DE102014203688A1 - Method for detecting outgassing effects in a hydraulic fluid - Google Patents

Abstract

The invention relates to a method for detecting Ausgasungseffekten in a hydraulic fluid, such as in a hydraulic timing drive of an internal combustion engine, wherein an air pressure signal is detected by a pressure sensor in an air supply duct or an air discharge channel and is evaluated, whereby a gas exchange valve can be influenced / influenced.

Description

Field of the invention

The invention relates to a method for detecting outgassing effects in a hydraulic fluid, such as in a hydraulic timing drive of an internal combustion engine.

Air absorption in hydraulic systems occurs by contact with air under a wide range of conditions in terms of temperature, pressure and hydraulic oil. Hydraulic systems are widely used in many industrial machines and vehicles. Many systems require high precision for their actuators in terms of timing accurate actuation and precise actuation movements.

In 1 A typical hydraulic system with air contact in its oil chamber is shown. If the air absorption occurs in the oil paths, the hydraulic actuator and the valve will not provide timely and accurate performance corresponding to the command issued by the valve control unit. Consequently, the activity of the plant deviates from the specification. On the other hand, if it is possible to measure the amount of deviation (delay, early timing and / or amount of movement) based on the response signal of the equipment, the air absorption effect on the system can be indirectly learned. In this way, the air-absorbing effect on the system can be detected indirectly at an earlier time, and the control unit can adjust / compensate for such deviation or error caused by the air-absorbing effect.

In the 1 A typical hydraulic system with air absorption risk is presented. The system may be aerodynamic in nature, eg air paths or exhaust paths of an internal combustion engine, or mechanical nature, such as industrial robots, etc. relate. Thick arrows indicate hydraulic oil paths 1 and thin arrows signal paths 2 ,

An air-contact oil chamber, an oil pump, a solenoid valve, a hydraulic actuator / valve, an aerodynamic / mechanical equipment, a response signal, and a valve control unit are identified by the reference numerals 1 to 9 busy.

• 1. Ein unmittelbarer Drucksensor, der stromaufwärts oder stromabwärts des hydraulisch betriebenen Ventils installiert ist;
• 2. Ein unmittelbarer Strömungsmesser, der stromaufwärts oder stromabwärts des hydraulisch betriebenen Ventils installiert ist;
• 3. Ein Bewegungssensor für das hydraulisch betriebene Ventil;
• 4. etc.

An essential component in air absorption sensing in such systems is a sensor that directly or indirectly provides the immediate response of the equipment during the hydraulic actuation time. For an aerodynamic / aerodynamic system, the response signal can be obtained in the following way:

• 1. An immediate pressure sensor installed upstream or downstream of the hydraulically operated valve;
• 2. An immediate flowmeter installed upstream or downstream of the hydraulically operated valve;
• 3. A motion sensor for the hydraulically operated valve;
• 4. etc.

In the present document, the focus is on the first alternative, i. on the response signal from a pressure sensor. One reason for this is that such sensors are widely used in vehicle and engine parts by first-time manufacturers. On the other hand, the new method can also be slightly modified and used in situations with other response signals, e.g. B. in flow meters and motion sensors.

One such hydraulic system is, for example, the hydraulic valve drive (e.g., UniAir system) in an air / exhaust path in an internal combustion engine.

When an engine with such a system shifts back to idle at high temperatures from high speeds, the effect of air absorption occurs, resulting in very unstable engine operation, and may even result in the engine stalling. In fact, the air previously dissolved in the hydraulic oil is released in the form of tiny bubbles caused by the hydraulic pressure drop. As a result, the compressibility and other properties of the hydraulic oil in the system change. So the precision of the hydraulic actuator is at risk or the actuator stops working completely in the worst case.

• – Abwürgen des Motors bei heißem Leerlauf aufgrund von nicht wirksamer Betätigung des hydraulisch betriebenen Ventils;
• – Instabile Leerlaufdrehzahl aufgrund von instabilen hydraulischen Betätigungen;
• – Grenzwertüberschreitende Emissionen aufgrund von falschen Luftmengen für die Verbrennung.

