Method for determining the condition of a fuel system of a motor vehicle and motor vehicle

Abstract

The invention relates to a method for determining the state of a fuel system of a motor vehicle designed to supply an internal combustion engine with fuel, in which, upon starting the internal combustion engine, a first comparison is performed by means of an electronic computing device (step S1), in which at least one fuel value, which characterizes a quantity of fuel consumed by the internal combustion engine during operation prior to starting, is compared with a first reference value. A second comparison is then performed by means of the electronic computing device (step S2), in which at least one temperature value, which characterizes a temperature of a component of the internal combustion engine measured by means of a temperature sensor, is compared with a second reference value.A third comparison is carried out using the electronic computing device (step S3), in which a time value, which characterizes a period of time between the end of operation and the start of the internal combustion engine, during which the internal combustion engine was continuously deactivated, is compared with a third comparison value.

Description

The invention relates to a method for determining the state of a fuel system of a motor vehicle. The invention also relates to a motor vehicle. German patent DE 10 2005 053 406 A1 and US patent 7 383 804 B2 disclose a method for detecting a depressurized fuel system in a vehicle with an internal combustion engine. In this method, a parameter characterizing the fuel system temperature is recorded when the internal combustion engine is switched off. During a subsequent driving cycle, a parameter characterizing the fuel system temperature is recorded when the internal combustion engine is started. The pressure in the fuel system is then inferred from the difference between the switch-off and start temperatures. According to US 8,881,707 B2, fuel pressure varies depending on whether a fuel pressure sensor and a high-pressure pump are malfunctioning. Therefore, a first threshold is defined to determine if the fuel pressure sensor is faulty, and a second threshold is defined to determine if the high-pressure pump is faulty. The second threshold is higher than the first. By comparing a fuel pressure sensor reading to the first and second thresholds, a fuel pressure sensor malfunction and a high-pressure pump malfunction are distinguished. A first fail-safe or a second fail-safe is executed according to the fault code. US Patent 2010 / 0 108 035 A1 discloses an engine system and a method for starting an internal combustion engine of the engine system. In one embodiment, the method comprises setting a fuel pressure in a fuel line to a first value; after the fuel pressure in the fuel line has reached the first value, introducing the fuel supply to the internal combustion engine from the fuel line by successively injecting fuel directly into the combustion chambers of the internal combustion engine; and after at least one first A fuel injection event is the reduction of the fuel pressure in the fuel line from a first value to a second value via subsequent successive fuel injection events by adjusting an operating parameter of the high-pressure fuel pump. The method can optionally include increasing an air-fuel ratio via successive fuel injection events after the fuel supply has been initiated, by varying the amount of fuel injected directly into the combustion chambers. The object of the present invention is to create a method and a motor vehicle such that the state of the fuel system can be determined in a particularly advantageous manner. This problem is solved according to the invention by a method with the features of claim 1 and by a motor vehicle with the features of claim 9. Advantageous embodiments of the invention are the subject of the dependent claims. A first aspect of the invention relates to a method for determining the state, particularly the current state, of a fuel system of a motor vehicle, also referred to as a fuel supply system or fuel supply device. The fuel system is designed to supply an internal combustion engine of the motor vehicle with fuel, particularly liquid fuel. Thus, the motor vehicle, also simply referred to as a vehicle and preferably designed as a motor car, particularly a passenger car, in its fully manufactured state comprises the internal combustion engine and the fuel system by means of which the internal combustion engine can be supplied with fuel, particularly liquid fuel. The motor vehicle can be driven by means of the internal combustion engine. In order to determine the current state of the fuel system particularly advantageously, the invention provides that, during a start-up of the internal combustion engine (also referred to as starting or engine start), a first comparison is carried out by means of an electronic computing device, particularly of the motor vehicle. The electronic computing device is or comprises, in particular at least or exactly, a control unit, or is also referred to as a control unit.The characteristic that the first comparison is carried out when the internal combustion engine is started means, in particular, that the first comparison is performed by means of the electronic computing device as a result of detecting or receiving a signal, especially an electrical one, to start the internal combustion engine, and before the rotational speed of an output shaft of the internal combustion engine reaches idle speed, and before a high-pressure fuel pump delivers the fuel, and while the output shaft is rotating. In other words, the internal combustion engine has the aforementioned output shaft, which, particularly when the internal combustion engine is designed as a reciprocating engine, i.e., a piston engine, is designed as a crankshaft. The output shaft is rotatably mounted on the engine housing about an output shaft axis of rotation relative