DE102020124868B3 - Method for determining the fuel consumption of an internal combustion engine and motor vehicle - Google Patents

Abstract

The invention relates to a method for determining the fuel consumption of an internal combustion engine (10) with at least one combustion chamber (12). A fuel injection valve (14) for introducing fuel (18) into the respective combustion chamber (12) is provided on each combustion chamber (12). The method comprises the following steps: - detecting a refueling process of a fuel tank (20) for supplying fuel to the internal combustion engine (10), - mixing the fuel (18) in the fuel tank (20) with the newly refueled fuel (19), - determining an energy density for the fuel mixture (18, 19) from the fuel (18) in the fuel tank (20) before the refueling process and the newly refueled fuel (19), and calculating the current fuel consumption of the internal combustion engine (10) from the fuel pressure in a fuel supply device (30 , 34, 36) and the opening times of the fuel injection valves (14) of the internal combustion engine (10) and the determined energy density of the fuel mixture (18, 19). The invention also relates to a motor vehicle (1) with an internal combustion engine (10) and a fuel supply system (62 ) to carry out such a procedure.

Description

The invention relates to a method for determining and monitoring the fuel consumption of an internal combustion engine and a motor vehicle with an internal combustion engine and a tank system for carrying out such a method according to the preamble of the independent patent claims.

With exhaust gas legislation becoming more and more stringent, manufacturers of internal combustion engines, in particular internal combustion engines for driving a motor vehicle, are obliged in the future to monitor fuel consumption during operation of the internal combustion engine. This process is also referred to as "On Board Fuel Consumption Monitoring". The amount of fuel consumed in the vehicle is related to the kilometers driven and can be read out via an interface. Narrow tolerance limits are specified for the measuring accuracy of this function, which must be observed.

Systems are known from the prior art, in which the amount of fuel consumed i.a. is calculated from the pressure of the fuel rail and the opening times of the injection valve. These calculations include standard values for fuel density, fuel viscosity and its energy content, among other things. Deviations of these sizes from the standard values can lead to errors that are currently not taken into account in the calculations. The value given does not contain any information about the sustainability character of the fuel. Nevertheless, the quantity stored in the fuel tank always represents a mixed value of the refueling processes in the past. This mixed value relates in particular to the aspects of sustainability and fuel quality.

From the US 2017 / 0 066 322 A1 a system and a method for determining the fuel quality in a motor vehicle with a hybrid drive are known. When the motor vehicle is refueled, the fuel in the fuel tank is mixed with new fuel with different fuel properties and the engine parameters are adjusted in such a way that when the internal combustion engine is restarted, optimal combustion takes place with the fuel mixture of the two different fuels.

the EP 2 037 103 B1 discloses a controller for an internal combustion engine. The control device includes a refueling detection device for detecting the presence or absence of refueling of the fuel tank and an ignition control unit which controls the ignition of the internal combustion engine. The ignition control unit contains means for estimating a mixing ratio of alcohol contained in fuel, based on an operating state of the internal combustion engine, in order to achieve optimal combustion in the combustion chambers and in particular to avoid knocking combustion.

DE 10 2012 020 913 A1 describes a method for detecting a type of fuel or a fuel characteristic when refueling a motor vehicle. In this case, a detection unit is integrated into a pipeline which connects a tank neck of a motor vehicle to the fuel tank. When the motor vehicle is refueled, the type of fuel or the fuel characteristics are recorded while the fuel is flowing through the pipeline into the tank. As a result, it is possible to precisely detect the fuel in the tank or the fuel characteristic of the fuel in the tank instead of the fuel mixture or the fuel characteristic of a fuel mixture in the tank.

the DE 10 2006 044 502 A1 describes a method for estimating the composition of fuel in a fuel tank of a motor vehicle. To this end, a refueling event is recorded. Fuel composition is monitored during several phases after the refueling event. A plurality of fuel trim offset values are determined with respect to the phases. The fuel trim offset values are used to estimate a fuel composition change. This eliminates the need for a hardware fuel composition sensor.

