necessary to store physical parameters as a function of fuel temperature in order to correctly determine the fuel type under various environmental conditions. For determining fuel compositions comprising more than one fuel (more than one fuel component), reference is made to our patent application DE 102020216593.9.

[0026] According to one aspect, the vapor pressure of the fuel is determined by the control unit using a second set of reference data stored in the control unit as a function of fuel temperature and fuel type. In other words, vapor pressure profiles for multiple fuels can be stored in the control unit as a function of fuel temperature. To determine the current vapor pressure of the detected fuel, the corresponding value can be obtained from the corresponding profile at the currently measured temperature. The temperature range of the vapor pressure profile can be 0℃ to 150℃.

[0027] The subject matter described herein further includes a fuel supply system for an internal combustion engine, the internal combustion engine including a fuel pump for supplying fuel from a fuel tank to a high-pressure pump and a feed pipe for connecting the fuel pump and the high-pressure pump. Preferably, the fuel pump can be a roller-type battery pump driven by an electric motor. Most preferably, the electric motor can be a DC motor controlled by a control voltage via a duty cycle.

[0028] The fuel supply system also includes a first measuring device for measuring the pressure of the fuel in the fuel supply system, a second measuring device for measuring the temperature of the fuel in the fuel supply system, and a third measuring device for measuring the physical parameters of the fuel in the fuel supply system.

[0029] The first measuring device can be a pressure sensor, preferably a piezoresistive pressure sensor. Any other type of pressure sensor can also be used to measure the fuel pressure in the fuel supply system. The second measuring device can be a temperature sensor, preferably a temperature sensor using an NTC sensor element. Any other type of temperature sensor suitable for measuring the fuel temperature in the fuel supply system can also be used.

[0030] The third measuring device is preferably a tuning fork resonator. Optionally or additionally, a capacitive sensor or any other type of sensor suitable for detecting the above-mentioned physical parameters can be used.

[0031] Furthermore, the fuel supply system includes a control unit electrically connected to a first measuring device, a second measuring device, and a third measuring device. The control unit is configured to receive fuel pressure measured by the first measuring device, fuel temperature measured by the second measuring device, and physical parameters measured by the third measuring device. Additionally, the control unit is configured to perform the aforementioned method using signals received from the measuring devices. Preferably, the control unit may be an engine control unit, or may be integrated into an engine control unit. Alternatively, the control unit may be a separate device located away from the engine control unit.

[0032] According to one aspect, the first, second, and third measuring devices can be disposed in the feed pipe for measuring the pressure, temperature, and physical parameters of the fuel flowing in the feed pipe. This means that the measuring devices can be installed between the fuel pump and the high-pressure pump on the low-pressure side of the gasoline direct injection system. Preferably, the first and second measuring devices can be disposed near the high-pressure pump to determine the fuel condition directly before the fuel enters the high-pressure pump. This reliably prevents the formation of air bubbles upstream of the high-pressure pump.

[0033] According to one aspect, the sampling rate of the first measuring device can be higher than the piston stroke frequency of the high-pressure pump. To accurately determine the pressure amplitude of fuel in the fuel supply system, particularly the pressure amplitude of fuel of the type between the fuel pump and the high-pressure pump, the pressure must be detected at a sampling rate higher than the frequency of pressure pulsations occurring in the fuel line. Since the pressure pulsations in the fuel line between the fuel pump and the high-pressure pump are caused by the oscillating motion of the piston in the high-pressure pump, the sampling rate can be higher than the piston stroke frequency.

[0034] The subject matter described herein also includes controllers for controlling internal combustion engines and for performing the methods described above. Preferably, the controller may be an engine control unit or integrated within an engine control unit. Alternatively, the controller may be a separate device located away from the engine control unit.

[0035] Additionally, the subject matter described herein includes computer program products that can be stored in memory, the memory including instructions that, when executed by a computer, cause the computer to perform the methods described above. Advantages of the invention

[0036] In summary, the subject matter described in this paper prevents fuel injection failures caused by fuel vapor lock and minimizes the risk of cavitation corrosion on the high-pressure side of the high-pressure pump inlet valve and injection system. The method also achieves efficient fuel pump operation by measuring fuel pressure and determining the associated vapor pressure, thus avoiding unnecessary increases in target pressure. Attached Figure Description

