Method for evaluating at least one injector, control device for carrying out such a method, and internal combustion engine assembly comprising such a control device

Abstract

The invention relates to a method for evaluating at least one injector (7) of an internal combustion engine (5) having a plurality of injectors (7), wherein the injectors (7) are evaluated on the basis of a power rating which is associated with an electrical device (9) operatively connected to the internal combustion engine (5).

Description

[0001] DESCRIPTION

[0002] Method for evaluating at least one injector, control device for carrying out such a method and internal combustion engine arrangement with such a control device

[0003] The invention relates to a method for evaluating at least one injector of an internal combustion engine having a plurality of injectors, a control device for an internal combustion engine arrangement, configured to carry out such a method, and an internal combustion engine arrangement having such a control device.

[0004] Injectors designed to deliver fuel into the air path or combustion chambers of an internal combustion engine may exhibit fuel quantity variations or various faults, or even fail completely. For example, an injector may tend to meter too much or too little fuel due to abnormal opening behavior, or an injector may have a reduced or enlarged opening due to aging or contamination and therefore meter too little or too much fuel. An injector may also be permanently open (continuous injection) or permanently closed (missing injection) due to a defect. Such deviations or faults in individual injectors are generally difficult to determine and require comparatively high effort. Therefore, there is a need for a simple and reliable method of evaluating the injectors of an internal combustion engine.

[0005] The invention is based on the object of providing a method for evaluating at least one injector of an internal combustion engine having a plurality of injectors, a control device for an internal combustion engine arrangement configured to carry out such a method, and an internal combustion engine arrangement with such a control device, wherein the aforementioned disadvantages are at least reduced, preferably not occurring at all. This object is achieved by providing the present technical teaching, in particular the teaching of the independent claims and the preferred embodiments disclosed in the dependent claims and the description.

[0006] The object is achieved in particular by providing a method for evaluating at least one injector of an internal combustion engine having a plurality of injectors, wherein the injectors are evaluated based on a performance variable assigned to an electrical device operatively connected to the internal combustion engine. By relying on the performance variable of the electrical device operatively connected to the internal combustion engine, it is possible to evaluate the injectors in a both simple and reliable manner. The performance variable of the electrical device advantageously depends on the insertion behavior of the injectors, so that it can be used to evaluate the injectors. Furthermore, the performance variable of the electrical device can be measured easily and precisely.

[0007] In the context of the present technical teaching, the fact that an injector is evaluated is understood in particular to mean that a deviation of the insertion behavior of the injector relative to an expected or average insertion behavior - in particular of the other injectors of the internal combustion engine - is determined, and / or that an injector error of the injector is determined, in particular identified.

[0008] In the context of the present technical teaching, an injector is understood, in particular, to be a device configured to meter a fuel into an air path or combustion chamber of an internal combustion engine, in particular to introduce it in a quantity-controlled manner, in particular by controlling the injector with a predetermined opening time and a predetermined opening duration, in particular by energizing the injector, i.e., in particular, by applying an electrical voltage or an electrical current to it. The injector can be configured to introduce a fuel that is liquid under standard conditions, i.e., at 25°C and 1013 mbar, or a fuel that is gaseous under standard conditions, i.e., a fuel gas.

[0009] In the context of the present technical teaching, a power variable is understood to mean, in particular, a variable that is characteristic of a physical power. A power variable assigned to an electrical device is, in particular, characteristic of the physical power of the electrical device. In one embodiment, the power variable is, in particular, a torque variable, i.e., in particular, a variable that is characteristic of a torque.

[0010] In the context of the present technical teaching, the fact that the electrical device is operatively connected to the internal combustion engine means, in particular, that the electrical device receives the energy required or consumed for its operation from the internal combustion engine. For this purpose, the electrical device can be directly mechanically driven by the internal combustion engine and / or connected to the internal combustion engine via an operative electrical connection such that electrical energy generated by the internal combustion engine can be supplied to the electrical device via the operative electrical connection.

[0011] According to a further development of the invention, it is provided that in at least two operating states of the internal combustion engine, respectively assigned values ​​of the power variable are determined, wherein the injectors are evaluated based on a comparison of the power variable values ​​assigned to the operating states. In this way, the different power variable values ​​can advantageously be used to infer different behavior of the internal combustion engine in the at least two operating states, and an evaluation of the injectors can be derived therefrom.

[0012] In particular, the at least two operating states differ by a respective associated activation state of the injectors. This means, in particular, that in a first operating state of the at least two operating states, a number and / or identity of activated injectors differs from a number and / or identity of the injectors activated in a second operating state of the at least two operating states. An activated injector is understood, in particular, to be an injector that is controlled to introduce fuel. In contrast, a deactivated or switched-off injector is understood to be an injector that is not controlled to introduce fuel.