A new method described herein is for detecting air absorption in a system having hydraulically operated actuators. To describe the essential content of the new process, a specific application, the INA UniAir System, is taken as an example of air path control in the engine. In this particular case, the new method can be used to handle the following abnormal engine operating events, such as:

• Stalling the engine at hot idling due to ineffective operation of the hydraulically operated valve;
• - Unstable idling speed due to unstable hydraulic operations;
• - Exceeding emissions due to incorrect air volumes for combustion.

There are already patents or patent applications regarding MAP signals for the detection of inactive MV, P. Traversa, et al. and air absorption predictors for air absorption prediction, P. Traversa, et al.

The procedure for using MAP signals for inactive engine valves is to determine if a valve is inactive and remains closed during its actuation span. Although high air absorption could cause a MV to remain seated without opening, this strategy is generally not suitable for air absorption detection.

The method of the air absorption counter was developed according to the experimental relationship between future air absorption and the current operating conditions. This prediction strategy requires considerable calibration work and its predictive accuracy is greatly reduced by certain "recalibration" effects, e.g. Deviations of the motor geometry and the operating conditions, aging of the components, etc.

It is the object of the invention to eliminate or at least mitigate the disadvantages of the prior art.

• 1. Verzögerung des Öffnungswinkels (dPhi1 >= 0) aufgrund von erhöhter Ölkompressibilität;
• 2. Verschiebung des Schließwinkels in zwei mögliche Richtungen: a. Verzögerung (dPhi2 >= 0) im Falle einer großen Verzögerung des Öffnungswinkels oder, b. Frühzeitigkeit (dPhi2 < 0) im Falle einer geringen Verzögerung des Öffnungswinkels und der Luftabsorptionseffekt länger anhält.
• 3. Verkürzung der Zeitspanne der gesamten Ventilöffnung (dSpan);
• 4. Verzögerung des Hubprofils sowie des Hubmaximums (dPeaktime);
• 5. Hubreduktion (dLift) in zwei verschiedene Situationen: a. Stärkere negative Steigung des Drucks aufgrund von schnellerem Luftstrom durch eine mäßige Ventilöffnung und / oder mäßige Öffnungszeitspanne mit mäßiger Hubreduktion, siehe 2b, oder, b. Flachere Steigung des Drucks aufgrund von sehr langsamer oder sehr schneller aber kurzer Strömung (der Sensor verliert hier seine Empfindlichkeit) durch eine sehr kleine Ventilöffnung und / oder sehr kurze Öffnungzeitspanne, die in Fällen von zu starker Luftabsorption auftritt oder die MV-Öffnungsanfrage ist zu kurz, siehe 2b;

During operation of an internal combustion engine with hydraulic actuators in the valve drive, a few dynamic properties, such as opening / closing angles and the stroke of the valves, are changed when there is a certain rate of air absorption in the hydraulic system. In fact, the higher the rate of air absorption, the greater the change in these dynamic properties. In 2a the changes of these dynamic characteristics are shown for intake valves in an internal combustion engine, in detail:

• 1. Delay of the opening angle (dPhi1> = 0) due to increased oil compressibility;
• 2. Shift the closing angle in two possible directions: a. Delay (dPhi2> = 0) in case of a large delay of the opening angle or, b. Prolongation (dPhi2 <0) in the case of a small delay of the opening angle and the air absorption effect lasts longer.
• 3. shortening the time span of the entire valve opening (dSpan);
• 4. Delay of the lift profile and the maximum lift (dPeaktime);
• 5. Stroke reduction (dLift) in two different situations: a. Greater negative slope of pressure due to faster air flow through moderate valve opening and / or moderate opening time with moderate stroke reduction, see 2 B , or, b. Flatter slope of pressure due to very slow or very fast but short flow (the sensor loses its sensitivity here) due to a very small valve opening and / or very short opening time that occurs in cases of excessive air absorption or the MV open request is too short , please refer 2 B ;

The principle described for the intake valve for an air path can also be used for exhaust valves for internal combustion engines. However, the exhaust pressure signal should be used there instead of the MAP signal.

In the 2a and 2 B on the abscissa the time or the angle is plotted and on the ordinate the stroke. A stroke with moderate valve opening, a normal stroke without air absorption, a stroke with a very small valve opening, and an opening period is denoted by the reference numerals 10 to 13 referenced. Differences b dPhi1, dPhi2, dPeaktime and dLift are indicated by the reference numbers 14 to 17 referenced. Normal and abnormal lift profiles when operating hydraulic valves with and without air absorption effect. dPhi1, dPhi2, dPeactime and dLift are defined as the difference between the detected value and the corresponding required value. Line legend: solid line: normal stroke without air absorption; dashed line: stroke with air absorption effect.