[0037] The subject matter will be further explained below based on at least one preferred example in conjunction with the example figures, wherein: [ Figure 1 ] Figure 1 An example of a fuel supply system integrated into a gasoline direct injection system according to the subject described herein is illustrated schematically; [ Figure 2 ] Figure 2 A graph is shown that schematically illustrates an example of the vapor pressure curve of any fuel as a function of temperature. [ Figure 3 ] Figure 3 The vapor pressure curves of methanol and ethanol are schematically illustrated as a function of temperature and increased fuel pressure provided by the fuel supply system according to the subject matter described herein. [ Figure 4 ] Figure 4 A diagram is shown that schematically illustrates an example of a predetermined pressure margin as a function of temperature; Figure 5 ] Figure 5 A diagram schematically depicting different types of pressure pulsations occurring in the fuel line before the high-pressure pump is shown; Figure 6 ] Figure 6 A graph schematically depicting two characteristic curves of the second target pressure value as a function of temperature is shown; [ Figure 7 ] Figure 7 A graph showing the relationship between the first target pressure and the second target pressure is presented; [ Figure 8 ] Figure 8 A flowchart illustrating the steps of the method described herein is provided as an example. [ Figure 9 ] Figure 9 A block diagram of an exemplary functional block for performing the methods described herein is shown. Detailed Implementation

[0038] Figure 1 An example of a fuel supply system 20 according to the subject matter described herein is schematically shown, wherein the fuel supply system 20 is integrated into a gasoline direct injection system. The fuel supply system includes a fuel pump 2 installed in a fuel tank 1 and a feed line 11 connecting the fuel pump 2 to a high-pressure pump 7. The fuel pump may also be installed externally to the fuel tank 1.

[0039] Fuel pump 2 delivers fuel to high-pressure pump 7 at pressures ranging from 1 bar to 25 bar. The pressure of the fuel compressed by high-pressure pump 7 can range from 50 bar to 600 bar.

[0040] Furthermore, the fuel supply system 20 includes three measuring devices 4, 5, and 6 installed in the fuel line 11 between the fuel pump 2 and the high-pressure pump 7. The first measuring device 4 measures the fuel pressure in the supply line 11, the second measuring device 5 measures the fuel temperature in the supply line 11, and the third measuring device 6 detects a physical parameter indicating the type of fuel flowing through the supply line 11. The first measuring device 4 can be a pressure sensor, preferably a piezoresistive pressure sensor. The second measuring device 5 can be a temperature sensor, preferably a temperature sensor using an NTC sensor element. Any other type of pressure and / or temperature sensor suitable for detecting the fuel pressure / temperature in the supply line 11 can also be used. The third measuring device 6 can preferably be a tuning fork resonator. Alternatively or additionally, a capacitive sensor or any other type of sensor suitable for detecting a physical parameter indicating the type of fuel can be used.

[0041] Furthermore, the fuel supply system 20 includes a control unit 10, which is electrically connected to measuring devices 4, 5, and 6, and receives measurements from these devices to determine vapor pressure and pressure pulsations. The control unit 10 is further electrically connected to the fuel pump 2, the high-pressure pump 7, and the fuel injector 9, controlling these components. The described fuel supply system 20 has an additional temperature sensor 3, which is disposed in the fuel tank 1 and also electrically connected to the control unit 10. The additional temperature sensor 3 can be of the same type as the second measuring device 5. Other types of sensors capable of measuring the fuel temperature in the fuel tank can also be used. The additional temperature sensor 3 enables the detection of temperature changes (below operating temperature) in the fuel tank during refueling of hybrid vehicles or during prolonged engine shutdown.

[0042] The fuel supply system 20 is connected to the high-pressure pump 7, which is in turn connected to the fuel rail 8. Fuel is distributed from the fuel rail 8 to four high-pressure fuel injectors 9, each of which injects fuel into the combustion chamber of the internal combustion engine (not shown). Figure 1 The four high-pressure fuel injectors 9 depicted are merely examples of any number of fuel injectors that can be connected to the fuel rail.

[0043] The fuel supply system 20 described in this article is also applicable to a low-pressure injection system. In this case, the high-pressure pump 7 is absent, and the fuel pump 2 delivers fuel directly to the fuel rail 8, from which fuel is distributed to the low-pressure fuel injectors 9.

[0044] High-pressure fuel injectors can be fuel injectors designed to inject fuel in the range of 50 bar to 600 bar, and low-pressure fuel injectors can be fuel injectors designed to inject fuel in the range of 1 bar to 25 bar.