From the DE 10 2007 054 612 A1 a monitoring system for a catalytic converter is known. The monitoring system includes a fuel determination module that determines a fuel composition based on a sensed composition of fuel in a fuel system. The monitoring system further includes an air/fuel determination module that selectively determines an air stoichiometric ratio based on fuel composition. The monitoring system also includes an oxygen storage capability diagnostic module that calculates a target oxygen storage capability of the catalyst based on the air stoichiometric ratio, compares this target oxygen storage capability to a reference value, and diagnoses the catalyst based on the comparison.

the DE 10 2008 013 776 A1 discloses an engine control module that includes an alcohol compensated Fuel consumption value determined. The engine control module includes an alcohol percentage module that determines a percentage of alcohol in a fuel and a fuel mass module that determines a mass of the fuel. The engine control module further includes a fuel volume module that calculates a volume of the fuel based on the mass of the fuel, a density of the fuel, and the alcohol percentage.

Furthermore, from the JP H11 - 182 371 A a fuel supply device for an internal combustion engine with an electric fuel pump for supplying fuel to a fuel injection valve is known. The current consumption of the combustion engine is calculated from the opening times of the fuel injection valves and the fuel pressure in the fuel supply system.

A disadvantage of the known solutions, however, is that the fuel consumption is calculated on the basis of variables stored in the system for the energy content of the fuel. However, different fuels have different energy densities and different ignition tendencies, which not only affect the ignition behavior of the fuel and require ignition adjustment in order to avoid unwanted self-ignition, but also lead to deviations in the calculation of the instantaneous consumption. In the case of petrol engines, for example, it is possible to fill up the internal combustion engine with standard fuel (E5), fuel with a higher proportion of bioethanol (E10) or fuel with a higher octane number (usually referred to as "Super plus" and labeled with at least 98 octane). In diesel vehicles, an increased proportion of biodiesel can lead to a lower energy density and thus to increased fuel consumption. In addition, fuel has different fuel qualities in different regions and countries, so that these regional or national differences can also lead to errors in the calculation of the current fuel consumption.

The object of the invention is now to be able to determine the fuel consumption more precisely during the operation of the internal combustion engine and, in particular when refueling, to adapt the consumption parameters to the changed fuel quality in order to improve the measuring accuracy.

• - Erkennen eines Betankungsvorgangs eines Kraftstofftanks zur Kraftstoffversorgung des Verbrennungsmotors,
• - Vermischen des im Kraftstofftank befindlichen Kraftstoffs mit dem neu getankten Kraftstoff,
• - Ermitteln einer Energiedichte für das Kraftstoffgemisch aus dem vor dem Tankvorgang im Kraftstofftank befindlichen Kraftstoff und dem neu getankten Kraftstoff, und
• - Berechnen des aktuellen Kraftstoffverbrauchs des Verbrennungsmotors aus dem Kraftstoffdruck in einer Kraftstoffzufuhreinrichtung und den Öffnungszeiten der Kraftstoffeinspritzventile des Verbrennungsmotors sowie der ermittelten Energiedichte des Kraftstoffgemischs.

According to the invention, this object is achieved by a method for determining the fuel consumption of an internal combustion engine with at least one combustion chamber, a fuel injection valve for introducing fuel into the combustion chamber being provided on the combustion chamber, which comprises the following steps:

• - Recognizing a refueling process of a fuel tank for supplying fuel to the internal combustion engine,
• - mixing the fuel in the fuel tank with the new fuel,
• - Determining an energy density for the fuel mixture from the fuel in the fuel tank before the refueling process and the newly refueled fuel, and
• - Calculation of the current fuel consumption of the internal combustion engine from the fuel pressure in a fuel supply device and the opening times of the fuel injection valves of the internal combustion engine and the determined energy density of the fuel mixture.

The method according to the invention enables a significantly more exact and precise determination of the current fuel consumption than with solutions known from the prior art, since the calculation is not based on statically stored average energy densities for the fuel, but rather the actual fuel density of the fuel in the fuel tank is used to calculate the fuel consumption current consumption can be taken as a basis.

Advantageous improvements and further developments of the method described in the independent patent claim are possible as a result of the features listed in the dependent claims.

