Device and Method for Supplying Water Into a High-Pressure Fuel Pump of an Internal Combustion Engine Provided in a Motor Vehicle

Abstract

A device supplies water into a high-pressure fuel pump of a motor vehicle internal combustion engine, wherein the water is admixed to the fuel in the inlet region of the high-pressure fuel pump in a controlled manner by a metering valve, and wherein the device is designed to guide the water at least from a part of a supply line back to the storage container. When viewed in the flow direction from the storage container to the high-pressure fuel pump, a shut-off valve is provided in the supply line upstream of the metering valve, and the supply line is designed to elastically deformably change its volume in a line section positioned between the valves. In an operating method, wherein, after the parking of the motor vehicle in conditions that make it possible for the liquid that is at risk of freezing to freeze, and/or after delivery of the liquid to the high-pressure fuel pump, and with a suitably adjusted upstream fluid pressure, the metering valve is opened and remains open until a portion of the fluid in the section of the supply line leading from the metering valve to the high-pressure fuel pump flows out through the metering valve.

Claims

1.-7. (canceled)

8. A device for supplying a liquid at risk of freezing into a high-pressure fuel pump of an internal combustion engine provided in a motor vehicle, comprising: a metering valve by which the liquid at risk of freezing is admixed as required in a controlled manner with fuel present in an inlet region of the high-pressure fuel pump, wherein the device is designed to return the liquid at risk of freezing at least from a portion of a supply line, through which the liquid passes from a reservoir to the high-pressure fuel pump, to the reservoir; and a shut-off valve arranged upstream of the metering valve in the supply line as viewed in a flow direction from the reservoir to the high-pressure fuel pump, wherein the supply line is designed to elastically deformably change its volume in a line section situated between the shut-off and metering valves.

9. The device according to claim 8, wherein the line section of the supply line that is situated between the shut-off valve and the metering valve is designed to elastically deformably change its volume to such a degree that a volume increase occurring upon freezing of the liquid situated in the line section is accommodated by the elastic deformation.

10. The device according to claim 8, wherein the line section between the shut-off valve and the metering valve is designed with respect to a targeted freezing such that, by virtue of higher wall thicknesses in a region producing the elastic deformation, a freezing of liquid situated in said region occurs later in time than in other regions of the line section of the supply line.

11. The device according to claim 8, wherein the elastic deformability for volume change is formed by a wall portion of the line section of the supply line that is displaceable against a force of a spring element.

12. The device according to claim 9, wherein the elastic deformability for volume change is formed by a wall portion of the line section of the supply line that is displaceable against a force of a spring element.

13. The device according to claim 10, wherein the elastic deformability for volume change is formed by a wall portion of the line section of the supply line that is displaceable against a force of a spring element.

14. An operating method for a device for supplying a liquid at risk of freezing into a high-pressure fuel pump of an internal combustion engine provided in a motor vehicle, comprising: admixing, via a metering valve, the liquid at risk of freezing as required in a controlled manner from a supply line with fuel present in an inlet region of the high-pressure fuel pump; and after parking the motor vehicle, at least under conditions which make possible freezing of the liquid at risk of freezing, and/or subsequent to a delivery of the liquid to the high-pressure pump, opening the metering valve, with liquid pressure suitably set upstream thereof, for so long that some of the liquid situated in a section of the supply line leading from the metering valve to the high-pressure fuel pump flows off through the metering valve.

15. The operating method according to claim 14, wherein the liquid at risk of freezing is returned at least from a portion of a supply line, through which the liquid passes from a reservoir to the high-pressure fuel pump, to the reservoir, and at a time before said return, a certain liquid pressure lying above ambient pressure is produced in the supply line upstream of the closed metering valve, whereupon a shut-off valve, which, as viewed in the flow direction from the reservoir to the high-pressure fuel pump, is arranged upstream of the metering valve in the supply line, is closed.

16. The operating method according to claim 15, wherein the liquid pressure produced lies in terms of magnitude below the fuel pressure prevailing at the inlet region of the high-pressure fuel pump.

Description

BRIEF DESCRIPTION OF THE DRAWING

[0017] FIG. 1 is a schematic diagram of an exemplary embodiment of the invention in a principle-illustrating arrangement of only the elements or constituent parts which are necessary for understanding the invention.

