WO2006074849A1

WO2006074849A1 - Method for correcting the injection behavior of at least one injector having a magnetic valve

Info

Publication number: WO2006074849A1
Application number: PCT/EP2005/056827
Authority: WO
Inventors: Andreas Rettich
Original assignee: Robert Bosch Gmbh
Priority date: 2005-01-12
Filing date: 2005-12-15
Publication date: 2006-07-20
Also published as: DE102005001427A1

Abstract

The invention relates to a method for correcting the injection behavior of at least one injector having a magnetic valve by storing information on the at least one injector and controlling the at least one injector using the stored information. Said information are determined and obtained by comparing desired values with actual values in a plurality of individual test points of the at least one injector. The inventive method is characterized that the information used is the lift of the magnetic valve.

Description

Method for correcting the injection behavior of at least one injector having a solenoid valve

State of the art

The invention relates to a method for correcting the injection behavior of at least one injector having a magnetic valve according to the preamble of claim 1.

Electrically driven injectors for injecting fuel are used, for example, in the context of common rail systems. In the "common rail" accumulator injection, pressure generation and injection are decoupled. The injection pressure is generated independently of the engine speed and the injection quantity and is ready for injection in the "rail". The injection timing and the injection amount are calculated in an electronic engine control unit and converted by an injector on each engine cylinder via a remote-controlled valve. For example, injectors operated by a solenoid valve are used. Such injectors have different quantity maps due to their mechanical manufacturing tolerances. Under a quantity map is the name between injection quantity, rail pressure and driving time to understand. These different quantity maps cause, despite electrically defined control, each individual injector fills the combustion chamber with different amounts of fuel. In order to achieve the lowest possible fuel consumption in compliance with strict emission standards and a very good smoothness, the injectors may have only very small tolerances in terms of injection quantity during operation. These required low tolerances can due to the mechanical manufacturing tolerances are not met. In order nevertheless to ensure a defined injection quantity in the injectors, the injectors are measured after production at characteristic operating points on their injection quantity and divided into classes. The particular class must be known to the engine controller during operation of the injectors, so that the controller can be specifically adapted to the specific features of the class injector specific. The class information is stored in various ways on the injector, for example, by different codes, such as by barcode, by resistors on the injector or by plain text on the injector. The class information is transmitted to the controller by means of a code recognition and subsequent programming. The classification of the injectors is advantageously carried out so that the injectors are tested at several test points with respect to the Einspritzmengenzumessung.

From DE 102 15 610 a method is now known, which offers the advantage that the information is determined by comparing setpoint values with actual values and that this information is individually related to several test points of at least one injector. This gives the control unit accurate information about multiple test points or operating points of each injector. As a result, there is the possibility that the control duration is corrected by measures in the control unit individually for each injector depending on the target amount and rail pressure compared to a nominal characteristic map in order to come as close as possible to the target amount. In the case of this method, the control unit contains a plurality of, preferably four test values from production, for each injector. From these variables, a correction quantity map is built up. For this purpose, the quantity correction for a number of pressure / control combinations is determined from the deviations of the injection quantities from their desired values from the test values at these test points. This method is also advantageous because it provides the opportunity to allow greater tolerances on the manufacturing test values and thus increase the yield of the production.

In modern vehicle engines now very short injection distances must be realized. For example, the distance between, for example, a pilot injection and a main injection is typically between about 200 to 450 μs. Since very precise injection quantities are required at these short injection intervals, the described injector quantity comparison (IMA), in which the setpoints are compared with actual values at different operating points, in each case to two additional measuring points, namely a pilot injection and a main injection, extended. It has now been found that the repeated measurement of these two test points is insufficient. The two additional test points also require longer cycle times for the test.

The invention is therefore based on the object, a method for correcting the injection behavior of at least one, a solenoid valve injector educate so that the Injektormengenabgleich is improved in the two additional measuring points pilot injection and main injection and the cycle times for the test are reduced.

Advantages of the invention

This object is solved by the features of claim 1.

The basic idea of the invention is to take into account the main influencing parameters of stroke of the solenoid valve and overstroke of the solenoid valve in the above-described Injektormenggenabgleich and at each injection point as additionally the injection behavior of the injector determining information store and use for later control of the injector. On the basis of this information, the correction amount of the injection valve is then determined.

The determined correction quantity is taken into account in a main injection immediately following a pilot injection.

drawing

Further advantages and features of the invention are described below, with reference to the accompanying drawings, with reference to embodiments in more detail. In the drawing show:

Fig. 1 is a known from the prior art schematic representation of a

Part of a common rail system, in which the inventive method is used;

Fig. 2 is a known from the prior art quantity correction map as

Diagram of the dependency of the injection quantity on the rail pressure;

Fig. 3 is a schematic sectional view of a solenoid valve injector and

Fig. 4a, b schematically shows the stroke over the time of the armature of the solenoid valve shown in Fig. 3 without (4a) and with (4b) overstroke.

