Device for supplying a liquid at risk of freezing into the combustion chambers of an internal combustion engine

Abstract

Device for supplying a liquid at risk of freezing into the combustion chambers of an internal combustion engine, in particular one driving a motor vehicle, which is further designed to convey the liquid at risk of freezing back to the storage container (2) from at least a section of a supply line (4), through which the liquid passes from a storage container (2) to a supply device (1) to the internal combustion engine, characterized in that a venting valve (8) branching off from the supply line (4) is provided near the supply device (1), via which venting valve the supply line (4) is connected to the environment (U) in the open state, and in that, viewed in the direction of the storage container (2), downstream of this venting valve (8), an air separator-pressure accumulator assembly (10) connected to the supply line (4) is provided, which is designedTo at least partially separate air components from the supply line (4) and from the liquid in the supply line (4) in a section located at the top in the installed state and to act as a pressure accumulator acting on the liquid in the supply line (4).

Description

[0001] The invention relates to a device for supplying a liquid at risk of freezing into the combustion chambers of an internal combustion engine, in particular one driving a motor vehicle. The device is further configured to convey the liquid at risk of freezing back to the storage tank from at least a portion of a supply line through which the liquid flows from a storage tank to a supply device for the internal combustion engine. In particular, the liquid at risk of freezing is water, which is why, in the following, only water will be referred to as a liquid at risk of freezing, without implying a restriction to water (as a liquid at risk of freezing).

[0002] In the future, there will be an increasing number of vehicle internal combustion engines in which water is added to the fuel combustion process, at least at certain operating points. This water is preferably taken from an on-board reservoir and conveyed by means of a conveying device to at least one injection valve, which injects a specific quantity of water, for example, into the air intake system of the internal combustion engine or into one of its combustion chambers. The latter can also be achieved by injecting the desired water through the existing fuel injection valves assigned to the individual combustion chambers of the (usually multi-cylinder) internal combustion engine, namely in the form of an emulsion formed in a high-pressure fuel pump, to which, for compression, water is supplied in addition to the fuel and, depending on the respective operating point of the internal combustion engine.In such an embodiment, the high-pressure fuel pump can be referred to as a supply device for water within the meaning of the preamble of patent claim 1 or represents this supply device. In an alternative embodiment specified above with (at least) one injection valve for water, for example on the air intake system of the internal combustion engine, the injection valve(s) would be or would be the said supply device.

[0003] If the motor vehicle is parked for several hours after use during the cold season, water remaining in a supply line, for example to the high-pressure fuel pump or generally to a supply device through which the water ultimately reaches the internal combustion engine, could freeze. Then, after the internal combustion engine is restarted, no water would be able to reach its combustion chambers for a longer period of time. The supply line itself could also be damaged by ice pressure. (On the other hand, small amounts of water in an emulsion of fuel and a small amount of water - if present at all - are harmless.

[0004] The documents DE 10 2010 030 050 A1, DE 10 2014 204 509 A1 and US 2007 / 0 068 525 A1 show the state of the art.

[0005] To solve the aforementioned problem, it is known to return, at least as needed (namely, depending on the ambient temperature), at least the water still present in a certain area of ​​the supply line to a reservoir in a suitable manner when or after the vehicle is parked. From this reservoir, a delivery device delivers water to the supply device, for example, to the high-pressure fuel pump, as needed during operation of the internal combustion engine. For example, the aforementioned delivery device could be operated in the opposite direction for this return.

[0006] The aim of the present invention is to demonstrate how this return can be carried out safely and easily. This object is achieved by the features of claim 1 and is characterized in that a venting valve is provided near the feed device, branching off from the feed line, via which valve the feed line is connected to the environment when open, and in that, viewed in the direction of the storage container, downstream of this venting valve there is provided an air separator / pressure accumulator assembly connected to the feed line, which is designed to at least partially separate air components from the feed line and from the liquid in the feed line in a section located at the top when installed, and to act as a pressure accumulator acting on the liquid in the feed line. Advantageous embodiments and further developments are the subject of the subclaims.

