Method for Actuating a Dosing Valve, Tank Ventilation System, and Motor Vehicle

Abstract

A method actuates a dosing valve of a tank ventilation system. The dosing valve is opened not only once but twice at every activation time, and thus a generated pressure wave is depleted. An associated tank ventilation system and an associated motor vehicle make use of the method.

Claims

1.-10. (canceled)

11. A method for actuating a dosing valve of a tank ventilation system, wherein the dosing valve is incorporated between a filter of the tank ventilation system and an engine suction connection, wherein the method comprises the steps of: setting a repetition frequency, which specifies a multiplicity of activation times, setting a first opening duration, setting a closing duration and setting a second opening duration, wherein the second opening duration is shorter than the first opening duration; at every activation time: opening the dosing valve for the first opening duration, then closing the dosing valve for the closing duration, then opening the dosing valve for the second opening duration, and then closing the dosing valve, wherein the dosing valve, after the second opening duration, remains closed until the next activation time.

12. The method according to claim 11, wherein the first opening duration and the closing duration together differ from half of the time interval between two activation times.

13. The method according to claim 11, wherein all of the opening durations and closing durations together are shorter than the time interval between two activation times.

14. The method according to claim 11, wherein the repetition frequency has a value between 1 Hz and 100 Hz, or a value of 10 Hz.

15. The method according to claim 11, wherein at least one of the first opening duration, the second opening duration, or the closing duration have a length between 4 ms and 40 ms, or a length of 15 ms or 20 ms.

16. The method according to claim 11, wherein the first opening duration, the closing duration and the second opening duration are set such that, during the second opening duration, a pressure wave that forms during the first opening duration and propagates in the tank ventilation system is allowed to pass through, or is partially allowed to pass through, by the dosing valve.

17. An electronic control device comprising a processor and associated memory configured to actuate a dosing valve of a tank ventilation system, wherein the dosing valve is incorporated between a filter of the tank ventilation system and an engine suction connection, wherein the electronic control device is configured to: set a repetition frequency, which specifies a multiplicity of activation times, setting a first opening duration, setting a closing duration and setting a second opening duration, wherein the second opening duration is shorter than the first opening duration; at every activation time: open the dosing valve for the first opening duration, then close the dosing valve for the closing duration, then open the dosing valve for the second opening duration, and then close the dosing valve, wherein the dosing valve, after the second opening duration, remains closed until the next activation time.

18. A tank ventilation system, comprising: a filter; a ventilation line for ventilation of a tank, wherein the ventilation line is connected to the filter; an engine suction connection; a connecting line between the engine suction connection and the filter; a dosing valve which is incorporated in the connecting line; and an electronic control device according to claim 17.

19. A motor vehicle, comprising: an internal combustion engine; a tank for storing fuel for the internal combustion engine; and a tank ventilation system according to claim 18 for ventilation of the tank.

20. A computer product comprising a nonvolatile computer-readable medium having stored thereon program instructions which, when executed by a processor, causes the processor to actuate a dosing valve of a tank ventilation system, wherein the dosing valve is incorporated between a filter of the tank ventilation system and an engine suction connection, by: setting a repetition frequency, which specifies a multiplicity of activation times, setting a first opening duration, setting a closing duration and setting a second opening duration, wherein the second opening duration is shorter than the first opening duration; at every activation time: opening the dosing valve for the first opening duration, then closing the dosing valve for the closing duration, then opening the dosing valve for the second opening duration, and then closing the dosing valve, wherein the dosing valve, after the second opening duration, remains closed until the next activation time.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0047] FIG. 1 shows a tank ventilation system with further components in an installation situation.

[0048] FIG. 2 shows typical profiles of a valve lift and of a pressure wave.

[0049] FIG. 3a shows a valve lift according to the prior art.

[0050] FIG. 3b shows a pressure profile according to the prior art.

[0051] FIG. 4a shows a valve lift according to the method disclosed here.

[0052] FIG. 4b shows a pressure profile according to the method disclosed here.

DETAILED DESCRIPTION OF THE DRAWINGS

[0053] FIG. 1 shows an internal combustion engine 1 with further components, a tank 10 with further components, and a tank ventilation system 100 according to an exemplary embodiment. These constituent parts, and the further components, will be described below. The components shown may in particular be part of a motor vehicle according to an exemplary embodiment.

[0054] The internal combustion engine 1 is a conventional internal combustion engine of a motor vehicle. In particular, this may be a gasoline engine, because the components described below can be particularly advantageously used in the case of a gasoline engine. It may however also be some other internal combustion engine.

[0055] Attached to the internal combustion engine 1 is an injection rail 2, to which there is in turn connected an intake line 3. The intake line 3 is connected to an air filter 4.

[0056] The internal combustion engine 1 is furthermore connected to an exhaust system 5, to which an oxygen sensor 6 is connected. The oxygen sensor 6 measures the oxygen concentration in the exhaust gas in order to be able to control the internal combustion engine 1 in an ideal manner. This is performed by an engine control unit 7, which performs different control functions for the engine 1 and further illustrated components, wherein one part of this functionality will be discussed in more detail further below.

[0057] For the supply of fuel, a tank 10 is provided in which liquid fuel 15 is situated. This may be in particular gasoline, in the case of which the embodiment provided here can be particularly advantageously used.

