EP3564514A1 - Method for controlling a control valve - Google Patents

Abstract

Method for controlling a control valve (1), wherein the control valve (1) controls a fluid flow from a filter (2) of a tank (3) to a suction pipe (4) of an internal combustion engine (5), wherein the control valve (1) for opening and Closing is controlled by a control unit (6) by means of a signal (7); the method comprising at least the following steps:
a) performing a closing operation (8) of the control valve (1) and
b) determining a first control value (9) of a duty cycle (10), wherein a closing time (13) of the control valve (1) is determined via a sensor (11) based on a change of a measured by the sensor (11) measured variable (12) ;
c) using the first control value (9) at least in one of the steps a) and b) following actuation of the control valve (9) for opening and closing the control valve (9).

Description

The invention relates to a method for controlling a control valve, in particular a control valve of a tank ventilation system, preferably the tank ventilation system of a motor vehicle.

Control valves in tank ventilation systems regulate fluid flow from a filter of a tank to a suction pipe (or a connecting path between the filter and at least one combustion chamber) of an internal combustion engine.

The filter is regularly an activated carbon filter which binds the components of the fluid (eg a fuel) stored in the tank, which have been degassed from the tank. The activated carbon filter can be fluidly connected to the intake manifold of the internal combustion engine via the control valve, so that the fluid bound or temporarily stored in the filter can be supplied to the combustion chamber in a regulated manner.

The component spreads in the tank venting system cause inaccuracies in the air or fuel mass supplied to the combustion chamber. This can result in inaccuracies in the mixture formation for the combustion chamber. These errors or deviations in the mixture formation have an effect, in particular, on the lambda control quality, so that a discharge can be brought about by an accurate determination of the control of the control valve and thus a stabilization of the combustion processes can be achieved.

From the EP 2 294 306 B1 is known, based on a built-in tank venting pressure sensor opening time of the control valve to determine and thus adapt the components scattering of the tank ventilation system.

The object of the present invention is at least partially to solve the problems mentioned with reference to the prior art. In particular, a further method for controlling a control valve is to be proposed.

To solve these problems, a method with the features according to claim 1 contributes. Advantageous developments are the subject of the dependent claims. The features listed individually in the claims can be combined in a technologically meaningful manner and can be supplemented by explanatory facts from the description and / or details of the figures, with further embodiments of the invention are shown.

1. a) Durchführen eines Schließvorganges des Regelventils und
2. b) Bestimmen eines ersten Regelwertes eines Tastverhältnisses, bei dem über einen Sensor anhand einer Änderung einer durch den Sensor überwachten Messgröße ein Schließzeitpunkt des Regelventils festgestellt wird;
3. c) Verwenden des ersten Regelwertes zumindest bei einer auf die Schritte a) und b) folgenden Betätigung des Regelventils zum Öffnen und Schließen des Regelventils.

It is proposed a method for controlling a control valve, wherein the control valve regulates a fluid flow from a filter of a tank to a suction pipe of an internal combustion engine. The control valve is actuated by a control unit for opening and closing by means of a signal (eg a pulse width modulated (PWM) signal). The method has at least the following steps:

1. a) performing a closing operation of the control valve and
2. b) determining a first control value of a duty cycle, wherein a closing time of the control valve is determined via a sensor based on a change in a monitored by the sensor measurement;
3. c) using the first control value at least in an operation following the steps a) and b) of the control valve for opening and closing the control valve.

In the present case, it is proposed to determine the closing time (and not the opening time) of the control valve. The closing time is present when a fluid flow could flow through the control valve until the closing time, while after the closing time no fluid flow can flow through the control valve. After the closing time is the line through which the fluid flow is passed and which is closed by the control valve, so closed.

The switching behavior of the control valve is in particular by mechanical and electrical component tolerances, eg. B. electrical resistance of a coil, spring constant, mechanical friction, z. B. on the valve seat, influenced.

