EP2376762A1

EP2376762A1 - Method for operating a fuel injection system of an internal combustion engine

Info

Publication number: EP2376762A1
Application number: EP09765102A
Authority: EP
Inventors: Rainer Wilms; Matthias Schumacher; Joerg Kuempel; Matthias Maess
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 2008-12-11
Filing date: 2009-12-07
Publication date: 2011-10-19
Anticipated expiration: 2029-12-07
Also published as: DE102008054513A1; CN102245880A; KR20110106848A; US8925525B2; EP2376762B1; JP2012511659A; JP5383820B2; US20110295493A1; KR101650216B1; WO2010066675A1; CN102245880B

Abstract

The invention relates to a fuel injection system (10) of an internal combustion engine that delivers fuel into a fuel rail (18) by means of a high-pressure pump (16). The amount of the delivered fuel is influenced by an amount control valve (30), which is actuated by an electromagnetic actuating device (34). A control signal fed to the electromagnetic actuating device (34) is defined by at least two parameters. It is proposed that a) in an adaptation method, wherein the second parameter is established, at least one first parameter of the control signal fed to the electromagnetic actuating device (34) is gradually changed from a starting value to an end value, wherein a closing or opening of the amount control valve (30) is at least indirectly no longer or only just detected, that b) afterwards, the first parameter is at least provisionally established based on the end value, and that c) the provisionally established first parameter is adapted based on at least one current operating variable of the fuel injection system (10) or the second parameter is adapted based on at least one current operating variable of the fuel injection system (10) and the provisionally established first parameter.

Description

description

title

Method for operating a fuel injection system of an internal combustion engine

State of the art

The invention relates to a method for operating a fuel system of an internal combustion engine according to the preamble of claim 1. The invention also relates to a computer program, an electrical storage medium and a control and regulating device.

DE 101 48 218 A1 describes a method for operating a fuel injection system using a quantity control valve. The known quantity control valve is realized as a magnetically actuated by a solenoid solenoid valve with a magnet armature and associated Wegbegrenzungsanschlägen. The known solenoid valve is open in the energized state of the coil. However, known from the market are also such quantity control valves, which are open in the de-energized state of the solenoid. In the latter case, closing the

Quantity control valve, the solenoid with a constant voltage or a pulsed voltage (pulse width modulation - "PWM") driven, whereby the current in the magnetic coil increases in a characteristic manner. After switching off the voltage, the current again falls in a characteristic manner, whereby the quantity control valve opens.

Disclosure of the invention

Object of the present invention is to provide a method for operating a fuel system of an internal combustion engine, wherein a as quiet as possible operation of the fuel injection system is achieved by simple means.

This object is achieved by a method having the features of claim 1. Advantageous developments of the method according to the invention are in

Subclaims specified. Further possible solutions are also mentioned in the independent patent claims. For the invention important features can be found also in the following description and in the drawing, these features may be essential both in isolation and in different combinations for the invention, without being explicitly pointed out.

When using the method according to the invention, the stop velocity of an actuating element of the electromagnetic actuator is minimized at a stop, whereby the

Operating noise of the quantity control valve is reduced. The basis for this is on the one hand an adaptation, with which a parameter of a drive signal of the electromagnetic actuator is optimized so that the actuating element of the electromagnetic actuator is just moved to its end position during energization, but with extremely low speed. Ultimately, this adaptation takes into account that there are electromagnetic actuators with varying efficiency, namely fast-absorbing, that is, efficient as well as slow-moving, inefficient systems. Even tolerance deviations from one quantity control valve to the other can be taken into account in this way.

On the other hand, the invention is based on the fact that the current operating variables of the fuel injection system are taken into account in the definition of the drive signal of the electromagnetic actuator. To this

It is ensured that in very different operating situations with correspondingly different operating variables of the fuel injection system, a drive signal is used which has the lowest possible stop velocity of the actuating element at the stop result. In addition to reducing noise emissions, the scattering of the noise, measured over a given sample size, is also minimized. Compliance with specified maximum noise limits is therefore even more reliable possible, the risk of complaints of individual high-pressure pumps or quantity control valves is reduced. By reducing the velocity of the stop, the load of stops associated with an actuator of the electromagnetic actuator is also reduced. As a result, the corresponding load collective decreases, and the wear and strength requirements on the mechanical parts of the quantity control valve decrease. That too

Risk of wear-related failures decreases. By means of the adaptation method, said advantages can be achieved over the entire service life of the quantity control valve. The advantages can be achieved without significant additional costs, since the invention can be realized by simple software engineering measures without additional

Components are required.