to the engine housing.The internal combustion engine can provide drive torque for propelling the vehicle via the output shaft. When the internal combustion engine is idling after starting, the output shaft rotates relative to the engine block around its axis of rotation at the idle speed. In other words, when the internal combustion engine is idling after starting, the output shaft rotates around its axis of rotation relative to the engine block at a speed equal to the idle speed.To start the internal combustion engine, that is, to carry out the starting of the internal combustion engine, the initially stationary output shaft, which therefore does not rotate around the output shaft axis and relative to the housing, is driven by means of an electric motor and thereby rotated around the output shaft axis relative to the housing, particularly as a result of detecting or receiving the signal.The first comparison is preferably carried out as a result of detecting or receiving the signal to start the internal combustion engine and before the internal combustion engine is in its idling operation, wherein the first comparison is preferably carried out as a result of detecting or receiving the signal before the internal combustion engine is in its idling operation, that is, before the speed at which the output shaft rotates about the output shaft axis of rotation relative to the housing corresponds to the idling speed, and preferably before the high-pressure fuel pump delivers the fuel, and while the output shaft is rotated by means of the electric motor as a result of detecting or receiving the signal, but at a speed which is lower than the idling speed.In idle mode, i.e., when the output shaft rotates at idle speed relative to the housing around the output shaft axis, the electric motor does not drive the output shaft. The high-pressure fuel pump is a primary pump in the fuel system, comprising the high-pressure fuel pump and a secondary pump, also known as the low-pressure fuel pump. The high-pressure fuel pump is also referred to as the high-pressure pump, and the low-pressure fuel pump is also referred to as the low-pressure pump. The pumps are arranged in a fuel line, with each pump capable of pumping the fuel through at least a certain length of the fuel line, which is also simply called the line. Specifically, the low-pressure pump can draw fuel from a vehicle tank and deliver it to the high-pressure pump, generating a first pressure of the fuel. This first pressure then supplies the high-pressure pump with fuel at this pressure.The high-pressure pump can deliver fuel from itself to the internal combustion engine, thereby generating a second fuel pressure that is higher than the first. In the direction of fuel flow, as the fuel is delivered by the pumps and flows through the fuel line, the low-pressure pump is located downstream of the fuel tank (also referred to simply as the tank) and upstream of the high-pressure pump and the internal combustion engine, while the high-pressure pump is located downstream of the low-pressure pump and upstream of the internal combustion engine. Thus, for example, the internal combustion engine can be supplied with the fuel at the second pressure generated by the high-pressure pump, i.e., with fuel exhibiting the second pressure generated by the high-pressure pump.In particular, the first comparison is carried out by means of the electronic computing device as a result of the detection or reception of the signal and while the low-pressure pump (second pump) is delivering the fuel, but while the high-pressure pump (first pump) is not delivering the fuel. The term "determining" or "receiving" the signal includes, in particular, the following: For example, the electronic computing device determines or receives the signal. For example, the signal, and thus the determination or reception of the signal, results from a person operating the motor vehicle activating a control element of the motor vehicle, whereby the control element is used to start the internal combustion engine, particularly one that is initially deactivated, thus enabling the engine to be started. In other words, the signal, and consequently the starting of the internal combustion engine, can be effected by operating, particularly by activating, the control element. In the first comparison, at least one fuel value is compared with a first reference value, which can be specified or predetermined, using the electronic computing device. The fuel value characterizes the quantity of fuel consumed by the internal combustion engine during an operation preceding, in particular immediately preceding, the start of the internal combustion engine. In other words, the aforementioned operation of the internal combustion engine preceded, in particular immediately, the current start of the internal combustion engine, for example, during a driving cycle in which the motor vehicle was powered and thus driven by the internal combustion engine. The aforementioned driving cycle is also referred to as the first driving cycle.The characteristic that the aforementioned operation of the internal combustion engine immediately precedes the, in particular, current, start of the internal combustion engine means that no further start of the internal combustion engine occurs or has occurred between the aforementioned operation of the internal combustion engine and the, in particular, current, start of the internal combustion engine, so that during the period between the aforementioned operation of the internal combustion engine and the, in particular, current, start of the internal combustion engine, the internal combustion engine is or was deactivated, in particular continuously and thus without interruption. The start of the internal combustion engine is, for example, the beginning of a second driving cycle of the motor vehicle, which follows the first driving cycle immediately and is, for example, driven by the internal combustion engine during the