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

Abstract

The subject matter described herein relates to a method, a controller, and a computer program product for controlling a fuel pump of a fuel supply system for an internal combustion engine, and a fuel supply system for an internal combustion engine. The problem to be solved is to provide an efficient fuel supply system that can supply various types of fuels without forming bubbles under different environmental conditions. The method includes the steps of measuring a pressure of the fuel in the fuel supply system by a first measuring means, measuring a temperature of the fuel by a second measuring means, measuring a physical parameter of the fuel by a third measuring means, determining, by a control unit, a fuel type based on the measured physical parameter of the fuel, determining a vapor pressure of the fuel based on the determined fuel type and the measured temperature, and determining 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 calculating a pressure difference between the first target pressure value and a predetermined second target pressure value, and if the calculated pressure difference is greater than 0, adjusting, by the control unit, a control value for controlling an operating point of the fuel pump based on the calculated pressure difference.

Description

[Technical Field]

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

[0002] To slow global climate change, significant reductions in CO2 emissions from industry and transport are necessary. In addition to the increasing use of electric drives, internal combustion engines in vehicles are still needed to enable them to cover longer distances.

[0003] To achieve the required CO2 reductions, biofuels and so-called electrofuels for internal combustion engines will play an important role. Biofuels such as ethanol have already proven their importance as an alternative to gasoline. Currently, the production of second-generation ethanol, which can be obtained, for example, from cellulose, is gaining importance. Electrofuels are synthetic fuels produced by reacting hydrogen from renewable energies with carbon dioxide. Examples of liquid electrofuels that can be used in gasoline engines are methanol and dimethyl carbonate (DMC). It is expected that these synthetic fuels will be supplied at filling stations in the future both in pure form and mixed with conventional fuels.

[0004] However, when handling different types of fuel in the fuel supply system of an internal combustion engine, different fuel properties must be taken into account. In particular, the vapor pressure of the fuel used must be taken into account to avoid the formation of gas bubbles in the fuel supply system, which can interfere with fuel injection and damage fuel-carrying components. Gas bubbles that form in the fuel supply system (the low-pressure side of a gasoline direct injection system) can be transported to the high-pressure side, where they are compressed and implode. If the gas bubbles implode on the surfaces of the injection components, this can lead to cavitation erosion, causing serious damage to the components.

[0005] Therefore, what is needed is a fuel delivery system that ensures that fuel pressure within the system always exceeds vapor pressure, regardless of the fuel being used. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] U.S. Patent No. 6,742,479 Summary of the Invention

[0007] technical challenges Patent Document 1 describes a fuel supply system for a dimethyl ether engine, in which dimethyl ether is pressurized by a pressure pump to a saturated vapor pressure or higher and supplied from a fuel tank to a high-pressure fuel pump. The fuel supply system includes a dimethyl ether detection device for detecting the state of dimethyl ether from the pressure pump, and an electronic control unit for driving the high-pressure fuel pump when dimethyl ether in a fuel pipe 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 operate with dimethyl ether and is therefore unable to accommodate different types of fuel.

[0009] The object of the subject matter described herein is to provide an efficient fuel supply system that can supply various types of fuel without forming bubbles under different environmental conditions. This problem is solved by the subject matter of the independent claims. Further preferred developments are described in the dependent claims.

[0010] Solutions to the problem The subject matter described herein includes a method for controlling a fuel pump of a fuel supply system for an internal combustion engine, the method including measuring a pressure of fuel in the fuel supply system with a first measurement means, measuring a temperature of the fuel with a second measurement means, and measuring a physical parameter of the fuel with a third measurement means.

[0011] The control unit then determines the fuel type based on the measured physical parameters of the fuel, and determines the vapor pressure of the fuel based on the determined fuel type and the measured temperature. Preferably, the physical parameters of the fuel measured / detected by the third measuring means 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 physical parameters for various fuels. In particular, it becomes clear that the dielectric constant of each fuel varies significantly. Therefore, measuring the dielectric constant can reliably detect the fuel type. [Table 1]

[0013] To increase the accuracy of the detection, further physical parameters such as the density and kinematic viscosity of the fuel in the fuel supply system may also be measured.

[0014] Once the fuel type is identified, the vapor pressure of the fuel is determined based on the identified fuel type and the measured temperature. Vapor pressure is defined as the pressure exerted by a vapor in thermodynamic equilibrium with its condensed phase (solid or liquid) at a given temperature in a closed system. For a fuel in a fuel supply system, this means that the fuel will form bubbles if the fuel pressure is lower than the vapor pressure. Vapor pressure is a function of temperature (higher temperatures result in higher vapor pressure) and varies among 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 the formation of bubbles. 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 prevailing conditions.

