DE102022207729A1 - Method for diagnosing a sensor element, computer program which is designed to carry out the method and control device for carrying out the method - Google Patents

Abstract

Method for diagnosing a sensor element (20), in particular a sensor element (20) for determining a pressure (p), the sensor element (20) being in contact with a space (13) in such a way that a property (20) is applied to the sensor element (20). 23) of a content (26) of this one space (13) acts, and between this one space (13) and another space (15) a valve (17) is arranged, characterized in that the valve (17) is opened and then the sensor element (20) is diagnosed.

Description

State of the art

For example, internal combustion engines that are operated with so-called diesel fuel are known from the prior art. For example, the diesel fuel is injected under high pressure, which is previously pumped into a so-called common rail using a high-pressure pump and compressed there at high pressure (for example greater than 1000 bar). In this “common rail” (high-pressure accumulator), a pressure, fuel pressure, in the high-pressure accumulator is determined using a sensor element. Such an approach is generally known. In such devices it is desirable that a state of the sensor element is determined. Condition here is understood to mean, for example, the functionality of the sensor element. For example, devices of the type mentioned above are also known, which are used to inject water into an intake manifold of a spark-ignited internal combustion engine in order to influence subsequent combustion events in a combustion chamber of the internal combustion engine. For example, this water is intended to influence the combustion process in such a way that unfavorably high temperatures do not occur, which is achieved by evaporation or evaporation of the water then located in the combustion chamber. Overall, this measure is intended to avoid or prevent knocking in the combustion chamber. So that when operating such an internal combustion engine it is known in good time whether such a water injection device is ready for operation, it is provided to determine an operating state of the sensor element.

To protect the components of this system from freezing, the water injection system is drained after the vehicle is switched off. To do this, the delivery direction of the pump is reversed, the valves are opened, and a large part of the water is pumped back from the water-carrying components into the tank. An optional shut-off valve may prevent water from running from the tank back into the pump and the pipe system after suction. If the water injection system has been emptied after the vehicle has been parked, the system is filled after the internal combustion engine is started. The pump and the hydraulic system (pipes, rail/high-pressure accumulator and injectors) must be filled with water and the air contained in the system must be discharged through the injectors/valves. The air contained must be removed as completely as possible before the active water injection begins, since air inclusions can lead to an undesirable reduction in the water metering when the air is removed through the injectors. During this phase, a leak test and plausibility check of the water injection system is also carried out. If no pressure build-up can be detected by the pressure sensor during the filling phase, this may be due either to a sensor defect or to a shut-off valve that is stuck closed, if one is present.

A diagnostic function of the water injection system is provided. The task of the method described in more detail below is to detect as early as possible - ideally before filling the water injection system and before any leakage diagnosis - a sensor stub (clamps of the pressure transducer or sensor element) of the sensor or pressure sensor in the water injection system and subsequently even To prevent engine damage. The separate diagnosis of a sensor piece, according to which it is OK, i.e. fully functioning, makes it possible to conclude that the tank shut-off valve is stuck closed in the absence of pressure increases in the intended phase of pressure build-up during filling.

Embodiments of the invention

According to a first aspect of the invention, a method for diagnosing a sensor element is provided, in particular a sensor element for determining a pressure. It is generally provided that the sensor element is in contact with a space in such a way that a property of a content of this space is imprinted on the sensor element room works. A valve is arranged between this one room and another room. As part of this method, it is provided that the valve is opened and then a property or the condition of the sensor element is determined as part of the intended diagnosis.

In this general form, a space, or its contents, which acts on the sensor element can be a general space in which, for example, a liquid or a gas is stored. A possible liquid is water, for example, and a gas, for example, is air or any other gas mixture. In a slightly different, more general case, a fluid is stored in the space, which, as the content of this space, acts on the sensor element with one of its properties. As already mentioned, another room is arranged in a neighborhood of this one room. It can be provided that one room communicates exclusively with the other room - and vice versa - the other room communicates exclusively with one room. This procedure makes it possible for the room to be clearly verified before it is filled It can be determined whether the sensor element, possibly pressure sensor, of the system, possibly water injection system, has a stuck sensor element (“sensor piece”).

According to another embodiment, one room can have an inflow and the other room can have an outflow. In a further embodiment, the other room can receive not only an inflow from the room, but also an inflow from another room. This space can be, for example, a space in a charger and/or a space in an air filter box. The other space can have a drain into a combustion chamber of an internal combustion engine as a drain. In addition to a drain into a combustion chamber, there can also be another or several additional drains into another or several additional combustion chambers.

One room in particular can be a high-pressure storage facility for water (e.g. a so-called water rail) with an inflow. The other space can be, for example, a suction pipe or suction pipe space. Such a space as a suction pipe can be limited, for example. The other space can, for example, be delimited by another component at one or more intended inflows. For example, this can be a connecting pipe or another valve. A boundary can, for example, be a housing of this space, and a valve can also represent a boundary of this space, for example. Such a valve can, for example, be an inlet valve in a combustion chamber of an internal combustion engine, such a limitation can also be a throttle valve in such a room, and the already mentioned valve between one room and the other room can also represent a limitation or is a limit . The other space mentioned can also be essentially unlimited, for example in that this space generally represents an environment. In this sense, the mentioned arrangement of one room, the valve and the other room would be, for example, a room that can communicate via the valve with the other room, which is referred to here as the free environment.