[0007] The aim of the present invention is, on the one hand, to pump the water in the supply line (as a liquid at risk of freezing) back into the storage tank, ideally from at least a section of the supply line, after the vehicle has been parked, at least during the cold season. To minimize construction costs, this pumping can generally be carried out using an existing pumping device by reversing its pumping direction, whereby the pump sucks the water out of the supply line, and does so over a wide area thereof, ideally as close as possible to a previously mentioned feed device. The existing pumping device pumps the water from the storage tank to the feed device when the internal combustion engine is in operation.As will be explained later, the present invention also allows for a different method of conveying at least a portion of the water in the supply line. Before discussing this in more detail, however, another feature in the characterizing part of claim 1 will first be explained: In order to ensure successful return of water from at least one section of the supply line located near the supply device, the end section of the supply line located near the supply device should be ventilated, which is why an air line branch or similar should be provided that branches off from the supply line in the return direction (towards the storage tank) close to and upstream of the supply device and opens into the environment. Through this air line branch, air from the environment can enter the supply line when water is returned towards the storage tank, so that no negative pressure develops in the supply line when the water is returned. To prevent dirt particles from the environment from entering the supply line, an air filter device can be provided at the free end section of this air line branch.

[0008] In order to prevent water conveyed from the conveying device to the supply device from escaping into the environment (or into the air filter device) through the aforementioned air line branch when the motor vehicle, or more precisely from its internal combustion engine, is restarted, a so-called venting valve is provided in the aforementioned air line branch. This venting valve is usually closed and opens when at least some of the water is conveyed back from the supply line in the direction of the storage tank. This valve can be a check valve opening towards the storage tank, and the aforementioned air line branch can also be formed solely by this check valve, which then blocks the flow of water towards the internal combustion engine or the aforementioned supply device when the internal combustion engine and the conveying device are in operation. Instead of a check valve, however, a suitably controllable orA suitably controllable switching valve may be provided, which may also form the said air line branch, so that the latter is merely an optional feature.

[0009] However, a further essential feature is a pressure accumulator provided in the supply line or coupled to it, which here, in a special embodiment, forms a structural unit with an air separator and is therefore referred to as an “air separator-pressure accumulator structural unit”. By means of the air separator integrated in this structural unit, air or air components can be separated at least partially from the supply line and from the liquid in the supply line in a section (of the structural unit) that is located at the top when installed, and specifically from the water, which is then located in a lower section of this structural unit (when installed in the vehicle). As long as water is pumped into the supply line and thus also into the air separator-pressure accumulator structural unit by means of the aforementioned pumping device, a pressure builds up in this or that section.in the section containing essentially only water, an excess pressure compared to ambient pressure occurs as long as the feed device and the aforementioned venting valve are closed, so that no water is discharged from the feed line through these elements. The mere fact that the air separator / pressure accumulator assembly has a significant volume, which can, for example, be approximately equal to the total volume of the feed line, means that this assembly can act as a pressure accumulator for the water in the feed line. Furthermore, in the description and partly also in the patent claims, only the term "assembly" is used, and refers to the air separator / pressure accumulator assembly according to the invention.

[0010] Turning now to the pressure accumulator function of this unit, it is possible, with the aid of the fluid pressure stored therein (also in conjunction with gravity), to pump water back toward the reservoir from a section of the supply line located near the supply device or the venting valve. Thus, if the supply device is shut off and a tank shutoff valve provided in the supply line near the storage tank and the aforementioned venting valve are open, and the aforementioned pumping device is not operating, at least a certain amount of water will automatically flow back into the reservoir from the pressure accumulator and thus also from a section of the supply line located near the supply device.The installation height of the individual components of a device according to the invention in the vehicle, measured above the roadway, naturally has a significant influence on how much water flows back from the supply line into the reservoir. However, in conjunction with the pressure accumulator of the said assembly, a sufficient amount of water always flows back into the reservoir, since the supply device in the vehicle is usually located well above the roadway or, viewed in the vertical axis direction of the vehicle, is further away from the roadway than the reservoir.