[0015] The control unit further determines the pressure amplitude of the measured pressure. The average pressure in the fuel supply system is usually superimposed by pressure fluctuations / pressure pulsations, caused, for example, by the oscillating piston movement of the high-pressure pump. This pressure pulsation must be taken into account to ensure that the minimum pressure occurring in the fuel supply system does not fall below the vapor pressure. The pressure amplitude can be determined from the measured pressure signal by determining the average pressure and the minimum measured pressure over a predetermined time interval and then forming the difference between the average pressure and the minimum pressure. For example, the predetermined time interval may be in the range of 0.2 seconds to 2 seconds. This process can be repeated continuously during operation of the fuel supply system.

[0016] The control unit further calculates a first target pressure value as the sum of the determined vapor pressure, the determined pressure amplitude, and a predetermined pressure margin. The predetermined pressure margin may be a safety margin that ensures the first target pressure always exceeds the vapor pressure. The predetermined pressure margin may vary depending on the temperature and / or operating point of the fuel pump to prevent the fuel pump from operating outside its optimized operating range. For example, the predetermined pressure margin may be in the range of 0.2 bar to 1 bar.

[0017] A currently effective target pressure is specified that ensures the fuel pressure in the fuel supply system remains above the vapor pressure by calculating a first target pressure value as the sum of the determined vapor pressure, the determined pressure amplitude, and a predetermined pressure margin.

[0018] To provide a control value for controlling the operating point of the fuel pump, the control unit calculates a pressure difference between the first target pressure value and a predetermined second target pressure value. If the calculated pressure difference is greater than zero, the control unit adjusts the control value for controlling the operating point of the fuel pump 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 if the first target pressure value is greater than the predetermined second target pressure, adjusts the control value for controlling the operating point of the fuel pump so that fuel is delivered at a higher pressure.

[0019] The above-described method prevents fuel injection failures caused by fuel vapor lock and minimizes the risk of cavitation erosion at the inlet valve of the high-pressure pump and along the high-pressure side of the injection system. Additionally, the method enables efficient operation of the fuel pump by measuring fuel pressure and determining the associated vapor pressure, thereby avoiding unnecessary increases in target pressure.

[0020] According to one aspect, the 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 may be generally valid across engine maps, but which can be adjusted for specific engine operating points and / or specific environmental conditions.

[0021] For example, the second target pressure value may be stored in a characteristic curve as a function of fuel temperature, such that a higher target pressure is output at higher fuel temperatures. Alternatively, the second target pressure value may be stored in a map as a function of fuel temperature and engine speed, such that the target pressure increases further at higher engine speeds to maintain the high-pressure pump delivery speed. It is also conceivable that the control unit may be provided with multiple characteristic curves or maps in which second target pressure values ​​for different fuels are stored.

[0022] This means that the vapor pressure of the fuel used is already taken into account to some extent in the second target pressure value, and therefore the control value of the fuel pump is only adjusted in certain situations where the first target pressure value determined from the current measured values ​​exceeds the second target pressure value.

[0023] According to one aspect, the control value for controlling the operating point of the fuel pump can be adjusted by first 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. Using the PID controller, the control value difference can be amplified 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 a fuel pump characteristic curve, 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 maps for providing the control value.

[0024] Alternatively, the calculated pressure difference and the predetermined Second target pressure value By calculating a third target pressure value, which is the sum of and, the control value for controlling the operating point of the fuel pump can be adjusted. The third target pressure value can then be converted into a control value using the characteristic curve of the fuel pump, as described above, whereby the currently determined pressure difference between the first and second target pressure values ​​can already be taken into account when generating the control value for controlling the operating point of the fuel pump.

[0025] According to one embodiment, 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 maps for a plurality of different fuels, each containing one or more physical parameters that can be used to identify the fuel type as a function of fuel temperature. This is necessary because physical parameters change at different fuel temperatures. For example, the dielectric constant, density, and viscosity decrease with increasing temperature. Therefore, to accurately determine the fuel type under various environmental conditions, it is necessary to store the physical parameters as a function of fuel temperature. For determining a fuel composition containing multiple types of fuel (multiple fuel components), see German Patent Application Publication No. 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 curves for multiple fuels may be stored in the control unit as a function of fuel temperature. To determine the current vapor pressure of the detected fuel, a corresponding value from each curve at the currently measured temperature may be obtained. The temperature range of the vapor pressure curves may be between 0°C and 150°C.

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

[0028] The fuel supply system further comprises a first measuring means for measuring the pressure of the fuel in the fuel supply system, a second measuring means for measuring the temperature of the fuel in the fuel supply system, and a third measuring means for measuring a physical parameter of the fuel in the fuel supply system.

[0029] The first measuring means may be a pressure sensor, preferably a piezoresistive pressure sensor. Any other type of pressure sensor suitable for measuring fuel pressure in a fuel supply system may be used as well. The second measuring means may be a temperature sensor, preferably a temperature sensor using an NTC sensor element. Any other type of temperature sensor suitable for measuring fuel temperature in a fuel supply system may be used as well.

