EP1087106B1 - Camshaft phase changing method in an internal combustion engine - Google Patents

Abstract

The camshaft position is adjusted by an actuator controlled by a controller and proportional valve. From a comparison of an actual (wnwise) and desired angle a manipulated variable in the form of a pulse duty factor for the valve is determined. Before the comparison a predicted angle (wnwpe) is added to the actual shaft angle the sum corresponding to the final shaft angle. This is reached after changing the duty factor to the holding value until the valve has completely closed i.e. for the period (znwve).

Description

The invention relates to a method for adjusting the camshaft in one Internal combustion engine according to the preamble of claim 1.

To adapt the valve control to different operating situations Internal combustion engine, it is known, by means of a swivel adjuster and under Using the oil pressure a relative angle between the camshaft and the Adjust crankshaft. This results in advantages in terms of power delivery, Consumption and pollutant emissions of the internal combustion engine. Regarding the However, the swivel adjuster has the following disadvantages: The maximum Adjustment speeds of the camshaft adjuster are not constant and for one positive or negative jump different. There are operating points at which the oil pressure is not sufficient for adjustment. The actual angle value is in the static range often restless.

From US 5 417 187 is a method for angularly adjusting a camshaft known. A hydraulic valve with two chambers is provided for angle adjustment, where only one of the chambers is loaded with oil in the direction "Early" occurs, when only the corresponding other chamber is charged with oil Adjustment in the direction of "late" and when both chambers are acted upon by Essentially equal amount of oil is held at a momentary angle of the camshaft. This loading of both chambers with essentially the same amount of oil is called 50% duty cycle of the control signal for the control valves. It is here a three-step control in which an "early value" for an adjustment in the direction "early" (early opening of intake valves), a "late value" for an adjustment in Direction "late" (late opening of intake valves) and a "hold value" for holding the current angular position. It becomes a control routine again and again The expected one is repeated and every time the control program routine is run Position for the camshaft at the start of the next run of the Control program routine and an adjustment speed determined. Furthermore, determines whether the camshaft is the target position based on the expected position reached if "hold" before the next execution of the control program routine value "is switched. If it turns out that the camshaft is so close to the target position that the camshaft Switch to the "hold value" due to the inertia of the adjustment mechanism the PID control is abandoned and instead the "hold value "toggled.

The present invention therefore has the object of a method of the above. Kind with to provide the following properties: Consistently high control quality all operating conditions, simplification of application and collection of Scattering and tolerances through intelligent adaptation strategy.

This object is achieved by a method of the above. Kind of with the in Characteristics characterized claim 1 solved. Advantageous embodiments of the Invention are specified in the dependent claims.

For this purpose, it is provided according to the invention that the before each setpoint / actual value comparison Prediction angle as the product of adjustment speed and closing time of the Proportional valve is determined.

This has the advantage that a precise camshaft adjustment without essential Overshoot is achieved because a further pivoting of the camshaft during the The closing time of the proportional valve is already taken into account in the setpoint / actual value comparison. Furthermore, there is a simplified application, because instead of a complex data entry important sizes are calculated.

The determination of the respective adjustment speed of the camshaft before each Setpoint / actual value comparison by means of edge signals from one assigned to the camshaft Quick start sensor wheel takes into account an influence of the oil pressure on the Prediction angle. For example, the higher the oil pressure, the Adjustment speed, which leads to a larger prediction angle.

The speed of adjustment is expediently determined by a change in position between two associated negative flank changes associated with one of the camshafts Quick start sensor wheel calculated, preferably one over all flank changes complete rotation of the quick start sensor wheel is expected.

However, provided there is no edge signal over a period of time greater than the calculation grid of the quick start sensor wheel occurs, the actual angle value for a subsequent one Setpoint / actual value comparison updated using the adjustment speed. For this purpose, if there is no edge signal from the quick start sensor wheel between two arithmetic cycles with the next arithmetic cycle the new actual angle value from the actual angle value obtained at the last calculation cycle together with an angle correction determined, the angle correction from the adjustment speed and the duration a computing cycle is calculated.

A precise camshaft adjustment independent of a viscosity of the oil is achieved one in that the closing time of the proportional valve before each Setpoint / actual value comparison depending on an engine temperature, preferably the Oil temperature, is determined from a map.