The control valve is driven in particular with a frequency between 5 and 50 hertz. The control valve is actuated by a (PWM) signal, wherein from a certain duty cycle (hereinafter referred to as the first control value) in particular a successive opening of the control valve takes place. In particular, a fluid flow flowing via the control valve can be controlled with regard to the mass flow via the pulse duty factor.

The first control value used for the control of the control valve is determined during a closing operation of the control valve.

In particular, a duty cycle, preferably initially 100% (fully open), is set before the start of the method, which is reduced as part of the method until a closing time of the control valve is determined (eg at a duty cycle between 1% and 15%). , The determination of the closing time takes place, in particular, by evaluating a measured variable monitored by a sensor.

The closing time is in particular assigned to a first control value (the duty cycle). In particular, the first control value designates a closed state of the control valve. If the control valve according to step c) to be operated, this first control value is used or considered. It is therefore used for the desired state (open, partially open, closed) of the control valve in response to the first control value determined duty cycle for controlling the control valve.

• der Sensor ein Drucksensor und in Schritt b) zumindest eine Veränderung eines Druckes beim Erreichen des Schließzeitpunktes messbar sein; und/oder
• der Sensor ein Durchflusssensor und in Schritt b) zumindest eine Veränderung eines Durchflusses beim Erreichen des Schließzeitpunktes messbar sein; und/oder
• der Sensor ein Lambdasensor und in Schritt b) zumindest eine Veränderung eines Lambdawertes beim Erreichen des Schließzeitpunktes messbar sein.

In particular, can

• the sensor is a pressure sensor and in step b) at least one change of a pressure when reaching the closing time be measurable; and or
• the sensor is a flow sensor and in step b) at least one change of a flow when reaching the closing time be measurable; and or
• the sensor may be a lambda sensor and in step b) at least one change of a lambda value may be measurable when the closing time is reached.

The sensor is in particular between at least one combustion chamber of an internal combustion engine and the filter (eg an activated carbon filter or activated carbon container) (pressure sensor, flow sensor) and / or between at least one combustion chamber and an exhaust system (ie downstream of the combustion chamber) (lambda sensor). arranged. Preferably, the sensor in the suction pipe and / or between the filter or control valve and the suction pipe (in a pipe connecting, for example, the tank to the suction pipe) and / or arranged between the filter and the control valve.

1. i. Einstellen zumindest eines ersten Prüfwertes eines Tastverhältnisses für eine erste Zeitdauer während eines Schließvorganges des Regelventils;
2. ii. Ermitteln eines Verlaufs der durch den Sensor überwachten Messgröße und
3. iii. Feststellen des Schließzeitpunktes anhand der Änderung der Messgröße und Bestimmen des ersten Regelwertes.

In particular, step b) comprises at least the following substeps:

1. i. Setting at least a first test value of a duty cycle for a first period of time during a closing operation of the control valve;
2. ii. Determining a course of the monitored by the sensor measured variable and
3. iii. Determining the closing time based on the change in the measured variable and determining the first control value.

In particular, a first test value of the duty cycle is set and held for a first (predetermined) period of time. The first test value is preferably already in the vicinity of a duty cycle, in which a closing of the control valve can be assumed.

If the course of the measured variable monitored by the sensor changes for this duty cycle in a manner in which closing of the control valve can be concluded, this first check value can already be used as the first control value. In particular, it is proposed to set several test values, so that the first control value can be determined with higher accuracy.

In particular, a measured variable z. B. proportional to the change in the duty cycle (starting from the open state of the control valve) change. Only when the closing time is reached will the measured variable behave noticeably differently (since the control valve is then closed).

In particular, after step ii. a new step i. is performed (or step i., repeated) in which a further second test value of the duty cycle is set for a second (predetermined) period of time, wherein the second test value is different from the first test value (eg smaller, in particular the difference at least 1% of the duty cycle of the first test value). The steps i. and ii. can be repeated with further test values until a duty cycle at which the closing time is established, is determined with a predetermined accuracy and thus the first control value is determined.