[0030] The third measuring means may preferably be a tuning fork resonator. Alternatively or additionally, a capacitive sensor or any other type of sensor suitable for detecting the aforementioned physical parameters may be used.

[0031] Furthermore, the fuel supply system includes first, second, and third Measuring means The control unit is electrically connected to the first Measuring means Fuel pressure measured by the second Measuring means the fuel temperature measured by the Measuring meansThe control unit is configured to receive the physical parameter measured by the measuring means. Furthermore, the control unit is configured to perform the aforementioned method using the signal received from the measuring means. Preferably, the control unit may be the engine control unit or may be integrated into the engine control unit. Alternatively, the control unit may be a separate device located remotely from the engine control unit.

[0032] According to one embodiment, the first, second and third measuring means may be arranged in the supply pipe for measuring the pressure, temperature and physical parameters of the fuel flowing through the supply pipe. This means that the measuring means may 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 means may be arranged near the high-pressure pump to determine the state of the fuel just before it enters the high-pressure pump. This ensures that the generation of air bubbles upstream of the high-pressure pump is prevented.

[0033] According to one embodiment, the sampling rate of the first measuring means may be higher than the piston stroke frequency of the high-pressure pump. To accurately determine the pressure amplitude of the fuel in the fuel supply system, particularly the fuel type between the fuel pump and the high-pressure pump, it is necessary to detect the pressure at a sampling rate higher than the frequency of pressure pulsations occurring in the fuel pipe. Because the pressure pulsations in the fuel pipe between the fuel pump and the high-pressure pump are induced by the oscillatory movement of the piston in the high-pressure pump, the sampling rate may be higher than the piston stroke frequency.

[0034] The subject matter described herein further comprises a controller for controlling the internal combustion engine to perform the aforementioned method. Preferably, the controller may be an engine control unit or may be integrated into the engine control unit. Alternatively, the controller may be a separate device located remotely from the engine control unit.

[0035] Additionally, the subject matter described herein includes a computer program product storable in a memory containing instructions that, when executed by a computer, cause the computer to perform the aforementioned methods. Advantageous Effects of the Invention

[0036] In summary, the subject matter described herein prevents fuel injection failures caused by fuel vapor lock, minimizes the risk of cavitation erosion at the inlet valve of the high-pressure pump and along the high-pressure side of the injection system, and enables efficient operation of the fuel pump by measuring fuel pressure and determining the associated vapor pressure, thereby avoiding unnecessary increases in target pressure. [Brief explanation of the drawings]

[0037] The subject matter will be further explained below on the basis of at least one preferred example with reference to the accompanying exemplary drawings. [Figure 1] 1 illustrates a schematic diagram of an example of a fuel delivery system according to the subject matter described herein incorporated into a gasoline direct injection system. [Figure 2] 1 shows a diagram that schematically illustrates an example of a vapor pressure curve as a function of temperature for any fuel; [Figure 3] 1 shows a diagram that schematically illustrates vapor pressure curves of methanol and ethanol as a function of temperature and increased fuel pressure provided by a fuel delivery system according to the subject matter described herein. [Figure 4] 1 shows a diagram that schematically illustrates an example of a predetermined pressure margin as a function of temperature; [Figure 5] 1 shows a diagram that schematically illustrates different types of pressure pulsations that occur in the fuel pipe before the high-pressure pump; [Figure 6] 3 shows a diagram that schematically depicts two characteristic curves of the second target pressure value as a function of temperature; [Figure 7] FIG. 10 shows a diagram illustrating the relationship between first and second target pressures. [Figure 8] 1 shows a flow chart illustrating the individual steps of the method described herein by way of example. [Figure 9] FIG. 1 shows a block diagram illustrating exemplary functional blocks for performing steps of the methods described herein. DETAILED DESCRIPTION OF THE INVENTION

[0038] 1 shows a schematic diagram of an example of a fuel supply system 20 according to the subject matter described herein, the fuel supply system 20 being integrated into a gasoline direct injection system. The fuel supply system comprises a fuel pump 2 located within a fuel tank 1 and a supply pipe 11 connecting the fuel pump 2 to a high-pressure pump 7. The fuel pump may also be located external to the fuel tank 1.

[0039] The pressure range at which the fuel pump 2 discharges fuel to the high-pressure pump 7 may be in the range of 1 bar to 25 bar. The pressure range at which the fuel is compressed by the high-pressure pump 7 may be in the range of 50 bar to 600 bar.

[0040] The fuel supply system 20 also comprises three measuring means 4, 5, 6 installed in the fuel pipe 11 between the fuel pump 2 and the high-pressure pump 7. The first measuring means 4 measures the fuel pressure in the supply pipe 11, the second measuring means 5 measures the fuel temperature in the supply pipe 11, and the third measuring means 6 may detect a physical parameter representative of the type of fuel flowing through the supply pipe 11. The first measuring means 4 may be a pressure sensor, preferably a piezoresistive pressure sensor. The second measuring means 5 may 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 / fuel temperature in the supply pipe 11 may also be used. The third measuring means 6 may preferably be a tuning fork resonator. Alternatively or additionally, a capacitance sensor or any other type of sensor suitable for detecting a physical parameter representative of the fuel type may be used.

