Method for Preventing Icing of an Injection System of an Internal Combustion Engine

Abstract

A method prevents icing of an injection system of an internal combustion engine of a motor vehicle having a high-pressure fuel pump to which, in addition to fuel, water can also be supplied via a feed line. When the motor vehicle is stopped, water still located in a wide region of the feed line is extracted, at least if required. For this purpose, a conveying device provided for conveying water to the high-pressure fuel pump is operated with the direction of rotation reversed. When the motor vehicle or the internal combustion engine is re-started, that region of the feed line from which water located therein has previously been extracted is flushed with water, the air located therein beings discharged into the surroundings.

Claims

1.-7. (canceled)

8. A method for preventing icing of an injection system of an internal combustion engine of a motor vehicle having a high-pressure fuel pump to which fuel and also water is feedable via a feed line, the method comprising: when the motor vehicle is in a shut-down state, extracting water still remaining in an extensive region of the feed line at least as required, wherein the extraction is by suction.

9. The method according to claim 8, wherein for the extraction of water by suction, a conveying device provided for conveying water to the high-pressure fuel pump is operated with a reversed direction of rotation.

10. The method according to claim 8, wherein upon a restart of the motor vehicle or of the internal combustion engine, that region of the feed line from which water present therein was previously extracted by suction is flushed with water, wherein air situated therein is discharged into surroundings.

11. A device, comprising: a feed line; a high pressure fuel pump to which fuel and water is feedable via the feed line; a check valve, or switchable shut-off valve, which is provided in the feed line close to the high-pressure fuel pump or to a merging point with a fuel line leading to the high-pressure fuel pump, wherein the check valve or switchable shut-off valve blocks in a direction of a conveying device for the water.

12. The device according to claim 11, wherein as viewed in a conveying direction of the conveying device during operation of the internal combustion engine, a line branch which opens into the surroundings branches off from the feed line upstream of the check valve or the shut-off valve.

13. The device according to claim 12, wherein in the line branch, a check valve or a switchable shut-off valve is provided, which opens in the direction of the conveying device.

14. The device according to claim 13, wherein in the line branch, an air filter device is provided, which has a water outlet which protects an air filter element from being impinged on with conveyed water.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0009] FIG. 1 is a schematic diagram of an exemplary embodiment.

DETAILED DESCRIPTION OF THE DRAWING

[0010] FIG. 1 schematically shows a possible exemplary embodiment. Here, the reference designation 1 denotes a high-pressure fuel pump by means of which, during the operation of a vehicle internal combustion engine (not shown), fuel which is conveyed by means of an in-tank pump 2 through a fuel line 4 from a fuel tank (not shown) to the high-pressure fuel pump 1 is normally further compressed and provided to multiple injection valves 3, which (can) inject the compressed fuel into combustion chambers of the internal combustion engine.

[0011] In the present case, instead of pure fuel, it is also possible as required for an emulsion of fuel and water to be introduced through the injection valves 3 into the combustion chambers. The water is admixed as required to the fuel quantity fed to the high-pressure fuel pump 1, for which purpose a feed line 5 which conducts the water in opens into the fuel line 4 via a suitably designed line merging point 6. The required water is conveyed in by the feed line 5 from a reservoir 7 by means of a conveying device 8 which is arranged in this case outside the reservoir 7, which conveying device is normally designed as a pump. The conveying device 8 can selectively convey water from the reservoir 7 through a check valve 9, described in the next paragraph, to the fuel line 4, or can be operated with a reversed direction of rotation or conveying direction and thus convey water that is situated in the feed line 4 out of an extensive region of the feed line back into the reservoir 7.

[0012] As discussed in detail prior to the description of the FIGURES, in the feed line 5 upstream (as viewed in a conveying direction of the conveying device 8 during the operation of the internal combustion engine) of the line merging point 6, as close as possible or directly upstream of this or upstream of the fuel line 4, there is provided a check valve 9 which blocks in the direction of the conveying device 8. A line branch 10, likewise discussed prior to the description of the FIGURES, branches off from the feed line 5 substantially directly upstream of the check valve 9, which line branch ultimately opens into the surroundings U. In the line branch 10, as viewed from the feed line 5 in the direction of the surroundings U, there is provided firstly a shut-off valve 11a, which can be actuated by means of an electric motor 11b, and then an air filter device 12, which is equipped with a suitably designed water outlet 13, likewise as described further above.

[0013] The function of the individual elements shown will not be described once again—this can be found prior to the description of the FIGURE using the same terminology. In addition to the elements already described thus far, a suitably activatable icing prevention valve 14 is also provided in the feed line 4 upstream (as viewed in a conveying direction of the conveying device 8 during the operation of the internal combustion engine) of the conveying device 8, which icing prevention valve, after the feed line 5 has been evacuated by suction (by means of the conveying device 8), is closed for safety purposes at least in the presence of low ambient temperatures. The icing prevention valve 14 prevents water from being sucked into the line 5 as a result of a decrease in size of the enclosed gas volume as the latter cools. At the same time, the valve serves for maintaining pressure without the use of energy, if it is activated, so as to open, only for as long as the conveying device 8 operates.