In particular, a closing time is actually present at a certain control value, wherein the first control value (which is determined in the context of the method) differs from the actual control value by at most 20%, preferably by at most 10%, of the duty cycle (ie, for example, actually Closing time at a duty cycle of 10%, the first control value deviates from this duty cycle by a maximum of 2 percentage points, ie between 8% and 12%).

In particular, a desired accuracy (ie the highest deviation of the first control value from a control value at which the actual closing time is) can be predetermined. In particular, several test values are set in the context of the method and the course of the measured variable is determined for each of these test values. The test values used are in particular so far apart that a closing time can be determined with the predetermined accuracy.

In particular, after a step i. a first interval between the first check value and the second check value, wherein a second interval between the second check value and a third check value is smaller than the first interval. In particular, in the context of the procedure a successively more accurate determination of the closing time or the first control value take place.

In particular, the interval between each subsequent test value is reduced by at least 20%, preferably by 50% in each case.

The following relationship may preferably apply: first test value> third test value> second test value.

The following relationship may apply: first test value> second test value> third test value.

In a first embodiment, the method is performed after each closing operation of the control valve.

In a second embodiment, a first control value is determined and used for further subsequent closing operations. The re-determination of a first control value (or the implementation of the method) may, for. B. after the presence of a specific event or z. B. condition of the tank ventilation system done. An event can, for. B. be a restart of the motor vehicle or the internal combustion engine. A state can z. B. a change in temperature, for. As a temperature of the control valve include. In particular, the first control value is then determined again (or the method is performed) when a temperature or a temperature gradient of the control valve has reached or exceeded a certain limit temperature.

In particular, a first control value is determined and checked over a plurality of following closing operations (thus used again and again) and thereafter (if the course of the measured variable does not change accordingly) used for further subsequent closing operations.

It is further proposed a motor vehicle, at least comprising an internal combustion engine with at least one combustion chamber, a tank for a convertible in the internal combustion engine fuel with a filter, a suction tube, via which at least air and the fuel can be supplied to the combustion chamber, a sensor for monitoring a Measured variable and a control valve that controls at least the fuel comprehensive fluid flow from the filter to the suction pipe. The fluid flow may contain between 0 and 100% fuel. The control valve can be actuated by a control unit for opening and closing by means of a signal (eg a pulse width modulated (PWM) signal). The control unit is designed or carried out for carrying out the method already described. The control unit can thus carry out the described method or execute it during operation of the motor vehicle.

Furthermore, the method can also be executed by a computer or with a processor of a control unit.

Accordingly, there is also proposed a data processing system comprising a processor adapted / configured to perform the method or part of the steps of the proposed method.

A computer-readable storage medium may be provided that includes instructions that, when executed by a computer / processor, cause it to perform the method or at least part of the steps of the proposed method.

The statements relating to the method are transferable in particular to the motor vehicle or the computer-implemented method, and vice versa.

By way of precaution, it should be noted that the number words used here ("first", "second",...) Primarily (only) serve to distinguish a plurality of similar objects, variables or processes, ie in particular no dependence and / or order of these objects, quantities or mandate processes to one another. If a dependency and / or order are required, this is explicitly stated here or it obviously results for the person skilled in the art when studying the concretely described embodiment.

Fig. 1:

ein Kraftfahrzeug;

Fig. 2:

eine erste Ausführungsvariante des Verfahrens;

Fig. 3:

eine zweite Ausführungsvariante des Verfahrens; und

Fig. 4:

eine dritte Ausführungsvariante des Verfahrens.

The invention and the technical environment will be explained in more detail with reference to the accompanying figures. It should be noted that the invention should not be limited by the stated embodiments. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and to combine them with other components and findings from the present description. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. Show it:

Fig. 1:

a motor vehicle;

Fig. 2:

a first embodiment of the method;

3:

a second embodiment of the method; and

4:

a third embodiment of the method.