second driving cycle. Furthermore, according to the invention, it is provided that when the internal combustion engine is started, that is, preferably as a result of detecting or receiving the signal to start the internal combustion engine, and preferably before the speed of the output shaft reaches the idle speed, and preferably before the high-pressure fuel pump delivers the fuel, and most preferably while the output shaft is rotated by the electric motor around the output shaft axis of rotation and relative to the housing in order to start the internal combustion engine, a second comparison is carried out by means of the electronic computing device, in which at least one temperature value is compared with a second comparison value, in particular a predefinable or predetermined one. The temperature value characterizes the temperature of a component of the internal combustion engine, measured by a temperature sensor. The component of the internal combustion engine is, for example, the aforementioned engine housing. In particular, the aforementioned housing is a crankcase of the internal combustion engine. More specifically, the temperature of the component is understood to be the material temperature of the component, that is, the temperature of a material, preferably a solid, from which the component is formed. Preferably, the component is the aforementioned solid. It is conceivable that the temperature of the component, also known as the component temperature, is measured and thus recorded using the temperature sensor in the process. Furthermore, according to the invention, it is provided that when the internal combustion engine is started, that is, preferably as a result of detecting or receiving the signal to start the internal combustion engine and preferably before the speed of the output shaft reaches the idle speed and preferably before the high-pressure fuel pump delivers the fuel and preferably while the output shaft is rotated by the electric motor around the output shaft axis relative to the housing, a third comparison is carried out by means of the electronic computing device, in which a time value is compared with a third comparison value, in particular a predefinable or predetermined one.The time value characterizes the aforementioned period of time between the end of operation and the start of the internal combustion engine, during which the engine was continuously and thus without interruption deactivated. In other words, the time value characterizes or defines the length of time between the end of the operation immediately preceding the start of the internal combustion engine and the start of the engine itself. Furthermore, according to the invention, it is provided that when the internal combustion engine is started, preferably as a result of determining or receiving the signal to start the internal combustion engine and preferably before the speed of the output shaft reaches the idle speed and preferably before the high-pressure fuel pump delivers the fuel and preferably while the output shaft is being rotated, the, in particular current, state of the fuel system is determined as a function of a first result of the first comparison and as a function of a second result of the second comparison and as a function of a third result of the third comparison, in particular by means of the electronic computing device.The method according to the invention enables a particularly precise, meaningful and reproducible and therefore advantageous determination of the, in particular current, state of the fuel system, which, for example, subsequently allows for a particularly advantageous operation of the motor vehicle, in particular of the internal combustion engine and / or the fuel system. The amount of fuel consumed by the internal combustion engine during the operation preceding the start, particularly immediately, and also referred to as the fuel quantity, is also called fuel consumption and is preferably a cumulative fuel consumption, which in the method according to the invention is used as a first indicator that the internal combustion engine, also referred to as the motor, is in an advantageous state, particularly with regard to its temperature, and thus that the state is, for example, an advantageous state with regard to the temperature of the internal combustion engine in order to be able to perform at least one function.In the method according to the invention, the temperature value, i.e., the temperature of the component, is also used as a second indicator of whether the current state of the internal combustion engine is advantageous for performing at least one function. Furthermore, the time value, i.e., the time interval or its duration, is used as a third indicator of whether the current state of the internal combustion engine, particularly the fuel system, is advantageous for performing the function. This means that not only the temperature value is used as an indicator of whether the state of the internal combustion engine, particularly the fuel system, is advantageous for performing the function, but also the first and second indicators. In order to determine the, in particular current, state of the fuel system particularly advantageously and consequently to achieve a particularly advantageous operation of the motor vehicle, it is provided in one embodiment of the invention that the state includes a, in particular current, pressure state of the fuel system, so that determining the pressure state, i.e., determining the state, includes drawing conclusions about a pressure in the fuel system depending on the first result, depending on the second result, and depending on the third result. Another embodiment is characterized in that at least one function of the motor vehicle is performed depending on the determined state. This ensures particularly advantageous operation. In particular, it is preferably provided that the at least one function is performed when, and preferably only when, it can be