[0041] Furthermore, the fuel supply system 20 comprises a control unit 10 electrically connected to the measuring means 4, 5, 6 and receiving measured values ​​therefrom in order to determine the vapor pressure and pressure pulsations. The control unit 20 is also electrically connected to the fuel pump 2, the high-pressure pump 7 and the fuel injectors 9 and controls them. The illustrated fuel supply system 20 comprises an additional temperature sensor 3 arranged in the fuel tank 1 and also electrically connected to the control unit 10. The additional temperature sensor 3 may be of the same type as the second measuring means 5. It is also conceivable to use other types of sensors capable of measuring the fuel temperature in the tank. The additional temperature sensor 3 makes it possible to detect temperature changes (below the operating temperature) in the tank during refueling or long-term engine shutdown in a hybrid vehicle.

[0042] Fuel supply system 20 is connected to a high-pressure pump 7, which is connected to a fuel rail 8, from which fuel is distributed to four high-pressure fuel injectors 9, each of which injects fuel into a combustion chamber of an internal combustion engine (not shown). The four high-pressure fuel injectors 9 shown in Figure 1 serve only as examples of any number of fuel injectors that may be connected to a fuel rail.

[0043] The fuel delivery system 20 according to the subject matter described herein is also suitable for low pressure injection systems, in which case the high pressure pump 7 is eliminated and the fuel pump 2 delivers fuel directly to the fuel rail 8, which distributes the fuel to the low pressure fuel injectors 9.

[0044] The high pressure fuel injector may be a fuel injector designed to inject fuel in the range of 50 bar to 600 bar, and the low pressure fuel injector may be a fuel injector designed to inject fuel in the range of 1 bar to 25 bar.

[0045] Figure 2 shows the temperature T f Vapor pressure curve p as a function of vap 1 shows an example of a vapor pressure curve p where the fuel exists in liquid form. vapThe pressure and temperature region above is indicated by the thick grey arrow and corresponds to the vapor pressure curve p vap The lower pressure and temperature region is indicated by a thick white arrow. Furthermore, a constant fuel pressure value p FP,0 From Figure 2, the temperature T vap When the fuel pressure value p FP、0 It can be seen that the vapor pressure of the fuel may become lower than the vapor pressure of the fuel, which may cause bubbles to form in the fuel supply system 20.

[0046] Figure 3 shows the fuel temperature T f The methanol p determined by the control unit 10 as a function of vap,meth and ethanol p vap,eth 1 shows an example of a vapor pressure curve of the predetermined second target pressure value p calculated by the control unit 10. tar,2 and methanol p tar,1_meth and ethanol p tar,1_eth A first target pressure value of is shown.

[0047] respectively, fuel temperature T f、vap、m and T f、vap、e If the pressure drops below a predetermined second target pressure p tar、2 is the first target pressure value p calculated as the sum of the determined vapor pressure, the determined pressure amplitude, and a predetermined pressure margin; tar、1_meth and p tar、1_eth Therefore, it can be recognized that the temperature T f、vap、m , T f、vap、e Until the fuel pressure p f Therefore, it is not necessary to adjust the control value for controlling the operating point of the fuel pump 2 in order to increase the value.

[0048] However, the fuel temperature T f are the temperatures T f,vap,m ,T f,vap,e When the first target pressure value p tar,1_meth ,p tar,1_eth is the predetermined second target pressure p tar,2 Since the value of p exceeds the limit, the control value of the fuel pump 2 is adjusted, and the fuel pressure p in the supply pipe 11f are the first target pressure values ​​p tar,1_meth ,p tar,1_eth rises to.

[0049] FIG. 4 shows the methanol p determined by the control unit 10. vap,meth 1 is a diagram showing an example of a vapor pressure curve of the predetermined pressure margin p m An example of this is the fuel temperature T f In this case, the determined vapor pressure curve p vap,meth However, the fuel temperature T f and / or depending on the operating point of the fuel pump 2, a predetermined pressure margin p m may vary. m may be an offset as shown in FIG. 4 or may be a relative value. The predetermined pressure margin p m may be in the range of 0.2 bar to 1 bar.

[0050] Figure 5 shows the relationship between the fuel temperature and the f The various pressure pulsations p that may occur in the supply pipe 11 to the high-pressure pump 7 as a function of time t at pul,1 ,p pul,2 and p pul,3 The figure also shows the average fuel pressure p FP,m , fuel p vap The figure shows the vapor pressure of the material and the risk area where bubbles are expected to form.