[0045] Figure 2 The diagram shows the vapor pressure curve p describing any fuel. vap As temperature T f A graph of an example function of . The vapor pressure curve p of fuel in liquid form. vap The pressure and temperature regions above are marked with thick gray arrows, along with the steam pressure curve p of fuel in steam form. vap The pressure and temperature areas below are marked with thick white arrows. Additionally, a constant fuel pressure value p is depicted. FP,0 This represents the typical fuel pressure value in the fuel supply system 20 prior to the high-pressure pump 7. From Figure 2 It can be seen that at temperature T vap The above is the fuel pressure value p. FP,0 The pressure is lower than the vapor pressure of the fuel, which may cause bubbles to appear in the fuel supply system 20.

[0046] Figure 3 The diagram illustrates the methanol p determined by control unit 10. vap,meth and ethanol p vap,eth The steam pressure curve is used as the fuel temperature T f A graph illustrating an example of a function. Furthermore, a predetermined second target pressure value p is described. tar,2 And methanol p calculated by control unit 10 tar,1_meth and ethanol p tar,1_eth The first target pressure value.

[0047] It can be recognized that, respectively below fuel temperature T f,vap,m and T f,vap,e At that time, the predetermined second target pressure p tar,2 The first target pressure value p is higher than the sum of the calculated determined steam pressure, the determined pressure range, and the predetermined pressure margin. tar,1_meth and p tar,1_eth Therefore, when the temperature reaches T... f,vap,m and T f,vap,e At that time, in order to increase fuel pressure p f There is no need to adjust the control value used to control the operating point of fuel pump 2.

[0048] However, if the fuel temperature T f Exceeding temperature T f,vap,m and T f,vap,e Then the first target pressure value p tar,1_meth and p tar,1_eth Exceeding the predetermined second target pressure p tar,2 The value of the fuel pump 2 is adjusted to regulate the fuel pressure p in the feed pipe 11. f Increase to the first target pressure value p respectively tar,1_meth and p tar,1_eth .

[0049] Figure 4 The vapor pressure curve P of methanol, determined by control unit 10, is shown. vap,meth Example diagram. Additionally, the predetermined pressure margin p... m An example is described as fuel temperature T f The function, in this case, fuel temperature T f The defined steam pressure curve P vap,meth A constant offset. However, the predetermined pressure margin p m It may also be based on the fuel temperature T f The pressure margin p varies depending on the operating point of fuel pump 2 and / or fuel pump 2. m It can be like Figure 4 The offset shown can also be a relative value. The predetermined pressure margin p m It can be in the range of 0.2 bar to 1 bar.

[0050] Figure 5 This shows the effect at a constant fuel temperature T. f Below, different pressure pulsations p pul,1 ,p pul,2 and p pul,3 The graph of pressure pulsation p as a function of time t pul,1 ,p pul,2 and p pul,3 This may occur in the feed line 11 to the high-pressure pump 7. Additionally, the average fuel pressure p in the feed line 11 is also shown. FP,m The vapor pressure p of the fuel vap And the danger zone where bubbles are expected to form.

[0051] Pressure pulsation p pul,1 The pressure pulsation showed an exponential increase, which means that the fuel pressure p f As time increases. In this case, the pressure pulsation p pul,1 The lowest pressure that occurs will drop below the steam pressure p. vap The risk is relatively small. However, temporarily constant pressure pulsations p pul,2 It shows a decrease to below the steam pressure P vap This causes the pulsation p pul,2 The downward thrust reached the danger zone where bubbles were expected to form. This means that in this situation, to avoid bubble formation in the fuel, the mean fuel pressure p needs to be increased. FP,m If a pulsation occurs in the feed pipe 11 that indicates a decrease in the pressure index, such as a pressure pulsation p... pul,3This situation will be exacerbated. In this case, the pressure in the feed pipe 11 decreases over time, causing even partial pulsation overshoot to reach the danger zone. Therefore, to avoid the formation of bubbles in the fuel, the average fuel pressure p FP,m It must be increased further.

[0052] from Figure 5 It can be seen that monitoring pressure pulsations in the fuel supply system helps to avoid bubbles in the system, because different types of pressure pulsations may occur depending on the fuel flow rate in the fuel supply system.

[0053] Figure 6 Figure 500 schematically illustrates two characteristic curves depicting the second target pressure value as a function of temperature. The upper curve p... tar,2_nmax The second target pressure value at maximum engine speed and the lower curve p are shown. tar,2_nmin The second target pressure value is shown at the minimum engine speed. Figure 500 shows that the second target pressure value p can be... tar,2 The characteristic curve is stored as a function of temperature and engine speed; that is, a further characteristic curve representing the range of engine speeds between maximum and minimum engine speeds can be stored in the characteristic curve. Different characteristic curves can be generated for different fuels, or for multiple fuels, a second set pressure value p can be included. tar,2 A single characteristic curve.