Because the closing time for different swiveling directions of the camshaft of the proportional valve is determined from different maps, it is possible to Effects on the camshaft, for example of valve lifters, which are used for different swivel directions different effect on the prediction angle have to take into account.

From the beginning of an adjustment of the camshaft, the Proportional valve closing time from zero to maximum or maximum minimum value changed by means of integration and from the changeover of the manipulated variable to the stop duty cycle means the closing time of the proportional valve from the last value Integration calculated to zero.

To ensure the convergence of the control method to the angle setpoint, a each determined closing time of the proportional valve with such a sign provided that the product of the closing time of the proportional valve and Prediction angle resulting adjustment speed has such a sign that when added to the actual angle value, there is a change in the actual angle value in Direction of the angle setpoint results. In other words, the amount of Angle setpoint increased by the prediction angle if the angle setpoint is in the amount is greater than the actual angle value or the absolute value of the angle setpoint is determined by the Prediction angle reduced if the angle setpoint is smaller in magnitude than Angle value.

For example, the stop duty cycle, the duty cycle for adjustment to a Direction and the duty cycle for adjusting in the opposite direction predetermined.

In a preferred embodiment, a is above and below the setpoint Capture area provided with a predetermined width, already then on the Stop duty cycle is switched if the supplemented by the prediction angle Actual angle value falls into the capture range. This is based on a precise adjustment a new angle without overshoot or ringing while adjusting the Camshaft selected to a new angle the capture range smaller than during the Holding the angle setpoint with the hold duty cycle. The larger catch area when holding also prevents the control from operating undesirably the angle adjustment switches, which leads to a restless controller behavior would.

A precise and quiet controller characteristic achieved when holding an angle setpoint a PI control while holding an angle setpoint is performed, with an I component derived from the hold duty ratio and a P component from a setpoint deviation multiplied by a predetermined factor is calculated.

Fig. 1

eine schematische Übersicht einer Nockenwellenanordnung, welche das erfindungsgemäße Verfahren ausführt,

Fig. 2

eine graphische Darstellung des Verhaltens des tatsächlichen Winkelistwertes, des um einen Prädiktionswinkel korrigierten Winkelistwertes und der Verschließzeit des Proportionalventils über die Zeit;

Fig. 3

ein schematisches Blockschaltbild einer das erfindungsgemäße Verfahren ausführenden Reglervorrichtung,

Fig. 4

ein schematisches Blockschaltbild der Modellbildung des Ventils gemäß Fig. 3,

Fig. 5

einen schematischen, blockschaltbildartigen Ablaufplan einer bevorzugten Ausführungsform des erfindungsgemäßen Verfahrens,

Fig. 6

einen schematischen, blockschaltbildartigen Ablaufplan der Berechnung der Nockenwellengeschwindigkeit gemäß der Ausführungsform von Fig. 5,

Fig. 7

einen schematischen, blockschaltbildartigen Ablaufplan des Beobachters mit Modellbildung des Ventils, Prädikation und Berechnung des Winkelistwertes mittels Integration,

Fig. 8

einen schematischen, blockschaltbildartigen Ablaufplan der Modellbildung des 4/2-Proportionalventiles gemäß Fig. 7,

Fig. 9

einen schematischen, blockschaltbildartigen Ablaufplan der Adaption der Ventilschließzeit gemäß Fig. 7,

Fig. 10

einen schematischen, blockschaltbildartigen Ablaufplan der Ausgabe des Tastverhältnisses mittels eines 3-Punkt-Reglers gemäß der Ausführungsform von Fig. 5,

Fig. 11

einen schematischen, blockschaltbildartigen Ablaufplan der Berechnung des Betriebspunktes gemäß der Ausführungsform von Fig. 5,

Fig. 12

einen schematischen, blockschaltbildartigen Ablaufplan der Freigabe der Berechnung des Betriebspunktes gemäß Fig. 11.

Further features, advantages and advantageous embodiments of the invention result from the dependent claims and from the following description of the invention with reference to the accompanying drawings. These show in

Fig. 1

2 shows a schematic overview of a camshaft arrangement which carries out the method according to the invention,

Fig. 2

a graphic representation of the behavior of the actual actual angle value, the actual angle value corrected by a prediction angle and the closing time of the proportional valve over time;

Fig. 3

2 shows a schematic block diagram of a controller device that executes the method according to the invention,

Fig. 4

3 shows a schematic block diagram of the modeling of the valve according to FIG. 3,

Fig. 5

2 shows a schematic, block diagram-like flow chart of a preferred embodiment of the method according to the invention,

Fig. 6

FIG. 5 shows a schematic, block diagram-like flowchart for calculating the camshaft speed according to the embodiment of FIG.