Fig. 1 shows a motor vehicle 22. The motor vehicle 22 includes an internal combustion engine 5 with a plurality of combustion chambers 23, a tank 3 for a convertible in the internal combustion engine 5 fuel 24 with a filter 2, a suction pipe 4, on the at least air and the fuel 24 toward Combustion chamber 23 can be supplied, and a control valve 1, which controls a at least the fuel 24 comprehensive fluid flow from the filter 2 via the line 25 to the suction pipe 4.

The control valve 1 can be controlled by a control unit 6 by means of a signal 7 for opening and closing. The control unit 6 is designed or carried out for carrying out the method. About the control unit 6, the signal 7 with the duty cycle 10 is adjustable. First control value 9, first test value 14, first time duration 15, second test value 17, second time duration 18, third test value 19, first interval 20 and second interval 21 are determined, stored or predetermined in control unit 6.

The motor vehicle 22 further comprises a sensor 11 on the intake manifold 4, by which a measured variable 12 (here, for example, a pressure) in the intake manifold is monitored. The measured variable 12 or its course 16 over the time 26 is monitored in the control unit 6.

Fig. 2 shows a first embodiment of the method. Fig. 3 shows a second embodiment of the method. Fig. 4 shows a third embodiment of the method; each based on a diagram. The Fig. 2 to 4 will be described together below.

On the vertical axis, the duty cycle is 10 (100% duty cycle: control valve 1 in the (fully) open state; 0% duty cycle: control valve 1 when closed) and the pressure applied. The time 26 is plotted on the horizontal axis.

In the context of step a), a closing operation 8 of the control valve 1, starting from an open state (duty cycle 10 of 100%) of the control valve is performed. As part of a partial step i. the duty cycle 10 is lowered to a first test value 14 of the duty cycle 10 and held for a first time period 15 during the closing operation 8 of the control valve 1. In the context of sub-step ii. a course 16 of the monitored by the sensor 11 measured variable 12 (here a pressure 27) is monitored.

The first test value 14 of the duty ratio 10 is already in the vicinity of a duty cycle 10, in which a closing of the control valve 1 can be assumed. Here, the course 16 of the monitored by the sensor 11 measured variable 12 changes in proportion to the change in the duty cycle 10, so that it is detected that the control valve at the first test value 14 is not completely closed.

After step ii. Therefore, a new sub-step i. performed, in which a further second test value 17 (second test value 17 is smaller than the first test value 14) of the duty cycle 10 for a second time period 18 is set, the second test value 17 is different from the first test value 14 (in this case is smaller). The course 16 is in the context of a further sub-step ii. again monitored.

The steps i. and ii. are repeated with a third check value 18, the third check value 19 being smaller than the second check value 17 and less than the first check value 14. The course 16 is in the context of a further sub-step ii. again monitored. Here it is stated that measured variable 12 is not proportional to the duty cycle 10 changes. Obviously, the control valve 1 is already closed here, so that the measured variable 12 (the pressure 27) continues to drop. The closing time 13 is recognizable between the second test value 17 and the third test value 19, so that according to step b) the first control value 9 can be determined with sufficient accuracy.

Fig. 3 shows that initially set a first test value 14 and the course 16 of the measured variable 12 is monitored. Thereafter, a second test value 17 is set and the course 16 is monitored again. From these two curves 16 of the measured variable 12, the first control value 9 can already be determined. By means of a plurality of the following closing operations 8, the first control value 9 is checked and then used for further subsequent closing operations 8 (that is to say also control operations in which the control valve 1 is not completely closed).

Fig. 4 shows a further embodiment of the method. After setting a first test value 14 and performing a closing operation 8, a first interval 20 between the first test value 14 and the second test value 17 (and thus the second test value 17) is determined and a further closing operation 8 is performed. Here, an exclusively proportional change of the measured variable 12 is already detected, so that it is clear that the first control value 9 lies within the first interval 20. Subsequently, a second interval 21 between the second check value 17 and a third check value 19 (and thus the third check value 19) is determined, wherein the second interval 21 is smaller than the first interval 20. The following applies: first check value 14> third check value 19> second check value 18. From the course 16 of the measured variable 12, it becomes obvious that the first control value 9 lies within the second interval 21. There will be another closing action with another check value, which in turn by an interval different from the third check value 19 performed. Thus, in the context of the method, a successively more accurate determination of the closing time 13 or of the first control value 9 can take place.