[0054] It is evident that at maximum engine speed, the required p is greater than that at minimum engine speed. tar,2_nmin Higher fuel pressure p tar,2_nmax This is to maintain the fuel flow rate required by the high-pressure pump. Furthermore, in both cases, the second target pressure value increases with increasing temperature to prevent bubble formation. This means that the vapor pressure of the fuel used is taken into account to some extent in the second target pressure value p. tar,2 In this configuration, the control value of the fuel pump is preferably adjusted only when a first target pressure value determined from the current measurement exceeds a second target pressure value. Alternatively, the second target pressure p can also be determined without considering the vapor pressure of the fuel. tar,2 Because it is based solely on the first set pressure p tar,1 It is also possible to use calculations to set the control values ​​of the fuel pump appropriately.

[0055] Examples of possible relationships between the first target pressure and the second target pressure are as follows: Figure 7 As shown, Figure 7 Allow understanding by, for example Figure 8 The diagram shows different scenarios with different target pressure values ​​selected for control.

[0056] Specifically, Figure 7 The diagram schematically illustrates two linear curves p as a function of temperature. tar,1_nmax p tar,1_nmin , representing the first target pressure values ​​at the maximum and minimum engine speeds, and P, representing the determined vapor pressure of methanol at the corresponding engine speeds. vap,meth Pressure margin p m and a defined pressure pulsation p pul,nmax p pul,nmin The sum of. Furthermore, Figure 6 The second target pressure values ​​p are given at the maximum and minimum engine speeds. tar,2_nmax p tar,2_nmin Two characteristic curves.

[0057] It can be seen that the pressure pulsation p at the minimum engine speed pul,nmin The amplitude (indicated by the dashed arrow) is lower than the pressure pulsation p at maximum engine speed. pul,nmax The magnitude (indicated by solid arrows). The reason for the different pressure magnitudes is the lower fuel flow rate required at lower engine speeds. However, due to pressure pulsations p pul,nmin At low fuel temperatures, the first target pressure becomes higher than the second target pressure. This is because at lower engine speeds and temperatures, only lower pressure is needed to provide the fuel flow rate for the high-pressure pump, allowing for the selection of a lower second target pressure value p within the engine's operating range. tar,2_nmin Due to the first target pressure p within this range tar,1_nmin Higher than the second target pressure p tar,2_nmin Therefore, the control unit can increase the control value of the fuel pump to compensate for pressure pulsations p. pul,nmin The impact.

[0058] However, at maximum engine speed and at low to moderate fuel temperatures, the second target pressure p tar,2_nmax Higher than the first target pressure p tar,1_nmax This eliminates the need to adjust the fuel pump control value at this operating point. It can be recognized that at high temperatures, the first target pressure value p... tar,1_nmax Only exceeding the corresponding second target pressure value p tar,2_nmax Therefore, the fuel pump control value only needs to be adjusted at the maximum engine speed under high temperature conditions.

[0059] Figure 8 A flowchart illustrating the various steps of the method described herein is provided by way of example. The method begins with step S100, which involves checking and measuring the physical parameter X. f,0 Whether any sensor is malfunctioning, physical parameter X f,0 Indicates fuel type X f Temperature T for fuel pressure p f If so, the fuel supply system must be checked in the workshop (S101), and the process ends in step S107. If all sensors are ready, the physical parameter X is measured in step S102. f,0 Temperature T f and fuel pressure p f Based on the measured sensor signals, the fuel type X is determined in step S103. f Steam pressure P var,f and pressure pulsation p pul The range.

[0060] Fuel type X f For example, fuel type X can be detected by measuring the dielectric constant, density, and / or kinematic viscosity of the fuel in the fuel supply system 20, as well as based on a first set of reference data stored in the control unit (20). f To determine this. The first set of reference data may include characteristic curves or graphs for a variety of different fuels, each fuel including one or more physical parameters X. f,0 The physical parameter X f,0 It can be used to identify fuel temperature T f The function of fuel type X f Then, the vapor pressure p of the tested fuel can be determined using vapor pressure profiles stored in a second set of reference data for various fuels. vap,f To determine the current vapor pressure p of the fuel being tested. vap,f It can be determined from the current measured temperature T f The corresponding value is obtained from the corresponding steam pressure curve. The pressure amplitude p is determined from the measured pressure signal by determining the average pressure and the lowest measured pressure within a predetermined time interval, and then calculating the difference between the average pressure and the lowest pressure. pul .