Schematic pressure signals related to various influences on the hydraulic valve lift with and without air absorption are shown in FIG 2a and b reproduced. The solid line 18 gives the normal stroke without air absorption, the dashed line 19 and 20 the hub with air absorption effect again. The minimum gradient position of the pressure signal, a maximum of the pressure signal, a pressure with respect to normal stroke (no air absorption), a pressure with respect to a very small stroke (strong air absorption), a minimum of the pressure and a pressure with respect to a moderate stroke (moderate air absorption) is denoted by the reference numerals 21 . 22 . 18 . 20 . 23 and 19 each provided

As mentioned in the previous paragraphs, an INA UniAir system for a four-cylinder engine is used as an example to describe the new method of detecting air absorption in the intake-valve hydraulic drive and the corresponding algorithm. In fact, the method itself is generally valid and can be used in any hydraulic system requiring high precision actuation (timing, timing, movement, etc.) for the hydraulic actuators.

In addition, the new method of detecting the effect of air absorption on the performance of the plant, but not the air absorption itself. In hydraulic systems, the air is at high Oil pressure well dissolved in the hydraulic oil and so has only a small negative impact on the operation of the hydraulic system. At low pressure or shortly after the transition from high to low pressure, on the other hand, air absorption severely affects the performance of the system, which is the focus of this document. To keep the description short, no difference is made between detection of air absorption and air absorption effect, unless otherwise specified. In addition, it is assumed that the abnormal valve operation, if any, is caused solely by the air-absorbing effect. In the following, the essential elements of the new method will be described in detail.

To the pressure signals:

MAP (Manifold Absolute Pressure) sensors are often installed in internal combustion engines in the automotive / engine industry. By having a pressure sensor, the practical application of the air absorption detection in the hydraulic drive for intake valves is easily possible. There is no need for an additional sensor and the implementation is merely software related, which is an advantage over other first-party vehicle and engine parts solutions.

A MAP sensor can provide the necessary differential pressure signals for air absorption sensing from one to four individual hydraulic actuators, each of which is mounted on a cylinder. In cases where there are more than 4 cylinders, the applicability of the new method is limited only by the degree of disturbance caused by the overlapping of the intake strokes of the various cylinders of the internal combustion engine. The higher the degree of overlap, the lower the applicable operating range in which the method should be used.

For the cases described in this document, a MAP sensor signal has been used which has a precision of 1 mbar and a resolution of 6 ° CA (crank angle) and the pressure information is only for an angle <180 ° CA starting at the inlet stroke TP (FIG. top dead center) is required for each cylinder of a four-cylinder engine. If detection is needed for an engine with more than 4 cylinders, the process can be used, but with limited operating conditions.

On the other hand, a sensor for the exhaust pressure behind the valves is needed if the air absorption detection is desired for a hydraulic drive of an exhaust valve. However, an exhaust pressure sensor is not widely available, at least not for automotive engines. If available, an exhaust pressure sensor may provide a better signal regarding opening / closing of the exhaust valves when installed near the valves in the exhaust passage.

In the following, only one intake valve drive will be used as an example to describe the new method and the corresponding algorithm is based on the application of a pressure sensor signal.

To the detection method:

The new method described herein serves to establish a correlation between the pressure signal and the opening characteristics of a valve operated by a hydraulic actuator in an internal combustion engine. These characteristics change greatly when there is a certain amount of air absorption in the hydraulic valve drive. See in 4.1 a typical case with a pressure signal and the corresponding stroke of the actuated by the hydraulic actuator valve in a four-cylinder engine.

A schematic pressure signal and valve lift with their characteristic times during the intake stroke for an internal combustion engine is in 3 played. On the abscissa the time or the angle is plotted and on the ordinate the hub or MAP. With the reference number 24 is the stroke of the hydraulically driven valve marked. The time when the valve is open or closed, a delay, a slope of the pressure in the valve opening is denoted by the reference numerals 25 . 26 and 27 such as 28 Mistake.