As part of the aforementioned diagnosis of the condition of the sensor element, it is intended to assess a property of the content and its effect on the sensor element. It is provided, for example, that the result of the state of the sensor element is that the sensor element works or does not work. In other words, the result of the diagnosis includes, as a set of results, for example a non-function (no function, lack of function) and alternatively a function, i.e. H. Partial function or full function. A partial function can, for example, mean functionality over a determinable or specific value range of the sensor element. In the context of this previously described embodiment of the method, it is advantageously possible for a state of the contents of one room to change by opening the valve and, based on this change, to make it possible to achieve a function, in particular functionality, by possibly having a different effect on the sensor element. of the sensor element. For example, if a fluid with a property is allowed into one room by opening the valve from the other room, the property of the contents of the room into which the fluid flows changes. In other words: If the fluid flowing into one room - be it a liquid such as water, be it a gas or gas mixture such as air - has a higher temperature than the original contents in the one room, for example, the temperature of the contents increases of one room, so that content in this room with an increased temperature acts on the sensor element. This changing state of the contents of the room results in a change in a signal of the sensor element at an evaluation unit, particularly in the case of an analog sensor element, so that an evaluation unit can, for example, determine that an increase in temperature in the room and a corresponding change in the signal of the sensor element are obvious the sensor element works (e.g. fully functional). This is of course not limited to a sensor element such as a temperature sensor, but can be used, for example, in a pressure sensor, i.e. H. can be applied in a corresponding manner to a sensor element that functions as part of a pressure sensor. For example, if the sensor element is a pressure sensor, which is loaded, for example as a kind of piston, by the contents of the room and here its pressure, then in the functional case of the sensor element, its position can be changed by the pressure. This change in position of the sensor element results in a signal which was different before the change in position, so that the signal which is transmitted to an evaluation unit is recognized as a different signal and consequently the functionality of the sensor element is determined from this change in the signal (sensor element functional or sensor element fully functional).

According to a further aspect of the invention it is provided - already mentioned - that one space is a storage, in particular a pressure storage, and the other space is a so-called suction pipe. This enables the method to be applied to such devices and thus determining the functionality of a sensor element on components that are required for the functionality of an internal combustion engine.

According to a further embodiment of the invention, before the contents act on the sensor element, a liquid is to be sucked out of one space, or is to be pushed out or let out of it, and a gas, preferably air, is to be let in as a replacement. Such a process has the advantage that the functionality (sensor element works) of the sensor element is desirably determined before one space is filled with the liquid again. In the event that this liquid is, for example, the water already mentioned, which is admitted into a combustion chamber of the internal combustion engine by injecting it into an intake manifold via gas exchange in order to influence combustion there, this leads to the fact that before refilling of one room, a functionality of the sensor element has been determined, so that this space is only refilled, for example, if the sensor element and thus the sensor is functioning, and therefore a possibility of correct pressure build-up can be made possible by, for example, a control device. For the functionality of this metering device (injecting water into the intake pipe), it is important what pressure prevails in the room in order to introduce a suitable amount of water into the combustion chamber and therefore and thereby be able to carry out a combustion process in the combustion chamber as planned. A malfunction of this sensor element would possibly result in a measured amount of water not being able to be provided in the technically intended amount and as a result, for example, the combustion process would run too hot (too small amount of water) and there would be either a risk of knocking combustion in the combustion chamber or Even a knocking combustion occurs with the risk of destroying the internal combustion engine. If the sensor element does not work, the space does not need to be refilled and as a result a device that controls and/or regulates processes in the internal combustion engine (control unit) can be set accordingly. This means that it is stored in this device that no water can be injected to cool the combustion processes. This makes it possible to run the control from the outset in such a way that knocking burns in one or more combustion chambers are avoided or safely ruled out. In addition, such a diagnosis enables a signal to be set so that, for example, a vehicle driver is made aware that a sensor element or sensor of the device is defective or should be checked.

According to a further embodiment of the invention, it is provided that in order to check the functionality of the sensor, a signal is transmitted from the sensor element to an evaluation unit before the valve is opened, and a signal is transmitted from the sensor element to the evaluation unit after the valve is opened. Such an approach makes it possible for material to be transferred from the other room through the opened valve in one room. This potentially enables a change in at least one property of the material or content of a room. Such a change enables the sensor element to detect a changed property and thus, after opening the valve, to transmit the signal to the evaluation unit, which deviates or differs from the signal which was transmitted to an evaluation unit before the valve was opened. If the property of the substance that is transferred into one room through the valve differs, this change can be detected by acting on the sensor element and transmitted as a signal to the evaluation unit if the sensor element is fully or possibly only functionally functional. If the substance flowing through the valve into one room does not differ from the other substance, the sensor element is, as expected, not able to transmit a signal to the evaluation unit after the valve is opened, which deviates from the signal before opening of the valve was transferred to the evaluation unit.

Accordingly, according to a further aspect of the invention, it is provided that the two signals are processed in the evaluation unit, and the evaluation unit determines whether the sensor element transmits signals that do or do not represent different values of the property. According to a further aspect of the method, it is provided that this is carried out without the action of an actuator. Or to put it another way: The method should be applied to a device on which influences other than those of an actuator act. For example, the method can be used when thermal energy acts on the device, ie here, for example, on the two rooms. For example, if one room is the memory already mentioned and the other room is the suction pipe already mentioned, then after operation of the device the situation can arise that the memory mentioned is heated by the internal combustion engine and as a result a pressure in the memory increases. In such a situation, a suction pipe is also under the influence of heat an internal combustion engine; However, due to the “openness” of the suction pipe, pressure equalization occurs with the surroundings. If you compare the two rooms, the suction pipe and the accumulator, you can see that after a certain time there is a significantly higher pressure in the accumulator than in the suction pipe (ambient pressure). If the valve between the storage space and the suction pipe space is opened in such a situation, pressure equalization takes place from the storage tank into the suction pipe. The pressure in the storage decreases.

In particular, it is provided that the valve is opened and an actuator, in particular an internal combustion engine, causes a change in a property of the contents of the room and the sensor element is then diagnosed. Such a procedure has the advantage that the operation of the actuator in the other room changes a property of the content there and thus, after opening the valve, a change in the content in the one room, the property of which is to include the sensor element, is brought about . While the sensor element may not always be correctly diagnosed in the previously mentioned exemplary embodiment, this is certainly possible according to the further proposed method. If the actuator is in operation, a change in a property of the contents of the other room is inevitably brought about, which has a mandatory effect on the other room with the sensor element when the valve is opened. It is provided that the actuator does not necessarily have to be a cylinder of the internal combustion engine or an internal combustion engine; rather, this actuator can also be another pump that causes a change in the property of the contents of the other space. In an alternative exemplary embodiment, it is also possible for, for example, a flap that delimits the other room or is arranged in it to cause a change in the properties of the contents in the other room by actuation. For example, it would be possible that - if this flap is arranged in an intake manifold of an internal combustion engine - this flap is actuated when the piston drive is not actuated and, through its folding movement, causes a pressure difference through the valve in one room and thus also on the sensor element. It is thus possible to determine whether the sensor element is functional (fully functional) or whether it is inoperable (not functional).