concluded from all three indicators that the state of the internal combustion engine, especially the fuel system, is advantageous for performing the at least one function. This ensures particularly advantageous operation. Another embodiment is characterized in that at least one function is performed depending on the pressure of the fuel system, which allows for a particularly advantageous operation. In a further, particularly advantageous embodiment of the invention, the at least one function is performed if and preferably only if the first result is that the fuel value is greater than the first reference value, if the second result is that the temperature value is less than the second reference value, and if the third result is that the time value is greater than the third reference value. Then, and for example only then, do all three indicators show that the condition of the internal combustion engine or the fuel system is favorable for performing the function. Thus, particularly advantageous operation can be ensured. In a further, particularly advantageous embodiment of the invention, at least one function is performed during the starting of the internal combustion engine, preferably as a result of detecting or receiving the signal to start the internal combustion engine, and preferably before the speed of the output shaft reaches idle speed, and preferably before the high-pressure fuel pump delivers the fuel, and preferably while the output shaft is being rotated. This ensures particularly advantageous operation of the motor vehicle. In order to achieve a particularly advantageous operation, it is further incorporated in the invention that the at least one function includes testing a pressure sensor of the fuel system, wherein the pressure sensor is provided or designed to measure a pressure, in particular of the fuel, in the fuel system, in particular in the fuel line. To achieve particularly advantageous operation, a further embodiment of the invention provides that testing the pressure sensor includes comparing the pressure measured by the pressure sensor with a reference pressure. For example, testing the pressure sensor includes determining, particularly by means of the electronic computing unit, a pressure signal, especially an electrical one, provided by the pressure sensor and characterizing the pressure measured by the pressure sensor. For example, the electronic computing unit receives the pressure signal, thereby determining the pressure signal and thus the pressure measured by the pressure sensor. Subsequently, the electronic computing unit compares the pressure characterized by the pressure signal with the reference pressure.If this comparison reveals, for example, that the pressure measured by the pressure sensor deviates from the reference pressure, or that a deviation of the pressure measured by the pressure sensor from the reference pressure exceeds a predefined threshold, particularly because the pressure measured by the pressure sensor is greater than the reference pressure, then it is concluded, for example, that the pressure sensor is defective, i.e., that the pressure sensor is malfunctioning. In particular, it is then concluded that the pressure sensor has drifted, i.e., that sensor drift of the pressure sensor is present.In a subsequent step, for example, sensor drift can be validated, particularly during vehicle operation, where, for instance, the second driving cycle includes the driving operation itself. During sensor drift validation, a mixture test is performed, for example.For example, if a deviation of a mixture with which the internal combustion engine is operated, also referred to as mixture deviation, exceeds a predefined or predetermined error threshold for a predefined or predetermined time, then the aforementioned malfunction, in particular sensor drift, of the pressure sensor is confirmed, and an error is entered into an error memory, in particular an electrical or electronic one, of the electronic computing device, whereby the error characterizes, defines, or indicates that the pressure sensor is malfunctioning, in particular exhibiting sensor drift. A second aspect of the invention relates to a motor vehicle, also referred to simply as a vehicle, and preferably configured as a motor car, in particular as a passenger car, which is configured to carry out a method according to the first aspect of the invention. Advantages and advantageous embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention and vice versa. The invention enables precise, informative, and robust determination of the system's condition, particularly in determining whether the fuel system is depressurized, i.e., whether the pressure in the fuel system is greater than a predefined or predetermined level. For example, if it is determined that the fuel system is depressurized, i.e., if the pressure in the fuel system is less than or equal to the predetermined level, then at least one function can be advantageously performed. Testing the sensor is also referred to as diagnostics or sensor diagnostics.This method ensures, for example, that the sensor diagnosis is performed when, and preferably only when, the fuel system is depressurized, i.e., when the pressure in the fuel system is less than or equal to the level. This ensures that the sensor can be tested precisely and thus meaningfully through the diagnosis, allowing for a precise determination of whether the sensor exhibits the described sensor drift or not. It is preferably provided that the at least one function is performed without regard to the fluid temperature, i.e., that the at least one function is performed independently of a fluid temperature such as intake air temperature, oil temperature, coolant temperature, ambient temperature, or fuel temperature. Further details of the invention will become apparent from the following description of a preferred embodiment with the accompanying drawing. Figure 1, the only one in the drawing, shows a block diagram