METHOD FOR CONTROLLING A REGULATION VALVE

Description

[0001] The invention relates to a method for controlling a control valve, in particular a control valve of a tank venting system, preferably the tank venting system of a motor vehicle.

[0002] Control valves in tank venting systems regulate a fluid flow from a filter of a tank to a suction pipe (or a connecting section between the filter and at least one combustion chamber) of an internal combustion engine.

[0003] The filter is typically an activated carbon filter that binds the components of the fluid stored in the tank (e.g., fuel) that have been released from the tank. The activated carbon filter is 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 fed to the combustion chamber in a controlled manner.

[0004] Component variations in the fuel tank venting system cause inaccuracies in the air and 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 mixture formation particularly affect the lambda control accuracy, so that by precisely determining the control valve's regulation, a reduction in the load can be achieved, thus stabilizing the combustion process.

[0005] From EP 2 294 306 B1 it is known to determine the opening time of the control valve using a pressure sensor installed in the tank venting system and thus to adapt the component variations of the tank venting system.

[0006] US Patent 5,299,544 A discloses a method by which a flow sensor and / or a valve can be checked.

[0007] The object of the present invention is to at least partially solve the problems mentioned with reference to the prior art. In particular, a further method for controlling a control valve is to be proposed.

[0008] A method with the features according to claim 1 contributes to solving these problems. Advantageous further developments are the subject of the dependent claims. The features listed individually in the claims can be combined in a technologically meaningful way and can be supplemented by explanatory facts from the description and / or details from the figures, thereby showing further embodiments of the invention.

[0009] A method for controlling a control valve is proposed, wherein the control valve regulates a fluid flow from a filter of a tank to an intake manifold of an internal combustion engine. The control valve is opened and closed by a control unit using a signal (e.g., a pulse-width modulated (PWM) signal). The method comprises at least the following steps: a) Performing a closing operation of the control valve and b) Determining a first control value of a duty cycle, where a closing time of the control valve is determined via a sensor based on a change in a measured quantity monitored by the sensor; c) Using the first control value at least during an actuation of the control valve following steps a) and b) to open and close the control valve.

[0010] This document teaches how to determine the closing time (and not the opening time) of the control valve. The closing time occurs when, up to that point, fluid could flow through the control valve, while after that point, no fluid could flow through it. After the closing time, the line through which the fluid flow is directed and which can be closed by the control valve is therefore closed.

[0011] The switching behavior of the control valve is influenced in particular by mechanical and electrical component tolerances, e.g. electrical resistance of a coil, spring constant, mechanical friction, e.g. at the valve seat.

[0012] The control valve is operated, in particular, at a frequency between 5 and 50 Hertz. The control valve is actuated via a (PWM) signal, whereby, starting from a certain duty cycle (hereinafter referred to as the first control value), the control valve opens, in particular, successively. The duty cycle allows, in particular, the control of the mass flow of the fluid flowing through the control valve.

[0013] The initial control value used to actuate the control valve is determined during a closing cycle of the control valve. Specifically, a duty cycle, preferably initially 100% (fully open), is set before the process begins. This duty cycle is then reduced during the process until the closing point of the control valve is determined (e.g., at a duty cycle between 1% and 15%). The closing point is determined, in particular, by evaluating a measured value monitored by a sensor.

[0014] The closing point is assigned to a first control value (of the duty cycle). This first control value specifically defines a closed state of the control valve. If the control valve is to be operated according to step c), this first control value is used or taken into account. Thus, a duty cycle determined for the desired state (open, partially open, closed) of the control valve, depending on the first control value, is used to control the valve.

[0015] In particular, the sensor is a pressure sensor and in step b) at least a change in pressure must be measurable when the closing time is reached; and / or the sensor is a flow sensor and in step b) at least a change in flow rate must be measurable when the closing time is reached; and / or the sensor is a lambda sensor and in step b) at least a change in lambda value must be measurable when the closing time is reached.

[0016] The sensor is arranged, in particular, between at least one combustion chamber of an internal combustion engine and the filter (e.g., an activated carbon filter or activated carbon canister) (pressure sensor, flow sensor) and / or between at least one combustion chamber and an exhaust system (i.e., downstream of the combustion chamber) (lambda sensor). Preferably, the sensor is arranged in the intake manifold and / or between the filter or control valve and the intake manifold (in a line connecting, for example, the tank to the intake manifold) and / or between the filter and the control valve.