Fig. 7

a schematic, block diagram-like flow chart of the observer with modeling of the valve, predication and calculation of the actual angle value by means of integration,

Fig. 8

7 shows a schematic, block diagram-like flow chart of the model formation of the 4/2 proportional valve according to FIG. 7,

Fig. 9

7 shows a schematic, block diagram-like flow chart of the adaptation of the valve closing time according to FIG. 7,

Fig. 10

2 shows a schematic, block diagram-type flow chart of the output of the duty cycle by means of a 3-point controller according to the embodiment of FIG. 5,

Fig. 11

3 shows a schematic, block diagram-type flow chart of the calculation of the operating point according to the embodiment of FIG. 5,

Fig. 12

a schematic, block diagram-like flowchart of the release of the calculation of the operating point according to FIG. 11.

The method according to the invention is described below with reference to the accompanying drawings for the intake camshaft described by what the index "e" in the respective names for signals, parameters or bits can be seen. However, this is only an example. The explanations shown apply analogously also for the exhaust camshaft.

The exemplary camshaft arrangement shown in Fig. 1 for an adjustable Camshaft 10 comprises a swivel adjuster 12, a swivel adjuster Ansteuemdes 4/2 proportional directional valve 14, an engine control unit 16, one of the Camshaft 10 assigned quick start sensor wheel 18, one of these Quick start sensor wheel 18 scanning camshaft sensor 20 and a camshaft 10 chain 22 with a crankshaft, not shown Camshaft sensor 20 scans the quick start sensor wheel 18, the latter Has elevations 24 which follow one another when the camshaft 10 rotates move past the camshaft sensor 20 and there corresponding edge signals generate, which are transmitted from the camshaft sensor 20 to the engine control unit 16 become. The engine control unit 16 in turn controls the proportional valve 14 in such a way that that the swivel adjuster with the corresponding oil pressure from an oil circuit 26 is supplied. This oil pressure is generated by an engine oil pump 28.

2 graphically illustrates the operation of the engine control unit 16 (FIG. 1) arranged regulator according to the invention. 2 shows a time period, which adjusts the camshaft from an angle of 0 ° KW (KW = crankshaft) represents up to an angle of 20 ° KW. At a time t = 0 s, a bit B_nwvpos set to 1, which means adjusting the camshaft to a new relative angle signaled with respect to the crankshaft. 20 ° KW is set as the angle setpoint. The line 30 illustrates the actual angle value of the crankshaft changing over time, which is referred to below as wnwise.

Depending on the position of the proportional directional control valve 14 (FIG. 1), this requires one predetermined time znwve until it is closed again. This valve closing time znwve is shown with line 32. In other words, the valve needs to be reset of the bit B_nwvpos to zero the time period znwve until it is completely closed. In in the illustrated embodiment, this is 40 ms. During this 40 ms Swivel adjuster 12 moves further by the oil pressure, which also causes the relative angle the camshaft 10 changed to the crankshaft. This change in angle depends on essentially from the slope of curve 30, i.e. on the speed at which the actual angle value changes (adjustment speed). The product of this Adjustment speed vnwde and the valve closing time znwve result in one Prediction angle wnwpe. The sum of the current actual angle value wnwise and Prediction angle wnwpe thus results in a final angle of camshaft 10 compared to the crankshaft, which by resetting after completion of the adjustment of the bit B_nwvpos to "0" is ultimately reached by the camshaft 10.

According to the invention, it is now provided in the controller that a setpoint / actual value comparison not with the actual actual value wnwise, but with the sum of wnwise and the prediction angle wnwpe. The controller ends the adjustment accordingly at t = 200 ms in time such that the camshaft 10 continues to run in Range t = 200 ms to t = 240 ms due to the closing time znwve des Proportional directional control valve 14 as precisely as possible the desired target angle of 20 ° KW is achieved.

