DE102009000132A1 - Method for operating a fuel injection system - Google Patents

Abstract

The present invention relates to a method for operating a fuel injection system in which fuel from an electromagnetically actuated injection valve (1) enters at least one combustion chamber of the internal combustion engine, and at least partially the movement of a valve element (3) of the injection valve (1) by an electromagnetic Brake pulse (16) is affected. A closing delay time of the injection valve (1) or a corresponding variable is determined and the determined closing delay time or the corresponding variable is used to determine at least one parameter of the braking pulse (16).

Description

State of the art

The The invention relates to a method of operating a fuel injection system According to the preamble of claim 1. Subject of the invention Furthermore, a computer program, an electrical storage medium and a control and / or regulating device.

From the market, fuel injection systems for automobiles are known, with which gasoline from injectors is injected directly into respective combustion chambers. Such injection valves have a valve element (valve needle), which is actuated by an electromagnetic actuator, which essentially comprises a magnetic coil and a magnet armature. For very fast switching injectors, as z. For example, to control common-rail injectors for diesel injection or gasoline direct-injection valves, valve closure causes perceptible noise. The main reason for this is the rapid impact of the valve element in the associated seat of the injection valve. The DE 101 48 218 A1 proposes to generate a short braking pulse to decelerate the valve element before reaching the valve seat.

Disclosure of the invention

task The invention is to develop a method of the type mentioned, in which the fuel injection system, in particular when closing of the injector, works very quietly, without that at the expense of a metering accuracy of the injection valve goes.

The The object is achieved by a method having the features of the claim 1 solved, as well as by a computer program, an electrical Storage medium and a control and / or regulating device with the Features of the independent claims. For the invention important features are also found in the following Description and in the drawing, the features in both Unique position as well as in different combinations for the invention may be important without wishing to do so is explicitly noted. Advantageous developments can be found in the subclaims.

Of the Braking pulse causes the development of a braking force and allows such a gentle placement of the valve element in the seat. This results the brake pulse usually from a brake current pulse in the magnetic coil. According to the invention, it has been recognized that the injectors have a different closing dynamics (due to specimen scatters, for example, a closing spring force, a Ventilnadelhubs or a magnetic force curve) and therefore react differently to the braking current pulse. So the structure of the braking current pulse takes place with injection valves with a rather long closing delay still at comparatively large valve needle lift and correspondingly low valve element speed. For injectors with a low closing delay time at the time of Bremskraftaufbaus, the valve element already a significant impulse (high valve element speed) and would as a result with the same brake current pulse can be slowed down only slightly. Furthermore can the closing delay time from the operating point of the injectors depend. All this affects the valve opening time, which results in the same brake current pulse being copy-dependent Can cause fluctuations in the fuel injection quantity.

With Help of the method according to the invention is the Closing speed of the injector changed so that the valve element reliable and largely independent of manufacturing tolerances and the current operating point with reduced speed can sit on the valve seat of the fuel injection valve. Instead of the application of the closing time to determine the Target injection quantity is also the application of other operating variables conceivable, such as the valve opening duration or an electrical Size for actuating the valve element. The method can be used for one-piece and multi-part armature be applied.

to Determining the closing delay time are already different Known method. For example, the timing of the actual Closing the valve element detected by structure-borne noise measurements and then at the time of a shutdown a drive signal for actuating the valve element be compared. The inventive method thus reduces the disturbing noise when driving the valve element in the seat and ensures the required Metering accuracy.

Especially advantageous for the invention Method is when the / the parameters of the braking pulse a temporal Location, duration and / or amplitude is / are. So can eg. the brake current pulse in injectors with a short closing delay time temporally closer to the Ansteuerende lie and with a higher Amplitude impressed in the solenoid of the injector than injectors with a long closing delay time. The mentioned paramaters offer the possibility of a very exact interpretation of the braking pulse.

In order to ensure the required metering accuracy, it is advantageous if under use tion of the closing delay time or the corresponding size and the at least one parameter of the brake pulse, a valve opening duration or a corresponding size is determined.

Advantageous is also when the valve opening duration or the corresponding Size dependent on a target injection quantity is set. Thus it is possible that through the brake current pulse influenced valve duration (or the corresponding size) fed to a controller and with a known method to one of the desired injection quantity dependent setpoint of the valve opening duration becomes. By combining the determination of the appropriate brake current pulse with the valve duration control is a reaction of the Brake pulse to the closing time advantageously compensated and the metering accuracy is maintained or will even improved.

