JP4695743B2 - Method and apparatus for operating a fuel supply system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a method and an apparatus for operating a fuel supply system of an automobile internal combustion engine, in particular of a type in which fuel is pumped by a pump and then supplied to a combustion part by a fuel injection valve which is controlled by an electric final stage.
[0002]
[Prior art]
In order to ensure reliable operation of the internal combustion engine, it is necessary to allow a sufficient amount of fuel to reach the combustion chamber of the internal combustion engine before each combustion. Therefore, the operation of the fuel injection valve is controlled over a specified time so that the amount of fuel required for combustion reaches the combustion chamber. For example, in the case of a direct injection internal combustion engine, fuel is directly injected into the combustion chamber of the cylinder at a high pressure.
[0003]
In order to achieve reliable fuel injection, fuel is first pumped into a storage chamber in today's systems. The fuel injected into the combustion chamber by the fuel injection valve is taken out from the storage chamber.
[0004]
The fuel injection valve must open reliably with respect to the fuel pressure in the storage chamber. Occurrence of a situation where the fuel injection valve or valves can no longer be opened relative to the fuel pressure in the storage chamber based on aging phenomena or system tolerances or due to excessive pressure in the storage chamber There is. For this reason, the fuel can no longer reach the combustion chamber, which causes misfires.
[0005]
[Problems to be solved by the invention]
An object of the present invention is to provide a reliable diagnostic method for a fuel supply system.
[0006]
[Means for Solving the Problems]
The constituent means of the present invention for solving the above-mentioned problem is that at least one operating characteristic quantity is detected, and at least the detected operating characteristic quantity and at least one characteristic influence factor of the internal combustion engine are detected. And determining the combustion abnormality, and if the at least one reference quantity R satisfies a predetermined criterion (criterion), the combustion abnormality is determined. The point is to store and store.
[0007]
A particularly significant advantage of the present invention is that an accurate diagnosis of the fuel supply system can be achieved without additional components.
[0008]
This also makes it possible to confirm critical obstacles to the exhaust gas. A further advantage is that fault search in a factory is facilitated by fault segmentation or localization.
[0009]
Other advantages of the invention will become apparent on the basis of the description of the following examples, together with the description of the dependent claims.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
Next, embodiments of the present invention will be described in detail with reference to the drawings.
[0011]
However, although the present invention will be described by taking a direct injection internal combustion engine as an example, the present invention can be applied to an intake pipe injection internal combustion engine in principle.
[0012]
The fuel supply system 10 shown in FIG. 1 is provided for use in an internal combustion engine. An electric fuel pump (EKP) 12, a fuel filter 13, and a low pressure regulator (DR) 14 are disposed in the fuel tank 11. A fuel conduit 15 leads from the fuel tank 11 to a high pressure pump (HDP) 16. A storage chamber (Rail) 17 is connected to the high-pressure pump 16. A plurality of fuel injection valves 18 are arranged in the storage chamber 17, and in particular the fuel injection valves are arranged directly in the combustion chamber 26 of the internal combustion engine. In the case of a direct injection internal combustion engine, at least one fuel injection valve 18 is disposed in each combustion chamber 26.
[0013]
Fuel is pumped from the fuel tank 11 by the electric fuel pump 12 to the high-pressure pump 16 through the fuel filter 13 and the fuel conduit 15. The fuel filter 13 serves to remove foreign particles from the fuel. The fuel pressure in the low pressure region of the fuel supply system is regulated to a specified value by the low pressure regulator 14. This pressure regulation brings the fuel to a pressure of about 4-5 bar. In particular, the high-pressure pump 16 driven directly by the internal combustion engine compresses the fuel and pumps it into the storage chamber 17. The fuel pressure here reaches a pressure value of up to 150 bar.
[0014]
In FIG. 1, only one combustion chamber 26 of a direct injection internal combustion engine is shown. In general, an internal combustion engine can have a plurality of combustion chambers 26.
[0015]
The combustion chamber 26 has at least one fuel injection valve 18, one spark plug 24, one intake valve 27, one exhaust valve 28, and one piston 29.