DETAILED DESCRIPTION OF THE DRAWING

[0018] Reference number 1 denotes a high-pressure fuel pump of an internal combustion engine (not shown) which functions as a drive unit of a motor vehicle (likewise not shown). This high-pressure fuel pump 1 compresses not only the fuel which is supplied to an inlet region of the high-pressure fuel pump 1 by a fuel line 20 and which is to be supplied to the internal combustion engine after this compression, but this high-pressure fuel pump 1 can also admix water with this supplied fuel in selected operating points of the internal combustion engine. Here, the fuel passes from a fuel tank (not shown), delivered by a so-called predelivery pump (likewise not shown), through the fuel line 20 under a pressure for example in the order of magnitude of 6 bar to the inlet region of the high-pressure fuel pump 1. Provided as close as possible upstream of the high-pressure fuel pump 1 in the fuel line 20 is a line T-piece 28 for admixing water.

[0019] The water to be supplied to the high-pressure fuel pump 1 as required and in particular in dependence on the current operating point of the internal combustion engine is removed from a reservoir 2, which is carried along in the motor vehicle, by means of a delivery device 3a (=pump) whose delivery outlet is adjoined by a supply line 4 leading ultimately up to the supply device 1 or opening into the aforementioned line T-piece 28. A tank shut-off valve 3b is provided in the supply line 4 very close to the delivery device 3a and the reservoir 2. This valve is followed in the supply line 4 further downstream (as viewed in the delivery direction of the delivery device 3a) by a fine filter 5 and subsequently, already relatively close to the supply device 1, by an air separator 21. Starting from this air separator 21, the supply line 4 continues further to a so-called engine shut-off valve 6a which is assigned to the internal combustion engine and downstream of which there is arranged a metering valve 6b, starting from which the supply line 4 ultimately opens with a section 4c in the high-pressure fuel pump 1 or, more precisely, in the fuel line 20 via the line T-piece 28.

[0020] Sinceas specified further abovethe fuel pressure in the fuel line 20 is approximately 6 bar, a successful admixing of water should require the water pressure prevailing, with the metering valve 6b opened, at the inlet region of the high-pressure fuel pump 1, and hence also the water pressure prevailing in the section 4c of the supply line, to lie at least slightly above the fuel pressure of 6 bar.

[0021] The section of the supply line 4, or this portion of the supply line 4, leading from the tank shut-off valve 3b to the engine shut-off valve 6a is also referred to hereinbelow as section 4a, whereas the line section of the supply line 4 extending between the engine shut-off valve 6a and the metering valve 6b is also referred to as line section 4b (and prior to the description of the figure only as line section). Moreover, an air line branch 7 branches off from the air separator 21 and opens into the surroundings U via a venting valve 8 and a filter element 9 arranged downstream or upstream thereof.

[0022] Returning to the aforementioned line section 4b, the latter is provided in a metal body 22, which is also referred to as a metering module 22 which further comprises a receptacle for the engine shut-off valve 6a and a receptacle for the metering valve 6b. The line section 4b extends between these two valves 6a, 6b in the metal body 22, and there branches off in the metal body 22 from this line section 4b on the one hand a first branch line 24a leading to a sensor unit 23 and additionally a further branch line 24b which leads to a blind hole 25 which is provided in the metal body 22 and in which there is displaceably guided a piston 26 which is supported on the bottom of this blind hole 25 via a spring element 27. The sensor unit 23 can be used to measure the pressure and possibly also the temperature of the water situated in the line section 4b, which value or which values is or are then suitably processed by an electronic control and computing unit (not shown) which ensures correct operation of the device shown and which in particular also executes or controls an operating method presented here. In dependence on the operating state or operating point of the internal combustion engine, this electronic control and computing unit actuates the delivery device 3a, the tank shut-off valve 3b, the engine shut-off valve 6a and also the engine metering valve 6b and the venting valve 8 in a suitable manner. This occurs as described in the present documents:

[0023] With the internal combustion engine deactivated, no water should be situated in the section 4a of the supply line 4, whereas, during operation of the internal combustion engine, the supply line 4 is completely constantly filled with water under pressure or excess pressure in relation to ambient pressure that is removed from the reservoir 2. In order then to comply with this stated requirement, this section 4a of the supply line is emptied when or after deactivating the internal combustion engine, but defined pressure values are still set beforehand in different sections of the supply line 4.