[0061] Subsequently, in step S104a, the first target pressure value p tar,1 The steam pressure p is calculated as a given. vap,f The predetermined pressure margin p m and pressure pulsation p pul The sum of their magnitudes. The predetermined pressure margin p m This can be to ensure the first target pressure p tar,1 Always higher than the steam pressure p vap,f Safety margin. Predetermined pressure margin p m The temperature and / or operating point of fuel pump 2 can be varied to ensure that fuel pump 2 does not exceed its optimal operating range.

[0062] Meanwhile, the predetermined second target pressure ptar,2 This is derived from the characteristic curve or stored in the control unit 10 based on engine speed (the above explanation addresses two different cases, "minimum" and "maximum"; however, more engine speeds can be considered, such as...). Figure 6 The described, determined fuel type X f and a determined temperature T f The characteristic curve is used to determine this (S104 b). Then, the first target pressure value p is calculated. tar,1 Compared with the predetermined second target pressure value p tar,2 The pressure difference between them. In other words, the first target pressure value p tar,1 Compared with the second target pressure value p tar,2 Comparison. If the second target pressure p tar,2 Below the first target pressure p tar,1 Then adjust the control value FP of the feed pump. s (For example Figure 9 ), making the first target pressure value p tar,1 This will be the control objective to be achieved (S105). This means that if the second target pressure p tar,2 Below the first target pressure p tar,1 Then the control value FP of the feed pump s Adjustment makes the fuel pressure p f Equal to the first target pressure value p tar,1 .

[0063] Conversely, maintain the existing control value FP of the feed pump. s That is, controlling the fuel pressure p f Make it equal to or equal to the second target pressure p tar,2 (S106). The described process is repeated as long as the engine is running, and ends when the engine is turned off (S107).

[0064] Figure 9 A block diagram of an exemplary functional block for performing the steps of the method described herein is shown. In functional block 800, the determined steam pressure P is... vap,f The predetermined pressure margin p m and a defined pressure pulsation p pul The magnitudes are added together to calculate the first target pressure value p. tar,1 .

[0065] Function box 500 indicates Figure 5 The known schematic characteristic curves show that the second target pressure value p can be read from them. tar,2In function block 801, the difference Δp between the first target pressure and the second target pressure is calculated, and it is limited by a subsequent limiter 802, which has a lower limit of zero, to a value greater than or equal to zero. Limiter 802 ensures that the control value FP is adjusted only if the calculated pressure difference ΔP is greater than zero. s This means the first target value p tar,1 Greater than the second target pressure value p tar,2 The restricted pressure difference Δp lim The input is fed into the PID controller, which then processes the pressure difference Δp. lim Converted to control value difference ΔFP s Using a PID controller allows for amplification of control value differences to respond to large detected pressure differences Δp. lim Control value difference ΔFP s Then it is added to the existing control value FP. s,0 And as the adjusted control value FP s The input is sent to the fuel pump controller 805. The existing control value FP... s,0 Based on a second target pressure value, which is input into function block 804, function block 804 includes fuel pressure and fuel volumetric flow rate Q. f,s The characteristic curve of fuel pump 2 as a function of the function. This means the second target pressure p tar,1 And the pressure difference is converted into a control value FP suitable for controlling the operation of the fuel pump. s,0 and ΔFP s .

[0066] Furthermore, Figure 9 The output of fuel pump controller 805 is shown as an updated pressure control value input to fuel pump 2. This is due to the adjustment of the control value FP. s This could lead to changes in the output value of the fuel pump controller 805, which in turn could cause pressure pulsations P. pul The change in pressure causes the actual pressure value of fuel pump 2 to be fed back to function block 800, resulting in pressure pulsation P. pul The input values ​​are continuously updated.

[0067] Alternatively, input the control value FP of the fuel pump controller 805. s The third target pressure value can be calculated as a restricted pressure difference p. lim and the predetermined second pressure value p tar,2 The sum is used for adjustment. Then, in the same manner as above, the third target pressure value can be input into function block 804 to be converted into the control value FP using the characteristic curve of fuel pump 2. s,0 (In this case, it equals the control value FP). In this situation, a PID controller can be used to amplify the limited pressure difference Δp. limInstead, it generates control value FP. s Previously, this pressure difference Δp lim It may have already been considered.

[0068] By conducting according to Figure 7 Flowcharts and Figure 8 The method described in the block diagram can prevent the formation of bubbles in the fuel supply system 20 by ensuring that the minimum fuel pressure in the fuel supply system 20 is always greater than the steam pressure.

[0069] To summarize, the subject matter described in this paper prevents fuel injection failures caused by fuel vapor lock and minimizes the risk of cavitation corrosion on the high-pressure side of the high-pressure pump inlet valve and injection system. The method also achieves efficient fuel pump operation by measuring fuel pressure and determining the relevant vapor pressure, thus avoiding unnecessary increases in target pressure.