illustrating a method for determining the state of a fuel system of a motor vehicle. The following describes a method for determining, in particular the current state, of a motor vehicle's fuel system with reference to Fig. 1. This means that the motor vehicle, also referred to simply as the vehicle and preferably designed as a motor car, especially a passenger car, comprises the internal combustion engine and the fuel system. The internal combustion engine is also referred to as the combustion engine, internal combustion engine, or motor, and the motor vehicle can be driven by means of the internal combustion engine. The fuel system is a fuel supply device by means of which the internal combustion engine can be supplied with fuel, preferably liquid fuel. For this purpose, the motor vehicle has, for example, a fuel tank, also referred to simply as the tank, in which the fuel is received or stored in the process.The fuel system allows fuel to be conveyed from the tank to the internal combustion engine, thus supplying the engine with fuel from the tank. The fuel system includes, for example, a fuel line, also simply called a line, through which the fuel flows from the fuel tank to the internal combustion engine. Once the engine is supplied with fuel, the fuel can be introduced into at least one combustion chamber. This fuel supply allows, for example, at least one fuel-air mixture, also called a mixture, to be created and taken up in the combustion chamber.The mixture comprises at least air and the fuel with which the internal combustion engine was or can be supplied. In the combustion chamber, the mixture can be combusted, in particular ignited and burned. The internal combustion engine has a housing, for example, designed as a crankcase, and an output shaft, for example, designed as a crankshaft, which is rotatably mounted on the housing about an output shaft axis of rotation relative to the housing. By burning the mixture, the output shaft can, for example, be driven and thereby rotated about the output shaft axis of rotation relative to the housing. Via the output shaft, the internal combustion engine can provide drive torques for propelling the motor vehicle. The process includes a first step S1, which is performed when the internal combustion engine is started, particularly when it is initially deactivated. Starting the internal combustion engine, also referred to as starting or engine start, means that by starting the internal combustion engine, it is switched from a deactivated state to an activated state. In the deactivated state, the output shaft is stationary. This means that the output shaft does not rotate around its axis of rotation relative to the housing. In the activated state, the internal combustion engine is in its firing mode, in which, within each operating cycle of the internal combustion engine, the fuel-air mixture is first drawn into the combustion chamber and then combusted.The feature that the first step S1 is performed when the internal combustion engine is started means, in particular, that the first step S1 is performed as a result of detecting or receiving a signal, especially an electrical one, to start the internal combustion engine, and preferably before the output shaft, which is rotatable or rotating about its axis of rotation relative to the housing, reaches an idle speed, and preferably before a high-pressure fuel pump of the fuel system delivers the fuel, and preferably while the output shaft is being rotated, but such that the speed at which the output shaft is rotated about its axis of rotation relative to the housing is lower than the idle speed. The method, and thus the first step S1, is performed by means of an electronic computing device, in particular in the motor vehicle. The fuel system includes a high-pressure fuel pump, also known as a high-pressure pump, as its first pump, which is located, for example, in the fuel line. Furthermore, the fuel system includes, for example, a second pump, also known as a low-pressure pump or low-pressure fuel pump. The second pump is located, for example, in the fuel line, specifically such that, in the direction of fuel flow from the tank to the internal combustion engine, the second pump is located downstream of the fuel tank and upstream of the first pump and upstream of the internal combustion engine, and the first pump is located downstream of the fuel tank, downstream of the second pump, and upstream of the internal combustion engine.The low-pressure pump can transfer fuel from the tank to the high-pressure pump, thereby creating, for example, an initial fuel pressure. This allows the high-pressure pump to supply fuel at this initial pressure. The high-pressure pump can then transfer fuel away from itself, towards the internal combustion engine, creating a second fuel pressure that is higher than the initial pressure. This allows the internal combustion engine to be supplied with fuel at this second pressure. It is conceivable that the first step, S1, is carried out while the low-pressure pump transfers fuel through at least a section of the fuel line, while the high-pressure pump does not transfer fuel. In the first step S1, an initial comparison is performed using the electronic computing device, in which a fuel value is compared with a first reference value, which can be predefined or predetermined. The fuel value characterizes the quantity of fuel consumed by the internal combustion engine during operation immediately preceding, and especially before, the engine's start-up. In other words, the fuel value characterizes or defines the fuel consumption of the internal combustion engine during operation immediately preceding, and especially before, the engine's start-up.In other words, the quantity of fuel consumed by the internal combustion engine during the operation preceding the start, in particular immediately, is a consumption quantity of fuel, wherein the internal combustion engine has consumed the consumption quantity