According to a further aspect of the invention, it is provided that the diagnosis takes place when the actuator is switched on, in particular when an internal combustion engine is started. Such a procedure enables the function of the sensor element to be determined in connection with the start of operation of an internal combustion engine or the device and thus close to the event (start). According to a further embodiment of the invention, it is provided that either the valve is opened and then the actuator is operated, or the actuator is operated first and then the valve is opened, or the actuator is switched on and the valve is opened at the same time. In the first case, it is advantageous that it can be determined very early on whether the sensor element is working or not. In the second case, the advantage is that the actuator acts on the other room (particularly the suction pipe) at an early stage and accordingly the properties of the contents of the suction pipe are changed at an early stage, which is then already applied to the one room when the valve is opened ( especially memory).

According to a further embodiment of the invention, it is provided that a first signal is transmitted to an evaluation unit before, after or during the valve opening. In particular, transmitting a first signal before the valve opens to an evaluation unit makes it possible, for example, to determine the state in one room before the end of operation of a previous (first) operating phase of the device. This has the advantage that a first result or a first evaluable signal can be made available to the evaluation unit at the beginning of the next (second) operating phase of the device, in particular the internal combustion engine, before the next operation or the next operating phase even begins . Accordingly, the second signal of the sensor element can be evaluated as soon as the next operating phase begins and the state of the sensor element can be analyzed particularly early. If the transmission of a first signal is transmitted to an evaluation unit during the valve opening, then, for example, a valve opening can begin relatively early. If the actuator is already in operation, changes to at least one property of the substance or contents of the one room are generated early and can be determined early. If the transmission of a first signal is transmitted to an evaluation unit after the valve opening, then, for example, a valve opening can begin even earlier. If the actuator is already in operation, changes to at least one property of the substance or contents of a room are generated even earlier and can be determined even earlier.

In order to determine the state of the signal element, the first signal and the second signal are processed in the evaluation unit and the evaluation unit determines whether the sensor element transmits signals that are different Values of the property stand or not stand. It is particularly provided that an evaluation is carried out by forming at least one difference, in particular a difference between the second signal and the first signal. The procedure can be such that the second signal is interpreted into a pressure value and the signal is also interpreted into a pressure value and thus a difference between these two signals is made based on the interpretation of the respective signals. This applies in any case in the case that the sensor element is a sensor element of a pressure sensor. If the sensor element is a sensor element of a temperature sensor, as can be the case with a general device, for example, the first signal is interpreted as a temperature value and the second signal is also interpreted as a temperature value and a difference between the two temperature values is formed, to determine whether the sensor element is working or not. The signals from the pressure sensor and the signals from the temperature sensor can each be electrical signals.

According to a further embodiment of the invention, an evaluation should be carried out by forming at least one difference. In particular, it is provided that several differences are evaluated, in particular several differences of signals that are received by the evaluation unit at different times. For example, it can be provided to evaluate a second signal from the sensor element when a valve between one room and the other room is closed and also to evaluate a signal from a sensor element when a valve between one room and the other room is opened. Such opening or closing phases of the valve can be carried out in particular in connection with an action of the actuator. For example, it can be provided that an actuator generates a particularly lower pressure in the other room, which then also generates a particularly lower pressure in the one room through the valve. In such a state, for example, the sensor element can be moved towards the interior of one room. By generating a particularly high pressure in the other room, a particularly high pressure can then also be generated by overflow via the valve into one room, so that a sensor element, for example, is moved in a direction out of the room. In particular, such a procedure makes it possible for a sensor element to be detached even after a non-function has been detected (so-called sensor stuck). A so-called “sensor piece” means that a sensor element is stuck at least temporarily. Accordingly, according to a further embodiment of the invention, it is provided that after an evaluation an opening state of the valve is changed and then an evaluation is carried out using a signal which was transmitted to the evaluation unit after the opening state of the valve was changed.

The diagnostic result “sensor stuck” can be assigned directly and does not have to be reported as a “possible sensor stuck” because a closed tank shut-off valve between a container and the room can also be the cause of an undetected pressure build-up while filling the water injection system would come. Another advantage of the method proposed here is that, due to the early point in the water injection process, appropriate countermeasures can be initiated based on the diagnostic result. For example, the water injection system can be banned from use before it is even filled. This means, for example, B. engine damage can be avoided if a diagnostic method for injector leakage is used, which is based on a reaction of the intake manifold pressure via the injector leakage point on the water rail pressure sensor, but incorrectly indicates that the injectors are leaky due to the sensor stucco.

In this process, a targeted injector or valve opening is used to establish a connection between the suction pipe and the water rail or the interconnected rooms for diagnosis. Based on measurable effects of the conditions in the intake manifold when the engine is running on the conditions in the water rail via the opened injectors or valves (measurable, for example, by the pressure sensor), it can be proven before the water injection system is filled or put into operation whether the Pressure sensor of the water injection system has a sensor piece.

Furthermore, a computer program is provided which is designed to carry out all steps of one of the aforementioned methods or is programmed in such a way that it carries out one of the methods when it is executed on a computer. Furthermore, a machine-readable storage medium is provided on which the computer program is stored or on which the computer program is stored for use in one of the methods. Finally, a control device with a computer is provided, which is designed such that all steps of one of the methods are carried out or that it is programmed for use in one of the aforementioned methods.

• 1 zeigt eine erste Vorrichtung, an der das Verfahren vorgenommen wird,
• 2 zeigt eine Variante der Vorrichtung aus 1, an der das Verfahren ausgeübt wird,
• 3 zeigt ein weiteres Ausführungsbeispiel einer Vorrichtung, an welcher das Verfahren ausgeübt wird,
• 4 zeigt einen schematischen Längsschnitt durch einen Aktuator, hier ausgeführt als Brennkraftmaschine,
• 5 bis 9 verschiedene schematische Druckverläufe.