[0013] In particular, in a first operating state of the at least two operating states, all injectors of the internal combustion engine can be activated, wherein in a second operating state of the at least two operating states, a specific injector of the internal combustion engine can be deactivated, with all other injectors of the internal combustion engine being activated. It is possible that in a third operating state of the at least two operating states, a different injector of the internal combustion engine is deactivated than in the second operating state, while all other injectors—including the injector deactivated in the second operating state—are activated.In particular, it is possible that n+1 operating states are used to evaluate an internal combustion engine having n injectors, namely one operating state in which all injectors are activated and n operating states in which one of the injectors is deactivated in turn while the other injectors are each activated.

[0014] In particular, the injectors are evaluated by comparing the performance variable values ​​assigned to the operating states. In particular, the injectors are evaluated by comparing the performance variable values ​​assigned to the operating states with a deactivated injector with the performance variable value assigned to the operating state in which all injectors are activated. This approach, in particular, advantageously enables a simple and reliable evaluation of the individual injectors.

[0015] According to a further development of the invention, it is provided that a) the internal combustion engine is operated in a test state with activated injectors, wherein the injectors are each assigned the same, constant test injection quantity of a fuel, wherein a test value of the power variable is determined, wherein b) the internal combustion engine is successively operated in a plurality of switch-off states, wherein in the switch-off states one of the injectors assigned to the respective switch-off state is switched off - and in particular the other injectors are activated -, wherein the other - activated - injectors are each assigned the same, constant test injection quantity of fuel, and wherein in the switch-off states one measured value of the power variable assigned to the respective switch-off state is determined, wherein c) the measured values ​​are compared with the test value, wherein d) the injectors are evaluated based on the comparison.This approach, in particular, advantageously enables a simple and reliable evaluation of the individual injectors. In particular, it follows that, assuming unrestricted and intended functionality of an injector, its shutdown in a shutdown state should result in the test injection quantity required to operate the internal combustion engine being missing in the shutdown state compared to the test state. This, in turn, should result in an expected change in the power output in the shutdown state relative to the test state. If the observed change in the power output deviates from the expected change, it can be concluded that the injector is actually not delivering the test injection quantity, but rather a different injection quantity of fuel, making it possible to evaluate the injector's behavior.In particular, the actual change in power can be used to determine whether the injector is delivering more or less fuel than the test input quantity; a lack of change in power can also indicate whether the injector is continuously injecting or not opening. However, it is not possible to distinguish between continuous injection and a completely missing opening (missing injection); in both cases, there is no change in power, since the injector exhibits the same behavior regardless of its activation or deactivation.

[0016] In the context of the present technical teaching, the fact that an injection quantity is assigned to an injector means in particular that the injector is controlled in such a way that it delivers the injection quantity assigned to it as intended - that is to say, provided there is no deviation or error.

[0017] In particular, in step b), the injectors of the internal combustion engine are deactivated in turn, with a different injector being deactivated in each deactivation state, while all other injectors are activated. In particular, in step b), all injectors are iterated over in this way.

[0018] In particular, the test state is a first operating state of the at least two operating states. In particular, all injectors of the internal combustion engine are activated in the test state. In particular, the test value is determined as a first value of the assigned values.

[0019] In particular, the test condition is a steady-state test condition. This means, in particular, that the internal combustion engine is operated in the test condition over a predetermined time interval at a constant test speed within a predetermined speed tolerance band. In one embodiment, the test speed is 1800 min 1A constant test injection quantity is understood to mean, in particular, an injection quantity that is defined and constant per injection, i.e., per injection event, and per injector. In particular, the test injection quantity is a defined fuel mass or a defined fuel volume. In one embodiment, the test injection quantity is 50 mm 3 Fuel, especially 50 mm 3 Diesel (based on standard conditions).

[0020] In particular, the shutdown states are further operating states of the at least two operating states. In particular, the measured values ​​of the power quantity assigned to the shutdown states are determined as further assigned values ​​of the power quantity.

[0021] In particular, each of the shutdown states is a stationary shutdown state. This means, in particular, that the internal combustion engine is operated in the respective shutdown state over a predetermined time interval at a shutdown speed that is constant within a predetermined speed tolerance band. In particular, in one embodiment, the shutdown speed is identical to the test speed, in particular equal to a test speed. In one embodiment, the shutdown speed is 1800 min 1 . In particular, the test speed is 1800 min 1 . In particular, the internal combustion engine is operated in the shutdown states at the same speed as in the test state, in particular at the test speed.

[0022] According to a further development of the invention, it is provided that a device is used as the electrical device which is selected from a group consisting of an electrical machine drivingly connected to the internal combustion engine, an electrical consumer, and a combination thereof.

[0023] In one embodiment, the electric machine drivingly connected to the internal combustion engine is a generator.

[0024] In one embodiment, at least one electrical load is electrically connected to an electrical machine configured as a generator, which electrical machine, in turn, is drive-connected to the internal combustion engine. In particular, the at least one electrical load is a cooling fan, in particular a cooling fan provided for cooling the air in a cooling circuit of the internal combustion engine. In one configuration, two electrical loads, configured in particular as cooling fans, are electrically connected to the electrical machine.