[0051] Pressure pulsation p pul,1 indicates the exponential increase of pressure pulsation, and the fuel pressure p f This means that the pressure pulsation p pul,1 The minimum pressure that occurs at vap However, there is little risk of the pressure pulsation p pul、2 is the vapor pressure p vap Since it has been shown that this pulsation p pul、2 The undershoot of p reaches the risk region where the formation of bubbles is expected. This means that in this case, the mean fuel pressure pFP,m This means that the pressure pulsation p in the supply pipe 11 indicates an exponential pressure drop. pul,3 The situation worsens if pulsations such as those described above occur. In this case, the pressure in the supply pipe 11 decreases over time, so even a part of the pulsation overshoot reaches the risk area. Therefore, to prevent bubbles from forming in the fuel, the average fuel pressure p FP,m needs to be made larger.

[0052] From Figure 5, it can be seen that monitoring the pressure pulsation in the fuel supply system is beneficial to avoid air bubbles in the system, as different types of pressure pulsation can occur depending on the fuel flow rate in the fuel supply system.

[0053] 6 shows a diagram 500 illustrating two characteristic curves of the second target pressure value as a function of temperature. tar,2_nmax indicates the second target pressure value at maximum engine speed, and the lower curve p tar,2_nmin indicates the second target pressure value at the minimum engine speed. tar、2 as a function of temperature and engine speed, i.e., a further characteristic curve representing the engine speed range between the maximum and minimum engine speed may be stored in the map. Different maps may exist for different fuels, or the second set pressure value p tar,2 There may be a single map containing

[0054] At maximum engine speed, the fuel pressure p at minimum engine speed must be maintained to maintain the required fuel flow rate of the high-pressure pump. tar,2_nmin Fuel pressure higher than p tar,2_nmax Furthermore, the second target pressure value is increased at higher temperatures in both cases to prevent the formation of bubbles. This is because the vapor pressure of the fuel used is higher than the second target pressure value p tar,2This means that the fuel pump control value is preferably adjusted only in certain situations where the first target pressure value determined from the current measurements exceeds the second target pressure value. tar,1 It is also possible to appropriately set the fuel pump control value based only on the calculation of the second target pressure p without taking the fuel vapor pressure into account. tar,2 It may also be possible to determine

[0055] An example of a possible relationship between the first and second target pressures is shown in Figure 7 below, which makes it possible to understand different scenarios in which different pressure target values ​​are selected by the control, for example as shown in Figure 8.

[0056] Specifically, FIG. 7 shows the first target pressure values ​​at the maximum and minimum engine speeds, and the determined vapor pressure p of methanol at each engine speed. vap,meth , pressure margin p m , and the determined pressure pulsation p pul、nmax , p pul、nmin As a function of temperature, which is the sum of two linear curves p tar、1_nmax , p tar、1_nmin 6. Furthermore, the second target pressure values ​​p tar、2_nmax , p tar、2_nmin Two characteristic curves are shown.

[0057] Pressure pulsation p at minimum engine speed (shown by the dotted arrow) pul,nmin The amplitude of the pressure pulsation p pul,nmax The reason for the different pressure amplitude is the lower fuel flow rate required at lower engine speeds. However, the pressure pulsation p pul,nmin Therefore, at low fuel temperatures, the first target pressure is higher than the second target pressure. This is because at low speeds and temperatures, only low pressure is required to provide the fuel flow of the high pressure pump, and as a result, the low second target pressure value p is required in this operating range of the engine. tar,2_nminThis is due to the fact that the first target pressure p tar,1_nmin is the second target pressure p tar,2_nmin Since the pressure pulsation p pul,nmin The fuel pump control value may be increased to compensate for the effect of

[0058] However, at maximum engine speed, the second target pressure p tar、2_nmax is the first target pressure p at low to medium fuel temperatures. tar、1_nmax Therefore, no adjustment of the fuel pump control value is required at this operating point. tar、1_nmax is the corresponding second target pressure value p tar、2_nmax , it can be appreciated that adjustment of the fuel pump control value at maximum engine speed is only necessary at high temperatures.

[0059] 8 shows a flow chart illustrating, by way of example, the individual steps of the method described herein. The method begins in step S100 with the selection of fuel type X f , temperature T f , or fuel pressure p f represents the physical parameter X f,0 The method starts by checking whether any of the sensors measuring the physical parameter X indicates a fault. In this case, the fuel supply system must be checked in the workshop (S101) and the method ends in step S107. If all sensors are ready for operation, in step S102, the physical parameter X is measured. f、0 , temperature T f and fuel pressure p f Based on the measured sensor signal, in step S103, the fuel type X f , vapor pressure p var、f , and pressure pulsation p pul The amplitude of is determined.