The invention is explained in more detail using the figures listed below.

• 1 shows a first device on which the method is carried out,
• 2 shows a variant of the device 1 , where the procedure is carried out,
• 3 shows a further exemplary embodiment of a device on which the method is carried out,
• 4 shows a schematic longitudinal section through an actuator, here designed as an internal combustion engine,
• 5 until 9 various schematic pressure curves.

In 1 a device 10 is shown. This device 10 has a room 13 and another, different room 15. Both rooms 13, 15 are connected to one another by a valve 17. A sensor element 20 is connected to the room 13 and is suitable for detecting a property of a content 26 of the room 13. The sensor element 20 and an evaluation unit 29 are connected via a line 32, in particular an electrical line, so that a signal 35 is transmitted from the sensor element 20 to the evaluation unit 29 via the line 32. The valve 17 is also connected to a line 38 which leads to a control unit 40. The valve 17 can be controlled accordingly by the control unit 40 via the line 38, so that the signal can be opened or closed via the line 38 by means of a signal 43, output by the control unit 40.

In principle, a valve 17 can be arranged between the space 13 and the space 15, not only by way of example. Rather, several valves 17 can connect the two rooms 13, 15 parallel to one another and can each be controlled by one or the control unit 40.

With regard to the exemplary embodiment 1 It is procedurally provided that the sensor element 20 is diagnosed. In this case, the sensor element 20 can be a sensor element 20 of a pressure sensor, so that, for example, a pressure p in the space 13 is or could be determined as a property 23. Alternatively, the sensor element 20 could also serve to determine a temperature T, which would then be the property 23. The sensor element 20 is in contact with the space 13 in such a way that a property 23 of the contents 26 of this one space 13 acts on the sensor element 20. The valve 17 is arranged between this room 13 and the other room 15. It is provided in the method that the valve 17 is opened and then the sensor element 20 is diagnosed. It can be provided that in order to diagnose the sensor element 20, a signal 35 is transmitted from the sensor element 20 to the evaluation unit 29 in one step. In particular, it is provided that a content 45 is also arranged in the space 15 and accordingly this content 45 has a property 23, which can be, for example, a pressure p45 or a temperature T45. If the valve 17 is caused to be opened by the control unit 40 and the transmission of a signal 43, it is provided that after this opening of the valve 17, a signal 35 is transmitted from the sensor element 20 to the evaluation unit 39.

Accordingly, the evaluation unit 29 first has a first signal 35 and then a second signal 35.

These two signals 35 are received in the evaluation unit 29 and the evaluation unit 29 determines whether the sensor element 23 transmits signals 35 that represent different values of the property 23 or do not represent them. When the valve 17 is opened, depending on the state of the contents, 26, 45 different processes can occur. In the event that, for example, the contents 26 have a pressure 26 that is smaller than a pressure p45 of the contents 45 in the space 15, then after the valve 17 is opened, part of the contents 45 is released from the space 15 via the valve 17 flow over room 13. The pressure p26 increases as a result. The change in pressure 26 depends, among other things, on how high the pressures p26, p45 are before opening the valve 17 and how long the opening duration t17 of the valve 17 is. Accordingly, when the sensor element 20 is fully functional, a pressure p26 is transmitted before the valve 17 is opened, which is smaller than a pressure p26 after the valve 17 is opened and after material flows over from the space 15. If the sensor element 20 is fully functional, the evaluation unit would determine that the sensor element 20 transmits signals 35 that represent different values of the property 23. In this case, the property 23 would be represented by the two pressures p26 before opening the valve 17 and after opening the valve 17. For example, if the temperatures T26 and T45 before opening the valve 17 were different, for example the temperature T45 was greater than the temperature T26, then after the valve 17 was opened the state would arise, for example, that the temperature T26 would be after the valve was opened 17 would increase. Accordingly, if the sensor element 20 is fully functional, a temperature T26 or a corresponding signal 35 would be transmitted before the valve 17 is opened, which corresponds to a lower temperature T26 than is the case after the valve is opened 17 would be for temperature T26. This means that the evaluation unit 29, which processes the two signals 35, would determine that the sensor element 20 transmits signals 35 which stand for different values of the property 23, ie for different temperatures T26 before and after the valve 27 is opened.

The room 15 and especially its contents 45 and its properties 23 are monitored by means of its own sensor element 50, which is connected to an evaluation unit 60 by means of a line 56. Here too, a signal 59 is transmitted to the evaluation unit 60 via line 56.

2 shows a further variant of the device 10 on which the method is carried out. In this embodiment, which is close to the embodiment of the device 10 1 and the procedure described there, the differences will be discussed. In this exemplary embodiment, too, a method for diagnosing a sensor element 20, in particular a sensor element 20 for determining a pressure p, is provided, the sensor element 20 being in contact with one space 13 in such a way that the sensor element 20 also has a property 23 of the content 26 of this a room 13 works. The valve 17 is arranged between this one room 13 and the other room 15. The valve 17 is opened and then the sensor element 20 is diagnosed. The method therefore basically runs in the same way as in the first exemplary embodiment. One difference is that the room 15 is open to the environment, which is not separately provided with a reference number here. This means that under idealized conditions, a temperature T45 in the room 15 and a pressure p45 in the room 45 correspond or can correspond to a pressure of the environment and the temperature of the environment.

It is also provided here that before the valve 17 is opened, a signal 35 is transmitted from the sensor element 20 to the evaluation unit 29 and after the valve 17 is opened, a signal 35 is transmitted from the sensor element 20 to the evaluation unit 29. Here, too, it is provided that the two signals 35 are processed in the evaluation unit 29 and the evaluation unit 29 determines whether the sensor element 20 transmits signals 35 that stand for different values of the property 23 or not.

In principle, here too, a valve 17 can be arranged between the space 13 and the space 15, not just by way of example. Rather, several valves 17 can connect the two rooms 13, 15 parallel to one another and can each be controlled by one or the control unit 40.