[0058] Situated in the tank 10 is a swirl pot 20 in which fuel 15 is likewise situated. The swirl pot 20 is assigned a filling valve 30, and a fuel filter 40, with pressure-maintaining valve 45 arranged thereon, and a fuel pump 50 are also situated in said swirl pot. Also provided in the tank 10 is a jet pump 60 which likewise serves for filling the swirl pot 20 and for circulating fuel 15.

[0059] For filling purposes, a filler neck 70 is connected to the tank 10, which filler neck is connected via a flap 75 to the interior of the tank 10.

[0060] A fuel line 80 connects the tank 10 to the internal combustion engine 1 or to the injection rail 2. In this way, the internal combustion engine 1 can draw fuel 15 out of the tank 10.

[0061] For the control and monitoring of the tank 10, an intelligent module 90 and a fuel pressure regulator 95 are also provided. The intelligent module 90 and the fuel pump 50 may be controlled, as shown, by the engine control unit 7.

[0062] For the ventilation of the tank 10, a tank ventilation system 100 according to an exemplary embodiment is provided. This, too, is controlled by the engine control unit 7, which thus serves simultaneously as a control device for the tank ventilation system 100.

[0063] The tank ventilation system 100 has a ventilation line 110. This is connected by means of a total of three valves 115 to the interior of the tank 10. In this way, air or contained gases can pass from the interior of the tank 10 into the ventilation line 110.

[0064] The tank ventilation system 100 has an activated carbon filter 120. This is connected via a water and vapor separator 117 to the ventilation line 110. In this way, air can pass from the interior of the tank 10 into the activated carbon filter 120.

[0065] The activated carbon filter 120 is furthermore connected via a vacuum leak detector 130 and a dust filter 135 to the ambient air. In this way, air can pass from the interior of the tank 10 via the activated carbon filter 120 into the environment. Any contained hydrocarbons or other undesired substances that could lead to environmental damage or other problems in the ambient air are in this case collected in an effective manner in the activated carbon filter 120. The latter has a very large surface area on which such substances can be retained.

[0066] Since the activated carbon filter 120 becomes increasingly laden with hydrocarbons and other substances during operation, or during ventilation processes, and cannot regenerate itself, it is necessary for the hydrocarbons and other undesired substances contained in this activated carbon filter to be removed at regular intervals. Since most of the substances that are typically situated in the activated carbon filter 120 are hydrocarbons and other substances that are in any case a constituent part of the fuel 15, it is expedient for these to be fed to the internal combustion engine 1 for combustion.

[0067] For this purpose, use is made of a connecting line 140 which leads from the activated carbon filter 120 to an engine intake connection 145, which is in turn connected to the intake channel 3. Since the internal combustion engine 1 generates a negative pressure in the intake channel 3, this negative pressure also acts on the activated carbon filter 120, whereby air is conducted through the activated carbon filter 120, which air removes the hydrocarbons and other substances stored in this activated carbon filter.

[0068] For the control of this gas stream, a dosing valve 150 is incorporated in the connecting line 140. Said dosing valve may be controlled by the engine control unit 7. It is basically possible here, through suitable cycling of said dosing valve 150, to control the volume flow from the activated carbon filter 120 to the internal combustion engine 1. This will be discussed in more detail below.

[0069] FIG. 2 shows the profile with respect to time of a valve lift of the dosing valve 150 (dashed line) according to the prior art, and an associated typical pressure curve (solid line) in the connecting line 140. It can be seen here that, at an activation time, the dosing valve 150 is opened once for a certain opening time and is then closed again. Here, a negative pressure wave initially forms, as indicated by a falling pressure. A positive pressure wave subsequently forms, leading to a pressure increase above the prior steady-state level. The pressure then falls again into a negative pressure wave, and phases out in further harmonic oscillations.

[0070] It has been found that it is specifically the positive pressure wave that directly follows the opening time that is significantly responsible for vibrations which can also stimulate other components to vibrate and can generate an undesired and unpleasant introduction of noise into an interior of a motor vehicle.

[0071] FIG. 3a shows a further possible profile of a valve lift in embodiments according to the prior art. Here, too, only one opening time is provided. FIG. 3b shows an associated pressure profile, wherein the positive pressure wave that forms, and the further harmonic oscillations, can be clearly seen.

[0072] FIG. 4a shows a valve lift according to an exemplary embodiment. Here, it can be seen that, firstly, the valve is opened for a first opening duration, is then closed for a closing duration, and is then opened again for a second opening duration. Here, the second opening duration is shorter than the first opening duration.

[0073] FIG. 4b shows an associated pressure profile. It can be seen here that the positive pressure wave that directly follows the first opening duration does not form to nearly as great an extent as is the case in embodiments according to the prior art. The harmonic oscillations also do not form to nearly as great an extent as illustrated for example in FIGS. 2 and 3b. Thus, by means of the embodiment disclosed here with a first opening duration, a second opening duration and an interposed closing duration, the pressure profile is flattened considerably, which is effective in preventing the abovementioned undesired vibrations and generation of noise.

[0074] It is ultimately thus possible by means of corresponding configuration of the engine control unit 7 for the problem of the vibrations to be eliminated, because the pressure wave is depleted in an effective manner through the provision of a second opening duration.