In other words, a prediction controller is used to regulate the actual camshaft position used. If the control difference exceeds a threshold value, there is an increased one Position requirement before, the proportional directional control valve 14 with maximum duty cycle controlled what is achieved by setting bit B_nwvpos to "1" and for which Time duration from t = 0s to t = 200 ms. Corresponding channels in the Proportional directional control valve 14 release and guide the largest possible opening cross section vnwde to a maximum adjustment speed. To an optimal To achieve transient response, the prediction angle wnwpe is used. This Size takes into account the angle that the camshaft needs to move due to the finite valve closing time znwve from the current adjustment speed vnwde to come to a standstill. The control of the 4/2 proportional directional control valve 14 is already ended when the actual angle value reaches the angle setpoint up to the prediction angle wnwpe has reached. The prediction angle is calculated as the product of the current one Adjustment speed vnwde and valve closing time znwve.

The adjustment speed vnwde is based on the change in position of the camshaft between two negative signals of an edge of the quick start sensor wheel signal calculated. The determination of the adjustment speed vnwde takes into account the Influence of the oil pressure, so that an accurate determination of the prediction angle is possible.

In the control method according to the invention, the setpoint / actual value comparison is carried out continuously in Rhythm of a calculation grid of 4 ms, for example. However, it should be noted here that an edge signal of the Quick start sensor wheel 18 occurs and therefore not the actual one for every computing cycle Actual angle value can be determined. To now one at the next computing cycle According to the invention, the actual angle value becomes the target / actual value comparison wnwise is calculated from the determined adjustment speed vnwde or updated until an edge signal of the quick start sensor wheel 18 occurs again at which an exact position determination of the crankshaft, the camshaft 10 and thus a relative angle between these (actual angle value) can be measured. The current one Valve closing time znwve is also constantly dependent on the operating situation the internal combustion engine updated.

In the following, a concrete preferred one is made with reference to FIGS. 3 to 12 Embodiment of a control method according to the invention described.

3 illustrates in a block diagram a simplified structure of a three-point camshaft controller. In a block 34, the following is closer explained the current adjustment speed vnwde the camshaft is calculated. This adjustment speed vnwde is fed to an integrator 36, which consists of the Adjustment speed vnwde over time an estimated actual angle wnwise ' calculated if no edge signal of the quick start sensor wheel 18 and thus none measured actual angle value is present. At the same time, with every computing cycle, one Modeling of the proportional directional control valve in block 38 one for the current one Operating situation valid valve closing time znwve determined and output. Furthermore Block 38 controls a switch 40 by means of a bit B nwvhe such that either the Output from block 34 or a value "0" is given to integrator 36. This bit B_nwvhe is set to "1" if the camshaft angle is not adjusted to a new value, but the current actual value should be held. In this In this case, the actual angle value wnwise is not updated, since this is as possible should not change. From the current valve closing time znwve together with the Adjustment speed vnwde becomes the prediction angle wnwpe in a block 42 calculated. In block 44, the prediction angle wnwpe and the estimated one Actual angle value wnwise 'to the total angle wnwgsde for the setpoint / actual value comparison in Controller calculated. This setpoint / actual value comparison between wnwgsde and the Angle setpoint for the camshaft wnwse takes place in block 46. This block 46 switches by means of the bits B_nwvpos, B_nwvhe and B_nwvneg the operating mode of the controller, i.e. Holding or adjusting the relative angle between the camshaft and crankshaft. Provided the setpoint / actual value comparison shows that there is a large setpoint difference, then each after the sign of this difference, an adjustment in the positive or negative direction of the Relative angle between camshaft and crankshaft by setting either the bit B_nwvpos or bit B_nwvneg activated to "1". If the target / actual value comparison however, the total actual value wnwgsde is within a capture range the setpoint wnwse, the operating mode "keep angle" is activated by the bit B_nwvhe is set to "1".