[0025] According to a further development of the invention, it is provided that an electric cooling fan is used as the electrical device.

[0026] According to a further development of the invention, the power variable used is a variable selected from a group consisting of a generator torque, a consumer speed of an electrical consumer, and a combination thereof. These variables are particularly suitable for determining a power of the internal combustion engine related, in particular, to the at least one electrical device or a power component attributable to it.

[0027] The generator torque is, in particular, the torque of the electric machine configured as a generator and connected to the internal combustion engine for driving purposes. The load speed is, in particular, the speed of the electrical device configured as an electrical load or having an electrical load, in particular the speed of a cooling fan. The speed of a cooling fan is, in particular, directly linked to its power consumption and thus, at the same time, to the proportion of power generated by the internal combustion engine that is allocated to the cooling fan.If an electrical machine designed as a generator, which is drive-connected to the internal combustion engine, and at least one electrical load electrically connected to the electrical machine are provided, and the generator torque is detected, it is readily possible to treat the electrical load as the electrical device and to determine the torque component of the generator torque attributable to the electrical load as the power variable by subtracting any torque components attributable to other electrical loads that may be present. For this purpose, the power consumption of the other electrical loads can be easily detected by a control device, and the corresponding torque components can be determined.

[0028] According to a further development of the invention, it is provided that in at least one step selected from steps a) and b), preferably in both steps a) and b), the internal combustion engine is operated at the constant test speed above an idling speed, wherein the test injection quantity is adjusted by varying an electrical load of the electrical device. Advantageously, the test injection quantity corresponds to a specific amount of energy, so that this sum of the test injection quantities theoretically introduced by the injectors corresponds to a specific test power at the constant test speed. If at least one of the injectors introduces a fuel quantity that deviates from the test injection quantity, this in turn corresponds to a power of the internal combustion engine at the constant test speed that deviates from the specific test power.By varying the electrical load of the electrical device, the power delivered by the internal combustion engine at the constant test speed can be varied, thus adjusting the control of the injectors to deliver the test injection quantity in a control device of the internal combustion engine. The power actually delivered can then be determined via the electrical load of the electrical device and used to evaluate the injectors. In particular, the speed of the internal combustion engine is kept constant at the test speed by the control device by appropriately adjusting the injection quantity assigned to the injectors by the control device depending on the load. Accordingly, by varying the electrical load, the injection quantity assigned to the injectors in the control device can be adjusted to the test injection quantity.

[0029] In one embodiment, the idle speed is 1000 min 1.

[0030] In particular, the electrical load of the electrical device is increased starting from a predetermined starting load value—in particular, stepwise or continuously—until the test input quantity is set. In one embodiment, a rotational speed of the electrical device, in particular the load speed of the electrical load, in particular a cooling fan speed of a cooling fan, is varied as the electrical load. In particular, the load speed is increased starting from a load speed starting value—in particular, stepwise or continuously.

[0031] Alternatively, in the at least one step selected from steps a) and b), preferably in both steps a) and b), it is provided that the constant test injection quantity is assigned to the injectors, with the test speed being adjusted by varying the electrical load of the electrical device. This corresponds to a procedure reversed to the previously explained procedure, which advantageously leads to the same findings.

[0032] In one embodiment, in step a), the internal combustion engine is operated at the constant test speed, with the test injection quantity being adjusted by varying the electrical load of the electrical device. In step b), the constant test injection quantity is assigned to the injectors, with the test speed being adjusted by varying the electrical load of the electrical device.

[0033] Alternatively, in the at least one step selected from steps a) and b), preferably in both steps a) and b), it is provided that the test injection quantity and the test rotational speed are adjusted by - at least temporarily jointly - varying the electrical load of the electrical device on the one hand and the injection quantity assigned to the injectors on the other hand.

[0034] According to a further development of the invention, it is provided that—particularly after step a) and before step b)—the test value is compared with at least one reference test value. This advantageously allows, in particular, an evaluation of the internal combustion engine as a whole. In particular, it can be determined whether the internal combustion engine has average, below-average, or above-average performance or torque.

[0035] In one embodiment, the comparison test value is an individual value from a comparison internal combustion engine, in particular with known fully functional injectors, which additionally exhibit a small quantity variation within a predetermined variation range. Alternatively or additionally, the comparison test value is an average value obtained from the measurement of a plurality of internal combustion engines.

[0036] In one embodiment, steps b) to d) are omitted if a test value deviation of the test value from the at least one comparison test value exceeds a predetermined limit. In particular, the magnitude of the test value deviation is compared with the predetermined limit. If the test value deviation, in particular its magnitude, exceeds the predetermined limit, it is concluded, in particular, that the internal combustion engine has a serious fault, so that further investigations beyond the evaluation of the injectors are necessary.

[0037] In particular, steps b) to d) are only carried out if the test value deviation - in particular its magnitude - is at most as large as the predetermined limit value.