[0070] As will be understood by those skilled in the art, as described above and in the accompanying drawings, this disclosure may be embodied as a method, apparatus (including devices, machines, systems, computer program products and / or any other apparatus) or a combination thereof.

[0071] Accordingly, embodiments of this disclosure may take the form of a completely hardware embodiment, a completely software embodiment (including firmware, resident software, microcode, etc.), or an embodiment combining hardware and software aspects (which may generally be referred to herein as a "system"). Furthermore, embodiments of this disclosure may take the form of a computer program product on a computer-readable medium having computer-executable program code embedded therein.

[0072] It should be noted that arrows may be used in the accompanying drawings to represent communications, transmissions, or other activities involving two or more entities. Double-ended arrows typically indicate that the activity can occur in both directions (e.g., a command / request in one direction returns a corresponding response in the other, or peer-to-peer communication initiated by either entity), although in some cases the activity may not necessarily occur in both directions.

[0073] A single-ended arrow may typically indicate activity in only one direction or primarily in one direction; however, it should be noted that in some cases, such directional activity may actually involve activity in both directions (e.g., a message from sender to receiver and an acknowledgment from receiver to sender, or establishing a connection before transmission and terminating a connection after transmission). Therefore, the type of arrow used to represent a particular activity in a specific figure is exemplary and should not be considered limiting.

[0074] The foregoing flowcharts and / or block diagrams of the methods and apparatus, along with several example views of the graphical user interface generated by the methods and / or apparatus, describe several aspects. It should be understood that each box in the flowchart illustrations and / or block diagrams, and / or combinations of boxes in the flowchart illustrations and / or block diagrams, as well as the graphical user interface, can be implemented using computer-executable program code.

[0075] Computer-executable program code can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing apparatus to produce a particular machine, such that the program code, which is executed by the processor of the computer or other programmable data processing apparatus, creates means for implementing the functions / actions / outputs specified in the flowchart, block diagram, diagram, and / or written description.

[0076] These computer-executable program codes may also be stored in a computer-readable storage medium that can instruct a computer or other programmable data processing apparatus to operate in a particular manner, such that the program code stored in the computer-readable storage medium produces an article of manufacture, including instruction means that implement the functions / actions / outputs specified in flowcharts, block diagrams, figures, and / or written descriptions.

[0077] Computer-executable program code can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to generate a computer-implemented process, such that the program code executing on the computer or other programmable apparatus provides steps for implementing a flowchart, block diagram, diagram, and / or written description specifying a function / action / output. Alternatively, the steps or actions implemented by the computer program can be combined with steps or actions performed by an operator or person to perform an embodiment.

[0078] It should be noted that the terms "server" and "processor" may be used herein to describe devices that may be used in some embodiments, and should not be construed as limiting to any particular device type unless the context otherwise requires. Therefore, devices may include, but are not limited to, bridges, routers, brouters, switches, nodes, servers, computers, devices, or other types of devices. Such devices typically include one or more network interfaces for communicating over a communication network, and a processor (e.g., a microprocessor and / or dedicated hardware with memory and other peripherals) configured accordingly to perform device functions.

[0079] Communication networks can typically include public and / or private networks; they can include local area networks (LANs), wide area networks (WANs), metropolitan area networks (MANs), storage networks, and / or other types of networks; and they can employ communication technologies, including but not limited to analog technology, digital technology, optical technology, wireless technology (e.g., Bluetooth), network technology, and internet technology.

[0080] It should also be noted that the device may use communication protocols and messages (e.g., messages created, sent, received, stored and / or processed by the device) that may be transmitted by a communication network or medium.

[0081] Unless the context otherwise requires, this disclosure should not be construed as limiting to any particular type of communication message, communication message format, or communication protocol. Therefore, communication messages can generally include, but are not limited to, frames, packets, datagrams, user datagrams, cellular data, or other types of communication messages.

[0082] Unless the context requires otherwise, references to specific communication protocols are exemplary, and it should be understood that alternative embodiments may, as appropriate, employ variations of these communication protocols (e.g., modifications or extensions to the protocols that may be made over time) or other protocols known or developed in the future.

[0083] It should also be noted that the logic flow can be described herein to illustrate various aspects, and should not be construed as limiting the invention to any particular logic flow or logic implementation. Logic can be divided into different logical blocks (e.g., programs, modules, functions, or subroutines) without changing the overall result.