[0016]
In the intake stroke, fresh air is drawn into the combustion chamber 26 via the intake valve 27. Fuel is directly injected into the combustion chamber 26 of the internal combustion engine by the fuel injection valve 18. The fuel is ignited by the spark plug 24. The piston 29 is driven by the expansion of the ignited fuel.
[0017]
The crankshaft 35 is simultaneously driven by the movement of the piston 29. A segment disk 34 is disposed on the crankshaft 35. A rotation speed sensor 30 is disposed opposite the segment disk 34 and detects the segment disk. The rotational speed sensor 30 generates a signal that characterizes the rotational movement of the crankshaft 35 or segment disk 34.
[0018]
Exhaust gas generated during combustion reaches the exhaust pipe 33 from the combustion chamber 26 via the exhaust valve 28. An exhaust gas temperature sensor 31 and a lambda (λ) sensor 32 are disposed in the exhaust pipe 33. The exhaust gas temperature sensor 31 detects the temperature of the exhaust gas, and the lambda sensor 32 detects the oxygen content (excess air ratio) of the exhaust gas.
[0019]
A pressure sensor (DS) 21 and a pressure control valve (DSV) 19 are connected to the storage chamber 17. A storage chamber 17 is connected to the inlet side of the pressure control valve 19. A return conduit 20 that leads to the fuel conduit 15 is connected to the outlet side of the pressure control valve 19.
[0020]
In the fuel supply system 10, a quantity control valve can be used instead of the pressure control valve 19. However, for the sake of simplicity, only the pressure control valve 19 will be described here.
[0021]
The actual value of the fuel pressure in the storage chamber 17 is detected by the pressure sensor 21 and supplied to the controller (SG) 25. In the controller 25, an operation control signal for controlling the operation of the pressure control valve 19 is formed based on the detected actual value of the fuel pressure.
[0022]
The operation of the fuel injection valve 18 is controlled through an electrical final stage not shown in FIG. The final stage can be located inside or outside the controller 25.
[0023]
Various actuators and sensors are connected to the controller 25 via a plurality of control and signal conductors 22.
[0024]
Within the controller 25, various functions are performed which serve to control the internal combustion engine. In modern controllers, these functions are programmed with a computer and then stored in the memory of the controller 25. The functions stored in the memory are activated in connection with the demands imposed on the internal combustion engine. In this case, particularly severe requirements are imposed on the real-time property of the controller 25 in combination with the function. However, in principle, the function of the control device for the internal combustion engine can be realized by pure hardware.
[0025]
FIG. 2A is a first part of the flowchart of the operation method according to the present invention, and FIG. 2B is a second part of the flowchart. The circle surrounding number 1 represents the transition point between the first and second parts of the process diagram. Note that, as a precautionary note, the symbol J described in FIGS. 2A and 2B represents yes, and the symbol N represents no.
[0026]
The precondition for carrying out this method is that sufficient pressure in the storage chamber 17 is provided and the pressure sensor 21 is functioning.
[0027]
In FIG. 2A, the segment time Ts is detected by the rotational speed sensor 30 in the processing step 201 after the start of processing of the method. At the same time, a fuel mass signal RK representing the fuel mass to be injected for instantaneous combustion is prepared by the controller 25 for further processing.
[0028]
The segment time Ts is equal to the duration of one segment or the displacement time between pistons. For example, in the case of a four stroke cycle engine, the first cylinder is again in the same stroke after two revolutions (720 °) of the crankshaft. Therefore, in the case of a 4-cylinder engine, the piston is shifted by 180 °. In short, the segment time Ts is equal to the time required for the crankshaft 35 to make a half rotation or an angle of 180 °.
[0029]
For example, the rotational speed NMOT of the internal combustion engine can be used instead of the segment time Ts. It is also possible to use another quantity representing the rotational movement of the crankshaft 35 of the internal combustion engine.
[0030]
In the process step 202, a reference quantity, ie a reference signal R, is determined from the segment time Ts and the fuel mass signal RK. For this purpose, it is advantageous that the segment time difference ΔTs is first formed from the difference between the current segment time Ts and the average segment time TsMITEL.