The correlation is based on the flow dynamic characteristic of the air flow in the inlet duct. In fact, the pressure in the duct increases or remains constant before the valve opens (before time lo in 4.1 ); After the valve has opened and after a short delay (up to the time po), the pressure starts to decrease as the pull effect of the pistons in the cylinder is detected by the pressure sensor. The maximum value of the pressure at the time point po largely corresponds to the valve opening time lo. Similarly, the valve closing timing lc largely corresponds to the minimum value of the pressure at the time pc, see 3 ,

When a valve opens up to the maximum stroke, the pulling effect of the cylinder also increases, even though the fact that the piston position also plays a role in the strength of the drag effect is also considered.

Anyway, a strong drag effect results in a faster pressure drop and the local gradient / slope of the pressure gets smaller ( negative). When the maximum lift timing shifts due to a shift in the opening / closing angles, the time of the strong pull effect also shifts. The maximum stroke position (along with the stroke displacement) largely corresponds to the minimum position of the slope of the pressure, which can be used to detect the delay of the valve lift maximum (dPeaktime).

As previously mentioned, the stroke of the hydraulically operated valve decreases as air absorption occurs in the system. In view of the fact that only a few motors, with the exception of the test motors, are equipped with a stroke / motion sensor, the new method instead uses the slope of the pressure during the valve opening time. In fact, the operation of the valve is definitely abnormal when the slope deviates (higher or lower than the normal / reference gradient), which corresponds to the case without air absorption, and the air absorption is most likely the reason for this.

• • Zeitablauf: Ventilöffnungszeitpunkt (lo) und Zeitpunkt des Druckmaximums (po);
• • Zeitablauf: Ventilschließzeitpunkt (lc) und Zeitpunkt des Druckminimums (pc);
• • Zeitablauf: Zeitpunkt des maximalen Ventilhubs (lm) und Zeitpunkt des Druckgradientenminimums (pm);
• • Hubwert: maximaler Ventilhub (lm) und Steigung des Drucks / Gradienten in der Ventilöffnungszeitspanne.

In summary, the correlations / correspondences between valve lift and pressure signal can be described as follows:

• • Timing: Valve opening time (lo) and time of maximum pressure (po);
• • Timing: valve closing time (lc) and time of minimum pressure (pc);
• • Timing: time of maximum valve lift (lm) and time of pressure gradient minimum (pm);
• • Stroke value: maximum valve lift (lm) and slope of pressure / gradient in the valve opening period.

There are a few delays between these interactions since there is a short physical time required for the pressure change (wave) to travel upstream from the valve position back to the pressure sensor. In addition, the pressure sensor (also the pressure) is not very sensitive to very small pressure changes that occur during the small opening of the valve. Apart from that, the characteristics of the pressure signal largely correspond to the valve lift.

• 1. Vorgaben für die Ventilöffnungs- / Ventilschließwinkel (oder den maximale Hub) aus der Steuereinheit;
• 2. Steuerungs- / Betätigungsbefehle, die von diesen Vorgaben übertragen werden;
• 3. Statistische Ventilöffnungs-/ Ventilschließwinkel, den maximalen Hub und die durchschnittliche Steigung unter den momentanen Umgebungs- und Betriebsbedingungen;
• 4. Statistische Öffnungs-/ Schließwinkel der Steuerungs- / Betätigungsbefehle (oder des maximalen Hubs) unter den momentanen Umgebungs- und Betriebsbedingungen.

In order to measure air absorption, the absolute values for the angle or stroke are less important than the relative error, which is worked out based on a set of carefully selected reference values. With such considerations, the reference values may be selected from certain reference characteristics during a valve opening period, eg:

• 1. Specifications for the valve opening / closing angle (or the maximum stroke) from the control unit;
• 2. control / actuation commands transmitted by these specifications;
• 3. Statistical valve opening / closing angles, the maximum lift and the average slope under the current ambient and operating conditions;
• 4. Statistical opening / closing angles of control / actuation commands (or maximum lift) under current ambient and operating conditions.