[0060] Fuel Type X fFor example, by measuring the dielectric constant, density, and / or kinematic viscosity of the fuel in the fuel supply system 20 and determining the fuel type X based on a first set of reference data stored in the control unit 20. f This first set of reference data can be determined by detecting the fuel temperature T f as a function of fuel type X f one or more physical parameters X that can be used to identify f,0 The characteristic curves or maps of a plurality of different fuels each containing a vapor pressure p vap,f can be determined using vapor pressure curves stored in a second set of reference data for multiple fuels. The current vapor pressure p of the detected fuel vap,f To determine the temperature T f The corresponding values ​​can be obtained from the respective vapor pressure curves at the pressure amplitude p pul can be determined from the measured pressure signal by determining the average pressure and the lowest measured pressure over a predetermined time interval and then forming the difference between the average pressure and the lowest pressure.

[0061] Next, in step S104a, the first target pressure value p tar,1 is the determined vapor pressure p var,f , a given pressure margin p m , and pressure pulsation p pul The pressure margin p is calculated as the sum of the amplitudes of m is the first target pressure p tar is always the vapor pressure p var、f The predetermined pressure margin p may be a safety margin that is exceeded. m may vary with the temperature and / or operating point of the fuel pump 2 to prevent the fuel pump 2 from operating outside its optimized operating range.

[0062] In parallel, a predetermined second target pressure p tar,2, engine speed (two different cases "min" and "max" have been discussed above, but more engine speeds can be considered as explained in connection with FIG. 6), the determined fuel type X f , and determine the temperature T f Next, the first target pressure value p tar,1 and a predetermined second target pressure value p tar,2 In other words, the pressure difference between the first target pressure value p tar,1 is the second target pressure value p tar,2 The second target pressure p tar,2 is the first target pressure p tar,1 If the first target pressure value p tar,1 The control value FP of the discharge pump is set so that s (for example, FIG. 9) is adjusted (S105). This is because the second target pressure p tar,2 is the first target pressure p tar,1 If the fuel pressure is lower than f is the first target pressure value p tar,1 The control value FP of the discharge pump is set to be equal to s This means that the

[0063] In the opposite case, the existing control value FP of the discharge pump s is maintained, and the second target pressure p tar,2 The fuel pressure p f is controlled (S106). The procedure described is repeated as long as the engine is running and ends when the engine is turned off (S107).

[0064] 9 is a block diagram illustrating exemplary functional blocks for performing steps of the methods described herein. In functional block 800, the determined vapor pressure p vap、f , a given pressure margin p m , and the determined pressure pulsation p pul The amplitudes of the first target pressure value p tar、1 is calculated.

[0065] The function block 500 represents the schematic map already known from FIG. 5, from which the second target pressure value p tar,2 In function block 801, the difference Δp between the first target pressure and the second target pressure is calculated, and this is limited to a value equal to or greater than 0 by a subsequent limiter 802 with a lower limit value of 0. The limiter 802 sets the control value FP only if the calculated pressure difference Δp is greater than 0. s is adjusted, which means that the first target value p tar,1 is the second target pressure value p tar,2 This means that the limiting pressure difference Δp lim is the pressure difference Δp lim The control value difference ΔFP s The PID controller converts the currently detected large pressure difference Δp lim The control value difference ΔFP can then be amplified according to s is the existing control value FP s,0 The adjusted control value FP is added to s The existing control value FP is input to the fuel pump controller 805. s,0 are the fuel pressure and fuel volume flow rate Q f,s This is based on a second target pressure value input to a function block 804 which contains the characteristic curve of the fuel pump 2 as a function of the second target pressure p tar,1 and the pressure difference is a control value FP suitable for controlling the operation of the fuel pump. s,0 and ΔFP s means that it is converted to

[0066] 9 also shows that the output of the fuel pump controller 805 is input to the fuel pump 2 as an updated pressure control value. Control value FP s When the output value of the fuel pump controller 805 is adjusted, the pressure pulsation p pul Since the actual pressure value of the fuel pump 2 may change, the actual pressure value of the fuel pump 2 is fed back to the function block 800 to calculate the pressure pulsation p pul The input value is continuously updated.

[0067] Alternatively, the limiting pressure difference Δp lim and the specified Second target pressure value p tar,2 The control value FP input to the fuel pump controller 805 is calculated by calculating a third target pressure value, which is the sum of s The third target pressure value is then input to a function block 804, which adjusts the control value FP using the characteristic curve of the fuel pump 2 in the same manner as described above. s,0 (In this case, the control value FP s In this case, the limiting pressure difference Δp lim A PID controller cannot be used to amplify this pressure difference Δp lim is the control value FP s may already be considered before generating

[0068] By implementing the method described in accordance with the flowchart of FIG. 7 and the block diagram of FIG. 8, the formation of gas bubbles in the fuel supply system 10 can be prevented by ensuring that the minimum fuel pressure in the fuel supply system 10 is always greater than the vapor pressure.

[0069] In summary again, the subject matter described herein prevents fuel injection failures caused by fuel vapor lock, minimizes the risk of cavitation erosion at the inlet valve of the high-pressure pump and along the high-pressure side of the injection system, and enables efficient operation of the fuel pump by measuring fuel pressure and determining the associated vapor pressure, thereby avoiding unnecessary increases in target pressure.