[0024] Thus, at first a pressure of approximately 6 bar should prevail in the section 4c of the supply line, that is to say a pressure which corresponds to that in the fuel line 20 in orderas has already been stated further aboveto ensure that the described interface between fuel and water in the section 4c remains at a distance from the metering valve 6b. With the metering valve 6b opened, this pressure can be measured by the sensor unit 23 and, if not already present, this pressure can be set by operating the delivery device 3a with the valves 3b, 6a, 6b open. A lower water pressure or pressure of water situated in the line section 4b (between the engine shut-off valve 6a and the metering valve 6b) is subsequently set in the line section. For this purpose, the metering valve 6b is closed and the shut-off valve 6a opened and, with continued opening of the tank shut-off valve 3b, where appropriate with suitable operation of the delivery device 3b, the pressure determined by the sensor unit 23 is set in the order of magnitude of for example 3 bar here. Subsequently, the shut-off valve 6a is (also) closed and (at the latest now, possibly also already when setting the pressure of 3 bar in the line section 4b) the delivery device 3a is operated with its delivery direction reversed in relation to its customary operation. Consequently, water is fed back from the section 4a of the supply line 4 into the reservoir 2. To ensure here that no appreciable negative pressure builds up in the section 4a, the aforementioned electronic control and computing unit opens the (previously closed) venting valve 8, whereby air can pass from the surroundings U via the air line branch 7 into the system or into the section 4a of the supply line 4. In order to conclude this water removal process which has been described thus far and which follows a deactivation of the internal combustion engine (for a relatively long time period) and within which process water is fed back into the reservoir 2, the tank shut-off valve 3b and the venting valve 8 are closed. The metering valve 6b is then opened for a relatively short time period. This results in pressure equalization between the line section 4b and the section 4c of the supply line 4, that is to say some water passes into the line section 4b from the section 4c situated between the metering valve 6b and the inlet region of the high-pressure fuel pump 1, andas has been explained prior to the description of the figurethe interface between fuel and water in the section 4c is slightly displaced in the direction toward the metering valve 6b. After such pressure equalization has occurred, the metering valve 6b is also closed (again).

[0025] It is thus not possibleas has been already statedfor any ice formation to occur in the section 4a of the supply line when the motor vehicle is parked or when the internal combustion engine is deactivated under low ambient temperatures, since no water is situated in the section. Although ice formation can occur in the relatively short section 4c of the supply line, this section 4c is however not filled with water completely, namely only up to the aforementioned interface, the volume increase of which water upon ice formation is accommodated by the fuel situated in this section 4c.

[0026] And if the water situated in line section 4b and thus in the metering module 22 freezes, its volume increase is accommodated by the already explained piston 26 which can be displaced against the force of the spring element 27, that is to say that this piston 26 is displaced further into the blind hole 25 as a result of the volume increase of the water freezing in the metering module 22. This spring-loaded piston 26 in the blind hole 25 constitutes the measure provided here for the elastically deformable change in the volume of the line section 4b of the supply line 4. For this purpose, the metering module 22 is (preferably) designed with respect to targeted freezing. It is possible by suitable distribution of material (construction material) of the metering module 22, which is at least slightly capable of storing heat, to achieve a situation in which, as considered with regard to time, certain regions or sections of this metering module 22, under ambient temperatures below zero degrees Celsius, assume this ambient temperature earlier than other regions or sections. In the present case, the configuration is then such that the region or section around the blind hole 25 is the last to cool to the ambient temperature, whereas this occurs earlier in the other sections or regions. It is thereby ensured that the volume increase of the water freezing within this metering module is completely accommodated by the piston 26 displaced as a result.

[0027] Upon reactivation of the internal combustion engine it is possible, in those regions of the installation shown in the figure or of the system shown in the figure where water may indeed freeze, first of all for an electric heating device (not shown) to thaw this frozen water. Subsequently, by activating the delivery device 3a, the installation shown or the system shown can be filled with water after the tank shut-off valve 3b has been opened. Since no air must pass here to the supply device 1, the engine shut-off valve 6a remains initially closed. The delivery device 3a now delivers water in the direction of the closed engine shut-off valve 6a for such time until all air from the section 4a of the supply line has been removed via the air separator 21. The engine shut-off valve 6a can then be opened and the device can be operated as intended.

[0028] Moreover, as explained prior to the description of the figure, a displacement of the aforementioned interface in the section 4c of the supply line 4 leading from the metering valve 6b to the high-pressure fuel pump 1 can also be effected independently of an emptying of the section 4a of the supply line 4 when deactivating the internal combustion engine or parking the motor vehicle. This can in particular also be effected after each supply of water into the high-pressure fuel pump 1 in order to minimize the degree of contamination of water by components of the fuel.