In the following, for explanation of the method as an example, the above-described reference definitions of item 1 for dPhi1 and dPhi2 and that of item 3 for dSlope / dLift are taken. In particular, the error or difference is calculated in the following way: dPhi1 = (time of maximum pressure) - (engine requested valve opening time); (Equation 1) dPhi2 = (time of pressure minimum) - (engine requested valve closing time); (Equation 2) dSpan = dPhi1 + dPhi2; (Equation 3) dPeaktime = (time for minimum of the slope of the pressure) - (middle time between engine requested valve opening and closing times) (Equation 4) dSlope = (slope of pressure during valve opening) - (reference slope); (Equation 5) wherein the reference slope is determined in an operation without air absorption under the same environmental and operating conditions dLift = factor × | dSlope |; (Equation 6) where factor is a conversion constant used to transfer the difference of the slope into the difference / error of the stroke, depending on the temperature, load, etc.

In fact, the information dPhi1 and dPhi2 are contained in dSpan and combined. In the same way dSlope indirectly contains the essential information dLift. Due to the ease of practical application, in the following explanation only dPhi1 (equation 1), dPhi2 (equation 2) and dSlope (equation 5). 4a (with aeration effect) and b (without aeration effect) for dPhi1, dPhi2 and dSlope show a lot of postprocessed results, which were obtained in an experiment with an internal combustion engine. Leaving aside the characteristics of the pressure signal during the transient phase or before stabilizing the engine at 750 rmp id, shows a greater valve opening retardation and a large negative pressure rise in the initial idle mode. This is a critical phase for engine operation. In fact, the engine is started when the air absorption in this phase is too strong. Even in the case of a lower air absorption effect, the smooth operation of the engine is still disturbed. In both situations, the emission level of the engine will reach a critical level.

The graded angle difference / error in the upper and middle diagrams shows that the resolution for the pressure is only 6 ° CA. Despite such inaccurate pressure sensing, the method is still able to detect the angle / stroke variation of the hydraulic valve, which is reflected in the angular deceleration (dPhi1> 0) and the change in the slope of the pressure (dSlope <0). Both points to a strong air absorption effect in the system.

In addition, it can be seen that the air absorption affects the valve opening angle with a delay of 18 ° CA comparatively more than the valve closing angle with a delay or earlyness of only ± 6 ° CA (not shown in the diagrams, but the resolution is based on an angle of 6 ° C).

Post-processed test results for a pressure signal during the operation period of the intake valve for a case without air absorption (a) and a case with high air absorption (b) are the 4a and 4b refer to. dPhi1 and dPhi2 are respectively estimated by the maximum and minimum pressure signals during the valve opening period. The three views per figure relate to different speeds.

• – Die Erfassung basiert auf dem Signal von einem Drucksensor (z.B. MAP), der die Druckveränderung vor, während und nach dem Öffnen / Schließen des hydraulisch betriebenen Ventils (Ventile) misst;
• – Zur Beschaffung des finalen Erfassungsergebnisses werden verschiedene Eigenschaften, z.B. Zeitverzögerung oder Frühzeitigkeit und Steigung des Drucks, mit unterschiedlichen Prioritäten kombiniert, z.B.: – Der Fehler / die Differenz des Öffnungswinkels (dPhi1) ist gegenüber dem Luftabsorptionseffekt am empfindlichsten und wird als Indikator mit der höchsten Priorität angesehen; – Der Fehler / die Differenz des Schließwinkels (dPhi2) und der Steigung des Drucks (dSlope) sind weniger empfindlich und beinhalten eine gewisse Uneindeutigkeit; diesen zwei Informationen wird eine geringere Priorität beigeordnet;
• – Das endgültige Erfassungsergebnis besteht aus zwei Elementen/Indikatoren: – Luftabsorptionsintensität (Aeration Intensity = AI), angegeben mit der Einheit °CA und im Bereich von Null bis zu einem positiven Grenzwert zur Angabe der Höhe des Luftabsorptionseffekts; – Luftabsorptionserfassungsqualität (Aeration Detection Quality = ADQ), angegeben als ein dimensionsloser Parameter im Bereich von 0 bis 1 entsprechend niedriger/höherer Qualität zur Luftabsorptionserfassung.