It is particularly advantageous if the two parameters belong to the following group: duty cycle during a holding phase or an equivalent size; Duration of a suit pulse or an equivalent size. Ultimately, a kind of noise minimum is sought for a very specific combination of suit pulse duration and duty cycle. Many of today's conventional electromagnetic actuators use pulse width modulation (PWM), in which the energy supplied to the electromagnetic actuator is adjusted by a duty cycle. In a current-controlled output stage, the parameter can also be a continuous current value. A "pull-in pulse" is understood to be a pulse-like energization at the beginning of the drive signal with which the fastest possible build-up of the force acting on a magnet armature of the electromagnetic actuator should be achieved.

An important influencing factor on the force generated during activation by the electromagnetic actuating device is inter alia the so-called "harness resistance". This is the resistance of the leads, for example between the power amplifier and the electromagnetic actuator, and contact resistance Contacts. This electrical resistance can change depending on the temperature, and it is also subject to comparatively large manufacturing tolerances or aging effects. Therefore, is the temperature of the fuel or a component of the fuel injection system or an equivalent size in the adjustment of the

Parameter taken into account, the drive signal is optimized in a particularly efficient manner. Also, the voltage of a voltage source (for example, a vehicle battery) to which the electromagnetic actuator is at least indirectly connected, or an equivalent size, has a direct influence on the force exerted on the actuator of the electromagnetic actuator, and thus on its speed. Their consideration also helps in a very efficient way to optimize the drive signal.

It is furthermore particularly advantageous if after step c) in a step d), once again in an adaptation method, one of the two parameters which was not adjusted in step c) is successively changed from a starting value to such a final value, at which closing or opening of the quantity control valve is at least indirectly no longer or only just detected, and that thereafter this parameter on the basis of

Final value. According to the invention, therefore, a second adaptation is performed. This method thus offers a particularly good result and ensures that the speed of the actuator at the stop is really minimal over the entire life of the device.

In order to achieve an even better process result, steps c) and d) can be carried out repeatedly in the sense of an iterative method.

In order to save computing capacity, steps a) to c) or a) to d) can only be carried out if a rotational speed of the internal combustion engine is below a limiting rotational speed. In this way, the fact is taken into account that the initially mentioned noise problem is generally present only at idle and slightly higher speeds of an internal combustion engine, since only in this speed range, the operating noise of

Internal combustion engine is so low that the impact noises of Actuate the electromagnetic actuator play a role at all.

The method according to the invention leads to a comparatively low speed of the actuating element. This could lead to that

Actuator may indeed reached the stop with a very low velocity stop, but then rebounds again due to a too low magnetic force. This could lead to an unwanted interruption of fuel production. To avoid this, the invention proposes that the electromagnetic

Actuator supplied electrical energy is increased at least approximately at that time, to which the actuating element of the quantity control valve comes into contact with the stop.

Hereinafter, embodiments of the invention will be explained in more detail with reference to the accompanying drawings. In the drawing show:

Figure 1 is a schematic representation of a fuel injection system of a

Internal combustion engine with a high-pressure pump and a quantity control valve;

Figure 2 is a partial section through the quantity control valve of Figure 1;

Figure 3 is a schematic representation of various functional states of the high-pressure pump and the quantity control valve of Figure 1 with an associated timing diagram;

FIG. 4 shows three diagrams, in which a drive voltage, a current supply to a magnet coil, and a stroke of a valve element of the quantity control valve of FIG. 1 are plotted over time

Implementation of a method for optimizing the drive signal;

FIG. 5 shows a flow chart of a first embodiment of a method for

Operating the fuel injection system of FIG. 1;

FIG. 6 is a flowchart similar to FIG. 5 of a second embodiment; FIG. 7 is a flowchart similar to FIG. 5 of a third embodiment.

In FIG. 1, a fuel injection system bears the reference numeral 10 as a whole. It comprises an electric fuel pump 12, with which fuel is supplied from one

Fuel tank 14 is conveyed to a high-pressure pump 16. The high-pressure pump 16 compresses the fuel to a very high pressure and promotes it further into a fuel rail 18. To this several injectors 20 are connected, which inject the fuel in them associated combustion chambers. The pressure in the fuel rail 18 is detected by a pressure sensor 22.

In the high-pressure pump 16 is a piston pump with a delivery piston 24, which can be offset by a camshaft, not shown, in a reciprocating motion (double arrow 26). The delivery piston 24 defines a delivery chamber 28, which via a quantity control valve 30 with the

Outlet of the electric fuel pump 12 can be connected. Via an outlet valve 32, the delivery chamber 28 can also be connected to the fuel rail 18.