[0038] According to a further development of the invention, in step c) the measured values ​​are compared with the test value by calculating a test difference from the test value for each measured value. In particular, the injectors are evaluated based on the assigned test differences. In particular, the respectively assigned test difference can be used to assess whether an injector is injecting less than the test injection quantity or more than the test injection quantity. The test differences are always either zero or - depending on the definition of the test differences - always have the same sign, which in particular is always negative if the test value is subtracted from the respective measured value, or conversely is always positive if the respective measured value is subtracted from the test value.The respective measured value is at most equal to the test value, since the power output can at most decrease when an injector is deactivated, but not increase. This is because the injector can at most deliver a smaller injection quantity when deactivated, but not a larger injection quantity, than when activated. However, it is possible that no difference arises between the activated and deactivated states of the injector if it either injects continuously or no longer opens. In this case, the assigned test difference is zero.

[0039] In one embodiment, the test differences are each compared with a predetermined first threshold value and a predetermined second threshold value different from the first threshold value, wherein the injectors are evaluated based on the comparison of the test differences with the predetermined first and second threshold values. In particular, in one embodiment, to simplify the method, absolute values ​​of the test differences are compared with the threshold values, which is readily possible since the test differences always have an identical sign anyway. To simplify the presentation, it is therefore assumed below, without loss of generality, that both the test differences and the threshold values ​​are positive. In particular, in one embodiment, the second threshold value is greater than the first threshold value.

[0040] In one embodiment, the first threshold and the second threshold are empirically determined values, which are determined, in particular, in the application field on a variety of internal combustion engines or through test bench tests. It should be noted that the test differences and the threshold values ​​are power variables that cannot easily be assigned to analytically determined input quantities. Therefore, the empirical determination of the threshold values ​​represents a design that is both pragmatic and functional.

[0041] If it turns out that the test difference assigned to an injector is smaller than the first, smaller threshold value, in one embodiment it is advantageously concluded in particular that the injector, despite being controlled with the test injection quantity, is injecting less than this. The injector's contribution to the test value is therefore obviously smaller than the contribution assigned to the test injection quantity. If, on the other hand, the test difference is greater than the first threshold value but smaller than the second, larger threshold value, it is concluded that the injector is injecting the test injection quantity within a predetermined tolerance defined by the distance between the two threshold values. The injector's contribution to the test value thus corresponds to the contribution predetermined by the test injection quantity.If, on the other hand, the test difference is greater than the second threshold value, it is concluded that the injector is injecting more fuel than the test injection quantity despite being controlled with the test injection quantity. Thus, the injector's contribution to the test value is obviously greater than the contribution predetermined by the test injection quantity. If, on the other hand, the test difference is zero or lies within a predetermined zero tolerance band, the only conclusion that can be drawn is that deactivating the injector does not affect its behavior. This can, however, have two reasons: First, it is possible that the injector is continuously injecting; second, it is possible that the injector is permanently closed.

[0042] According to a further development of the invention, a mean difference of the test differences is calculated, with a difference deviation from the mean difference being calculated for each test difference. The injectors are additionally evaluated based on the difference deviations. This advantageously makes it possible to evaluate the injectors collectively as a whole.

[0043] In one embodiment, a median is calculated as the difference mean. In another embodiment, an arithmetic mean is calculated as the difference mean. In yet another embodiment, a geometric mean is calculated as the difference mean.

[0044] In one embodiment, a check is performed to determine whether the respective differential deviation of the injectors lies within a predetermined differential tolerance band. If this is the case for an injector, the injector is rated as OK, unless the test difference assigned to the injector is zero or within the zero tolerance band. If the test difference assigned to the injector lies within the zero tolerance band or outside the differential tolerance band, or if the test difference is zero, the injector is rated as defective.

[0045] The invention also includes a computer program comprising instructions that cause a computing device, in particular a control device for controlling an internal combustion engine arrangement, to carry out the method according to the invention or a method according to one or more of the previously described embodiments when the computer program is running on the computing device.

[0046] The invention also includes a machine-readable storage device on which the computer program according to the invention is stored.

[0047] The object is also achieved by providing a control device for an internal combustion engine arrangement, which is configured to carry out a method according to the invention or a method according to one or more of the previously described embodiments. In connection with the control device, the advantages that were previously explained in connection with the method arise, in particular.

[0048] In particular, the control device has a first interface for operative connection with the

[0049] Internal combustion engine, in particular to its injectors. In particular, the control device also has a second interface for operative connection to the electrical device.

[0050] Finally, the object is also achieved by providing an internal combustion engine arrangement comprising an internal combustion engine, wherein the internal combustion engine has a plurality of injectors. The internal combustion engine arrangement further comprises an electrical device operatively connected to the internal combustion engine and a control device according to the invention or a control device according to one or more of the previously described embodiments. In connection with the internal combustion engine arrangement, the advantages that were previously explained in connection with the method or the control device are particularly advantageous.