In a preferred embodiment of the method, it is provided that a refueling process is recognized when a detection means detects the stopping of the motor vehicle at a gas station and a triggering element registers that the fuel tank is being filled with new fuel. By detecting a stopping process at a gas station, the monitoring systems can be switched on and off as required, so that a correspondingly complex and energy-intensive continuous operation can be avoided.

In an advantageous embodiment of the method, it is provided that the newly filled fuel and/or the fuel mixture is analyzed and the result of this analysis is forwarded to a control device for calculating the fuel consumption. As a result, the average energy density of the fuel in the fuel tank can be calculated after each refueling operation, which can be stored as a parameter in the control unit until the next refueling operation and for the next refueling operation can be regarded as approximately constant.

Alternatively or additionally, it is advantageously provided that the detection means comprise a seat occupancy sensor, with an imminent refueling process being assumed when it is detected that the driver's seat has been vacated. By leaving the driver's seat when stopping the motor vehicle at a gas station, the system can be activated in an alternative way before refueling in order to switch the system from a stand-by mode to an activated mode.

In a further alternative embodiment of the method, it is provided that the detection means comprise a door sensor, with an imminent refueling process being assumed when the opening of the driver's door is detected. The opening of the driver's door of the motor vehicle when the motor vehicle is parked at a gas pump of a gas station is typical of an impending refueling process. As a result, the system can be activated before refueling in order to switch the system from a stand-by mode to an activated mode.

In a further improvement of the method, it is provided that when several occupied seats in the motor vehicle are detected, a refueling process is assumed if only the driver's seat is relieved and only the driver's door is opened, while at least one other seat remains occupied and no other vehicle door is opened . An impending refueling process is particularly likely if only the driver leaves his driver's seat when the motor vehicle is stopped and the other passengers remain in their seats. Furthermore, the probability of an impending refueling process increases as the tank content in the fuel tank of the motor vehicle decreases. The fill level of the fuel tank can be monitored by a fill level sensor. This can increase the probability that a refueling process is imminent and the system was not activated from its stand-by mode without refueling.

A further partial aspect of the invention relates to a motor vehicle with an internal combustion engine and a fuel supply system with a fuel tank for supplying the internal combustion engine with a fuel, the motor vehicle having a control unit which is set up to carry out such a method when a machine-readable program code is executed by the control unit will. In such a motor vehicle, it is possible to determine the current fuel consumption and monitor it particularly accurately and with few errors.

In an advantageous embodiment of the motor vehicle, it is provided that the fuel supply system comprises a fuel tank, a fuel pump, a fuel line and a high-pressure fuel accumulator, with the fuel pump being actuated and the fuel delivered in such a way that the fuel contained in the fuel tank before the refueling process is mixed with the newly refueled Fuel is mixed so that a substantially homogeneous fuel mixture is formed. As a result, the freshly refueled fuel can be mixed in a particularly simple manner with the fuel that was already in the fuel tank before the refueling process. This means that the freshly refilled fuel can be thoroughly mixed with the fuel already in the tank without additional components.

In a further preferred embodiment of the invention, it is provided that a fuel circulation system is arranged in or on the fuel tank. Alternatively, the freshly refueled fuel can be homogeneously mixed with the fuel that was already in the fuel tank before refueling by a fuel circulation system.

In a further advantageous embodiment of the motor vehicle it is provided that a level sensor is arranged on the fuel tank. A filling level sensor can be used to quantitatively determine the amount of fuel in the fuel tank before the refueling process and the freshly refueled fuel and set it in relation to determine an average fuel density, an average energy content or other fuel parameters.

Alternatively or additionally, it is advantageously provided that a fuel sensor for detecting a fuel quality, an energy density of the fuel and/or a density of the fuel is arranged on the fuel tank or on a filler neck connected to the fuel tank for filling the fuel tank. A fuel sensor can be used to determine the quantity of refilled fuel and the quality of the refilled fuel. As a result, an average energy content or an average fuel density of the fuel mixture in the fuel tank after the refueling process can be calculated in a simple manner.

In an advantageous embodiment of the motor vehicle, it is provided that the motor vehicle has detection means in order to prevent a stop to detect the process at a gas station and has a triggering element which triggers such a method when the motor vehicle is refueled with new fuel. As a result, the system can be brought from a stand-by mode into an activated mode in a simple manner immediately before a refueling process and switched back to a stand-by mode after the refueling process. This reduces the energy consumption. In particular, additional circulation activities can be avoided in order to mix the fuel when no further fueling process takes place.

