KR20210077638A - Method for operating a fuel supply system - Google Patents

Abstract

The present invention relates to a method for operating a fuel supply system for an internal combustion engine used to enable a fuel injector (110) including a switch valve formed as a solenoid valve (120) to introduce fuel into a combustion chamber of an internal combustion engine by receiving the fuel from a high-pressure accumulator. In the method, the solenoid valve (120) includes an armature (124) for the closing and opening of a tube opening (150), and an armature pin (125) placed in an opening (126) of the armature (124), and when a precipitate (200) attenuating or inhibiting the opening of the tube opening (150) performed through the armature (124) is determined as present between the armature (124) and an armature guide (125), pressure oscillations are actively produced to the fuel in the high-pressure accumulator during an oscillation procedure.

Description

METHOD FOR OPERATING A FUEL SUPPLY SYSTEM

The present invention relates to a method for operating a fuel supply system for an internal combustion engine in which a fuel injector comprising a switching valve formed as a solenoid valve is used, and to a computer unit and a computer program for executing the method.

In the case of today's internal combustion engines, high-pressure accumulators, ie fuel supply systems in which fuel with relatively high pressure is stored in so-called rails, can be used, in which case the fuel is directed into the combustion chambers of the internal combustion engine. In order to be introduced into the bar, they are supplied with individual fuel injectors. In this case, a fuel injector of a typical type is a fuel injector in which a solenoid valve is used as a switching valve or a servo valve.

Even if fuel filters are used in the fuel supply system, deposits or other contaminants may occur, either through unfiltered particles or substances in the fuel, or through coking. It is known from DE 103 16 391 B4 that carbonization in the fuel injector is eliminated, for example by means of an intended pressure rise.

According to the invention, a method of operating a fuel supply system having the features of the independent claims, a computer unit and a computer program for the execution of the method is proposed. Preferred embodiments are the subject of the dependent claims and the description below.

The present invention, as already mentioned in the introduction, relates to a fuel supply system in which a fuel injector comprising a switching valve formed as a solenoid valve is supplied with fuel from a high-pressure accumulator and used to introduce fuel into a combustion chamber of an internal combustion engine. Although such fuel supply systems or internal combustion engines are typically provided with several such fuel injectors and combustion chambers, it is self-evident that the same applies here and hereinafter to a single fuel injector and combustion chamber.

Solenoid valves are typically for armatures for closing and unclosing flow-through openings, and for armatures, for example in the form of armature pins arranged in a (suitably central) opening (or usually a bore) of the armature. Includes guide. The guides are functionally necessary to ensure reliable opening and closing of the perfusion openings in general. In this case, the flow-through opening generally defines a control chamber for fuel as part of the servo-hydraulic circuit, and to introduce or inject fuel, the armature is actuated to unclose the flow-through opening. As a result, fuel is expelled from the control chamber, resulting in actuation of a valve needle to open the valve or fuel injector. The armature is lifted through the activation or current supply of the associated electromagnet or the corresponding coil and against the spring force of the spring. To close the perfusion opening, the actuation of the electromagnet is correspondingly terminated.

In this regard, the armature moves up and down along its guide, for example along the armature pins. Manufacture and function, a certain gap is formed between the armature and its guide which allows for the movement of the armature. Also, the gap between the armature and the armature guide to the armature pin affects the permanent leakage that the fuel injector has in the closed state.

However, it also causes the fuel to reach within the gap. On the other hand, it has been confirmed that, in this case, deposits that can lower or even block the mobility of the armature may be formed in the gap. In the extreme case, thereby the armature is no longer able to unclose the flow-through opening, which causes the flow of fuel into the combustion chamber to cease. As has been identified, zinc present in some fuels is sometimes a decisive factor in the formation of deposits.

This is where the method proposed herein begins, in which case, if it is determined that there is a deposit between the armature and the armature guide that aggravates or prevents the unclosing of the flow-through opening by the armature, an oscillation process is initiated. In , a pressure oscillation is actively created in the fuel in the high-pressure accumulator.