FIG. 4 illustrates a simplified structure of block 38 of FIG. 3, which is one Modeling of the proportional directional control valve 10 of FIG. 1 includes. In dependence of a parameter tmot, which represents an engine temperature, is used for the different adjustment directions from a respective map 48, 50 each maximum valve closing speed for an adjustment in positive or negative Direction determined and passed to an integrator 52. This integrator 52 receives one Input signal to be integrated from a logic 54. This logic is through verification of the bits B_nwvpos and B_nwvneg in which control situation the controller is is currently located. Furthermore, the logic 54 via feedback 56 is the current one State of integrator 52 also known. With an appropriate input signal from the logic 54, the integrator 52 increases at its output from the beginning of one positive adjustment of the camshaft angle to a new value Valve closing time increases, as can be seen from curve 32 in FIG. 2. The values from The maps 48 and 50 represent the maximum valve closing times znwve for represents the positive or negative direction of adjustment. This lies in the example according to FIG. 2 at 40 ms, so that the output of the integrator 52 remains constant from this point in time. After a corresponding sign correction in block 58, finally the modeling in block 38, the current valve closing time znwve and the bit for Signaling a hold state B_nwvhe output.

A specific embodiment is described below with reference to FIGS. 4 to 12 the functional sequence of the control according to the invention according to Figures 3 and 4 described.

5 illustrates an overview of the invention Camshaft controller. This includes the following: an observer 60, who the Functions of blocks 36, 38, 42 and 44 according to FIG. 3 combined, one Speed calculation 62, an adaptation of the working point 64, a Error handling 66 and an output of the duty cycle 68. The one in FIG. 5 The camshaft controller shown receives an angle setpoint wnwse as input values as well as an actual angle value wnwise. This camshaft governor gives the initial value in essentially a control value in the form of a duty cycle tanwre. This Duty cycle tanwre is fed to the proportional directional control valve and sets one corresponding valve position such that either the camshaft angle in negative direction is changed (duty cycle tanwre = tanwne) or the Camshaft angle is changed in the positive direction (duty cycle tanwre = tanwpse) or the current actual angle value is held (duty cycle tanwre = tanwrhfe + tanwpe, as explained in more detail below with reference to FIG. 10 becomes).

6 illustrates the calculation of the adjustment speed vnwde in block 62. This calculation is always carried out when the bit B_n is equal to "1" and thus signals that an edge signal of the quick start sensor wheel has been received. In in this case, operations are performed in a branch 70, these being Operations are marked with / 1 / to / 11 /, the digits being the order of Mark the function execution beginning with / 1 /. This is then done in block 72 Evaluation of several edge signals of the quick start sensor wheel over a full one Revolution of the same. Corresponding angles of rotation and periods between the Edge signals are recorded in shift registers 74 and 76 and in blocks 78 or 80 added up. In block 82 the summed angles are represented by the totaled times divided, from which the adjustment speed vnwde is averaged over a full revolution of the quick start sensor wheel. If applicable, takes place in a filter 84 filters the calculated adjustment speed vnwde, whereby the speed detection is smoothed. The rotation of the quick start sensor wheel However, it does not take place at the same frequency on which the calculation grid is based. As a result, an edge signal does not necessarily occur exactly at the time of one Arithmetic clock, but usually between two arithmetic clocks. Now, however a current position of the crankshaft at the time the edge signal occurs evaluated. By comparison with the associated flank of the quick start sensor wheel a relative angle between camshaft and crankshaft can thus be determined, however, this point in time is in the past at the time of the calculation cycle a certain amount between the occurrence of the edge signal and the next computing cycle Fraction of a computing cycle time has passed. The calculations of the in the figures The controller according to the invention shown takes place according to a determined in block 86 Timing. In order now from the position determination of the crankshaft at the time de Edge signal an exact actual angle value at the time of (later) To determine arithmetic clock, in block 88 is the time between the occurrence of the edge signal and the next computing cycle. This period of time is at 90 as the last function / 11 / passed to the observer 60. Unless, however, since the last computing cycle no edge signal of the quick start sensor wheel occurred, is the bit B_n is set to "0" and the program branch 92 is executed. In In this branch 92, only a function designated / 1 / is carried out, in which one Register 94 is added a computing clock time and a total elapsed time dtnwe is forwarded to the observer 60 since the last edge signal.