[0070] As will be appreciated by those skilled in the art, the present disclosure may be embodied as a method, an apparatus (including a device, machine, system, computer program product, and / or any other apparatus), or a combination of the above, as described above and in the accompanying drawings.

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

[0072] It should be noted that arrows may be used in the diagrams to represent communications, transfers, or other activities involving two or more entities. A double-headed arrow generally indicates that activity can occur in both directions (e.g., a command / request in one direction and a corresponding response in the other, or a peer-to-peer communication initiated by either entity), although in some circumstances activity may not necessarily occur in both directions.

[0073] It should be noted that while unidirectional arrows may generally indicate exclusively or primarily one-way activity, in certain circumstances such directional activity may actually include bidirectional activity (e.g., a message from sender to receiver and an acknowledgment from receiver to sender, or the establishment of a connection before a transfer and the termination of the connection after a transfer). Thus, the types of arrows used in particular drawings to represent particular activities are illustrative and should not be considered limiting.

[0074] Aspects are described above with reference to flowchart illustrations and / or block diagrams of methods and apparatus, and with reference to some sample views of graphical user interfaces generated by the methods and / or apparatus. It will be understood that each block of the flowchart illustrations and / or block diagrams, and / or combinations of blocks in the flowchart illustrations and / or block diagrams, and graphical user interfaces, can be implemented by computer-executable program code.

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

[0076] These computer-executable program codes may also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to function in a particular manner, such that the program code stored in the computer-readable memory produces an article of manufacture including instruction means that implement the functions / operations / output specified in the flowcharts, block diagram blocks, illustrations, and / or descriptions.

[0077] The computer-executable program code may also be loaded into a computer or other programmable data processing apparatus to generate a computer-implemented process, with a series of operational steps that execute on the computer or other programmable apparatus, such that the program code executing on the computer or other programmable apparatus provides steps for implementing the functions / operations / output specified in the flowcharts, block diagram blocks, illustrations, and / or specification. Alternatively, the computer-program implemented steps or operations may be combined with operator or human-implemented steps or operations to carry out the embodiments.

[0078] It should be noted that terms such as "server" and "processor" may be used herein to describe devices that may be used in particular embodiments and should not be construed as limiting to any particular device type unless the context otherwise requires. Thus, a device may include, but is not limited to, a bridge, router, bridge-router (router), switch, node, server, computer, appliance, or other type of device. Such devices typically include one or more network interfaces for communicating over a communications network and a processor (e.g., a microprocessor with memory and other peripherals and / or application-specific hardware) configured to perform the device functions accordingly.

[0079] Communications networks generally may include public and / or private networks, and may include local area, wide area, metropolitan area, storage, and / or other types of networks, and may use communications technologies including, but not limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies.

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

[0081] Unless the context requires otherwise, this disclosure should not be construed as limited to any particular communication message type, communication message format, or communication protocol. Thus, a communication message may generally include, but is not limited to, a frame, packet, dataclam, user dataclam, cell, or other type of communication message.

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

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

[0084] In many cases, logic elements can be added, modified, omitted, executed in a different order, or implemented using different logic constructs (e.g., logic gates, looping primitives, conditional logic, and other logic constructs) without changing the overall result.

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

[0086] Computer program logic implementing all or part of the functionality previously described herein may be embodied in various forms, including, but not limited to, source code form, computer executable form, and various intermediate forms (e.g., forms produced by an assembler, compiler, linker, or locator).

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

[0088] Computer-executable program code for carrying out operations of embodiments of the present disclosure may be written in an object-oriented, scripted, or non-scripted programming language, such as Java, Perl, Smalltalk, C++, etc. However, computer program code for carrying out operations of embodiments may also be written in conventional procedural programming languages, such as the "C" programming language or similar programming languages.

[0089] Computer program logic implementing all or part of the functionality previously described herein may execute at different times on a single processor (e.g., simultaneously), or may execute at the same or different times on multiple processors, and may execute under a single operating system process / thread or under different operating system processes / threads.

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

[0091] A computer program may be in any form (e.g., source code form, computer executable form, or intermediate form) permanently or temporarily fixed on a tangible storage medium such as a semiconductor memory device (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM), a PC card (e.g., a PCMCIA card), or other memory device.

[0092] A computer program may be fixed in any form of signal that can be transmitted to a computer using any of a variety of communication technologies, including, but not limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies.

[0093] The computer program may be distributed in any form, such as on a removable storage medium with accompanying printed or electronic documentation (e.g., shrink-wrapped software), may be preloaded onto a computer system (e.g., on a system ROM or fixed disk), or may be distributed from a server or electronic bulletin board via a communications system (e.g., the Internet or World Wide Web).