The quantity control valve 30 comprises an electromagnetic

Actuator 34 which operates in the energized state against the force of a spring 36. When de-energized, the mass control valve 30 is open, in the energized state, it has the function of a normal inlet check valve. The exact structure of the quantity control valve 30 is shown in FIG. 2:

The quantity control valve 30 comprises a disc-shaped valve element 38, which is acted upon by a valve spring 40 against a valve seat 42. The latter three elements form the above-mentioned inlet check valve.

The electromagnetic actuating device 34 comprises a magnetic coil 44 which cooperates with a magnetic armature 46 of an actuating tappet 48. The spring 36 acts on the actuating plunger 48 in the currentless solenoid 44 against the valve element 38 and forces it to its open position.

The corresponding end position of the actuating plunger 48 is replaced by a first stop 50 defined. When the solenoid is energized, the actuating plunger 48 is moved against the force of the spring 36 away from the valve element 38 against a second stop 52.

The high-pressure pump 16 and the quantity control valve 30 operate as follows (see FIG. 3):

In FIG. 3, at the top, a stroke H of the piston 34 and, below that, an energization I of the magnetic coil 44 are plotted over the time t. In addition, the high pressure pump 16 is shown schematically in various operating conditions. During one

Suction (left in Figure 3), the solenoid 44 is de-energized, whereby the actuating plunger 48 is pressed by the spring 36 against the valve member 38 and this is moved to its open position. In this way, fuel can flow from the electric fuel pump 12 into the delivery chamber 28. After reaching the bottom dead center UT the delivery stroke of the delivery piston 24 begins. This is shown in Figure 2 in the middle. The solenoid 44 is still de-energized, whereby the mass control valve 30 is further forced to open. The fuel is discharged from the delivery piston 24 via the open quantity control valve 30 to the electric fuel pump 12 out. The exhaust valve 32 remains closed. A promotion in the

Fuel rail 18 does not take place.

At a time ti, the magnetic coil is energized, whereby the actuating plunger 48 is pulled away on the valve element 38. At the end of the movement of the actuating rod 48 comes with the second stop 52 in

Plant (Figure 2). It should be noted at this point that in Figure 3, the course of energization of the solenoid 44 is shown only schematically. As will be explained below, the actual coil current is not constant, but may drop due to mutual induction effects. In addition, in the case of a pulse-width-modulated drive voltage, the coil current is wave-shaped or jagged.

Due to the pressure in the delivery chamber 28, the valve element 38 applies to the valve seat 42, the quantity control valve 30 is thus closed. Now, a pressure can build up in the delivery chamber 28, leading to an opening of the exhaust valve

32 and leads to a promotion in the fuel rail 18. This process is in Figure 3 shown on the far right. Shortly after reaching the top dead center OT of the delivery piston 24, the energization of the solenoid 44 is terminated, whereby the quantity control valve 30 returns to its forced open position. By varying the time ti, the amount of fuel delivered by the high-pressure pump 16 to the fuel rail 18 is influenced.

The time t-i is determined by a control and regulating device 54 (Figure 1) so that an actual pressure in the fuel rail 18 as closely as possible corresponds to a target pressure. For this purpose, 54 signals supplied by the pressure sensor 22 are processed in the control and regulating device.

In order to reduce the impact noise of the actuating plunger 48 when it strikes the second stop 52 when energized, a method is used here, with which the speed at which the actuating plunger 48 moves against the second stop 52 is kept as low as possible , First of all, this process involves a first one

Adaptation method, which will now be explained with reference to FIG. 4:

In FIG. 4, the curve of a drive voltage U over the time t applied to the magnet coil 44 is plotted in the upper diagram. It can be seen that this drive voltage U is clocked in the sense of a

Pulse width modulation. The middle diagram of Figure 4 shows the corresponding coil current I, the height of which results from the duty cycle of the voltage signal U. In the lower diagram of Figure 4, the corresponding stroke H of the actuating plunger 48 is shown over time.

It can be seen from FIG. 4 that the voltage signal U and the coil current I resulting therefrom initially have a so-called "starting pulse" 56. This serves to build up the magnetic force acting on the magnet armature 46 as quickly as possible. The pull-in pulse 56 is followed by a holding phase 58, whose effective drive voltage U is defined by the duty cycle of the pulse-width-modulated voltage signal. The result is a coil current I, which is designated by the reference numeral 60a in FIG. The corresponding lift curve H is designated 62a. It can be seen that due to the movement of the actuating tappet 48 and of the magnet armature 46 coupled thereto in the magnet coil 44, a mutual induction is generated, which in the present case leads to a reduction of the effective coil current I. leads. The curves 60a and 62a apply to a first cycle of the high-pressure pump 16, wherein a working cycle consists of a suction stroke and a delivery stroke.