[0017] Step b) includes at least the following sub-steps: i. Setting at least one initial test value of a duty cycle for an initial period of time during a closing process of the control valve; ii. Determining a trend of the measured variable monitored by the sensor and iii. Determining the closing time based on the change in the measured variable and determining the first control value.

[0018] An initial test value for the duty cycle is set and held for a predetermined period. This initial test value is preferably close to a duty cycle at which the closing of the control valve can be expected.

[0019] If the behavior of the measured variable monitored by the sensor changes for this duty cycle in a way that suggests the control valve is closing, this initial test value can be used as the first control value. The system teaches how to set multiple test values ​​so that the first control value can be determined with greater accuracy.

[0020] A measured value will change, for example, proportionally to the change in the duty cycle (starting from the open state of the control valve). Only when the closing point is reached will the measured value behave noticeably differently (since the control valve is then closed).

[0021] After step ii, a new step i is performed (or step i is repeated), in which a second test value of the duty cycle is set for a second (predefined) time period. This second test value differs from the first test value (e.g., it is smaller; in particular, the difference is at least 1% of the duty cycle of the first test value). Steps i and ii can be repeated with further test values ​​until a duty cycle at which the closing time is reached is determined with a predetermined accuracy, thus establishing the first control value.

[0022] In particular, a closing time actually occurs at a specific control value, whereby the first control value (which is determined within the framework of the procedure) deviates from the actual control value by a maximum of 20%, preferably a maximum of 10%, of the duty cycle (i.e., actual closing time at a duty cycle of 10%; first control value deviates from this duty cycle by a maximum of 2 percentage points, i.e., is between 8% and 12%).

[0023] In particular, a desired accuracy (i.e., the maximum deviation of the first control value from a control value at which the actual closing time lies) can be predetermined. Specifically, several test values ​​are set within the procedure, and the course of the measured variable is determined for each of these test values. The test values ​​used are sufficiently far apart to allow a closing time to be determined with the predetermined accuracy.

[0024] In particular, after step i., a first interval between the first test value and the second test value is defined, wherein a second interval between the second test value and a third test value is smaller than the first interval. In particular, the procedure allows for a successively more precise determination of the closing time or the first control value.

[0025] In particular, the interval between each subsequent test value is reduced by at least 20%, preferably by 50%.

[0026] The following relationship is preferred: first test value > third test value > second test value.

[0027] The following relationship may apply: first test value > second test value > third test value.

[0028] In a first embodiment, the procedure is carried out after each closing operation of the control valve.

[0029] In a second embodiment, an initial control value is determined and used for subsequent closing operations. The re-determination of an initial control value (or the execution of the procedure) can occur, for example, after a specific event or condition of the tank venting system. An event could be, for example, a restart of the vehicle or the internal combustion engine. A condition could include, for example, a change in temperature, such as the temperature of the control valve. In particular, the initial control value is re-determined (or the procedure executed) when a temperature or temperature gradient of the control valve reaches or exceeds a specific limit temperature.

[0030] In particular, an initial rule value is determined and checked over a number of subsequent closing processes (i.e., used repeatedly) and then (if the course of the measured quantity does not change accordingly) used for further subsequent closing processes.

[0031] A motor vehicle according to claim 8 is further proposed, comprising at least an internal combustion engine with at least one combustion chamber, a tank for fuel usable in the internal combustion engine with a filter, an intake manifold through 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 regulates a fluid flow comprising at least the fuel from the filter to the intake manifold. The fluid flow can contain between 0 and 100% fuel. The control valve can be opened and closed by a control unit by means of a signal (e.g., a pulse-width modulated (PWM) signal). The control unit is configured or suitably designed to carry out the method already described. The control unit can therefore carry out the described method or carries it out during operation of the motor vehicle.

[0032] Furthermore, the process can also be carried out by a computer or with a processor of a control unit.

[0033] Accordingly, a data processing system is also proposed, which includes a processor that is adapted / configured to execute the procedure or part of the steps of the proposed procedure.

[0034] A computer-readable storage medium may be provided, containing instructions which, when executed by a computer / processor, cause it to execute the procedure or at least part of the steps of the proposed procedure.