[0051] In particular, the internal combustion engine arrangement has at least one feature, in particular a combination of features, which were previously explained explicitly or implicitly in the presentation of the method in connection with components of the internal combustion engine arrangement.

[0052] In particular, the control device is operatively connected to the internal combustion engine, in particular to its injectors, and is configured to control the internal combustion engine, in particular to assign a respective injection quantity to the injectors. In particular, the control device is also operatively connected to the electrical device and configured to control the electrical device.

[0053] According to a further development of the invention, the electrical device comprises an electrical machine operatively connected to the internal combustion engine drive and an electrical load electrically connected to the electrical machine. The control device is configured, in particular, to vary, in particular adjust, an electrical load, in particular the load speed, of the electrical load. In particular, the control device is operatively connected to the electrical load for this purpose.

[0054] The internal combustion engine is designed in one embodiment as a reciprocating piston engine, in particular as a diesel engine. The invention also includes a motor vehicle which has an inventive

[0055] Internal combustion engine arrangement or an internal combustion engine arrangement according to one or more of the previously described embodiments.

[0056] The invention is explained in more detail below with reference to the drawings, which show:

[0057] Figure 1 is a schematic representation of an embodiment of an internal combustion engine arrangement with an embodiment of a control device;

[0058] Figure 2 is a schematic representation of a first part of an embodiment of a method for evaluating injectors of the internal combustion engine of the internal combustion engine arrangement according to Figure 1;

[0059] Figure 3 is a schematic representation of a first embodiment of a second part of the method according to Figure 2;

[0060] Figure 4 is a schematic representation of a second embodiment of the second part of the method according to Figure 2, and

[0061] Figure 5 is a schematic representation of a third part of the method according to Figures 2 to 4.

[0062] Fig. 1 shows a schematic representation of an embodiment of an internal combustion engine arrangement 1 with an embodiment of a control device 3.

[0063] The internal combustion engine arrangement 1 comprises an internal combustion engine 5 with a plurality of injectors 7, of which only one is identified with the corresponding reference numeral for the sake of clarity. Furthermore, the internal combustion engine arrangement 1 comprises an electrical device 9 operatively connected to the internal combustion engine 5. The control device 3 is operatively connected, in particular, to the internal combustion engine 5, in particular to the injectors 7, and is configured to control the internal combustion engine 5, in particular to assign a respective injection quantity to the injectors 7. In particular, the control device 3 is also operatively connected to the electrical device 9 and configured to control the electrical device 9.The electrical device 9 preferably has an electrical machine 11 designed as a generator, which is drive-connected to the internal combustion engine 5, and at least one electrical consumer 13 which is electrically connected to the electrical machine 11 and is preferably designed as a cooling fan 14, in particular as a cooling fan 14 provided for cooling the air in a cooling circuit of the internal combustion engine 5. The internal combustion engine arrangement 1 preferably has two such cooling fans 14. The control device 3 is in particular designed to vary, in particular adjust, an electrical load, in particular a consumer speed, of the at least one electrical consumer 13. The control device 3 is preferably operatively connected to the electrical machine 11 or to the electrical consumer 13.In particular, it is possible for the control device 3 to be operatively connected to the electric machine 11 on the one hand and to the electrical load 13 on the other. Preferably, the control device 3 is configured to detect a generator torque of the electric machine 11 as a power variable. Alternatively or additionally, the control device 3 is configured to detect the rotational speed of the electrical load 13 as a power variable.

[0064] The internal combustion engine 5 is preferably designed as a reciprocating piston engine, in particular as a diesel engine.

[0065] Fig. 2 shows a schematic representation of a first part of an embodiment of a method for evaluating injectors of the internal combustion engine 5 of the internal combustion engine arrangement 1 according to Eigur 1.

[0066] Identical and functionally equivalent elements are provided with the same reference symbols in all figures, so that reference is made to the previous description in each case.

[0067] Within the scope of the method, the injectors 7 are evaluated based on the power variable assigned to the electrical device 9. In particular, in at least two operating states of the internal combustion engine 5, respective assigned values ​​of the power variable are determined, and the injectors 7 are evaluated based on a comparison of the power variable values ​​assigned to the operating states. The at least two operating states differ in particular by a respective assigned activation state of the injectors 7. In particular, the injectors 7 are evaluated based on a comparison of the power variable values ​​assigned to the operating states. In particular, the injectors 7 are evaluated by comparing those power variable values ​​assigned to operating states with one deactivated injector 7 each with a power variable value assigned to an operating state in which all injectors 7 are activated.