In 3 a further exemplary embodiment of a device 10 is shown on which the method is carried out. When describing this device 10, the differences from the exemplary embodiment will be discussed 1 received. The space 13 can be filled with a fluid 66 (for example water) using a pump 63. This fluid 66 is stored in a container 69. If, according to a requirement, the space 13 is filled with the fluid 66, the pump 63 is controlled in such a way that it pumps the fluid 66 out of the container 69 through the line 72 into the space 13. It can be provided that a flow path between the container 69 and the space 13 can be closed or opened by means of a valve 75. This valve 75 is optional. In the exemplary embodiment described here, this valve 75 is arranged between the pump 63 and the space 13.

In this exemplary embodiment, the procedure for diagnosing the sensor element 20 can be as follows: First, it is assumed that although a fluid is arranged in the space 13 and in the space 15, it is gaseous and is therefore, for example, air. Here too, the sensor element 20 is in contact with the space 13 in such a way that a property 23 of the contents 26 (gas) of this one space 13 acts on the sensor element 20. The property 23 can, for example, also be a temperature T26 or a pressure p26. The valve 17 is initially closed between the room 13 and the room 15, so that no exchange of substances can take place between the room 13 and the room 15. The space 15 here is the suction pipe already mentioned, to which air can be supplied by means of a valve 78 (throttle valve). An actuator 80 is connected to the room 15 as a suction pipe. In the exemplary embodiment shown here, this actuator 80 is implemented by an internal combustion engine. This actuator 80 here has a crank mechanism 83, which here has, for example, a connecting rod and a crank of a crankshaft, which are not specified here. One end of a connecting rod is hinged to a piston 86. A valve 89 is arranged between the space 15 and the piston 86. When the actuator 80 is designed as an internal combustion engine, this valve 89 has the function of a so-called inlet valve. A space 92 is arranged between the piston 86 and the valve 89, which is a so-called combustion chamber when the actuator 80 is designed as an internal combustion engine.

As already mentioned in the previously mentioned exemplary embodiments, several valves 17 The two rooms 13, 15 connect parallel to one another and are each controlled by one or the control unit 40. In addition, several actuators 80 can also be connected to the space 15 (suction pipe) via their own valves 89, as is the case, for example, with internal combustion engines with several cylinders. A number of valves 17 and a number of actuators 80 can be the same.

The space 13 can in particular be a memory, in particular a pressure accumulator. The other space 15 can be, for example, an intake manifold, in particular an intake manifold for an internal combustion engine. As part of the method, it is in particular provided that before the content 26 acts on the sensor element 20, any fluid that may be present or stored in the space 13, in particular a liquid such as water, is sucked out of this one space 13. In this context, a gas, in particular air, should be admitted into the room 13. In this context it is provided that the pump 63 pumps or pumps back the fluid or water through the optionally present and then opened valve 75 from the space 13 through the line 72 into the container 69. For this purpose, it is again provided that the valve 17 is opened particularly preferably when the pump 63 already exerts a suction on the space 13. This opening of the valve 17 in turn causes (based on the aforementioned case) a suction on the contents 45 of the space 15. Accordingly, in the case in which, for example, the valve 78 is (still) closed, only a relatively small amount of fluid is released from it Room 15 is conveyed through the valve 17 into the room 13. This process is accelerated by opening the valve 78. The process described above is to be used in particular to empty the space 13 of liquid such as water, so that no damage is caused when the device 10 is to be switched off. This is to be feared if the device 10 is stored under ambient conditions whose temperature is below the solidification temperature of the fluid water.

During a first start-up or a start-up after the room 13 has been emptied of water, a first method with its various variants - as described below - can be used. First, the sensor element 20 is in contact with the space 13 in such a way that a property 23 of the contents 26 of this one space 13 acts on the sensor element 20 and the valve 17 is arranged between this one space 13 and the other space 15. The valve 17 is opened and then the sensor element 20 is diagnosed. It is envisaged that before the content 26 acts on the sensor element 20, the previously used fluid (particularly preferably water), in particular a liquid, is sucked out of a space 13 and the air is admitted into the space 13. In this case, this air flows from room 15 into room 13 through valve 17. So that a pressure loss in the room 15 is compensated for, it is provided that air flows in through the valve 78.

In a first variant of this method it is provided that the actuator 80 does not influence the method. Before the valve 17 is opened, a signal 35 is transmitted from the sensor element 20 to the evaluation unit 29. After the valve 17 has been opened, a signal 35 should also be transmitted from the sensor element 20 to the evaluation unit 29. These two signals 35 are processed in the evaluation unit 29. As part of this processing of the evaluation unit 29, it is provided that this evaluation unit 29 determines whether the sensor element 20 transmits signals 35 that do or do not represent different values of the property 23. As part of this evaluation by the evaluation unit 29, various results can arise:

In the event that the first signal stands for a first value of the content 26, which is smaller than the second value of the content 26 after opening the valve 17, this means for the result of the evaluation that, for example, the temperature T26 before opening of the valve 17 was lower than it was after opening the valve 17. In the event that the sensor element 20 detects a pressure, this means that the pressure p26 before opening the valve 17 was smaller than after opening the valve 17.

In the event that the value is greater than the second value, this means that either the temperature T26 or, for example, a pressure p26 was greater before the valve 17 was opened than after the valve 17 was opened.

In the third case of an intermediate result of the evaluation by the evaluation unit 29, no clear result follows from the same signals 35 of the sensor element 20 before the valve 17 is opened and after the valve 17 is opened. As part of this evaluation, the method can either conclude that the function of the sensor element 20 is OK, that is, full functionality is given, because the evaluation unit then recognizes that the first value corresponds to the second value. However, the evaluation unit could also conclude a different result, namely that the sensor element 20 is defective and therefore delivers the same signal 35 as the second value as when determining the first value, because the sensor element 20 is unknown for some unknown reason is stuck for the reason and is therefore only able to output a single value or a single or (always) the same signal 35, so that the evaluation unit can only conclude on a single or (always) the same value or on a defect of the sensor element 20. A corresponding conclusion can be specified, for example, by a presetting of the system. If the two signals 35 are so identical, the system could also output the result that the corresponding component sensor element 20, for example, requires an inspection. As part of this first exemplary embodiment of the method in a device 10 according to 3 It is provided that the actuator 80, in particular on the internal combustion engine, does not cause a change in a property of a content 26, 45 of a space 13, 15, in particular is not in moving operation. In moving operation, for example, in the event that the actuator 80 is an internal combustion engine, it is provided that this internal combustion engine is stationary and is not in motion, be it in a self-propelling manner or in a driven manner, in which a starting device (e.g. starter) is Crank drive 83 of the device 10 or the actuator 80 is set in motion. This device 10 should not be influenced by an activity of the actuator 80.