[0094] Hardware logic (including programmable logic for use in a programmable logic device) implementing all or a portion of the functionality previously described herein may be designed using conventional manual methods, or may be designed, captured, simulated, or documented electronically 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 utilized, including, but not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or medium.

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

[0097] The programmable logic may be permanently or temporarily fixed in a tangible storage medium such as a semiconductor memory device (e.g., RAM, ROM, PROM, EEPROM, or flash programmable RAM), a magnetic memory device (e.g., a diskette or fixed disk), an optical memory device (e.g., a CD-ROM), or other memory device.

[0098] The programmable logic may be fixed to signals that can be transmitted to a computer using any of a variety of communication technologies, including, but not limited to, analog, digital, optical, wireless (e.g., Bluetooth), networking, and internetworking technologies.

[0099] The programmable logic may be distributed on a removable storage medium with accompanying printed or electronic documentation (e.g., shrink-wrapped software), may be preloaded onto a computer system (e.g., on a system ROM or fixed disk), or may be distributed from a server or bulletin board via a communications system (e.g., the Internet or World Wide Web). Of course, some aspects may be implemented as a combination of both software (e.g., a computer program product) and hardware. Still other embodiments may be implemented entirely in hardware or entirely in software.

[0100] While certain exemplary aspects have been described and illustrated in the accompanying drawings, it should be understood that such aspects are exemplary 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 are possible, in addition to those described in the preceding paragraphs.

[0101] Those skilled in the art will recognize that various adaptations, modifications, and / or combinations of the foregoing embodiments may be made. Accordingly, it should be understood that, within the scope of the appended claims, the present disclosure may be practiced other than as specifically described herein. For example, unless otherwise specified, the steps of processes described herein may be performed in an order different from that described herein, and one or more steps may be combined, separated, or performed simultaneously.

[0102] Additionally, one of ordinary skill in the art will recognize in light of this disclosure that different embodiments or aspects described herein can be combined to form other embodiments. [Explanation of symbols]

[0103] 1 fuel tank 2 fuel pumps 3 Temperature sensor (fuel tank) 4. First measuring means: pressure sensor 5 Second measuring means, temperature sensor (fuel pipe) 6. Third measuring means, fuel sensor 7. High-pressure pump 8 fuel rail 9 fuel injector 10. Control Unit 11 Supply Pipe

Claims

1. 1. A method of controlling a fuel pump of a fuel supply system for an internal combustion engine, comprising: measuring the pressure of fuel in the fuel supply system with a first measuring means; measuring the temperature of the fuel by a second measuring means; measuring a physical parameter of the fuel by a third measuring means; The control unit determining a fuel type based on the measured fuel physical parameters; determining a vapor pressure of the fuel based on the determined fuel type and the measured temperature; determining a pressure amplitude of the measured pressure; Steps and The control unit calculating a first target pressure value as the sum of the determined vapor pressure, the determined pressure amplitude, and a predetermined pressure margin; calculating a pressure difference between the first target pressure value and a predetermined second target pressure value; Steps and If the calculated pressure difference is greater than 0, adjusting, by the control unit, a control value for controlling an operating point of the fuel pump based on the calculated pressure difference; A method comprising:

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

3. The control value for controlling the operating point of the fuel pump is converting the calculated pressure difference into a control value difference using a PID controller; adding the control value difference to the control value, the control value being based on the predetermined second target pressure value; The method of claim 1 , wherein the method is adjusted by performing:

4. The control value for controlling the operating point of the fuel pump is calculating a third target pressure value by adding the calculated pressure difference to the predetermined second target pressure value; converting the third target pressure value into the control value using a characteristic curve of the fuel pump; The method of claim 1 , wherein the method is adjusted by performing:

5. 2. The method of claim 1, wherein 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 of claim 1 , wherein 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, the fuel supply system comprising: a fuel pump for supplying fuel from a tank to a high-pressure pump; a supply pipe for connecting the fuel pump and the high-pressure pump; a first measuring means for measuring the pressure of the fuel in the fuel supply system; second measuring means for measuring the temperature of the fuel in the fuel supply system; a third measuring means for measuring a physical parameter of the fuel in the fuel supply system; a control unit electrically connected to the first, second, and third measuring means; Equipped with the control unit receives the fuel pressure measured by the first measuring means, the fuel temperature measured by the second measuring means, and the physical parameter measured by the third measuring means; Implementing the method of claim 1 The fuel supply system is configured as follows.

8. 8. The fuel supply system of claim 7, wherein the first, second and third measuring means are disposed in the supply pipe for measuring pressure, temperature and physical parameters of the fuel flowing in the supply pipe.

9. 8. The fuel supply system of claim 7, wherein the sampling rate of said first measuring means is higher than a piston stroke frequency of said high pressure pump.

10. A controller configured to control an internal combustion engine and to perform the method of claim 1.

11. A computer program product storable in a memory comprising instructions which, when executed by a computer, cause the computer to perform the method of claim 1.

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