[0084] Typically, logical elements can be added, modified, omitted, performed in a different order, or implemented using different logical structures (e.g., logic gates, loop primitives, conditional logic, and other logical structures) without changing the overall result.

[0085] This disclosure may be embodied in a variety of different forms, including, but not limited to, computer program logic for a processor (e.g., a microprocessor, microcontroller, digital signal processor, or general-purpose computer), programmable logic for a programmable logic device (e.g., a field-programmable gate array (FPGA) or other PLD), discrete components, integrated circuits (e.g., application-specific integrated circuits (ASICs)), or any other means including any combination thereof. The computer program logic implementing some or all of the described functions is typically implemented as a set of computer program instructions that are translated into a computer-executable form, stored in a computer-readable medium, and executed by a microprocessor under the control of an operating system. The hardware-based logic implementing some or all of the described functions may be implemented using one or more appropriately configured FPGAs.

[0086] The computer program logic that implements all or part of the functions described above can be embodied in various forms, including but not limited to source code, computer executable, and various intermediate forms (e.g., forms generated by an assembler, compiler, linker, or locator).

[0087] Source code can include a set of computer program instructions implemented in various programming languages ​​(e.g., object code, assembly language, or high-level languages ​​such as Fortran, C, C++, JAVA, or HTML) for various operating systems or operating environments. Source code can define and use various data structures and communication messages. Source code can be in a computer-executable form (e.g., via an interpreter), or source code can be transformed (e.g., via a converter, assembler, or compiler) into a computer-executable form.

[0088] The computer executable program code used to perform the operations of the embodiments of this disclosure can be written in object-oriented, scripting, or non-scripting programming languages, such as Java, Perl, Smalltalk, C++, etc. However, the computer program code used to perform the operations of the embodiments can also be written in conventional programming languages, such as the "C" programming language or similar programming languages.

[0089] The computer program logic that implements all or part of the functions described earlier in this document may execute at different times on a single processor (e.g., in parallel), or may execute at the same or different times on multiple processors, and may run under a single operating system process / thread or different operating system processes / threads.

[0090] Therefore, the term "computer process" can generally refer to the execution of a set of computer program instructions, regardless of whether the computer processes executing on the same or different processors are different, and regardless of whether the computer processes running under the same operating system process / thread or different operating system process / thread are different.

[0091] Computer programs can be stored in any form (e.g., source code, computer executable, or intermediate form) in a tangible storage medium, such as semiconductor storage devices (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), magnetic storage devices (e.g., magnetic disks or fixed disks), optical storage devices (e.g., CD-ROMs), PC cards (e.g., PCMCIA cards), or other storage devices.

[0092] Computer programs can be embedded in signals transmitted to a computer in any form, and the computer can use various communication technologies, including but not limited to analog technology, digital technology, optical technology, wireless technology (e.g., Bluetooth), network technology, and Internet technology.

[0093] Computer programs can be distributed in any form as a removable storage medium preloaded with a computer system (e.g., system ROM or fixed disk) with accompanying printed or electronic documents (e.g., shrink wrapping software), or from a server or electronic bulletin board via a communication system (e.g., the Internet or the World Wide Web).

[0094] The hardware logic (including programmable logic for programmable logic devices) that implements all or part of the functions described above can be designed using conventional manual methods, or can be designed, captured, simulated, or electronically recorded using a variety of tools such as computer-aided design (CAD), hardware description languages ​​(e.g., VHDL or AHDL), or PLD programming languages ​​(e.g., PALASM, ABEL, or CUPL).

[0095] Any suitable computer-readable medium may be used. Computer-readable media may be, for example, but not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, devices, equipment, or media.

[0096] More specific examples of computer-readable media include, but are not limited to, electrical connections having one or more wires or other tangible storage media, such as portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical disc read-only memory (CD-ROM), or other optical or magnetic storage devices.

[0097] Programmable logic can be permanently or convertibly fixed in a tangible storage medium, such as semiconductor memory devices (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), magnetic memory devices (e.g., magnetic disks or fixed disks), optical memory devices (e.g., CD-ROMs) or other memory devices.

[0098] Programmable logic can be embedded in signals transmitted to a computer that can use various communication technologies, including but not limited to analog, digital, optical, wireless (e.g., Bluetooth), network, and internet technologies.

[0099] Programmable logic can be distributed as a removable storage medium preloaded with a computer system (e.g., system ROM or fixed disk) having accompanying printed or electronic documentation (e.g., shrink wrapping software), or from a server or electronic bulletin board via a communication system (e.g., the Internet or the World Wide Web). Of course, some aspects can be implemented as a combination of software (e.g., computer program products) and hardware. Another embodiment of the invention can be implemented as entirely hardware or entirely software.