LIST OF REFERENCE NUMBERS

1. 1 control valve
2. 2 filters
3. 3 tank
4. 4 intake manifold
5. 5 internal combustion engine
6. 6 control unit
7. 7 signal
8. 8 closing process
9. 9 first control value
10. 10 duty cycle
11. 11 sensor
12. 12 measured variable
13. 13 closing time
14. 14 first test value
15. 15 first period of time
16. 16 course
17. 17 second test value
18. 18 second time period
19. 19 third test value
20. 20 first interval
21. 21 second interval
22. 22 motor vehicle
23. 23 combustion chamber
24. 24 fuel
25. 25 line
26. 26 time
27. 27 pressure

Claims (10)

Method for controlling a control valve (1), wherein the control valve (1) controls a fluid flow from a filter (2) of a tank (3) to a suction pipe (4) of an internal combustion engine (5), wherein the control valve (1) for opening and Closing is controlled by a control unit (6) by means of a signal (7); the method comprising at least the following steps: a) performing a closing operation (8) of the control valve (1) and b) determining a first control value (9) of a duty cycle (10), wherein a closing time (13) of the control valve (1) is determined via a sensor (11) based on a change of a measured by the sensor (11) measured variable (12) ; c) using the first control value (9) at least in one of the steps a) and b) following actuation of the control valve (9) for opening and closing the control valve (9). Method according to claim 1, wherein • the sensor (11) is a pressure sensor and in step b) at least one change of a pressure upon reaching the closing time (13) is measurable; or • the sensor (11) is a flow sensor and in step b) at least one change of a flow when reaching the closing time (13) can be measured; or • the sensor (11) is a lambda sensor and in step b) at least one change of a lambda value upon reaching the closing time (13) is measurable. Method according to one of the preceding claims, wherein step b) comprises at least the following substeps: i. Setting at least a first test value (14) of a duty cycle (10) for a first time duration (15) during a closing operation (8) of the control valve (1); ii. Determining a course (16) of the measured variable (12) monitored by the sensor (11); and iii. Determining the closing time (13) based on the change in the measured variable (12) and determining the first control value (9). Method according to claim 3, wherein after step ii. a new step i. in which a further second check value (17) of the duty cycle (10) is set for a second time duration (18), the second check value (17) differing from the first check value (14); wherein the steps i. and ii. with repeated test values (19) are repeated until a duty cycle (10) at which the closing time (13) is established, is determined with a predetermined accuracy and thus the first control value (9) is determined. Method according to claim 4, wherein after a step i. a first interval (20) between the first check value (14) and the second check value (17) is determined, wherein a second interval (21) between the second check value (17) and a third check value (19) is smaller than the first interval (20). Method according to claim 5, wherein the following applies: first test value (14)> third test value (19)> second test value (17). Method according to one of the preceding claims, wherein the method is carried out after each closing operation (8). Method according to one of the preceding claims 1 to 6, wherein a first control value (9) is determined and used for further subsequent closing operations (8). Method according to one of the preceding claims, wherein a first control value (9) is determined and checked over a plurality of following closing operations (8) and thereafter used for further subsequent closing operations (8). Motor vehicle (22), at least comprising an internal combustion engine (5) with at least one combustion chamber (23), a tank (3) for convertible in the internal combustion engine fuel (24) with a filter (2), a suction tube (4) via the at least air and the fuel (24) can be supplied to the combustion chamber (23), a sensor (11) for monitoring a measured variable (12) and a control valve (1) that at least the fuel (24) comprising fluid flow from the filter ( 2) to the suction pipe (4) regulates; wherein the control valve (1) for opening and closing is controlled by a control unit (6) by means of a signal (7); wherein the control unit (6) is arranged to carry out a method according to one of the preceding claims.

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