Fig. 7 illustrates the functional sequence in the observer 60. Provided by the bit B_nwvhe indicates that the controller is in the "Adjust to a is the new angular value ", the adjustment speed calculated in block 62 vnwde fed an integrator 94. This calculates from the adjustment speed and the time since the last edge signal of the quick start sensor wheel an estimated actual angle wnwgse. However, if an edge signal of the Quick start sensor wheel an exact determination of the actual angle between Allows camshaft and crankshaft, the integrator 94 is adjusted via branch 96, the value of the angle determined at the time of the edge signal with the corresponding correction based on the time period between the edge signal and Calculation cycle is set as the new actual angle value wnwgse. The correction takes place at the Multiplication of the adjustment speed vnwde by the time period dtnwe since last edge signal in block 98 and leads to the correction angle wnwkrve which in block 100 is added to the actual angle value wnwise measured at the time of the edge signal is added. The actual value wnwgse leaving the integrator is finally in block 102 with the prediction angle wnwpe added to wnwgsde. Finally, in block 104 the setpoint / actual value comparison in which the supplemented actual angle value wnwgsde and the Angle setpoint must be subtracted from each other. The result is that Control difference dwnwe.

The determination of the prediction angle wnwpe in block 106 is illustrated in FIG. 8. 8 shows the logic 54, the integrator 52, the feedback 56, the characteristic maps 48, 50 and the sign correction 58 again. Additionally, at 108 and 110 Correction value for the maximum valve closing time znwvpe in the positive direction or znwvne introduced in the negative direction. The determination of these correction values znwadne and znwadpe is illustrated in FIG. 9. In block 112 it is checked whether a Adaption is necessary or not. In block 114 it is determined how to adapt and in Block 116 is a learning value limitation. The adaptation is deleted in block 118. The adaptation value takes into account, for example, oil viscosity, scatter and leakage.

10 finally illustrates the structure of block 68, which is a respective one Outputs duty cycle tanwre to control the proportional directional control valve. In block 120 takes place depending on the values of the bits B_nwvne (= B_nwvneg) and B_nwvpe (= B_nwvpos) the selection from three sources for the duty cycle tanwre to be output. In other words, the controller with the function block 120 is a three-point controller.

If the bit B_nwvne or B_nwvpe is set, a pulse duty factor is generated to register 122 or 124. These are duty cycles for Adjustment of the relative angle between camshaft and crankshaft in positive or negative direction. Unless there is currently a new relative angle for the camshaft the controller is in "hold mode", i.e. it will be a Hold duty cycle output. This is generated in the form of a PI controller and includes the duty cycle tanwpe as the P component and the hold duty cycle as the I component tanwrhfe, which are summed in block 126. The P share tanwpe is that Result of a multiplication from the control difference dwnwe by a fixed factor a register 128 in function block 130.

The setting or resetting of the bits B_nwvne and B nwvpe, respectively, which means an adjustment to signal a new relative angle between the camshaft and crankshaft takes place additionally depending on threshold values WSNW and WSRNWE in registers 132, 134, each of which forms a capture range around the setpoint. Here is a larger one WSNW capture range from register 132. active when the control is in hold mode located, i.e. if the current angle is maintained according to the set bit B_nwhe shall be. If, however, the controller is in an operating state in which a new relative angle between the camshaft and crankshaft is adjusted smaller catch area WSRNW from register 134 active.

FIG. 11 illustrates the structure and the mode of operation of block 64 from FIG. 5 for calculating the operating point, ie for determining the holding duty ratio tanwrhfe. A check is made in block 136 as to whether or not the calculation of the operating point should be activated. The activation takes place only when the angular position of the camshaft with respect to the crankshaft is to be kept constant. Block 64 then optimally adjusts the hold duty ratio tanwrhfe in such a way that a corresponding operating point for the control results. The structure and function of block 136 are illustrated in FIG. 12. In block 138, a setpoint / actual value comparison is carried out between the actual angle value wnwgse and the setpoint angle value wnwse without adding the prediction angle. This ensures that the calculation of the operating point is not already activated in the time interval in which the adjustment has ended, but the proportional directional control valve is not yet completely closed (valve closing time znwve). 2, this is the time range from t = 200 ms to t = 240 ms. The calculation of the operating point should only start in the time range after t = 240 ms. A feedback 140 finally ensures that the calculation of the operating point remains active even if, in the absence of the desire to adjust to a new relative angle value between the camshaft and crankshaft, the actual angle value is a little further away from the desired angle value.
The calculation of the operating point only stops when the angle setpoint has actually been set to a new value which must now be approached.

Instead of the swivel adjuster 12 shown as an example, any adjuster can be used be used, e.g. known from the prior art, with a Hydraulically operated axial piston adjusters with helical teeth.