[0100] While certain exemplary aspects have been described and illustrated in the accompanying drawings, it should be understood that these aspects are illustrative and that the embodiments are not limited to the specific constructions and arrangements shown and described, as various other changes, combinations, omissions, modifications and substitutions may be made in addition to those described in the preceding paragraphs.

[0101] Those skilled in the art will understand that various adaptations, modifications, and / or combinations of the foregoing embodiments can be configured. Therefore, it should be understood that this disclosure can also be implemented in ways other than those specifically described herein, within the scope of the appended claims. For example, unless expressly stated otherwise, the steps of the processes described herein may be performed in a different order than those described herein, and one or more steps may be combined, split, or performed simultaneously.

[0102] In view of this disclosure, those skilled in the art will also understand that the different embodiments or aspects described herein can be combined to form other embodiments. Reference Mark List

[0103] 1 fuel tank 2 fuel pumps 3 Temperature Sensors (Fuel Tank) 4. First measuring device: pressure sensor 5. Second measuring device: temperature sensor (fuel pipe) 6. Third measuring device: fuel sensor 7 High-pressure pump 8 fuel rails 9 fuel injectors 10 control units 11 Feed pipe

Claims

1. A method for controlling a fuel pump in an internal combustion engine fuel supply system, characterized in that, Includes the following steps: The pressure of the fuel in the fuel supply system is measured using a first measuring device; The temperature of the fuel is measured using a second measuring device; The physical parameters of the fuel are measured using a third measuring device; Control unit: Based on the measured physical parameters of the fuel, the fuel type is determined. Based on the determined fuel type and the measured temperature, the vapor pressure of the fuel is determined, and Determine the pressure amplitude of the measured pressure; Calculated by the control unit: A first target pressure value is the sum of the determined steam pressure, the determined pressure amplitude, and the predetermined pressure margin; and The pressure difference between the first target pressure value and the predetermined second target pressure value; as well as If the calculated pressure difference is greater than zero, then The control unit adjusts the control value for controlling the operating point of the fuel pump based on the calculated pressure difference.

2. The method according to claim 1, characterized in that, The predetermined second target pressure value is stored in the control unit as a function of fuel temperature.

3. The method according to claim 1, characterized in that, The control value used to control the operating point of the fuel pump is adjusted by performing the following steps: The calculated pressure difference is converted into a control value difference using a PID controller; as well as The control value difference is added to the control value, wherein the control value is based on the predetermined second target pressure value.

4. The method according to claim 1, characterized in that, The control value used to control the operating point of the fuel pump is adjusted by performing the following steps: A third target pressure value is calculated by adding the calculated pressure difference to the predetermined second pressure value; the third target pressure value is then converted into the control value using the characteristic curve of the fuel pump.

5. The method according to claim 1, characterized in that, The fuel type is determined by the control unit based on the measured physical parameters of the fuel, using a first set of reference data stored in the control unit as a function of fuel temperature.

6. The method according to claim 1, characterized in that, The vapor pressure of the fuel is determined by the control unit using a second set of reference data stored in the control unit as a function of fuel type and fuel temperature.

7. A fuel supply system for an internal combustion engine, characterized in that, include: A fuel pump is used to supply fuel from the fuel tank to the high-pressure pump in the fuel supply system. A feed pipe is used to connect the fuel pump and the high-pressure pump; A first measuring device is used to measure the pressure of the fuel in the fuel supply system; A second measuring device is used to measure the temperature of the fuel in the fuel supply system; A third measuring device is used to measure the physical parameters of the fuel in the fuel supply system; The control unit is electrically connected to the first measuring device, the second measuring device, and the third measuring device; The control unit is configured to receive fuel pressure measured by the first measuring device, fuel temperature measured by the second measuring device, and physical parameters measured by the third measuring device; as well as Perform the method as described in claim 1.

8. The fuel supply system according to claim 7, characterized in that, The first measuring device, the second measuring device, and the third measuring device are disposed in the feed pipe and are used to measure the pressure, temperature, and physical parameters of the fuel flowing in the feed pipe.

9. The fuel supply system according to claim 7, characterized in that, The sampling rate of the first measuring device is higher than the piston stroke frequency of the high-pressure pump.

10. A controller, characterized in that, It is configured to control an internal combustion engine and perform the method as described in claim 1.

11. A computer program product that can be stored in a memory, characterized in that, Includes instructions that, when executed by a computer, cause the computer to perform the method as described in claim 1.

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