The detection algorithm was developed and built with the path from pressure acquisition to the final detection of air absorption. The basic principles are as follows:

• The detection is based on the signal from a pressure sensor (eg MAP) which measures the pressure change before, during and after the opening / closing of the hydraulically operated valve (s);
• - To obtain the final detection result, different properties, eg time delay or early time and slope of pressure, are combined with different priorities, eg: - The error / difference of the opening angle (dPhi1) is the most sensitive to the air absorption effect and is considered the indicator with the highest Priority viewed; - The error / difference of the closing angle (dPhi2) and the slope of the pressure (dSlope) are less sensitive and contain some ambiguity; these two pieces of information are given a lower priority;
• - The final detection result consists of two elements / indicators: - Aeration Intensity (AI), expressed as the unit ° CA and in the range of zero to a positive limit for indicating the level of the air absorption effect; Aeration Detection Quality (ADQ), expressed as a dimensionless parameter in the range of 0 to 1, corresponding to lower / higher quality for air absorption detection.

Based on these principles and the essential part of the method explained in the preceding paragraphs, the algorithm can be found in the form of a flow chart in FIG 4.3 , In the following, each block of the flowchart will be described in more detail.

Data acquisition from the pressure sensor: The detection is based on the analysis or pressure signal obtained during actuation of the hydraulically operated valve. Typical properties obtained include the time resolution of 6 ° CA (or equivalent time) and 1 mbar pressure precision.

Air absorption prone area: The air absorption only has negative effects on a hydraulic system under certain environmental and operating conditions, e.g. Transition from high to low pressure in the hydraulic system, high temperature areas, etc. Outside these ranges, the air absorption detection is turned off by setting the air absorption intensity AI to 0 with an ADQ of 1.

Defining an analysis window: To save processing time, the analysis is not performed for all data received, but only in a smaller analysis window with fewer pressure points that depend on the operating conditions.

• – Finden der Zeitpunkte für den maximalen und minimalen Druck im Analysefenster;
• – Durchführen einer nichtlinearen Anpassung an den Druckpunkt um das Druckmaximum herum und Finden des Maximums der angepassten nichtlinearen Kurve; sowie Durchführen einer nichtlinearen Anpassung an den Druckpunkt um das Druckminimum herum und Finden des Minimums der angepassten nichtlinearen Kurve; • Durchführen zweier linearer Anpassungen an die Druckpunkte zur jeweils linken und rechten Seite der maximalen / minimalen Druckpunkte und Finden der entsprechenden Kreuzungspunkte der angepassten Linien.

Finding two times corresponding to the valve opening / closing and determining dPhi1 and dPhi2: The times corresponding to the valve opening and closing timing are taken from the pressure data:

• - find the times for the maximum and minimum pressure in the analysis window;
• - performing a nonlinear fit to the pressure point around the pressure maximum and finding the maximum of the fitted nonlinear curve; and performing a non-linear fit to the pressure point around the pressure minimum and finding the minimum of the adjusted non-linear curve; • Make two linear adjustments to the pressure points to the left and right sides of the maximum / minimum pressure points and find the corresponding intersection points of the fitted lines.

With the times and the selected references dPhi1 and dPhi2 can be calculated.

• • dem Druckmaximum und -minimum, oder alternativ,
• • den zwei von der Steuereinheit angeforderten Zeitpunkt- / Winkelvorgaben,
• • genommen werden.

Calculate the slope of the pressure between the two interrelated points and determine dSlope: The slope is estimated by the method of linear regression, by taking all pressure points between

• • the pressure maximum and minimum, or alternatively,
• The two time / angle defaults requested by the control unit,
• • be taken.

In 5 the algorithm for the detection of air absorption is visualized based on the pressure signal analysis in a hydraulic drive for an internal combustion engine. There are the steps 29 to 43 ,

It takes place in the steps 29 to 43 following takes place:
Data acquisition from the pressure sensor; Check if activity is in an air-absorbent-susceptible area; Defining an analysis window for the signal; Fixing two points in time that correlate with valve open / close and determining dPhi1 and dPhi2; Calculating the slope of the pressure between the two interrelated points and determining dSlope, deciding whether dPhi1> a threshold1; set ADQ1 = ADQ1c; set ADQ2 = 0; Decide if | dPhi2 | > tswitch value2; set ADQ2 = ADQ2c; set ADQ = ADQ1 + ADQ2 + ADQs and AI = dPhi1 - threshold1; set ADQ = 1 and AI = 0; set ADQs = 0; Decide if dSlope <thresholdsl or dSlope>thresholdsh; set ADQs = ADQsc.

dPhi1> threshold1: with the defined threshold / threshold1 being calibrated and depending on the operating conditions, a judgment on the air-absorption state can be made based on the condition whether dPhi1> threshold1 (see FIG 4 ).