[0035] The explanations regarding the procedure are particularly applicable to motor vehicles or computer-implemented procedures, and vice versa.

[0036] It should be noted as a precaution that the numerical terms used here ("first", "second", ...) primarily serve (only) to distinguish between several similar objects, quantities, or processes, and thus do not necessarily dictate any dependency and / or sequence between these objects, quantities, or processes. Should a dependency and / or sequence be required, this is explicitly stated here, or it will be obvious to a person skilled in the art upon studying the specific configuration described.

[0037] The invention and its technical context are explained in more detail below with reference to the accompanying figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the situations described in the figures and combine them with other components and findings from the present description. It should be emphasized that the figures, and especially the depicted dimensions, are only schematic. They show: Fig. 1: a motor vehicle; Fig. 2: a first embodiment of the method; Fig. 3: a second embodiment of the method; and Fig. 4: a third embodiment of the method.

[0038] Fig. 1Figure 1 shows a motor vehicle 22. The motor vehicle 22 comprises an internal combustion engine 5 with a plurality of combustion chambers 23, a tank 3 for a fuel 24 that can be converted in the internal combustion engine 5 and a filter 2, an intake manifold 4 through which at least air and the fuel 24 can be supplied to the combustion chamber 23, and a control valve 1 that regulates a fluid flow comprising at least the fuel 24 from the filter 2 via the line 25 to the intake manifold 4. The control valve 1 can be opened and closed by a control unit 6 by means of a signal 7. The control unit 6 is configured or suitably designed to carry out the procedure. The signal 7 can be set via the control unit 6 with a duty cycle 10. In the control unit 6, the 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, orspecified.

[0039] The motor vehicle 22 further includes a sensor 11 on the intake manifold 4, which monitors a measured variable 12 (e.g., pressure) in the intake manifold. The measured variable 12, or rather its progression 16 over time 26, is monitored in the control unit 6.

[0040] Fig. 2 shows a first implementation variant of the procedure. Fig. 3 shows a second variant of the procedure. Fig. 4 A third implementation variant of the procedure is shown, each illustrated with a diagram. Figs. 2 to 4 will be described together below.

[0041] The vertical axis shows the duty cycle (10) (100% duty cycle: control valve 1 in the (fully) open state; 0% duty cycle: control valve 1 in the closed state) and the pressure. The horizontal axis shows the time (26).

[0042] In step a), a closing process 8 of the control valve 1 is performed, starting from an open state (duty cycle 10 of 100%) of the control valve. In sub-step i., the duty cycle 10 is reduced to a first test value 14 and held for a first duration 15 during the closing process 8 of the control valve 1. In sub-step ii., the profile 16 of the measured variable 12 (here a pressure 27) monitored by the sensor 11 is monitored.

[0043] The first test value 14 of the duty cycle 10 is already close to a duty cycle 10 at which closing of the control valve 1 can be assumed. Here, the curve 16 of the measured quantity 12 monitored by the sensor 11 changes proportionally to the change in the duty cycle 10, so that it is recognized that the control valve is not yet completely closed at the first test value 14.

[0044] After step ii., a new sub-step i. is therefore performed, in which a further second test value 17 (second test value 17 smaller than first test value 14) of the duty cycle 10 is set for a second time period 18, whereby the second test value 17 differs from the first test value 14 (i.e., is smaller here). The curve 16 is monitored again in a further sub-step ii.

[0045] Steps i. and ii. are repeated with a third test value 18, where the third test value 19 is smaller than the second test value 17 and smaller than the first test value 14. The curve 16 is monitored again as part of a further sub-step ii. Here it is observed that the measured variable 12 does not change proportionally to the duty cycle 10. The control valve 1 is evidently already closed at this point, so the measured variable 12 (the pressure 27) continues to decrease. The closing time 13 is clearly 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.

[0046] Fig. 3This shows that first, an initial test value 14 is set and the curve 16 of the measured variable 12 is monitored. Then, a second test value 17 is set and the curve 16 is monitored again. From these two curves 16 of the measured variable 12, the first control value 9 can already be determined. The first control value 9 is checked over a number of subsequent closing operations 8 and then used for further closing operations 8 (i.e., also control operations in which the control valve 1 is not completely closed).