during the operation preceding the start, in particular immediately, in a cumulative manner.The characteristic that the operation of the internal combustion engine immediately precedes or has preceded the start means that between the start and the operation of the internal combustion engine immediately preceding the start, i.e., between the start and the end of the operation of the internal combustion engine immediately preceding the start, no further starting of the internal combustion engine occurs or has occurred, and the internal combustion engine is or has been continuously and thus without interruption in the deactivated state from which the internal combustion engine is brought into the deactivated state by the start. In this method, a second step S2 is performed by means of the electronic computing device, wherein the second step S2 is performed, for example, after the first step S1. The second step S2 is performed when the internal combustion engine is started. It is preferably provided that, in particular, the second step S2 is performed as a result of the detection or reception of the signal to start the internal combustion engine, and preferably before the speed of the output shaft reaches the idle speed, and most preferably before the high-pressure fuel pump delivers the fuel, and most preferably while the output shaft is being rotated about its axis of rotation relative to the housing. The signal for starting the internal combustion engine, also known as the start signal, results, for example, from a person operating a control element of the vehicle. By operating or activating this control element, the signal, and thus the start of the internal combustion engine, is triggered. In other words, the aforementioned person using the vehicle can, for example, operate the control element with one of their fingers, thereby starting the internal combustion engine. For instance, the person's operation of the control element is detected by a sensor in the vehicle, and as a result of this detection, the sensor provides the start signal.The electronic computing unit receives the start signal, for example, and thus determines the start signal. As a result of determining or receiving the start signal, an electric motor of the vehicle is activated, so that the output shaft is driven by the electric motor and thereby rotated around the output shaft's axis of rotation relative to the housing to perform the start, causing the output shaft to rotate around the output shaft's axis of rotation relative to the housing at a certain speed.Preferably, the first step S1 and the second step S2 are carried out while the output shaft is driven by the electric motor and consequently rotates around the output shaft axis relative to the housing at a speed, but the speed is lower than the idle speed at which the output shaft rotates around the output shaft axis relative to the housing in an idle operation of the internal combustion engine, in particular without being driven by the electric motor or another electric motor. In the second step S2, a second comparison is performed using the electronic computing device, in which at least one temperature value is compared with a second reference value, which is particularly predefinable or predetermined. The temperature value characterizes or defines a temperature of a component of the internal combustion engine, measured, i.e., recorded, by a temperature sensor of the motor vehicle. The component is, in particular, the housing, which is designed as a solid body. In particular, the component is a solid body. In the process, a third step S3 is also performed by means of the electronic computing device, which is carried out, for example, after the first step S1 and after the second step S2. The third step S3 is also carried out when the internal combustion engine is started. It is preferably provided that, in particular, the third step S3 is carried out as a result of the detection or reception of the start signal, and preferably before the speed of the output shaft reaches the idle speed, and preferably before the high-pressure fuel pump delivers the fuel, and most preferably while the output shaft is being rotated about its axis of rotation relative to the housing, especially such that the speed is even lower than the idle speed.In the third step S3, a third comparison is performed using the electronic computing device, in which a time value is compared with a third comparison value, which can be predefined or is predetermined. The time value characterizes a period of time between the aforementioned end of the operation of the internal combustion engine immediately preceding its start-up and the start-up of the internal combustion engine, during which the internal combustion engine was or is continuously deactivated. In this method, a fourth step S4 is performed by means of the electronic computing device, wherein, in particular, the fourth step S4 is performed during the starting of the internal combustion engine. Preferably, the fourth step S4 is performed as a result of the detection or receipt of the start signal for starting the internal combustion engine, and preferably before the speed of the output shaft reaches the idle speed, and preferably before the high-pressure fuel pump delivers the fuel, and preferably while the output shaft is being rotated about the output shaft axis relative to the housing. For example, the fourth step S4 is performed after the third step S4.In the fourth step S4, the electronic computing device determines the, in particular current, state of the fuel system depending on a first result of the first comparison, depending on a second result of the second comparison and depending on a third result of the third comparison. Preferably, the method, particularly a fifth step, includes the execution of at least one function of the motor vehicle, depending on the determined state and thus on the three comparison results. The fifth step is performed, for example, after