LIST OF REFERENCE NUMBERS

B_nwcoe

Bit for enabling the calculation of the operating point

B_nwie

Bit for occurrence of an edge of the quick start sensor wheel (interrupt)

B_nwvpos

Bit for adjusting the camshaft in the positive direction (maximum Duty cycle for adjustment in positive direction active)

B_nwvneg

Bit for adjusting the camshaft in the negative direction (maximum Duty cycle for adjustment in negative direction active)

B_nwvhe

Bit for holding the actual angle value in the range of the bit setpoint with PI control (Hold duty cycle active)

B_nwtve

Bit for controller calculation active

dnnwe

Angle between two edges of the Quick start sensor wheel

dnnwXe

Xth angle value, X = 1,2,3

dtnwe

Time period between two edges of the Quick start sensor wheel

dtnwXe

Xth period, X = 1,2,3

dwnwe

Difference: Angle setpoint of the camshaft minus predictive Actual angle value of the camshaft (target / actual deviation)

tanwne

Duty cycle to reduce the camshaft angle

tanwpe

Proportional share of the stop duty ratio

tanwpse

Duty cycle to increase the camshaft angle

tanwre

Duty cycle for camshaft control

tanwrhfe

adapted stop duty cycle (integral part)

tmot

engine temperature

tnwie

System timer time when an edge of the Quick start sensor wheel

tnwtv

Computing time frame

ttvie

system counters

ttvier

Takeover value of ttvie when an edge of the Quick start sensor wheel (B_nwtve = TRUE)

vnwde

Adjustment speed of the camshaft

vnwdze

Intermediate value of the adjustment speed of the camshaft

wnwgsde

Actual angle value + prediction angle (expected angle of the Camshaft, which would be reached if bit B_nwvhe was TRUE would go)

wnwgse

estimated intake camshaft angle

wnwkrve

Correction value for camshaft angle due to time between Occurrence of the flank of the quick start sensor wheel and the Calculation time of the calculation grid clock

wnwpe

Prädikationswinkel

wnwise

Actual angle value of the camshaft

wnwise '

Estimated actual angle value of the camshaft in calculation grids without Occurrence of an edge of the quick start sensor wheel

wnwse

Angular setpoint of the camshaft

wsnw

Value for catch range (if B_nwhe = TRUE, i.e. if the angle is held)

wsnrw

reduced value for catch area (if wnwise is on wnwse approximates)

znwadpe

Adaptation value for valve closing time with positive adjustment

znwadne

Adaptation value for valve closing time with negative adjustment

znwve

Valve closure timing

znwvpe

Limit value of the valve closing time with positive adjustment

znwvne

Limit value of the valve closing time with negative adjustment

10

camshaft

12

Schwenkversteller

14

4/2-proportional directional valve

16

Engine control unit

18

Schnellstartgeberrad

20

camshaft position sensor

22

Chain

24

Surveys of the quick start sensor wheel

26

Oil circuit

28

Engine oil pump

30

Angle value

32

Valve closure timing

34

Calculation of the adjustment speed vnwde

36

integrator

38

Modeling of the proportional directional valve

40

switch

42

Calculation wnwpe = znwve * vnwde

44

Calculation wnwpe + wnwise '

46

Setpoint / actual comparison

48

map

50

map

52

integrator

54

logic

56

feedback

58

sign correction

60

observer

62

speed calculation

64

Adaptation of the working point

66

error handling

68

Issuing the factual relationship

70

Function branch, IF condition true

72

Block adjustment speed calculation

74

Angle shift register

76

Time shift register

78

Block: Sum up angles

80

Block: Sum up time

82

division

84

filter

86

Calculation calculation grid

88

Determination of the time span between the edge signal and the computing cycle

90

Handover period

92

Function branch, IF condition incorrect

94

integrator

96

branch

98

Multiplication for correction

100

addition

102

addition

104

subtraction

106

Determination of the prediction angle

108

Addition correction value

110

Addition correction value

112

Block: Check whether adaptation is necessary

114

Block: how to adapt

116

Block: Learning value limitation

118

Block: delete the adaptation

120

Selection of duty cycle

122

register

124

register

126

addition

128

register

130

multiplication

132

register

134

register

136

Block: Release of the calculation of the operating point

138

Block of target / actual value comparison without prediction angle

140

feedback

Claims (15)