The following is based on the 3 a second example of the method is explained. Here too, a method for diagnosing the sensor element 20 takes place, which here too can in particular be a sensor element 20 for determining a pressure. Alternatively, this sensor element 20 can also be used, for example, to determine a temperature. Here too, the sensor element 20 is in contact with the space 13 in such a way that a property of the content 23 acts on the sensor element 20 in this one space 13. Depending on the suitability of the sensor element 20, the property 23 of the content 26 can be, for example, a pressure p26 or a temperature T26. Starting from a situation in which no liquid has flowed into the space 13 from the container 69, ie only air is arranged in the space 13, it is provided that the valve 17 is opened and the actuator 80, in particular designed as an internal combustion engine, is one Change in a property 23 of the contents of the room 15 and then the sensor element 20 is diagnosed. This process can take place both at the start of operation of the actuator 80 or, for example, towards the end of the operation of the actuator 80. What is important here is that the space 13 is either completely emptied of liquid (water) or is at least only partially filled with liquid. According to one variant, it is provided that the diagnosis takes place when the actuator 80 is switched on, in particular when the actuator 80 is started as an internal combustion engine. Switching on the actuator 80 can here be equivalent to turning on the actuator 80, in which an electrical machine (starter), for example, begins to rotate the actuator 80 in order to initiate combustion activity in a space 92 (combustion chamber) and thus a so-called self-running of the actuator 80 as an internal combustion engine. In order to enable or carry out the diagnosis, it is provided that a first signal 35 is transmitted to the evaluation unit 29 before, after or during the opening of the valve 17. In this method it is provided that the valve 17 is opened and then the actuator 80 is operated, or first the actuator 80 is operated and then the valve 17 is opened, or at the same time the actuator 80 is switched on and the valve 17 is opened.

An important component of this method described here is that the actuator 80 influences or changes the properties 23 of the contents 26, 45 of the rooms 13, 15 and thus influences the signals 35 emitted by the sensor element 20 to the evaluation unit 29. Since the method provides for a second signal 35 to be transmitted to the evaluation unit 29 after the first signal 35, it is provided that the actuator 80 influences at least the second signal and accordingly influences a property 23 of the content 26 of the room 13. Due to the fact that a certain dynamic emanates from the actuator 80, which is caused, for example, by the lifting movements of the crank mechanism 83, a total of several cases can be considered for the evaluation or diagnosis of the sensor element 20. In a first case, a first signal 35 can be sent by the sensor element 20 to the evaluation unit 29 when the valve 17 is still closed and accordingly an actuator 80 cannot have any effect on the first signal 35 and therefore also not on the sensor element 20 . In this case, a second signal 35 can be emitted by the sensor element 20 when the valve 17 is already open and particularly preferably the actuator 80 is in operation and, for example, at least one pressure change through the opened valve 89, for example a pressure increase or a pressure decrease , in particular pressure waves, are generated, which are transmitted through the valve 17 to the contents 26 of the space 13 and are accordingly also detected by the sensor element 20. Due to this activity of the actuator 80, in most cases the sensor element 20 detects a state of the contents 26 in the room 13 that deviates from the state transmitted by the first signal 35, at least in the functional state of the sensor element 20. Causes a Actuator 80, as can be the case, for example, with an internal combustion engine, a wave-like dynamic that is transmitted to the contents 26 of the space 13 through the open valve 89 and the open valve 17 In rare cases it happens that the same state of the content 26 arises as already occurred during the detection of the first state by the sensor element 20. In order not to detect a malfunction of the sensor element 20 in such a case of signal equality, provision can be made to carry out a further measuring process and therefore to compare a first signal 35 with a further second signal 35 and to evaluate it accordingly. To avoid the same incorrect measurements - however unlikely they may be - it can be provided that a sensor element 20 then sends a signal 35 to the evaluation unit 29 if the actuator 80 is in a different operating position during this second measurement. It is to be expected that a property 23 (e.g. pressure p26) of the contents 26 in the smallest possible space 92 (piston 85 at top dead center) is greater than a property 23 (e.g. pressure p26) of the contents 26 in the largest possible space 92 (piston 85 at bottom dead center).

It is also provided in this method that the first signal 35 and the second signal 35 are processed in the evaluation unit 29 and the evaluation unit 29 determines whether the sensor element 20 transmits signals 35 that represent different values of the property 23 or not stand. In this evaluation of the various signals 35, it is particularly provided that the evaluation is carried out by forming at least one difference D35. In connection with the formation of at least one difference D35, it is provided that the part of the signal 35 which represents an amount of the property 23 is evaluated. This means, for example, that the part of the first signal 35, which indicates, for example, a pressure value of 5.0 bar, is compared with the part of the second signal 35, which indicates, for example, a pressure value of 5.35 bar. According to this example, the evaluation unit 29 would determine a difference D35 of 0.35 bar and, for example, conclude that the sensor element 20 is fully functional. In the case where, for example, the difference D35 would result in a difference value of 0.00 bar because both signals 35 would be the same, the result would be that the sensor element 20 would be defective. As part of the method, with such a result (e.g. D35 = 0.00 bar or similarly small), the next method step can also be that a second signal 35 is determined a second time in a third measurement in order to determine a difference a second time D35 to form the signal 35. From such a repeated measurement, an evaluation can be carried out again by the evaluation unit 29 and a difference D35 can be formed again in order to draw conclusions about the operability or the state of the sensor element 20. As part of this further measurement or further detection of a state of the content 26 by the sensor element 20, it can be provided that an opening state of the valve 17 is changed and then an evaluation takes place by means of a signal 35, which after changing the opening state of the valve 17 the evaluation unit 29 was transmitted.