In this regard, if it is determined that the fuel inflow into the combustion chamber via the fuel injector is to be stopped, it may be determined that deposits are present between the armature and the armature guide, as this is the result of deposits as mentioned. Also, since ignition cannot be carried out without (sufficient) fuel in the combustion chamber, if it is determined that a misfire or interruption of ignition appears within the combustion chamber, it may be determined that the fuel flow into the combustion chamber through the fuel injector has ceased. Interruption of ignition can again be sensed or detected, for example, through non-uniformities in the number of revolutions, or through the absence of ignition noise.

Accordingly, if it is determined that there is a misfire in the combustion chamber, in other words, an oscillation process can be executed or carried out. This applies correspondingly to the further provided fuel injectors or combustion chambers.

The pressure oscillation now separates deposits from the armature or armature guide, as confirmed in the tests - based on the oscillating motion or vibration of the armature and armature guide caused through oscillation in the fuel, and thus the motion of the armature and some radial forces acting on the armature guide and the armature thus restoring functionality. Also, preferably during the oscillation process the solenoid valve is controlled to unclose the flow-through opening, ie the coil is energized. Thereby, the separated precipitate can be removed much better.

Preferably, in the oscillation process, an upper limit value, a lower limit value and a frequency for the oscillation are preset, the upper limit value being greater than the pressure value especially for the normal operation mode. For example, a frequency of 0.5 Hz is conceivable, and in this case the characteristic curve may be, for example, a sawtooth shape. The pressure gradient in this case can be, for example, about 500 or 700 bar/s, and can generally be chosen freely. However, there is usually a maximum upper limit for the pressure gradient. The maximum upper limit is derived based on the system layout, in particular through the discharge amount of the high-pressure pump.

Preferably, the oscillation process is used and/or repeated frequently until a predetermined termination criterion exists. In this case, the termination criteria may include reaching a predetermined maximum number of start-up processes and/or determining that the fuel inflow into the combustion chamber via the fuel injector is no longer stopped. In this case, the maximum number may be applied over the entire useful life of the fuel injector, or it may be applied only for one operating cycle until the next stoppage of the internal combustion engine. In such cases, a specific (maximum) period can be selected for the oscillation process.

Also, preferably, an error log entry is generated when the oscillation process is executed, ie if an underlying problem occurs. In this way, a replacement of the fuel injector can be carried out, for example at the next workshop visit.

A computer unit, such as a control unit, in particular an engine control unit, of a motor vehicle according to the invention is in particular programmatically configured to execute the method according to the invention.

It is also desirable to implement the method according to the invention in the form of a computer program or computer program product comprising program code for the execution of all method steps, since in particular the execution-side control device is also used for further tasks. This is because the above method causes particularly low cost if it exists anyway. Data storage media suitable for providing a computer program are, inter alia, magnetic, optical and electronic memories such as, for example, hard disks, flash memories, EEPROMs, DVDs and the like. It is also possible to download the program over a computer network (Internet, intranet, etc.).

Further advantages and configurations of the present invention refer to this specification and the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is schematically illustrated in the drawings on the basis of one embodiment and is described below with reference to the drawings.

1 is a schematic diagram of a fuel supply system for an internal combustion engine suitable for carrying out the method according to the invention;
2 is a schematic diagram of a solenoid valve of a fuel injector in which the method according to the invention can be implemented;
3 shows a sequence of a method according to the invention on the basis of different diagrams of an armature in one preferred embodiment;
Fig. 4 is a graph showing the sequence of the method according to the invention on the basis of a pressure characteristic curve in a high-pressure accumulator in one preferred embodiment;

1 schematically shows a fuel supply system 100 for an internal combustion engine 160 suitable for carrying out the method according to the invention. By way of example, the internal combustion engine 160 includes three combustion chambers or associated cylinders 165 . Each combustion chamber 165 is assigned a fuel injector 110 comprising a solenoid valve 120 , which is in turn each connected to a high-pressure accumulator 175 , ie a so-called rail, through which the fuel is supplied. receive

As should be evident, the method according to the invention can also be used in an internal combustion engine comprising any other number of cylinders, for example 1, 2, 4, 5, 6, 8, 10 or 12 cylinders. can be executed

In addition, the high-pressure accumulator 175 receives fuel from the fuel tank 195 through the high-pressure pump 161 . The high-pressure pump 161 is connected to the internal combustion engine 160 , more precisely in such a way that, for example, the high-pressure pump is driven via a crankshaft of the internal combustion engine or, on the other hand, via a camshaft in connection with the crankshaft. has been

Control of the fuel injectors 110 for introducing or metering fuel into the respective combustion chambers 165 is performed via a computer unit formed as the engine control unit 180 . For convenience, only the connection from the engine control unit 180 to one fuel injector 110 is shown, but it is obvious that each fuel injector 110 is equally connected to the engine control unit. In this case, each fuel injector 110 can be uniquely controlled.