[0031]
ΔTs = Ts− TsMITTEL
Furthermore, a standardized fuel mass signal RKN is formed from the quotient of the current fuel mass signal RK and the average value RKMITITE of the fuel mass signal.
[0032]
RKN = RK / RKMITTEL
The reference quantity or reference signal R results in particular from the product of the segment time difference ΔTs and the standardized fuel mass signal RKN.
[0033]
R = ΔTs × RKN
The detection of the set reference signal R is a particularly simple solution that can be realized particularly easily by a given means.
[0034]
The reference amount R is compared with the limit value S in the process step 203. If the reference quantity R is smaller than the limit value S, the processing stage 202 is repeated. However, if the reference amount R exceeds the limit value S, combustion abnormalities are recognized and stored in the processing stage 204.
[0035]
Combustion abnormalities have various causes. A particularly critical and possible source of failure is the final stage of the fuel injection valve, i.e. the ignition system (ignition plug, ignition coil), contaminated or burnt sticky fuel injection valve.
[0036]
The method is ultimately aimed at recognizing fuel injectors that are no longer open. For this reason, various possible sources of failure are checked in recognizing combustion anomalies. For this purpose, as shown in FIG. 2B, first the function of the final stage of the fuel injection valve 18 is checked in the process stage 205.
[0037]
For this purpose, as described in DE 4012109, for example, a logic circuit is connected in parallel to the final stage, to which the potentials of the input and output terminals of the final stage and A reference potential is applied. It is possible to reliably distinguish and diagnose fault conditions such as overload / short circuit due to a positive potential and load drop / short circuit due to a negative potential, and to diagnose a final stage that operates normally.
[0038]
If a fault in the last stage of the fuel injector 18 is recognized, this fault is stored and stored in the process stage 206 and corresponding measures are introduced to protect the internal combustion engine.
[0039]
On the other hand, if no failure in the final stage of the fuel injection valve 18 is confirmed, it is checked in the processing stage 207 whether or not the fuel reaches the exhaust pipe 33 from the combustion chamber 26 in an unburned state. . It is estimated whether this is an ignition failure due to the lack or insufficiency of the ignition function of the spark plug 24, or an ignition failure due to an excessively rich air / fuel mixture due to the fuel injection valve no longer closing. Is possible. For this estimation, it is possible to alternatively use various methods described below.
[0040]
For example, the temperature of the exhaust gas is detected by the exhaust gas temperature sensor 31 in order to recognize an ignition failure. The combustion state is estimated in reverse from the exhaust gas temperature TAB. For example, when the fuel reaches the exhaust pipe 33 from the combustion chamber 26 in the non-combustion state, the fuel is post-combusted in the exhaust pipe 33 based on the high temperature, and contributes to the temperature increase there. By comparing the exhaust gas temperature TAB with the limit value, it is recognized whether the fuel has burned in the exhaust pipe 33 or not. Accordingly, it is possible to estimate that the cause of the failure is an ignition failure after the final stage failure of the fuel injection valve 18 is excluded.
[0041]
As an alternative or in addition to the scheme, it is possible to evaluate the signal of the lambda sensor 32 in order to recognize ignition faults. The lambda sensor 32 detects the oxygen concentration in the exhaust gas. By comparing the signal of the lambda sensor 32 with the expected value, the combustion state is inferred, thereby presuming that the ignition error is the cause.
[0042]
It is also possible to evaluate the signal of the ion flow sensor in addition to or alternatively to the signal of the lambda sensor or the exhaust gas temperature sensor. The degree of ionization that occurs during combustion is detected by the ion flow sensor.
[0043]
When it is recognized in the process step 207 that the fuel has reached the combustion chamber 26 in an unburned state, an ignition failure is recognized and stored in the process step 208. On the other hand, if an ignition failure is not recognized, it is recognized in process step 209 that the fuel injector 18 is no longer correctly opened.