ADQ1 = ADQ1c, ADQ2 = 0 and ADQs = 0: initiating the air absorption detection quality for the opening angle, ADQ1, with a calibratable value, ADQ1c, which may also depend on the operating conditions; Set the air absorption detection quality for the closing angle, ADQ2, and the slope of the pressure, ADQs, to zero.

| DPhi2 | > threshold2: With the defined threshold, threshold2, which can be calibrated and depends on the operating conditions, if dPhi2> threshold2 (see 4.2 ), improves the judgment by dPhi1 by adding dPhi2 equal to a calibratable amount ADQ2c to ADQ; the air absorption intensity AI is not changed.

dSlope <thresholdsl or dSlope> thresholdsh: With the upper and lower threshold pressure thresholds, thresholdsl and thresholdsh, respectively, which are calibratable and dependent on operating conditions, the air absorption state assessed by dPhi1 can be further improved if any of the conditions are met will (see 4.2 ). If dSlope is outside the two thresholds, the total air absorption detection quality, ADQ, is improved by a calibratable amount, ADQsc; the air absorption intensity is not changed.

ADQ = ADQ1 + ADQ2 + ADQs and AI = dPhi1 - threhold1: With all the parameters defined, the final total air absorption detection quality, ADQ, and the air absorption intensity can be deduced as shown.

The detection results AI and ADQ may be provided to the control strategy to make appropriate adjustments or compensations to overcome the air absorption effect.

In addition, by introducing the air absorption intensity and the air absorption detection quality, this algorithm has some flexibility and can be easily converted to a true / false judgment only for dPhi1, for example, by giving ADQ1c = 1, ADQ2c = 0 and ADQsc = 0. It can also be converted to an AND condition for all three parameters, dPhi1, dPhi2 and dSlope, by e.g. ADQ1c = 0.4, ADQ2c = 0.3 and ADQsc = 0.3.

• 1. Ein Drucksignal wird genutzt um Wechselbeziehungen für die Ventilöffnungs- / Ventilschließbewegungen herzustellen und den Luftabsorptionseffekt auf das System zu erfassen;
• 2. Vier charakteristische Parameter des hydraulisch betriebenen Ventils können zur Luftabsorptionserfassung verwendet werden: a. Verzögerung des Öffnungszeitpunktes / -winkels; b. Verschiebung des Schließzeitpunktes / -winkels; c. Verschiebung des Hubmaximums; d. Reduzierung des Hubs / der Bewegung;
• 3. Vier charakteristische Parameter und ihre abgeleiteten Größen, die auf dem Drucksignal basieren (z.B. MAP), werden zur Erfassung der Luftabsorption im System verwendet: a. Ein Zeitpunkt, zu dem der Druck anfängt zu fallen oder der Druck sein Maximum erreicht, wird dem Ventilöffnungszeitpunkt zugeordnet: b. Ein Zeitpunkt, zu dem der Druck anfängt zu steigen oder der Druck sein Minimum erreicht, wird dem Ventilschließzeitpunkt zugeordnet; c. Ein Zeitpunkt, zu dem die Steigung des Drucks ihr Minimum während der Ventilöffnungszeitspanne erreicht, wird der Verschiebung des Hubs sowie dem Hubmaximum zugeordnet; d. Die Steigung des Drucks / der Gradient zwischen dem Druckmaximum und -minimum wird zur indirekten Angabe verwendet, ob sich der Ventilhub nicht an seinem erwarteten Maximalwert befindet;
• 4. Die zuvor in a and b definierten Zeitpunkte können wie folgt geschätzt werden: a. Finden der Zeitpunkte für den maximalen und minimalen Druck im Analysefenster; b. Durchführen einer nichtlinearen Anpassung an den Druckpunkt um das Druckmaximum herum und Finden des Maximums der nichtlinearen Kurve; sowie Durchführen einer nichtlinearen Anpassung an den Druckpunkt um das Druckminimum herum und Finden des Minimums der nichtlinearen Kurve; c. Durchführen zweier linearer Anpassungen an die Druckpunkte zur jeweils linken und rechten Seite der maximalen / minimalen Druckpunkte und Finden des entsprechenden Kreuzungspunkts der zwei angepassten Linien.
• 5. Der Zeitpunkt des Steigungsminimums des Drucks kann durch das Minimum der numerischen Ableitung des Drucksignals gefunden werden;
• 6. Die Steigung des Drucks kann durch die Methode der linearen Regression geschätzt werden, basierend auf den Druckpunkten zwischen: a. dem Druckmaximum und -minimum (definiert in Punkt 4 oben) oder, b. den zwei von der Steuerungseinheit angeforderten Zeitpunktvorgaben,
• 7. Die so erhaltenen Erfassungsergebnisse bestehen aus 2 Indikatoren: a. Luftabsorptionsintensität (AI); b. Luftabsorptionserfassungsqualität (ADQ); die nicht nur die Informationen über das Vorhanden- oder Nichtvorhandensein einer Luftabsorption liefern sondern auch die relative Intensität und den Zuverlässigkeits- / Qualitätsfaktuator der Erfassungsergebnisse.