[0068] Specifically, in the embodiment illustrated in Figure 2, the method is started in a first step S1. In particular, the internal combustion engine assembly 1 is initially operated at an idle speed of the internal combustion engine 1 and an idle consumer speed of the electrical consumer 13, which is designed in particular as a cooling fan 14. In one embodiment, the idle consumer speed is 600 min 1However, should the cooling requirement of the internal combustion engine 5 be higher even at idle, the electrical consumer 13 can also be operated at a higher consumer speed. Optionally, an operator of the internal combustion engine arrangement 1 can now deactivate an automatic control of the internal combustion engine 5. In a second step S2, the speed of the internal combustion engine 1 is increased to the test speed, in particular without increasing the electrical load, i.e., in particular while maintaining the consumer speed constant. In the following method steps, the test speed is constantly regulated by the control device 3 by allocating a suitable injection quantity to the injectors 7. Optionally, the electrical load is increased to a starting load value, for which purpose, in particular, the consumer speed is increased to a consumer speed starting value, for example, to 1500 min 1 .

[0069] In a third step S3, the electrical load, in particular the consumer speed, is increased - continuously or step by step - wherein, in parallel thereto or after each increase step, a fourth step S4 checks whether the test injection quantity has been reached. Increasing the electrical load simultaneously increases the torque to be generated by the internal combustion engine 5, so that the control device 3 correspondingly increases the injection quantity assigned to the injectors 7. This continues until it is determined in the fourth step S4 that the control device 3 is assigning the test injection quantity to each of the injectors 7, wherein the internal combustion engine 5 is operated in particular in a test state.

[0070] If this is the case, an optional check is performed to determine whether the operation of the internal combustion engine assembly 1 is steady-state. For this purpose, it is checked, in particular, whether the internal combustion engine 5 runs at the test speed for a predetermined period of time within a predetermined speed tolerance band. The internal combustion engine 5 is thus operated, in particular, in a steady-state test state.

[0071] In a fifth step S5, a test value T of the power variable is measured. In particular, a generator torque and / or the load speed can be used as the power variable.

[0072] In a sixth step S6, the test value T is compared with a comparison test value VT, in particular by calculating a test value deviation as the magnitude of a difference between the test value T and the comparison test value VT. The comparison test value VT can be an individual value of a comparison internal combustion engine, in particular with known fully functional injectors, which in particular additionally exhibit a small quantity scatter within a predetermined scatter range, or an average value obtained from the measurement of a plurality of internal combustion engines.

[0073] If the test value deviation exceeds a predetermined limit value GW in the sixth step S6, it is concluded that the internal combustion engine 5 has a serious fault, and the method is terminated in a seventh step S7. If, however, the test value deviation does not exceed the predetermined limit value GW, the method is continued in an eighth step S8 at a first jump marker A.

[0074] Fig. 3 shows a schematic representation of a first embodiment of a second part of the method.

[0075] The method continues here in the eighth step S8 at the first jump marker A. In a ninth step S9, the operation of the internal combustion engine assembly 1 is continued at the test speed and the test injection quantity assigned by the control device 3, as the internal combustion engine assembly 1 results from the previously performed method steps. In particular, the electrical consumer 13 also still has the last set consumer speed.

[0076] In a tenth step S10, an index i is initialized to 1. In an eleventh step S11, the injector 7 to which the current index i is assigned is switched off, with the control device 3 continuing to assign the test injection quantity to the remaining, activated injectors 7. The internal combustion engine 5 is thus operated in a switched-off state. If the switched-off injector i is functional—that is, it has neither continuous injection nor a permanently closed state—the speed of the internal combustion engine 5 subsequently drops, since without the contribution of the switched-off injector i, it can no longer deliver the power requested by the electrical consumer 13. Accordingly, in a twelfth step S12, it is checked whether the internal combustion engine 5 is running at the test speed; if this is not the case, the electrical load is reduced in a thirteenth step S13, in particular by lowering the consumer speed.The steps S12 and S13 are iterated until it is determined in the twelfth step S12 that the internal combustion engine 5 is running at the test speed.

[0077] If it is determined in the twelfth step S12 that the internal combustion engine 5 is running at the test speed, a measured value Mi of the power variable assigned to the current injector i is recorded in a fourteenth step S14. The current injector i is then reactivated in a fifteenth step S15.

[0078] Optionally, before recording the measured value Mi, it is checked whether the operation of the internal combustion engine assembly 1 is steady-state. For this purpose, it is checked, in particular, whether the internal combustion engine 5 runs at the test speed for a predetermined period of time within the predetermined speed tolerance range. The internal combustion engine 5 is thus operated, in particular, in a steady-state shutdown state.

[0079] Subsequently, in a sixteenth step S16, it is checked whether the current value of the index i corresponds to the total number N of injectors 7 of the internal combustion engine 5. If this is not the case, the index i is incremented in a seventeenth step S17, and the method is continued in the eleventh step S11 for a next injector 7. If, however, it is determined in the sixteenth step S16 that the index i already has the value N, the method is continued in an eighteenth step S18 at a second jump label B. Fig. 4 shows a schematic representation of a second embodiment of the second part of the method, which is an alternative to the first embodiment according to Fig. 3.