[0047] Fig. 4Figure 1 shows another variant of the procedure. After setting a first test value 14 and performing a closing operation 8, a first interval 20 is defined between the first test value 14 and the second test value 17 (and thus the second test value 17), and another closing operation 8 is performed. Here, a purely proportional change in the measured variable 12 is already observed, so it is clear that the first control value 9 lies within the first interval 20. Subsequently, a second interval 21 is determined between the second test value 17 and a third test value 19 (and thus the third test value 19), whereby the second interval 21 is smaller than the first interval 20. The following applies: first test value 14 > third test value 19 > second test value 18. From the curve 16 of the measured variable 12, it is evident that the first control value 9 lies within the second interval 21.A further closing process is carried out with another test value, which in turn differs from the third test value 19 by an interval. In this way, a successively more precise determination of the closing time 13 or the first rule value 9 can be achieved within the framework of the procedure. Reference symbol list

[0048] 1 Control valve 2 Filter 3 Tank 4 Intake manifold 5 Internal combustion engine 6 Control unit 7 Signal 8 Closing process 9 First control value 10 Duty cycle 11 Sensor 12 Measured variable 13 Closing time 14 First test value 15 First duration 16 Progression 17 Second test value 18 Second duration 19 Third test value 20 First interval 21 Second interval 22 Vehicle 23 Combustion chamber 24 Fuel 25 Line 26 Time 27 Pressure

Claims

1. Method for controlling a control valve (1), wherein the control valve (1) regulates a fluid flow from a filter (2) of a tank (3) to an intake manifold (4) of an internal combustion engine (5), wherein the opening and closing of the control valve (1) is controlled by a control unit (6) by means of a signal (7); wherein the method comprises 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) in which a closing time (13) of the control valve (1) is established via a sensor (11) using a change in a measured quantity (12) monitored by the sensor (11); c) using the first control value (9), at least when the control valve (9) is actuated following steps a) and b), to open and close the control valve (9); wherein step b) comprises at least the following sub-steps: i. setting at least a first test value (14) of a duty cycle (10) for a first time period (15) during a closing operation (8) of the control valve (1); ii. ascertaining a curve (16) of the measured quantity (12) monitored by the sensor (11); and iii. establishing the closing time (13) using the change in the measured variable (12) and determining the first control value (9); wherein, after step ii. and after repeating step a), a new step i. is performed in which a further second test value (17) of the duty cycle (10) is set for a second time period (18), wherein the second test value (17) differs from the first test value (14); wherein steps a) and i. and ii. are repeated with further test values (19) as often as necessary until a duty cycle (10) in which the closing time (13) is set is ascertained with a predetermined accuracy and thus the first control value (9) is determined.

2. Method according to claim 1, wherein • the sensor (11) is a pressure sensor and, in step b), at least a change in a pressure can be measured when the closing time (13) is reached; or • the sensor (11) is a flow sensor and, in step b), at least a change in a flow can be measured when the closing time (13) is reached; or • the sensor (11) is a lambda sensor and, in step b), at least a change in a lambda value can be measured when the closing time (13) is reached.

3. Method according to either of the preceding claims, wherein, after a step i., a first interval (20) is established between the first test value (14) and the second test value (17), wherein a second interval (21) between the second test value (17) and a third test value (19) is smaller than the first interval (20).

4. Method according to claim 3, wherein the following applies: first test value (14) > third test value (19) > second test value (17).

5. Method according to any of the preceding claims, wherein the method is performed after each closing operation (8).

6. Method according to any of the preceding claims 1 to 5, wherein a first control value (9) is determined and is used for further subsequent closing operations (8).

7. Method according to any of the preceding claims, wherein a first control value (9) is determined and is checked over a plurality of subsequent closing operations (8) and is then used for further subsequent closing operations (8).

8. Motor vehicle (22), at least comprising an internal combustion engine (5) having at least one combustion chamber (23), a tank (3) for a fuel (24) which can be used in the internal combustion engine, the tank having a filter (2), an intake manifold (4) via which at least air and the fuel (24) can be supplied to the combustion chamber (23), a sensor (11) for monitoring a measured quantity (12) and a control valve (1) which regulates a fluid flow comprising at least the fuel (24) from the filter (2) to the intake manifold (4); wherein the opening and closing of the control valve (1) is controlled by a control unit (6) by means of a signal (7); wherein the control unit (6) is configured to perform a method according to any of the preceding claims.