A novel method for detecting an air absorption effect in a hydraulic valve actuator described herein consists of the following essential elements:

• 1. A pressure signal is used to establish correlations for the valve opening / closing movements and to detect the air absorption effect on the system;
• 2. Four characteristic parameters of the hydraulically operated valve can be used for air absorption detection: a. Delay of opening time / angle; b. Shift of closing time / angle; c. Shift of the maximum lift; d. Reduction of the stroke / movement;
• 3. Four characteristic parameters and their derived quantities based on the pressure signal (eg MAP) are used to record air absorption in the system: a. A time when the pressure starts to fall or the pressure reaches its maximum is assigned to the valve opening time: b. A point in time when the pressure starts to rise or the pressure reaches its minimum is assigned to the valve closing time; c. A time when the slope of the pressure reaches its minimum during the valve opening period is assigned to the displacement of the stroke and the stroke maximum; d. The slope of the pressure / gradient between the pressure maximum and minimum is used to indirectly indicate whether the valve lift is not at its expected maximum value;
• 4. The times previously defined in a and b can be estimated as follows: a. Finding the times for the maximum and minimum pressure in the analysis window; b. Performing a non-linear fit to the pressure point around the pressure maximum and finding the maximum of the non-linear curve; and performing a non-linear fit to the pressure point around the pressure minimum and finding the minimum of the non-linear curve; c. Make two linear adjustments to the pressure points to the left and right sides of the maximum / minimum pressure points and find the corresponding intersection point of the two fitted lines.
• 5. The time of the minimum slope of pressure can be found by the minimum of the numerical derivative of the pressure signal;
• 6. The slope of the pressure can be estimated by the linear regression method, based on the pressure points between: a. the pressure maximum and minimum (defined in point 4 above) or, b. the two timings requested by the control unit,
• 7. The results of this survey consist of 2 indicators: a. Air absorption intensity (AI); b. Air Absorption Detection Quality (ADQ); which provide not only the information about the presence or absence of air absorption but also the relative intensity and the reliability / quality factor of the detection results.

LIST OF REFERENCE NUMBERS

1

 oil path

2

 signal path

3

 oil reservoir

4

 oil pump

5

 magnetic valve

6

 Actuator / valve

7

 investment

8th

 response signal

9

 Valve control unit

10

 stroke

11

 stroke

12

 stroke

13

 Period of time

14

 dPhi1

15

 dPhi2

16

 dPeaktime

17

 dLift / dHub

18

 MAP signal

19

 MAP signal

20

 MAP signal

21

 Mimimal gradient position of the MAP signal

22

 maximum

23

 Minimum of the MAP signal

24

 stroke

25

 Time (valve open)

26

 Time (valve closed)

27

 delay

28

 delay

29

 step

30

 step

31

 step

32

 step

33

 step

34

 step

35

 step

36

 step

37

 step

38

 step

39

 step

40

 step

41

 step

42

 step

43

 step

Claims (1)

Method for detecting outgassing effects in a hydraulic fluid, such as in a hydraulic control drive of an internal combustion engine, wherein an air pressure signal from a pressure sensor is detected and evaluated in an air supply channel or an air discharge channel, whereby a gas exchange valve can be influenced / influenced.

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