In a subsequent cycle, the duty cycle of the pulse width modulated voltage signal U during the holding phase 58 is set so that a lower effective current I of the solenoid coil 44 results, corresponding to a curve 60b in Figure 4. As a result, there is a delayed movement of the actuating plunger 48, according to the curve 62b. The duty cycle is now successively changed, so that the effective

Coil current I continues to drop. In a coil current I, not shown in FIG. 4, corresponding to a "limit duty cycle", the actuation tappet 48 is no longer sufficiently moved away from the valve element 38, the quantity control valve 30 therefore remains open. There is thus no promotion of fuel in the fuel rail instead. This in turn leads due to the fuel flow through the injectors 20 from the fuel rail 18 to a strong pressure drop in the fuel rail 18, so a strong and sudden deviation of the actual pressure in the fuel rail 18 from the target pressure, which is detected by the control and regulating device 54. With this adaptation method, therefore, it is possible to determine that duty cycle at which the quantity control valve 30 no longer or just just opens.

This limit duty cycle, also referred to as the end value, is used to characterize the efficiency of the electromagnetic actuator 34. Namely, a quantity control valve 30 having a more efficient electromagnetic actuator 34 has a lower end value than a quantity control valve 30 having a more inefficient electromagnetic actuator 34.

Now, in a further process step, the suit pulse 56 is adjusted.

For this purpose, a temperature of a component of the fuel injection system determined by a sensor (not shown) and a voltage of a voltage source (for example vehicle battery, not shown) to which the electromagnetic actuating device 34 is connected are set to a specific duty cycle (" Standard-

This results in a duration of the Tightening pulse 56 for this specific duty cycle. If the end value of the duty cycle determined in the first adaptation deviates from the standard duty cycle, this is taken into account by a corresponding correction factor. This is shown in FIG. 4 in the upper diagram by a dashed curve of the voltage signal U, in the middle diagram of FIG. 4 by a coil current I with the reference numeral 60c. This results in a corresponding lift curve 62c. Thus, both the length of the tightening pulse 56 and the duty cycle during the holding phase 58 are optimized by the presented method so that the

Stop speed of the actuating plunger 48 on the second stop 52 is minimal.

For further optimization, the above-described and described adaptation method for optimizing the duty cycle during the holding phase 58 is performed again in the method presented here, ie now based on the adjusted duration of the tightening pulse 56. The method just described is shown as a flow chart in FIG.

Thereafter, first in 64, the first adaptation method is performed

Monitoring of the actual pressure Pr in the fuel rail 18 in block 66. Then in 68 the duration dt _{A A} pull-in pulse 56 is adjusted as a function of a temperature T, a voltage U ₆ a voltage source, and the determined in 64 duty cycle TV, the supply voltage U _{6 of} the voltage source and the temperature T in FIG. 70. Using the thus obtained

Duration dt _{A of} the pull-in pulse 56 is then performed in 72 a second adaptation of the duty cycle TV, monitoring the system pressure P _r provided in FIG. The procedure for this adaptation in FIG. 72 is the same as described in FIG. 64 and above in connection with FIG. 4. In FIG. 72, therefore, that parameter of the drive signal U or I is adapted, which was not adapted in the preceding adaptation step 68, but served there as the input variable. In 74 one obtains a minimum impact speed under the given boundary conditions. An alternative embodiment of a method for optimizing the parameters of the drive signal U or I of the electromagnetic actuator 34 will now be explained with reference to FIG. Here, as below, such elements, regions and function blocks that have equivalent functions to elements,

Areas and functional blocks, which have already been explained in connection with previous figures, the same reference numerals and are not described again in detail.

In the method shown in Figure 6, the input and output variables of the two function blocks 68 and 72 are reversed. This means that in block 68, the duty cycle TV in the hold phase 58 is adjusted taking into account the temperature T and the supply voltage U ₆ , and that this adjusted duty cycle TV is then fed into the adaptation block 72, in which the duration dt _{A of} the pull-in pulse 56 is adapted. For this purpose, the

Duration dt _{A of} the suit pulse 56 from a starting value successively, ie from a work cycle to a subsequent work cycle, changed to such a final value, in which closing the quantity control valve 30 by monitoring the pressure P _r in the fuel rail in block 66 no longer detected becomes. On the basis of this final value, the duration dt _{A of} the

Tightening pulse 56 set, for example, from the final value plus a safety margin. With the duty cycle TV adjusted in 68 and the duration dt _{A of} the starting pulse 56 adapted in 72, the actuating signal U of the electromagnetic actuating device is defined such that a minimal noise when the magnet armature 46 is attracted and the actuating stop 48 abuts against the second stop 52 is reached.