Description of the embodiments

In Fig. 1, the high pressure wedge of the storage injection system common rail is shown. In the following, only the main components and those components which are essential to the understanding of the present invention will be explained in more detail. The arrangement comprises a high pressure pump 10, which communicates via a high pressure line 12 with the high pressure accumulator ("rail") 14 in connection. The high pressure accumulator 14 is connected via further high pressure lines 16 to the injectors. In the present illustration, a high pressure line 16 and an injector 18 are shown. The injector 18 is installed in the engine of a motor vehicle. The illustrated system is controlled by a motor controller 20. In particular, control of the injector 18 takes place by the engine control unit 20.

Provided on the injector 18 is a device 22 for storing information which relates individually to the injector 18. The information stored in the device 22 may be taken into account by the engine control unit 20 so that individual control of each injector 18 may occur. The information is preferably correction values for the quantity register of the injector. The device for storing the information can be stored as data storage as one or more electrical resistors, as a barcode, by alphanumeric encryption or also by an injector be realized semiconductor integrated circuit. The engine control unit 20 may also be a semiconductor integrated circuit for evaluating the information stored in the device 22.

The diagram shown in Fig. 2 shows a quantity correction map MKK, wherein a metered by the injector 18 amount M is plotted against the rail pressure P _R ^ ₁ . The quantity correction map MKK is based on several injection points (VL, EM, LL, VE). The adjustment values .DELTA.VL, .DELTA.EM, .DELTA.LL and .DELTA.VE are used for the quantity correction M, which are determined by the comparison of desired values with actual values at different rail backs P _Ra , i at different test points. The adjustment values ΔVL, ΔEM, ΔLL and ΔVE may be assigned a correction value KW _(n) . By way of example, the injection quantity M at a test point P is assigned the adjustment value ΔEM as a function of a pressure (rail pressure / activation duration combination) of the injection EM, from which a correction quantity ΔQ _(n) for the control unit in the respective test point is determined. The arithmetical correction quantities ΔQ _(n) are based on the adjustment values which are determined from quantity deviations ΔVL _ABW O ₎ , ΔEM _ABW O ₎ , ΔLL _{ABW (Π)} and ΔVE _ABW O ₎ ^{m of} the respective test points, and the associated correction values KW _{(n )} . In FIG. 2, for example, the check point P ΔEM is assigned a correction value KW _(n) .

Numerous test points P can be provided for an injector 18, these resulting over the entire operating range and the quantity correction map MKK. Between the interpolation points defined by test points, the adjustment values can also be interpolated linearly so that ultimately a reliable fuel quantity measurement can be carried out over the entire operating range. The determination of the quantity correction ΔQ _(n) for the respective test point is described in detail in DE 102 15 610 A1, column 6, lines 68 to column 8, line 61. For the purpose of disclosure, reference is hereby expressly made to this publication. The quantity corrections are calculated as the sums of the products of the correction values KW _(n) and the quantity deviations ΔVL _ABW O ₎ , ΔEMABWO), ΔLLABWO) ¹ ^ ΔVEABWCΠ determined from the desired value with the actual value comparison at the respective test points.

At the various test points, not only one injection but two consecutive injections occur in very short spray intervals. The diffe- Renzzeit between the two injections is typically 200 to 450 microseconds. It has now been found that the second injection at these small spray intervals is mainly influenced by the adjustment parameters overstroke and armature stroke of a two-part solenoid valve armature. For this reason, in the case of the above-described determination of the correction quantities at each test point, two additional measuring points are taken into account for each one pilot injection and one main injection. In many studies, it has now been shown that the repeated measurement of these somewhat combination test points is inadequate. In addition, longer cycle times for the two additional test points result for the so-called load test.

A sectional view of a solenoid valve injector, as used in a previously described common rail system is shown schematically in Fig. 3.

The fuel is supplied from the rail 14 via the high-pressure line 16 to a high-pressure connection 390 and from there via a high-pressure inlet channel 392 to an injection nozzle 360, also referred to as a nozzle needle, and via an inlet throttle 100 into a valve control chamber 350. The valve control chamber 350 is connected to a fuel return 310 via a discharge throttle 380, which can be opened by a magnetic valve, formed by a magnetic coil 320, a magnet armature 330 guided in an armature guide 335, and a valve ball 340.

In the closed state of the outlet throttle 380, the hydraulic force on a valve piston 110 outweighs the force on a pressure shoulder 362 of the nozzle needle 360. As a result, the nozzle needle 360 is pressed into its seat and closes the high-pressure inlet channel 392 close to (not shown in FIG ) Engine compartment off. When the engine is not running and there is no pressure in the rail 14, a nozzle spring 364 closes the injector.