[0044]
As already mentioned, the precondition here is that there is sufficient pressure in the storage chamber 17, which is because the error due to the fuel injection valve 18 not opening is caused by the storage chamber 17. The error caused by the excessively low pressure is to make a clear line.
[0045]
FIG. 3 schematically shows a diagram of the operation amount selected as an example, the influence factor amount, and the reference amount resulting from the operation amount and the influence factor amount. All of the three types of diagrams represent the selection amount as a function of the rotational motion angle (° KW) of the crankshaft 35.
[0046]
Diagram A represents the standardized fuel mass signal RKN, diagram B represents the segment time difference ΔTs, and diagram C represents the reference quantity R resulting from the combination of the two quantities. The lines shown with broken lines indicate equal crankshaft angles. The distance between each two lines corresponds to a spatial shift between one segment or two pistons 29.
[0047]
Roman numerals I, II, and III are examples of the state of the internal combustion engine described in detail below to help understanding of the present invention.
[0048]
In state I-combustion abnormality state I, as can be recognized from diagram A, the standardized fuel mass signal RKN is substantially unchanged compared to the preceding value or occupies a value approximating "1". . In other words, the current fuel mass signal RK is substantially equal to the mean value RKMITTEL of the fuel mass signal.
[0049]
As can be recognized from the diagram B, the segment time difference ΔTs is significantly different from the zero value or has a jump value compared to the preceding value. This means that the current segment time Ts is longer than the average value of segment times TsMITEL, or that the crankshaft rotational speed has suddenly decreased.
[0050]
By comparing the results of the diagram A and the results of the diagram B, it can be estimated that an error exists in the fuel supply system 10. If the fuel supply and the fuel combustion are constant as can be recognized from the diagram A, such a remarkable change cannot occur in the current segment time Ts (the diagram B).
[0051]
As can be recognized from the diagram C, the detected reference amount R significantly exceeds the limit value S, so that it can be reliably estimated that a combustion abnormality has occurred.
[0052]
In the state II-normal combustion state II, as can be recognized from the diagram A, the standardized fuel mass signal RKN is reduced in strength compared to the preceding value. In other words, the current fuel mass signal RK has a value significantly smaller than the average value RKMITTEL of the fuel mass signal. Such a situation may occur, for example, when the controller 25 interferes with the fuel supply for a short period of time based on the specific reason required for control of the internal combustion engine.
[0053]
In the diagram B, as in the case of the state I, it can be recognized that the segment time difference ΔTs is significantly different from the zero value or has a jump value compared to the preceding value. This means that the current segment time Ts is remarkably longer than the average value of segment times TsMITEL, or the crankshaft rotational speed has rapidly decreased.
[0054]
By comparing the result of diagram A with the result of diagram B, it can already be estimated that the fuel supply system is normal. This is because the segment time must be forcibly increased at the same time as the injected fuel mass decreases.
[0055]
As can be recognized in the diagram C, the detected reference amount R does not exceed the limit value S, so that it can be estimated with certainty that the combustion is normally normal.
[0056]
State III-normal combustion, side effect deviation state III. As can be seen from diagram A, the standardized fuel mass signal RKN is almost unchanged compared to the preceding value, or a value approximating "1" Accounted for. In other words, the current fuel mass signal RK is substantially equal to the average value of the fuel mass signal RKMITTEL.
[0057]
As can be recognized in the diagram B, the segment time difference ΔTs has a negligible deviation from zero and occupies a negative value. This means that the current segment time Ts has a value slightly smaller than the average segment time TsMITTEL, or the crankshaft rotational speed has been increased by a small value over a short period of time. . This negligible deviation of the segment time difference ΔTs from zero is mainly due to crankshaft vibration, wheel slip, different friction, different cylinder filling, changed road surface conditions (eg stones) and / or This occurs due to the influence parameter amount.
[0058]
The limit value S, which is fixedly set or adaptively set, forms a boundary between the deviation caused by the failed fuel supply system and the deviation caused by the influence factor amount.
[0059]
As can be recognized from the diagram C, the detected reference amount does not exceed the limit value S, but even occupies a negative value, so that it can be estimated with certainty that it is currently in a normal combustion state. It is.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a fuel supply system of an internal combustion engine.