Unless stated otherwise in the individual case, the various embodiments of the invention mentioned in this application can advantageously be combined with one another.

• 1 ein Kraftfahrzeug mit einem Verbrennungsmotor und einem Kraftstoffversorgungssystem in einer schematischen Darstellung;
• 2 einen Verbrennungsmotor mit einem Kraftstoffversorgungssystem in einer schematischen Darstellung; und
• 3 ein Ablaufdiagramm zur Durchführung eines erfindungsgemäßen Verfahrens zur Ermittlung und Überwachung des Kraftstoffverbrauchs eines Kraftfahrzeugs mit einem Verbrennungsmotor.

The invention is explained below in exemplary embodiments with reference to the associated drawings. Identical components or components with the same function are identified in the different figures with the same reference numbers. Show it:

• 1 a motor vehicle with an internal combustion engine and a fuel supply system in a schematic representation;
• 2 an internal combustion engine with a fuel supply system in a schematic representation; and
• 3 a flowchart for carrying out a method according to the invention for determining and monitoring the fuel consumption of a motor vehicle with an internal combustion engine.

1 shows a motor vehicle 1 with an internal combustion engine 10. The internal combustion engine 10 has a plurality of combustion chambers 12. FIG. The motor vehicle 1 also includes a fuel tank 20 in which a fuel 18 is stored. A filler neck 22 is formed on motor vehicle 1, with which fuel 18, 19 can be filled into fuel tank 20. The filler neck 22 can be closed by a tank cap 24 . The tank cap 24 is located behind a tank flap 26, which covers the tank cap 24 and protects it from external damage.

The motor vehicle 1 has several vehicle doors 66, 68 through which a driver or a passenger can enter an interior of the motor vehicle 1. The vehicle doors 66, 68 each have a door lock 74 and a door sensor 56, which can be used to detect whether the vehicle door is open or closed. A plurality of seats 64, 76, in particular a driver's seat 64 and at least one further vehicle seat 76 for a passenger, are arranged in the motor vehicle 1. The vehicle seats 64, 76 each have a seat occupancy sensor 54 to detect the occupancy of the vehicle seats 64, 76.

The motor vehicle 1 has at least one detection means 40, with which it can be recognized that the motor vehicle 1 is located at a gas station 100 and a refueling process is imminent. The detection means 40 can in particular include a GPS sensor 52, a transmitter unit 48, a receiver unit 50 or a vehicle sensor 54, 56.

The motor vehicle 1 has a control device 80 in order to calculate the fuel consumption of the internal combustion engine 1 and to monitor it during the operation of the internal combustion engine 10 .

In 2 An internal combustion engine 10 having a fuel supply system 62 is shown. In this exemplary embodiment, the internal combustion engine 10 is designed as a spark-ignited internal combustion engine 10 based on the Otto principle. The internal combustion engine 10 has a plurality of combustion chambers 12, on each of which a fuel injection valve 14 for metering a fuel 18, 19 into the respective combustion chamber 12 is provided. Furthermore, a spark plug 78 is assigned to each combustion chamber 12 in order to ignite an ignitable fuel-air mixture in the respective combustion chamber 12 . In addition, a combustion chamber sensor 16 is arranged on at least one of the combustion chambers 12 in order to monitor the combustion in the combustion chambers 12 and to prevent damage to the internal combustion engine 10 due to undesired self-ignition of the fuel 18 , 19 . Alternatively, the internal combustion engine 10 can also be designed as a diesel engine, in which case the spark plugs 78 are omitted.