In addition, the engine control unit 180 detects the fuel pressure in the high-pressure accumulator 175 using the pressure sensor 190 , and based on this, for example, reaches a determined or preset pressure in the high-pressure accumulator. is configured to control For this purpose, a pressure regulating valve 176 may also be used as the case may be.

2 schematically shows a solenoid valve 120 of a fuel injector 110 in which the method according to the invention can be practiced, for example used in the fuel supply system according to FIG. 1 .

The solenoid valve 120 is used here as a (pressure compensated) switching valve or servo valve of the fuel injector 110 , which is only partially illustrated. The solenoid valve 120 comprises an electromagnet 121 with a magnetic coil 122 which may be formed in an annular shape, for example. When a voltage is applied, for example via the engine control unit 180 according to FIG. 1 , a current I flows in the magnetic coil 122 .

Also provided is an armature 124 used to enable closing or unclosing the flow-through opening 150 of the solenoid valve 120 . Also, a spring 130 that interlocks with the armature 124 and closes the flow-through opening by bringing the armature 124 into or towards the flow-through opening 150 with no current supply to the magnetic coil 122 and thus no magnetic force. ) is also provided. The spring 130 may be secured to a suitable component 190 of the solenoid valve 120 , in particular the housing section, on the side facing away from the armature.

When current is supplied to the magnetic coil 122 , a magnetic force is generated, and the armature 124 is lifted against the spring force of the spring 130 and pulled in the direction of the magnetic coil 122 to the electromagnet 121 . In this case, the perfusion opening 150 is unclosed. Correspondingly, when current is supplied to the magnetic coil, the armature 124 can rise to a stop on the electromagnet 121 , or optionally a stop ring disposed on the electromagnet.

It exists in the valve chamber 140 or in the control chamber of the fuel injector connected thereto, and firstly presses the lower nozzle needle (not shown) due to high pressure to close the nozzle needle into the seat, and thus fuel injection The blocking fuel may be discharged into the return portion 155 upon unclosing of the flow-through opening 150 to be supplied to, for example, a fuel tank. The nozzle needle may rise if the pressure ratio and the amount of fuel guided into the return are corresponding thereto.

An armature pin 125 is also provided as an armature guide, the armature pin being disposed within or surrounded by the (central) opening to bore 126 of the armature 124, for example the component 190 in a housing fixing manner. fixed on top In the correct operating principle of the solenoid valve 120 , the armature 124 can move up and down or reciprocally along the armature pin 125 , in particular the armature 124 and its opening 126 and the armature pin 125 . ) is achieved based on a given gap between

In Fig. 3 a sequence of a method according to the invention in one preferred embodiment is shown and described on the basis of different drawings of an armature. To this end, the respective associated components of the solenoid valve 120 of FIG. 2 are shown in FIGS. 3A-3D , in particular the armature 124 , the armature pin 125 , the spring 130 and the valve chamber 140 .

Figure 3a now shows the starting position of the solenoid valve when the pressure in the high-pressure accumulator is low and no current is supplied to the coil. Here the solenoid valve should be closed normally. The spacing between the armature and the associated stop is denoted by Δh. Also, deposits 200, such as may form over time in certain fuels, as detailed in the introduction, on armature fins 125, or between armature fins 125 and 124. is also shown.

3b now shows the solenoid valve when the pressure in the high-pressure accumulator is low and the coil is energized (indicated by the lightning bolt). Due to the deposit, the armature cannot move at all, or at least in the usual way, under the action of a magnetic force, so that the separation Δh is maintained and the solenoid valve does not open. The result is an interruption of fuel injection and thus a misfire or interruption of ignition.