the fourth step S4. Preferably, the at least one function is performed if and preferably only if the first result is that the fuel value is greater than the first comparison value, the second result is that the temperature value is less than the second comparison value, and the third result is that the time value is greater than the third comparison value.Then, and only then, can it be assumed that the determined, in particular current, state of the internal combustion engine is such a state that enables or permits the advantageous performance of at least one function. The fuel system, for example, has at least one pressure sensor which is designed or configured to measure, i.e., detect, a pressure, in particular of the fuel, in the fuel system, especially the fuel line. The at least one function is or includes, for example, testing the pressure sensor, also referred to as diagnostics or sensor diagnostics. Preferably, the fifth step, and thus the at least one function, is performed when the internal combustion engine is started, such that the fifth step, and thus the at least one function, is preferably performed as a result of detecting or receiving the start signal, and preferably before the speed of the output shaft reaches idle speed, and preferably before the high-pressure fuel pump delivers the fuel, and most preferably while the output shaft is rotated about its axis of rotation relative to the housing. Testing the pressure sensor, i.e., the diagnostic process, includes, for example, comparing the pressure measured by the pressure sensor with a reference pressure. If, for instance, it is determined that the deviation of the pressure measured by the pressure sensor from the reference pressure, particularly upwards, exceeds a predefined threshold, it is concluded that the pressure sensor, also simply referred to as the sensor, is defective or malfunctioning. This malfunction might include, for example, sensor drift, so that the sensor drift is determined by testing the pressure sensor. The determined state is, for example, the pressure state of the fuel system. Thus, it is provided, for example, that depending on the three results of the three comparisons, it is determined that a pressure, in particular of the fuel, in the fuel system, especially in the fuel line, is lower than a predefined or predetermined level, and that, for example, depending on the result of the three comparisons, it is determined that the fuel system is depressurized. Thus, it is preferably provided that the at least one function is performed if and preferably only if it is determined that the pressure in the fuel system is lower than the predetermined level, and in particular that the fuel system is depressurized. This allows the at least one function to be performed particularly advantageously, especially in that it is possible to determine with particular robustness whether the pressure sensor exhibits sensor drift or not. Reference symbol list S1 first step S2 second step S3 third step S4 fourth step

Claims

Method for determining the state of a fuel system of a motor vehicle designed to supply an internal combustion engine with fuel, in which, upon starting the internal combustion engine: - a first comparison is carried out by means of an electronic computing device (step S1), in which at least one fuel value, which characterizes a quantity of fuel consumed by the internal combustion engine during operation prior to starting, is compared with a first comparison value; - a second comparison is carried out by means of the electronic computing device (step S2), in which at least one temperature value, which characterizes a temperature of a component of the internal combustion engine measured by means of a temperature sensor, is compared with a second comparison value;- a third comparison is carried out using the electronic computing device (step S3), in which a time value, which characterizes a period of time between the end of operation and the start of the internal combustion engine, during which the internal combustion engine was continuously deactivated, is compared with a third comparison value; and - the state of the fuel system is determined as a function of a first result of the first comparison, as a function of a second result of the second comparison and as a function of a third result of the third comparison (step S4).; Method according to claim 1, characterized in that the state comprises a pressure state of the fuel system, such that determining the pressure state comprises inferring a pressure in the fuel system depending on the three results of the comparisons. Method according to claim 1 or 2, characterized in that at least one function of the motor vehicle is performed depending on the determined state. Method according to claims 2 and 3, characterized in that at least one function of the motor vehicle is performed depending on the pressure of the fuel system. Method according to claim 3 or 4, characterized in that the at least one function is performed when: - the first result is that the fuel value is greater than the first reference value; and - the second result is that the temperature value is less than the second reference value; and - the third result is that the time value is greater than the third reference value. Method according to one of claims 3 to 5, characterized in that at least one function is performed during the start of the internal combustion engine. Method according to one of claims 3 to 6, characterized in that the at least one function comprises testing a pressure sensor of the fuel system, the pressure sensor of which is provided to measure a pressure in the fuel system. Method according to claim 7, characterized in that the testing of the pressure sensor comprises comparing the pressure measured by the pressure sensor with a reference pressure. Motor vehicle which is designed to carry out a method according to one of the preceding claims.

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