The internal combustion engine 10 is supplied with fuel 18 , 19 by a fuel supply system 62 . The fuel supply system 62 includes a fuel tank 20 in which a fuel 18 is stored. The fuel supply system 62 also includes a pre-supply pump 32 and a high-pressure pump 30, with which the fuel 18, 19 from the fuel tank 20 is compressed and a high-pressure fuel accumulator 36 is supplied. For this purpose, the fuel tank 20 is connected to the high-pressure pump 30 via a first fuel line 28 and the high-pressure pump 30 is connected to the high-pressure fuel reservoir 36 via a further fuel line 34 . The high-pressure fuel accumulator 36 is preferably designed as a common rail accumulator. A rail pressure sensor 60 and a pressure control valve or pressure limiting valve 70 are arranged on the high-pressure fuel accumulator 34 . To the high-pressure fuel accumulator 34 a fuel return line 72 is connected, via which the fuel 18, 19 can be fed back into the fuel tank 20. The high-pressure fuel accumulator 34 is connected to the respective fuel injection valves 14 via high-pressure lines in order to inject the fuel 18 , 19 and high pressure into the combustion chambers 12 of the internal combustion engine 10 .

The fuel supply system 62 also includes a filler neck 22 through which new fuel 19 can be filled into the fuel tank 20 . The filler neck 22 can be closed with a tank cap 24 in order to prevent fuel 18, 19 or fuel vapors from escaping. The tank cap 24 can be covered by a tank flap 26 in order to protect the tank cap from the effects of the weather and/or damage.

A triggering element 44 is provided on the tank cap 24 or the tank flap 26 and detects a refueling process. Furthermore, a fuel sensor 38 can be arranged in the filler neck 22 in order to detect the quantity and/or the quality of the fuel 19 that has been refilled.

A fuel circulation system 42 can be provided in the fuel tank 20 in order to mix the old fuel 18 in the tank with the refilled fuel 19 and thus to produce a substantially homogeneous fuel mixture 18 , 19 . Furthermore, an analysis unit 46 can be arranged in the fuel tank in order to determine the quality, the density and/or the energy content of the fuel 18, 19. Furthermore, the fuel tank 20 has a fill level sensor 58 to determine the fill level 58 of the fuel tank 20 .

In 3 a flowchart for carrying out a method according to the invention for determining and monitoring the fuel consumption of an internal combustion engine 10 in a motor vehicle 1 is shown. In a first method step <I>, it is determined whether motor vehicle 1 is stationary. In a method step <II>, a notification can be triggered manually that a refueling process of the motor vehicle 1 with fresh fuel 19 is imminent. As an alternative or in addition, it can be recognized in a method step <III> whether the tank cap 24 or the tank flap 26 is unlocked and/or opened. Alternatively or additionally, in a method step <IV>, the geodata, in particular the current position of the motor vehicle 1, can be determined and it can be checked whether the motor vehicle 1 is currently at a gas station 100. These data can be determined via the detection means 40, in particular via a transmitter unit 48, a receiver unit 50, preferably via a GPS sensor 52. Alternatively or additionally, the gas station 100, in particular a gas pump 102 of the gas station 100, emit a signal which is received by the detection means 40, in particular by the receiving unit 50, in order to detect an imminent refueling process. In a method step <VI>, the current tank content of the fuel tank 20 is determined with the fuel 18 in the fuel tank 20, i.e. the tank content before the start of the refueling process with the freshly filled fuel 19. On the basis of this data, a ratio of before the refueling process in Fuel tank 20 located fuel 18 and refueled fuel 19 are formed. In a method step <VIII>, the start of the refueling process is detected by the start of the refueling process, in particular by the triggering element 44 . During the refueling process, the fuel sensor 38 can determine the amount of fuel 19 that has been refilled and its fuel properties. After completion of the refueling process, the fuel circulation system 42 is started in a method step <VIII> in order to mix the fuel 18 already in the fuel tank before the refueling process with the freshly refueled fuel 19 and to produce a substantially homogeneous fuel mixture. Alternatively, this mixing can also take place through the fuel pumps 30, 32 and the return line 72, in which the fuel is pumped in the circuit 28, 34, 72 and thus mixed. In a method step <IX>, the fuel mixture 18, 19, which is in the fuel tank 20 after the mixing process, is analyzed. In particular, the density of the fuel, its energy content and/or the fuel temperature are determined. In a method step <X>, the parameters determined in method step <IX> are sent to control unit 80 in order to be able to determine an exact calculation of the current consumption of internal combustion engine 10 on the basis of this information and to monitor this consumption using an on-board unit be able.