Figure 3c now shows the starting position of the solenoid valve when the pressure in the high-pressure accumulator is high and no current is supplied to the coil. Here the solenoid valve should be closed normally. Here the spacing between the armature and the associated stop is also Δh. Through the high pressure of the fuel that is also applied within the valve chamber 140 and thus can act on the armature, a predetermined radial force is applied to the armature 124 as indicated by the small arrows shown in the radial direction.

The movement of the armature which very effectively separates the deposits through the transition between low and high pressure, ie between the states in FIGS. 3a and 3c , and thus the generation of active pressure oscillations in the fuel in the high-pressure accumulator, for example. or vibration may occur.

Also, the coil may be energized once or multiple times, which will cause the flow-through opening to be unlocked by allowing the armature to rise again after a predetermined time, and at least firstly at high pressure as shown in FIG. 3D . do.

In Fig. 4 the sequence of the method according to the invention in one preferred embodiment is shown on the basis of the pressure characteristic curve in the high-pressure accumulator. For this purpose, the pressure p in the high-pressure accumulator is plotted over time t.

In this case, the high-pressure pressure oscillation at the time point (t _0), a more accurate is the pressure oscillation having the upper and lower limits of the p ₁ of p ₂ for the pressure generation, the lower limit may correspond to the high-pressure accumulator in the normal pressure. Of course, it is self-evident that other limit values may be chosen. This pressure oscillation is actively generated, for example, up to the time point t ₁ and thus during the period Δt.

The process may be repeated if necessary, eg until the perfusion opening is again unclogged, as described with respect to FIG. 3 . It is also conceivable that the pressure oscillations are produced continuously until the perfusion opening can be unclogged again.

Claims (12)

The fuel injector 110 including the switching valve formed as the solenoid valve 120 receives fuel from the high-pressure accumulator 175 and is used to introduce the fuel into the combustion chamber 165 of the internal combustion engine. Fuel supply for the internal combustion engine 160 . A method for operating a system (100), the solenoid valve (120) having an armature (124) and an armature guide (125) for closing and unclosing a flow-through opening (150);
If it is determined that there is a deposit 200 between the armature 124 and the armature guide 125 that exacerbates or prevents the unclosing of the flow-through opening 150 through the armature 124, the high-pressure accumulator ( 175) A method of operating a fuel supply system, wherein a pressure oscillation is actively created in my fuel. 2. A determination as set forth in claim 1 wherein deposits (200) are determined to exist between the armature (124) and the armature guide (125) when it is determined that the fuel flow into the combustion chamber (165) through the fuel injector (110) has ceased. How the fuel supply system works. 3. A method according to claim 2, wherein when it is determined that a misfire is present in the combustion chamber (165), it is determined that fuel flow into the combustion chamber (165) through the fuel injector (110) is stopped. 4. A method according to any one of the preceding claims, wherein during the start-up process the solenoid valve (120) is controlled to unclose the flow-through opening (150) once or several times. 5. A method according to any one of the preceding claims, wherein the start-up process is used and/or repeated frequently until a predetermined termination criterion exists. 6. The termination criterion according to claim 5, wherein the termination criterion is that a predetermined maximum number of launch processes is reached, and/or determining that fuel flow into the combustion chamber (165) through the fuel injector (110) is no longer stopped. A method of operating a fuel supply system comprising: 7. The oscillation process according to any one of claims 1 to 6, wherein, in the oscillation process, an upper limit value (p ₂ ), a lower limit value (p ₁ ) and a frequency for the oscillation are preset, the upper limit value being the pressure for the normal operating mode. Greater than the value, how the fuel supply system works. 8. A method according to any one of the preceding claims, wherein an error log entry is generated when an oscillation process is used. 9. A method according to any one of the preceding claims, wherein the armature guide (125) comprises an armature pin (125) disposed within an opening (126) of the armature (124). A computer unit ( 180 ) configured to execute all method steps of the method according to claim 1 . A computer program which, when executed on a computer unit (180), causes said computer unit (180) to execute all method steps of the method according to any one of claims 1 to 9. A machine-readable storage medium storing the computer program according to claim 11 .

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