[0080] The method then continues in the eighth step S8 at the first jump label A. In a nineteenth step S19, the operator of the internal combustion engine assembly 1 first activates the automatic control of the internal combustion engine 5, so that the internal combustion engine 5 operates at idle speed and, in particular, the electrical consumer 13 operates at the idle consumer speed. However, if the cooling requirement of the internal combustion engine 5 is higher during idle, the electrical consumer 13, which is designed, in particular, as a cooling fan 14, can also be operated at a higher consumer speed.

[0081] Then, in a twentieth step S20, the index i is initialized with the value 1.

[0082] In a twenty-first step S21, the injector 7 assigned the current index i is deactivated. The internal combustion engine 5 is thus operated in a deactivated state. In a twenty-second step S22, the electrical load is increased to the starting load value, which means, in particular, that the consumer speed is increased to the consumer speed starting value.

[0083] In a twenty-third step S23, the electrical load, that is to say in particular the consumer speed, and / or the injection quantity assigned by the control device 3 to the injectors 7 that are not switched off are increased until it is determined in a twenty-fourth step S24 that both the internal combustion engine 5 is running at the test speed and the control device 3 is assigning the test injection quantity to the injectors 7 that are not switched off. In particular, it is possible for the electrical load and the injection quantity to first be increased in parallel until the test injection quantity is reached, with the electrical load then being varied further until the test speed is also reached.

[0084] Then, in a twenty-fifth step S25, the measured value Mi of the power variable assigned to the current injector i is recorded. Optionally, before recording the measured value Mi, it is checked whether the operation of the internal combustion engine arrangement 1 is steady-state. For this purpose, it is checked, in particular, whether the internal combustion engine 5 is running at the test speed for a predetermined period of time within the predetermined speed tolerance band. The internal combustion engine 5 is thus operated, in particular, in a steady-state shutdown state.

[0085] In a twenty-sixth step S26, the current injector i is reactivated.

[0086] Subsequently, in a twenty-seventh step S27, it is checked whether the current value of index i corresponds to the total number N of injectors 7 of internal combustion engine 5. If this is not the case, index i is incremented in a twenty-eighth step S28, and the method continues in the twenty-first step S21 for a next injector 7. If, however, it is determined in the twenty-seventh step S27 that index i already has the value N, the method continues in the eighteenth step S18 at the second jump label B.

[0087] Fig. 5 shows a schematic representation of a third part of the method. In the third part of the method, the measured values ​​Mi are compared with the test value T by calculating a test difference PDi from the test value T for each measured value Mi. In particular, the injectors 7 are evaluated based on the associated test differences PDi.

[0088] For this purpose, the method is continued in the eighteenth step S18 at the second jump mark B.

[0089] In a twenty-ninth step S29, the index i is again initialized with the value 1.

[0090] In a thirtieth step S30, the test difference PDi assigned to the injector 7 to which the current index i is assigned is calculated by subtracting the assigned measured value Mi from the test value T. The test difference thus defined is either zero or positive, since the measured value Mi is at most as large as the test value T. In a thirty-first step S31, it is checked whether the test difference PDi assigned to the current injector i falls within a zero tolerance band, i.e., within a predetermined interval [0,u] with an upper limit u > 0, wherein with respect to a first threshold value SW 1, the following preferably applies: u < < SW 1.

[0091] If it is determined in the thirty-first step S31 that the test difference PDi falls within the zero tolerance band, it is determined in a thirty-second step S32, i.e. - here and in the following - stored in particular for the current injector i, that the injector i is defective.

[0092] If, however, it is determined in the thirty-first step S31 that the test difference PDi does not fall within the zero tolerance band, a thirty-third step S33 checks whether the test difference PDi is greater than the first threshold value SW1. If this is not the case, a thirty-fourth step S34 determines that the current injector i is actually introducing an injection quantity that is less than the test injection quantity, which it is controlled to introduce by the control device 3.

[0093] If, however, it is determined in the thirty-third step S33 that the test difference PDi is greater than the first threshold value SW1, a thirty-fifth step S35 checks whether the test difference PDi is greater than a second threshold value SW2, for which SW2 > SW1 applies. If this is not the case, a thirty-sixth step S36 determines that the current injector i is actually delivering the test injection quantity, which it is controlled to deliver by the control device 3.

[0094] If, on the other hand, it is determined in the thirty-fifth step S35 that the test difference PDi is greater than the second threshold value SW2, it is determined in a thirty-seventh step S37 that the current injector i actually introduces an injection quantity that is greater than the test injection quantity for which it is controlled by the control device 3.

[0095] Subsequently, in a thirty-eighth step S38, it is checked whether the current value of the

[0096] Index i corresponds to the total number N of injectors 7 of the internal combustion engine 5. If this is not the case, the index i is incremented in a thirty-ninth step S39, and the method is continued in the thirtieth step S30 for a next injector 7.

[0097] If, however, it is determined in the thirty-eighth step S38 that the index i already has the value N, the method continues in a fortieth step S40, in which a difference mean M(PD) is calculated over all test differences PDi assigned to the injectors. In particular, a median, an arithmetic mean, or a geometric mean can be calculated as the difference mean.