Reference List

1

motor vehicle

10

combustion engine

12

combustion chamber

14

fuel injector

16

combustion chamber sensor

18

fuel

20

fuel tank

22

filler neck

24

gas cap

26

tank flap

28

fuel line

30

fuel pump

32

pre-supply pump

34

fuel line

36

high-pressure fuel accumulator

38

fuel sensor

40

detection means

42

fuel circulation system

44

release element

46

analysis unit

48

transmitter unit

50

receiving unit

52

GPS sensor

54

Seat occupancy sensor

56

door sensor

58

level sensor

60

rail pressure sensor

62

fuel supply system

64

driver's seat

66

vehicle door

68

vehicle door

70

vehicle door

72

vehicle door

74

door lock

76

additional vehicle seat

80

control unit

Claims (10)

Method for determining the fuel consumption of an internal combustion engine (10) of a motor vehicle (1) with at least one combustion chamber (12), a fuel injection valve (14) for introducing fuel (18) into the combustion chamber (12) being provided on the combustion chamber (12). , comprising the following steps: - Recognizing a refueling process of a fuel tank (20) for supplying fuel to the internal combustion engine (10), - Mixing the fuel (18) in the fuel tank (20) with the newly filled fuel (19), - Determining an energy density for the fuel mixture (18, 19) from the fuel (18) located in the fuel tank (20) before the refueling process and the newly refueled fuel (19), and - Calculation of the current fuel consumption of the internal combustion engine (10) from the fuel pressure in a fuel supply device (30, 34, 36) and the opening times of the fuel injection valves (14) of the internal combustion engine (10) and the determined energy density of the fuel mixture (18, 19). procedure after claim 1 , characterized in that a refueling process is recognized when a detection means (40) detects the stopping of the motor vehicle (1) at a gas station (100) and a triggering element (44) that the fuel tank (20) is filled with new fuel (19) registers . procedure after claim 1 or 2 , characterized in that the fuel mixture (18, 19) is analyzed and the result of this analysis is forwarded to a control unit (80) for calculating the fuel consumption. Procedure according to one of Claims 1 until 3 , characterized in that the detection means (40) include a seat occupancy sensor (54) and / or a door sensor (56), wherein upon detection of leaving the driver's seat (64) and opening the driver's door (66) an impending refueling process is assumed. procedure after claim 4 , characterized in that when several occupied seats (64, 76) in the motor vehicle (1) are detected, a refueling process is assumed if only the driver's seat (64) is relieved and only the driver's door (66) is opened while at least one other Seat (76) remains occupied and no other vehicle door (68, 70, 72) is opened. Motor vehicle (1) with an internal combustion engine (10) and a fuel supply system (62) with a fuel tank (20) for supplying the internal combustion engine (10) with fuel (18, 19), the motor vehicle (1) having a control unit (80). , which is set up to use a method according to one of Claims 1 until 5 to be carried out when a machine-readable program code is executed by the control unit (80). Motor vehicle (1) after claim 6 , characterized in that the fuel supply system (62) comprises a fuel tank (20), a fuel pump (30, 32), a fuel line (34) and a high-pressure fuel reservoir (36), with activation of the fuel pump (30, 32) promoting the Fuel (18, 19) takes place in such a way that the fuel (18) contained in the fuel tank (20) before the refueling process is mixed with the newly refueled fuel (19), so that a substantially homogeneous fuel mixture is produced. Motor vehicle (1) after claim 6 or 7 , characterized in that a fuel circulation system (42) is arranged in or on the fuel tank (20). Motor vehicle (1) according to one of Claims 6 until 8th , characterized in that on the fuel tank (20) a level sensor (58) and/or on the fuel tank (20) or on a filler neck (22) connected to the fuel tank (20) a fuel sensor (38) for detecting a fuel quality of the fuel ( 18, 19), an energy density of the fuel (18, 19) and/or density of the fuel (18, 19). Motor vehicle (1) according to one of Claims 6 until 9 , characterized in that the motor vehicle (1) has detection means (40) to detect a stopping process at a gas station (100) and a triggering element (44) which when the motor vehicle (1) is refueled with fuel (19). Procedure according to one of Claims 1 until 5 triggers.

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