FIG. 2 is a flowchart of a method for operating a fuel supply system according to the present invention.
FIG. 3 is a schematic diagram showing an example of the characteristic influence factor amount, the operation characteristic amount, and the reference amount obtained from the operation characteristic amount and the characteristic influence factor amount of the method of the present invention as a function of the crankshaft angle. .
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10 Fuel supply system, 11 Fuel tank, 12 Electric fuel pump (EKP), 13 Fuel filter, 14 Low pressure regulator (DR), 15 Fuel conduit, 16 High pressure pump (HDP), 17 Storage chamber (Rail), 18 Fuel injection Valve, 19 pressure control valve (DSV), 20 return conduit, 21 pressure sensor (DS), 22 control and signal conductor, 24 spark plug, 25 controller (SG), 26 combustion chamber, 27 intake valve, 28 exhaust valve, 29 piston, 30 rotation speed sensor, 31 exhaust gas temperature sensor, 32 lambda (λ) sensor, 33 exhaust pipe, 34 segment disc, 35 crankshaft, 201, 202, 203, 204, 205, 206, 207, 208, 209 Processing stage, Ts segment time, RK fuel mass signal, RKN standardized fuel mass signal, R reference quantity or reference No., S limit value, .DELTA.Ts segment time difference

Claims (5)

In a method of operating a fuel supply system (10) of an automobile internal combustion engine in which fuel is pumped by a pump (12, 16) and then supplied to a combustion section by a fuel injection valve (18) which is electrically operated and controlled. ,
At least one operation characteristic amount is detected, and at least one reference amount R is detected from the detected at least one operation characteristic amount and at least one characteristic influence factor amount of the internal combustion engine, and the at least one reference amount is detected. In the case where R satisfies the prescribed judgment criteria, the characteristic abnormality factor amount is at least one fuel mass signal RK and the operating characteristic amount is the fuel characteristic signal for checking and storing the combustion abnormality. Detecting at least one segment time signal Ts and / or rotational speed signal NMOT and / or rotational moment signal Md characterizing combustion, wherein said at least one reference quantity R is standardized with a segment time difference ΔTs and a fuel mass normalized The segment time difference ΔTs is the product of the segment time signal Ts. And the standardized fuel mass signal RKN is a quotient of the fuel mass signal RK and the average value RKMITTEL of the fuel mass signal,
When recognizing the abnormality of the combustion, at least the function of the electric means for controlling the operation of the fuel injection valve (18) is checked in the first processing stage, and if an error is recognized, the error is stored and accumulated. When no error of the electric means is recognized, the non-combustion state of the fuel is detected in the second processing stage, and when the error is recognized, the ignition error is recognized and stored, and there is no ignition error. A method for operating a fuel supply system, characterized in that an error caused by the fuel injector (18) not opening is recognized and stored. The method according to claim 1 , wherein at least one reference amount R is compared with a limit value S, and if the limit value S is exceeded, a combustion abnormality is recognized and stored. From the sensed segment time signal Ts, it is possible to form a speed signal NMOT the crankshaft (35), Method according to claim 1 or 2. Wherein the program suitable for implementing the method according to any one of a process can be processed by the computer the claims 1 to 3 is stored accumulated, the fuel supply system of the internal combustion engine Control element for the controller (25) operating (10). The apparatus for carrying out the method for operating the fuel supply system according to any one of claims 1 to 3 , further comprising means for detecting at least one operating characteristic amount, and at least one detected operation. Another means for determining at least one reference quantity R from the characteristic quantity and at least one characteristic influence factor quantity of the internal combustion engine is provided, and the at least one reference quantity R satisfies a prescribed judgment criterion In the case of checking and accumulating combustion anomalies, the characteristic influence factor quantity is at least one fuel mass signal RK, and at least one segment time characterizing fuel combustion as the operating characteristic quantity The fuel supply system is operated by detecting the signal Ts and / or the rotational speed signal NMOT and / or the rotational moment signal Md Location.

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