1. Method for adjusting a cam shaft in an internal combustion engine, the cam shaft being pivoted by a predetermined angle with respect to a crank shaft by means of an adjusting device, preferably a pivoting adjusting device, which is activated by a regulator and a proportional valve, in which the regulator compares an angle set point value with an angle actual value, determines, as a function of this comparison, a manipulated variable in the form of a pulse duty factor for the proportional valve, and, when the angle set point value and angle actual value correspond, sets this manipulated variable to a holding pulse duty factor in such a way that the angle set point value is held, in which, during an adjustment of the cam shaft before a restrictive set point value/actual value comparison a forecast angle is added to the angle actual value in such a way that the sum of the angle actual value and forecast angle corresponds to an angle of the cam shaft which said cam shaft reaches during a closing time of the proportional valve, by the time the proportional valve is completely closed after the manipulated variable has been switched over to the holding value, the forecast angle being added in such a way that by means of the forecast an integral distance with dead time is modelled, in which case an instantaneous adjustment speed of the cam shaft is also calculated before each set point value/actual value comparison, characterized in that, before each set point value/actual value comparison, the forecast angle is determined as a product of the adjustment speed and closing time of the proportional valve.
2. Method according to Claim 1, characterized in that the adjustment speed is calculated from a change in position between two associated edges of a high-speed starting sensor wheel which is assigned to the cam shaft.
3. Method according to Claim 2, characterized in that an average is taken of all the edge changes of one complete revolution of the high-speed starting sensor wheel.
4. Method according to at least one of the preceding claims, characterized in that a set point value/actual value comparison is carried out during each computing cycle on the basis of a computing grid.
5. Method according to Claim 4, and at least one of Claims 1 to 3, characterized in that, when an edge signal from the high-speed starting sensor wheel occurs, a position of the cam shaft is determined and a resulting angle difference between the cam shaft and the crank shaft is set as an angle actual value, this angle actual value being additionally provided with an angle correction which is calculated from the time period between the occurrence of the edge signal and the computing cycle as well as the adjustment speed.
6. Method according to Claim 4 or 5 and at least one of Claims 1 to 3, characterized in that, when an edge signal from the high-speed starting sensor wheel fails to occur between two computing cycles, the new angle actual value is determined from the angle actual value obtained during the last computing cycle, together with an angle correction, the angle correction being calculated from the adjustment speed and the duration of a computing cycle.
7. Method according to one of the preceding claims, characterized in that, before each set point value/actual value comparison, a maximum closing time of the proportional valve is determined from a characteristic diagram as a function of an engine temperature.
8. Method according to Claim 7, characterized in that the closing time of the proportional valve is determined from different characteristic diagrams for different pivoting directions of the cam shaft.
9. Method according to Claim 7 or 8, characterized in that, starting from the beginning of an adjustment of the cam shaft, the closing time of the proportional valve is changed from zero to at most the maximum or minimum value by means of integration.
10. Method according to Claim 9, characterized in that, starting from the switching over of the manipulated variable to the holding pulse duty factor, the closing time of the proportional valve is integrated from the last value to zero.
11. Method according to one of Claims 7 to 10, characterized in that a respectively specific closing time of the proportional valve is provided with a sign in such a way that the forecast angle which results from the product of the closing time of the proportional valve and adjustment speed has such a sign that when added to the angle actual value a change in absolute value of the angle actual value results in the direction of the angle set point value.
12. Method according to one of the preceding claims, characterized in that the holding pulse duty factor, the pulse duty factor for adjustment in one direction and the pulse duty factor for adjusting in the opposite direction are predetermined.
13. Method according to one of the preceding claims, characterized in that a capture region of predetermined width is provided above and below the set point value, the holding pulse duty factor being already switched over to when the angle actual value to which the forecast angle is added moves into the capture range.
14. Method according to Claim 13, characterized in that, during the adjustment of the cam shaft to a new angle, the capture range is selected to be smaller than during the holding of the angle set point value with the holding pulse duty factor.
15. Method according to one of the preceding claims, characterized in that during the holding of an angle set point value a PI control is carried out, an I component being derived from the holding pulse duty factor, and a P component being calculated from a set point value deviation multiplied by a predetermined factor.

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