When driving the solenoid valve, so the solenoid 320 and thus the armature 330 and the valve ball 340, the outlet throttle 380 is opened by the fact that the valve ball 340 is removed from its seat. The inlet throttle 100 prevents a complete pressure equalization, so that the pressure in the valve control chamber 350 and thus the hydraulic force on the valve piston 110 decreases. Once the hydraulic power is on the pressure shoulder 362 of the nozzle needle 360 falls below acting force, opens the nozzle needle 360. The fuel now passes through spray holes 370 in a combustion chamber of the engine (not shown in Fig. 3). When no longer activated solenoid valve (solenoid 320), the armature 330 is pressed by the force of the valve spring 322 down (in the closed position). The valve ball 340 closes the outlet throttle 380. As a result, pressure builds up again in the valve control chamber 350 via the inflow of the inlet throttle 100, which corresponds to the rail pressure. This increased pressure exerts a higher force on the valve piston 110, so that the nozzle needle 360 closes again. The flow rate of the inlet throttle 100 determines the closing speed of the nozzle needle 360.

This indirect control of the nozzle needle 360 via a hydraulic power amplifier system is used because the forces required to rapidly open the nozzle needle 360 can not be generated with the solenoid valve. The time required in addition to the injected amount of fuel control passes through throttles of the control chamber into the fuel return 310th

The solenoid 320 is controlled by the control unit 20 via control line 205, 210. As shown in FIG. 3, the solenoid valve injector has a two-part armature group. The actual armature 330 and an anchor plate 331 are decoupled. The anchor plate 331 is guided on the armature 330. On the armature 330, the spring force of the valve spring 322 acts. On the anchor plate 331, however, the spring force of an overstroke spring 332 acts. The armature 330 is positively coupled by a sickle disc 333 to the anchor plate 331. This results in the closing force as the difference between the force F1 produced by the valve spring 322 and the force F2 generated by the overstroke spring 332:

Closing force = Fl - F2,

which presses the valve ball 340 into the valve seat against the rail pressure applied in the valve control chamber 350. When opening, that is when energizing the magnetic coil 320, the magnetic force acts on the armature plate 331, which is pulled in the direction of the magnetic coil 320. When closing, that is, when the solenoid 320 is de-energized, the armature 330 is pushed back by the spring force, the anchor plate 331st is now moved by the positive engagement in the same direction. Meets the valve ball 340 on the seat, that is, the armature stroke is zero, the mass of the armature plate 331 decoupled from the mass of the armature 330 and moves by the inertia further down, that is, in the direction of the nozzle needle 360. Thus, inter alia Too much rebounding of the valve ball 340 and thus the armature 330 prevented. In addition, the closing force acting on the armature 330 is increased since the force of the overstroke spring 332 is no longer applied to the armature 330 because the positive lock armature plate 331 to the magnet armature 330 is only in the opening direction. The anchor plate 331 is returned by the over-stroke spring 332 back to the starting position. The anchor plate 331 has a distance from the armature guide 335, which is referred to as ÜH over-stroke, it is about 20 ± 10 microns. The overstroke ÜH may be adjusted by a selected group of multiple sickle disks 333 (not shown).

In modern diesel engines, the time between two injections should now be very short, preferably zero. A follow-up injection can only be triggered on such a solenoid valve injector when the anchor plate 331 is again in a defined starting position. In order to shorten the time of swinging through the anchor plate (see Fig. 4a), the path of the anchor plate is limited by a so-called over-stroke stop.

In Fig. 4, the stroke 410 of the armature 330 is shown by the anchor plate 331 over time, wherein in Fig. 4a, the overstroke 420 of the anchor plate without overstroke and in Fig. 4b of the overstroke 420 of the anchor plate are shown with overstroke. As a comparison of Fig. 4a with Fig. 4b shows, the amount of the overstroke 420 without Überhubanschlag for a much larger than with Überhubanschlag. On the other hand, the excess lift 420 also swings out. In contrast, the over-stroke 420 is limited by an over-stroke stop to a smaller defined value.

The basic idea of the invention is now to store the main influencing parameters solenoid valve lift 410 and overstroke 420, 430 in the device 22 of the injector 18 and to take it into account in the quantity correction of the second injection, which is usually a main injection, by the engine control unit 20. This is by the overtravel stop defines a lower and / or upper tolerance limit of the overstroke. In this way, the quantity value calculated for the main injection is corrected as a function of the applied spray distance and the parameters set on the injector.

Claims

claims

A method of correcting the injection behavior of at least one injector having a solenoid valve by storing information about the at least one injector determined and related by comparing target values with actual values at individually plural test points of the at least one injector and controlling the at least one injector taking into account the stored information, characterized in that is used as information of the stroke of the solenoid valve.

2. The method according to claim 1, characterized in that are used as information, a lower and / or upper tolerance limit of an overstroke.

3. The method according to claim 1 or 2, characterized in that on the basis of the information, a correction amount of the injection valve is determined.

4. The method according to claim 3, characterized in that the correction amount is taken into account in a following immediately after a pilot injection main injection.