FIG. 7 shows yet another alternative embodiment. This differs from the embodiments of FIGS. 5 and 6 in that the steps

68 and 72 are performed several times alternately in the sense of an iterative method. An adaptation in a block 68, with i = 1, 2, 3,..., Is thus always carried out alternately with an adaptation 72, with i = 1, 2, 3,. If the duration of the tightening pulse 56 is adjusted in FIG. 68, an adaptation of the duty cycle takes place in 72. If, on the other hand, the duty cycle is adjusted in 68, takes place in

72, an adaptation of the duration of the suit pulse 56. The iteration can be ended become, if the changes of the duty cycle or the duration of the suit pulse 56 falls below a certain level. Other convergence criteria are also possible. You can calculate from previous adaptation results and / or known map data.

The method steps described above in connection with FIGS. 5 to 7 are implemented in the control and regulating device 54 such that they are not performed above a specific rotational speed of a crankshaft of the internal combustion engine or a drive shaft of the high-pressure pump 16. Advantageously, the said method steps are carried out only in such an operation of the internal combustion engine, in which the speed is relatively low, for example, is in the range of idling.

Due to the abovementioned adaptations in FIGS. 64 and 72, comparatively low duty cycles during the holding phase 58 are realized. This could lead without countermeasures that the actuating plunger 48, although it comes to rest on the second stop 52, but at such a low speed that it bounces back again because of the very low magnetic force. In such a case, the mass control valve 30 would not close, so the high pressure pump 16 would not promote. To avoid this error case, the duty cycle is increased during the holding phase 58 at a pre-calculated time of contact of the actuating plunger 48 with the second stop 52 (time t ₂ in Figure 4), whereby the force acting on the armature 46 force reinforced and one

Re-lifting of the actuating plunger 48 from the second stop 52 is prevented. The duty cycle of the pulse width modulated voltage signal U is thus switched during the holding phase 58.

Claims

claims

1 . A method of operating a fuel injection system (10) of an internal combustion engine in which fuel from a high-pressure pump (16) in a fuel rail (18) is promoted, and wherein the amount of fuel delivered by one of an electromagnetic actuator

(34) actuated quantity control valve (30) is influenced, wherein a drive signal supplied to the electromagnetic actuator (34) is defined by at least two parameters, characterized in that a. in an adaptation method at least a first parameter of the control signal supplied to the electromagnetic actuator (34) is successively changed from a start value to a final value at a fixed second parameter, at which closing or opening of the quantity control valve (30) is at least indirectly no longer or it is just discovered that b. after that, the first parameter is set at least provisionally on the basis of the final value, and that c. the preliminarily set first parameter based on at least one current operating amount of the fuel injection system (10) or the second parameter based on at least one current one

Operating size of the fuel injection system (10) and the provisionally fixed first parameter is adjusted.

2. The method according to claim 1, characterized in that the two parameters belong to the following group: duty cycle during a

Holding phase or an equivalent size; Duration of a suit pulse or an equivalent size.

3. The method according to any one of claims 1 or 2, characterized in that the current operating size (s) belongs to the following group or include: temperature of the fuel or a component of Fuel injection system (10) or an equivalent size; Voltage of a voltage source to which the electromagnetic actuator (34) is at least indirectly connected, or an equivalent size.

4. The method according to any one of the preceding claims, characterized in that after step c) in a step d) again in an adaptation method that of the two parameters, which was not adjusted in step c), from a starting value successively changed to such a final value is at which a closing or opening of the quantity control valve (30) is at least indirectly or not just detected, and that thereafter this parameter is determined on the basis of the final value.

5. The method according to claim 4, that steps c) and d) are carried out repeatedly in terms of an iterative method.

6. The method according to any one of the preceding claims, characterized in that the steps a) to c) or a) to d) are only performed when a speed of the internal combustion engine is below a limit speed.

7. The method according to any one of the preceding claims, that the electromagnetic actuator (34) supplied electrical energy is increased at least approximately at that time, to which an actuating element (48) of the quantity control valve (30) at a stop

(52) comes into contact.

8. Computer program, characterized in that it is programmed for use in a method according to one of the preceding claims.

9. An electrical storage medium for a control and / or regulating device (54) of a fuel injection system (10), characterized in that a computer program for use in a method of claims 1 to 7 is stored on it.

10. A control and / or regulating device (54) for a fuel injection system, characterized in that it is programmed for use in a method according to one of claims 1 to 7.