A easy way to generate the braking pulse is in that a positive voltage to the solenoid of the electromagnetic operated injection valve is applied. This will which already fades during the closing process located magnetic force to one of the control and / or regulating device set point again increased and thereby a braking force for the injection valve is actively established. The positive tension can Optionally from the electrical system or from one to a higher Voltage level charged boost capacitor can be tapped.

alternative The brake pulse can also be generated by the solenoid the electromagnetically actuated injector shorted becomes. Short-circuiting corresponds to circuitry a freewheel of the output stage of the control and / or regulating device. At the same time eddy currents commute from the core of the magnetic coil and the armature back into the solenoid. It will No additional magnetic force built up, but the power reduction is based on a currently prevailing magnetic force level slowed down considerably. For example, the effect of the braking current is on the anchor movement the greater, the sooner after the Ansteuerende the solenoid coil is short-circuited.

to Determining the closing delay time is, for example, the detection the closing time necessary. In this case, the closing time (or the appropriate size) can be determined by closing on the basis of a course a voltage is determined at the magnetic coil. The brake current pulse is already completed at the time of magnetic armature closing, so that the detection of the closing time over the course of the voltage at the solenoid can take place at the time Magnetankerschließens still effective and thus measurable is.

alternative For this, the closing time (or the corresponding Size) can be determined by the closing time determined on the basis of a course of the current in the magnetic coil is because the braking current at the time of closing the Magnetic anchor is still effective and thus measurable.

In In another alternative, the closing time (or the appropriate size) can be determined by the closing time using a route observer is determined. Regardless of the duration of the braking current pulse can a determination of the closing time over the Track observers take place, the track observer a detected electrical Size (eg the magnet coil voltage) with a other observable electrical quantity (e.g. B. solenoid coil current) at least indirectly compares and conclusions about can pull the closing time.

Brief description of the figures

following is an embodiment of the invention with reference to the figures exemplified. Show it:

1 a schematic representation of a fuel injection valve in vertical section;

2 a greatly simplified flow and Ventilnadelhubverlauf the fuel injector 1 with and without brake pulse; and

3 a flow chart of the method according to the invention.

Detailed description

In 1 carries a fuel injection valve as a whole the reference numeral 1 , It may, for example, be installed in an internal combustion engine of a motor vehicle with a common rail for the direct injection of fuel into a combustion chamber (not shown). It comprises an electromagnetic actuator 2 and a valve needle forming a valve element 3 that with a valve seat 4 interacts. One around the valve needle 3 arranged spring element 5 presses the valve needle with its spring force 3 in the valve seat 4 , The electromagnetic actuator 2 includes a magnetic armature 6 , in the present embodiment with the valve needle 3 firmly connected, and a magnetic coil 7 , The magnetic coil 7 is controlled by a control device 8th and a power amplifier, not shown, energized.

For the operation of the electromagnetic injector 1 is powered by energizing the solenoid 7 generates an electromagnetic field that magnetizes a magnetic material. This will be the armature 6 attracted to the valve needle connected to it 3 from the valve seat 4 raising. Thus, outlet openings (not shown) of the injection valve 1 enabled, through which the fuel can escape to an injection. For completeness, it should be mentioned that the valve needle and the magnet armature can also be made in two parts (not shown).

2 shows in an upper diagram a time course of a drive current I and in a lower diagram thereby causing a stroke H of the valve needle 3 , The course of the drive current I shows a first rapid increase (see reference numeral 10 ) of the current I, which is then kept constant over a certain period of time, in order then to drop by about half (cf. 12 ). This current level is maintained until the end of the control period t _i . At the end of the activation period t _i , the current is switched off (cf. 14 ). In the area of turning off the current I, two scenarios are shown, wherein the first scenario is represented by a solid line and the second scenario by a dotted line and by a time period t _v forward in time. In each scenario, a short current pulse begins at a time interval t _x from the drive end 16 respectively. 16 ' , ie, the time t _x determines the timing of the current pulse 16 from the driving end. The amplitude, the time position and the length of the current or braking pulse are shown here by way of example and can vary in real operation depending on a valve delay time. A closer description will be given later.

The lower diagram shows that the valve needle 3 of the injection valve 1 after the start of the control only after a certain opening delay time t ₁₁ lifts (see reference numeral 18 ). Has the valve needle 3 after the time t _{1 has reached} its maximum stroke, a lesser current I is sufficient to hold this level. If the drive current I is switched off at the end of the activation period t _i , the valve needle begins 3 after a closing delay t ₂₁ to lower (reference numeral 20 ). During the lowering movement 20 sets the current pulse 16 (Brake current pulse), which is the lowering speed of the valve needle 3 thereby reduces that a magnetic force is generated by him, which counter to the lowering of the valve needle 3 acts. The valve needle 3 gently sinks into the valve seat 4 , which leads to a desired noise reduction. However, a closing time is shifted, ie a valve opening period T _op is thus extended by the time t _a .