A sensor element 50 is shown in all exemplary embodiments. This sensor element 50, especially if it detects the same property 23 as the sensor element 20, can additionally check the plausibility of whether the sensor element 20 is functioning. If the sensor element 50 detects a change in the property, a change in the property 23 in the space 13 may also occur when the valve 17 is open and thus be detected by the sensor element 20 (sensor element 20 works) or not detected in the event of a malfunction. Since the measuring ranges can be different, such a comparison may only work in the upper measuring range of the sensor element 50.

The valve 78, designed as a throttle valve, can also be used as the actuator 80. The throttle valve and thus the above-mentioned can be used as such an actuator 80. Procedures are carried out before the movement (starting) of the internal combustion engine as an actuator.

In 3 A control device 98 with a computer is shown by way of example and symbolically, which also has, by way of example, the evaluation unit 29, the control unit 40 and the control device 60. A computer program 100 is stored on a machine-readable storage medium 99. The computer program 100 is designed to execute all steps of one of the methods or is programmed to execute one of the methods when executed on a computer.

In 4 the actuator 80 is shown schematically in the form of the internal combustion engine. In this 4 a cylinder 103 is shown. A piston 86 slides in this cylinder 103. This piston 86 is articulated by means of a connecting rod 106 to a drive shaft of the internal combustion engine, not shown here. The drive shaft can be a crankshaft. Above the piston 86 - and thus between the piston 86 and a cylinder cover 109 - is the combustion chamber (space 92). The cylinder cover 109 here has, among other things, a typical cylinder head that closes the combustion chamber, but also, for example, other elements, such as a so-called valve cover. In this exemplary embodiment, an injection nozzle 112 is inserted into the cylinder cover 109 (cylinder head), which in this case injects fuel directly into the combustion chamber can. The combustion chamber is closed on the inlet side by means of an inlet valve (valve 89). On the exhaust side, the combustion chamber is closed by means of an exhaust valve 115. Upstream (intake air) from the combustion chamber is the intake pipe (room 15), through which air is sucked into the combustion chamber when the inlet valve is open. The throttle valve (valve 78) is also located in the intake manifold. An injector 118 (injection nozzle for water), which has the valve 17 mentioned, is also attached to the suction pipe. This injector 118 is aligned so that it is able to inject the water or fluid 66 into the intake pipe (space 15) during operation of the internal combustion engine. Depending on the design of this internal combustion engine, a glow plug (not shown) is arranged in the cylinder head or the cylinder cover 109, which, in the case of a design as a compression ignition engine/diesel engine, ensures that a mixture of fuel and air in the combustion chamber 65 is reliably ignited when the internal combustion engine is still cold serves. If the internal combustion engine is designed as a spark ignition engine (petrol engine), a spark plug is typically attached to the cylinder cover 109, by means of which the fuel-air mixture in the combustion chamber is ignited. After the fuel-air mixture has been ignited, it is discharged as exhaust gas into an outlet pipe 121 via an opening opened by the outlet valve 115. The exhaust gas flows via this outlet pipe 121 into a system (not shown here) for converting the exhaust gases.

5 shows different pressure curves in different cases in which the sensor element 20 is OK. The actuator (the internal combustion engine) is not moving. The pressure p15 in space 15 (suction pipe) is assumed to be constant. In case 1, due to heat influences (here temperature increase) and due to a closed valve 17, a pressure p13.1 is higher than the pressure p15 before time t1. By opening the valve 17, pressure equalization occurs, that is, p13,1 approaches the pressure p15 from a higher pressure until p13,1 = p15. In case 2, due to heat influences (here temperature reduction) and due to a closed valve 17, a pressure p13.2 is higher than the pressure p15 before time t1. By opening the valve 17, pressure equalization occurs, that is, p13,2 approaches the pressure p15 from a lower pressure until p13,2 = p15. In the third case, the pressure p13, 3 approaches the pressure p15 after the valve 17 is opened, but remains at a distance from the pressure p15 by an offset (offset, ΔpOffset). Even in such a situation, if there is a pressure sensor offset (ΔpOffset), the functional test of the sensor element 20 can be carried out and detected (course of p13.3). In the fourth case, the pressure p13.4 approaches the pressure p15 from a lower pressure. A first opening of the valve 17 takes place at time t1. At time t2 the valve 17 is closed again. Only a partial pressure equalization has taken place. At time t3, the valve 17 is opened again, so that the pressure p13.4 further approaches the pressure p15 (multiple opening of the valve). If no pressure equalization can be detected when the actuator 80 is not moving (not running, not rotating internal combustion engine), this does not lead to a “not OK” diagnosis of the sensor element 20. This could also be a system that has already been balanced . Only the “OK” diagnosis when the actuator 80 is not moving (not running, not rotating internal combustion engine) is clear, since an adjustment or equalization of the pressure p13 (p13.1 - p13.4) is achieved and thus a Mobility of the sensor element 20 has proven.

6 shows a case in which the method results in a defective sensor element 20. If the actuator 80 - here, for example, the internal combustion engine - is in motion, this affects the pressure p15 in space 15 (intake pipe). The dynamics of the actuator 80 results in a wave-shaped course of the pressure p15, which is overall below the ambient pressure. If the valve 17 is opened, an exchange of fluid 66 takes place between the space 15 and the space 13 (water storage). This exchange also results in a change in the property 23 - here for example the pressure p13 - of the contents 26 in the room 13. However, the sensor element 20 is not able to sense this pressure change due to a defect (sticking, “sensor stuck”). Accordingly, the sensor element 20 experiences changes in the pressure p13, but cannot convert these into corresponding signals 35. In the method, before the valve 17 is opened, the output signal 35 of the sensor element 20 is transmitted to the evaluation unit 29 and after the valve 17 is opened, the further signal 35 or further signals 35 of the sensor element 20 are transmitted to the evaluation unit 29. The functionality of the sensor element 20 can be deduced from changes in the signal 35 alone.