[0098] In a forty-first step S41, the index i is again initialized with the value 1.

[0099] In a forty-second step S42, a difference deviation Di(PD) associated with the injector 7 to which the current index i is assigned is calculated by subtracting the associated test difference PDi from the difference mean value M(PD).

[0100] In a forty-third step S43, a check is performed to determine whether the current injector i was previously marked as defective in the thirty-second step S32 because the test difference PDi assigned to it falls within the zero tolerance band. If this is the case, in a forty-fourth step S44, the injector i is reconfirmed as defective, or the defective marking is simply retained.

[0101] If, however, it is determined in the forty-third step S43 that the current injector i is not marked as defective, a forty-fifth step S45 checks whether the differential deviation Di(PD) falls within a predetermined differential tolerance band. If this is not the case, a forty-sixth step S46 determines that the injector i is defective. If, however, it is determined in the forty-fifth step S45 that the differential deviation Di(PD) falls within the predetermined differential tolerance band, the injector i is evaluated as OK in a forty-seventh step S47.

[0102] Subsequently, in a forty-eighth step S48, it is checked whether the current value of index i corresponds to the total number N of injectors 7 of internal combustion engine 5. If this is not the case, index i is incremented in a forty-ninth step S49, and the method continues in the forty-second step S42 for a next injector 7. If, however, it is determined in the forty-eighth step S48 that index i already has the value N, the method is terminated in a fiftieth step S50.

Claims

CLAIMS 1. Method for evaluating at least one injector (7) of an internal combustion engine (5) having a plurality of injectors (7), wherein the injectors (7) are evaluated on the basis of a power variable which is assigned to an electrical device (9) which is operatively connected to the internal combustion engine (5).

2. Method according to claim 1, wherein in at least two operating states of the internal combustion engine (5) respectively assigned values ​​of the power variable are determined, and wherein the injectors (7) are evaluated based on a comparison of the values ​​of the power variable assigned to the operating states.

3. Method according to one of the preceding claims, wherein a) the internal combustion engine (5) is operated in a test state with activated injectors (7), wherein the injectors (7) are each assigned the same, constant test injection quantity of a fuel, wherein a test value of the power variable is determined, wherein b) the internal combustion engine (5) is successively operated in a plurality of switch-off states, wherein in the switch-off states an injector (7) of the injectors (7) assigned to the respective switch-off state is switched off, wherein the remaining injectors (7) are each assigned the same, constant test injection quantity of the fuel, and wherein in the switch-off states a measured value of the power variable assigned to the respective switch-off state is determined, wherein c) the measured values ​​are compared with the test value, wherein d) the injectors (7) are evaluated on the basis of the comparison.

4. Method according to one of the preceding claims, wherein the electrical device (9) used is a device selected from a group consisting of an electrical machine (11) drivingly connected to the internal combustion engine (5), an electrical consumer (13), and a combination thereof.

5. Method according to one of the preceding claims, wherein an electric cooling fan (14) is used as the electrical device (9).

6. Method according to one of the preceding claims, wherein the power variable used is a variable selected from a group consisting of a generator torque, a consumer speed of an electrical consumer (13), and a combination thereof.

7. The method according to any one of claims 3 to 6, wherein in at least one step selected from steps a) and b), preferably in both steps a) and b), - the internal combustion engine (5) is operated at a constant test speed above an idle speed, whereby - the test application quantity is adjusted by varying an electrical load of the electrical device (9), or - the injectors (7) are assigned the constant test injection quantity, whereby - the test speed is adjusted by varying the electrical load of the electrical device (9).

8. Method according to one of claims 3 to 7, wherein the test value is compared with at least one comparison test value, wherein preferably steps b) to d) are omitted if a test value deviation of the test value from the at least one comparison test value exceeds a predetermined limit value.

9. Method according to one of claims 3 to 8, wherein in step c) the measured values ​​are compared with the test value by calculating a test difference from the test value for each measured value, wherein in particular the test differences are each compared with a predetermined first threshold value and a predetermined second threshold value different from the first threshold value, wherein the injectors (7) are evaluated based on the comparison of the test differences with the predetermined first and second threshold values.

10. The method according to claim 9, wherein a difference mean of the test differences is calculated, wherein for each test difference a difference deviation from the difference mean is calculated, wherein the injectors (7) are additionally evaluated on the basis of the difference deviations.

11. Control device (3) for an internal combustion engine arrangement (1), designed to carry out a method according to one of claims 1 to 10.

12. Internal combustion engine arrangement (1), with an internal combustion engine (5) having a plurality of injectors (7), an electrical Device (9), and a control device (3) according to claim 11.

13. Internal combustion engine arrangement (1) according to claim 12, wherein the electrical device (9) has an electric machine (11) which is drive-connected to the internal combustion engine (5) and an electric load (13) which is electrically connected to the electric machine (11), wherein the control device (3) is in particular designed to vary an electric load of the electric load (13).

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