Without the current pulse 16 would have the movement of the valve needle 3 a (idealized) course similar to the dashed line 22 , The injection would be finished in the intended valve opening period T _op . According to the extension time t _{a is} regulated by a control loop, so that despite the effect of the brake current pulse 16 the target valve opening period T _op can be maintained.

3 shows a flowchart of the inventive method. The illustrated sequence is individual for each injection valve of a motor vehicle in the control and regulating device 8th apply. The procedure works as follows: The control and regulating device 8th determined in step 50 a drive start and a drive end to a target valve opening period T _{op of} the injection valve 1 , Subsequently, in step 60 the individual closing delay time t _{21 of} the injection valve 1 determined. The closing delay time t ₂₁ is influenced by specimen scattering, for example a closing spring force, a valve needle stroke or a magnetic force course.

In step 70 are evaluated by evaluating the closing delay time t _21, the timing (time), the duration and the amplitude of the brake current pulse 16 determined. For example, the brake current pulse occurs 16 at an injection valve 1 with a rather long closing delay t ₂₁ even with a comparatively large valve needle stroke H and correspondingly low valve needle speed. So it is sufficient a brake current pulse 16 with small amplitude and small duration. At an injection valve 1 with a small closing delay t ₂₁ , the valve needle 3 quickly a high speed and would result in the same braking current pulse 16 can be slowed down only slightly. Therefore here is a brake current pulse 16 necessary with high amplitude and long duration. The closing delay time t ₂₁ is also from an operating point of the injection valve 1 dependent. In addition, the temporal position t _{x of} the brake current pulse 16 set by the driving end.

The brake current pulse 16 has an extension of the valve opening duration T _op result (see time t _a ). To compensate for this, will step in 80 by the braking current pulse 16 triggered extended valve duration (T _op + t _a ) by a control loop to the previously determined setpoint compensated. The result of the adjustment is in 3 shown dotted. In this case, the driving end of the valve needle 3 advanced by the determined time t _v (see upper diagram). This means that the drive signal and thus the drive time t _{i is} shortened (see edge 14 ' ). Since the braking current pulse 16 in the previously determined time interval t _x follows the drive end, the brake current pulse 16 ' also brought forward. The activation duration t _x is shortened in such a way that the closing end of the valve needle 3 ge Nau on the determined time of the target valve opening period T _op falls. Thus, the required metering accuracy is achieved.

QUOTES INCLUDE IN THE DESCRIPTION

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Cited patent literature

• DE 10148218 A1 [0002]

Claims (12)

Method for operating a fuel injection system, in which fuel from an electromagnetically actuated injection valve ( 1 ) enters at least one combustion chamber of the internal combustion engine, and at least temporarily the movement of a valve element ( 3 ) of the injection valve ( 1 ) by an electromagnetic brake pulse ( 16 ), characterized in that a closing delay time of the injection valve ( 1 ) or a corresponding variable and the determined closing delay time or the corresponding variable for determining at least one parameter of the braking pulse ( 16 ) is used. Method according to Claim 1, characterized in that the parameter (s) of the braking pulse ( 16 ) is / are a temporal position, a duration and / or an amplitude. Method according to one of the preceding claims, characterized in that, using the closing delay time or the corresponding magnitude and the at least one parameter of the braking pulse ( 16 ) a valve opening duration or a corresponding size is determined. Method according to claim 3, characterized that the valve opening duration or the corresponding size is set depending on a target injection quantity. Method according to one of the preceding claims, characterized in that the braking pulse ( 16 ) by actively applying a positive voltage to a magnetic coil ( 7 ) of the electromagnetically actuated injection valve ( 1 ) is constructed. Method according to one of claims 1 to 4, characterized in that the braking pulse ( 16 ) by short-circuiting a magnetic coil ( 7 ) of the electromagnetically actuated injection valve ( 1 ) is constructed. Method according to one of the preceding claims, characterized in that the closing delay time or the corresponding variable on the basis of a course of a voltage at the magnetic coil ( 7 ) is determined. Method according to one of claims 1 to 6, characterized in that the Schließverzugszeit or the corresponding size on the basis of a course of the current in the magnetic coil ( 7 ). Method according to one of the preceding claims, characterized in that the closing delay time under Use of a route observer is determined. Computer program, characterized in that it for use in a method according to any one of the preceding claims is programmed. Electrical storage medium for a control and / or regulating device ( 8th ) of an internal combustion engine, characterized in that a computer program for use in a method of claims 1 to 9 is stored on it. Control and / or regulating device ( 8th ) for an internal combustion engine, characterized in that it is programmed for use in a method according to one of claims 1 to 9.