For comparison purposes, a signal 59 from the sensor element 50 of the space 15 (suction pipe) can also be used. The actuator 80 can be set in motion before opening the valve 17 or after opening the valve 17. It is important to know the opening time t1 of the valve 17 so that any connection between pressure changes (not present or present) of the pressure p13 with pressure changes in the room 15 can be established. Apart from a stronger reaction to room 13 due to a larger and longer lasting one Opening, it initially does not matter for the method whether only one valve 17 or possibly several valves 17 are opened simultaneously, one after the other, clocked or permanently.

7 shows a case in which the method results in a functional sensor element 20. If the actuator 80 - here, for example, the internal combustion engine - is in motion, this affects the pressure p15 in space 15 (intake pipe). The dynamics of the actuator 80 results in a wave-shaped course of the pressure p15, which is overall below the ambient pressure. If the valve 17 is opened, an exchange of fluid 66 takes place between the space 15 and the space 13 (water storage). This exchange also results in a change in the property 23 - here, for example, the pressure p13 - of the contents 26 in the space 13. Accordingly, the sensor element 20 experiences changes in the pressure p13, but only in small amounts. The start of the movement of the actuator 80 and the opening time t1 of the valve 17 coincide or take place at the same time.

8th shows a similar process to 7 described. Here, the time at which the movement of the actuator 80 begins and the opening time t1 of the valve 17 do not coincide or do not take place at the same time. First, the actuator 80 is set in motion at time t80 and then the valve 17 is opened at time t1. It can be seen here that the pressure p13 initially remains at the initial level until time t1 and after the valve 17 is opened, the sensor element 20 experiences the reduced pressure p13. In order to be independent of a possible offset of the pressure sensor or sensor element 20, it is advisable to evaluate the curves not the absolute, but the relative change in the pressures to one another (pressure p13 in the water rail room 13 with pressure p15 in the suction pipe room 15). For this purpose z. B. simply save the pressure values of the respective pressures before or at the beginning of the engine start or the movement of the actuator 80 and then form the difference between the subsequent curves.

9 shows a pressure curve with several opening and closing events, which take place here after the start of the movement of the actuator 80. The sequence of opening and closing events can also alternatively take place with the start of the movement of the actuator 80 or after the start of the movement of the actuator 80. The functionality of the sensor element 20 can be deduced in a known manner from the course of the pressure p13. The sequence of opening and closing events (opening t10, t30, t50, closing t20, t40) can alternatively also take place with the motor or actuator 80 stopped.

Claims (18)

Method for diagnosing a sensor element (20), in particular a sensor element (20) for determining a pressure (p), the sensor element (20) being in contact with a space (13) in such a way that a property (20) is applied to the sensor element (20). 23) a content (26) of this one space (13) acts, and between this one space (13) and another space (15) a valve (17) is arranged, characterized in that the valve (17) is opened and then the sensor element (20) is diagnosed. Procedure according to Claim 1 , characterized in that one space (13) is a storage, in particular a pressure storage, and the other space (15) is a suction pipe. Procedure according to Claim 1 or 2 , characterized in that before the contents (26) act on the sensor element (20), a fluid, in particular a liquid, is sucked out of a space (13) and air is admitted. Method according to one of the preceding claims, characterized in that before the valve (17) is opened, a signal (35) is transmitted by the sensor element (20) to an evaluation unit (29) and after the valve (17) is opened by the sensor element (20) a signal (35) is transmitted to the evaluation unit (29). Procedure according to Claim 4 , characterized in that the two signals (35) are processed in the evaluation unit (29) and the evaluation unit (29) determines whether the sensor element (20) transmits signals (35) which represent different values of the property (23). stand or not stand. Method according to one of the preceding claims, characterized in that an actuator (80), in particular an internal combustion engine, does not cause a change in a property of a content (26) of the space (13), in particular is not in moving operation. Method according to one of the preceding claims, characterized in that a change in a property (E) of a content (26) of the space (13) is brought about by an actuator (80), in particular an internal combustion engine, and the sensor element (20) is then diagnosed. Procedure according to Claim 7 , characterized in that the diagnosis occurs when the actuator (80) is switched on, in particular when an internal combustion engine is started. Procedure according to Claim 7 or 8th , characterized in that the valve (17) is opened and then the actuator (80) is operated or first the actuator (80) is operated and then the valve (17) is opened or at the same time the actuator (80) is switched on and the valve (17) can be opened. Procedure according to one of the Claims 7 until 9 , characterized in that a first signal (35) is transmitted to an evaluation unit (29) before, after or during the opening of the valve (17). Procedure according to Claim 10 , characterized in that a second signal (35) is transmitted to the evaluation unit (29) after the first signal (35). Procedure according to Claim 11 , characterized in that the first signal (35) and the second signal (35) are processed in the evaluation unit (29) and the evaluation unit (29) determines whether the sensor element (20) transmits signals (35) which are for different values of the property (E) stand or not stand. Procedure according to Claim 12 , characterized in that an evaluation is carried out by forming at least one difference (D35). Procedure according to one of the Claims 7 until 13 , characterized in that after an evaluation, an opening state of the valve (17) is changed and then an evaluation takes place by means of a signal (35), which was transmitted to the evaluation unit (29) after changing the opening state of the valve (17). Method according to one of the preceding claims, characterized in that a pump (63) is first switched on when the diagnosis indicates a functioning sensor element (20) and a pressure (p13) in the room (13) is smaller than a target pressure ( p13soll), it is concluded that the pump (63) is defective. Computer program (100) which is designed to carry out all steps of one of the methods according to one of the Claims 1 until 14 to carry out or that it is programmed in such a way that it carries out a method according to one of the Claims 1 until 14 when running on a computer. Machine-readable storage medium (99) on which the computer program (100) can be stored Claim 15 is stored or that the computer program (100) is stored on it Claim 15 for use in a procedure Claims 1 until 14 is saved. Control device (98), which is designed to carry out all steps of one of the methods according to one of the Claims 1 until 14 to be carried out or that it is to be used in a procedure according to one of the Claims 1 until 14 is programmed.

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