[0011] A pressure accumulator provided according to the invention also has the advantage that with such a pressure accumulator the water delivery device does not have to be operated continuously and yet a certain amount of water can be made available to the supply device abruptly as needed, namely depending on the respective operating point of the internal combustion engine. The pressure accumulator is advantageously located as close as possible to the supply device, wherein in the supply line, viewed in the conveying direction of the delivery device (when the internal combustion engine is operating), an electronically controllable so-called engine shut-off valve and, if appropriate, an electronically controllable metering valve can be provided downstream of the pressure accumulator before the supply line opens into the supply device, for example the high-pressure fuel pump. The said engine shut-off valve is closed when the internal combustion engine is not operating.

[0012] In one possible embodiment, the air separator-pressure accumulator assembly is designed in the form of a container in whose, for example, approximately circular-cylindrical volume, a partition wall provided with a narrow passage opening is provided in a section which, when installed in the vehicle, is at the top. As long as there is air in the supply line, when the conveying device is started up and water is thus conveyed into the supply line, this air enters the assembly and can easily pass through the said narrow passage opening. However, as soon as water is conveyed into the assembly, its passage through the narrow passage opening is significantly impeded. As water is further conveyed by the conveying device, an overpressure will build up in the assembly below the said partition wall and this pressure will be maintained, i.e. stored, for a certain time.To ensure that the air flowing from the supply line to the partition wall in the structural unit according to the invention can collect as best as possible near the through-opening provided therein, the partition wall can be conical, with the through-opening located at the cone apex that is highest relative to the partition wall, i.e., furthest from the roadway. However, to allow water flowing through the through-opening to flow back into the system, i.e., into the supply line, at least after the described excess pressure has been relieved, a suitably small-sized water discharge opening can be provided, preferably in an edge section, and in particular in an edge section of a conical partition wall as described.

[0013] In that area of ​​the assembly which, as seen from the supply line, lies beyond the partition wall, air initially accumulates, as described, when the conveying device is put into operation after the internal combustion engine has been switched off and thus when the supply line has previously been at least partially emptied, which air can then act as an air cushion supporting the pressure storage function of the assembly if - which is preferred - escape of this air into the environment is prevented.In particular, it is proposed to connect the aforementioned venting valve to this area beyond the partition wall, which - as already explained - is only opened after the internal combustion engine has been switched off for the desired return of at least part of the water in the supply line to the storage tank, and ideally only after the excess pressure previously prevailing in the air separator-pressure accumulator assembly has been dissipated. As already mentioned, when the internal combustion engine is switched off, at least part of the supply line is emptied, i.e. water contained in at least one section of the supply line is pumped back into the storage tank.For this purpose, the existing overpressure in the air separator pressure accumulator assembly is first used and after this has been reduced, the aforementioned venting valve is opened.

[0014] Turning now to the design of the air separator-pressure accumulator assembly according to the invention, an inlet opening of this assembly, which is connected to the supply line, can open tangentially into an at least approximately circular-cylindrical interior of this assembly. This makes it possible to create a cyclone effect which, when water mixed with air enters the interior of the assembly in this way and is caused to flow in a circular manner by the tangential entry, promotes the successful separation of air from the water. It is further proposed that the inlet opening of the air separator-pressure accumulator assembly, which is connected to the supply line, be provided above (i.e. further away from the roadway in the vertical direction of the vehicle) a line section which conducts the water from the assembly and which branches off from the lowest point of the assembly when installed.This additional line section is part of the supply line, which ultimately leads to the aforementioned supply device. This measure ensures that no air, but only water, reaches the supply device, as desired. The height difference between the inlet opening of the assembly and the aforementioned line section determines the maximum possible inclination of the assembly (and thus of the vehicle) with regard to the desired air clearance.

[0015] Furthermore, a capillary filter can be provided in the liquid-filled volume of the air separator-pressure reservoir assembly between the said inlet opening and a pipe section or the pipe section that conducts the water (or the liquid at risk of freezing) from the assembly, thereby covering the cross-section of said volume. Such filters are generally known to those skilled in the art. Water must therefore penetrate this filter, whereby not only are unwanted particles retained, but air is also separated particularly effectively due to the capillary action. Of course, another, simpler filter element can also be provided in this area, which can also promote improved air separation.

[0016] An embodiment of the invention is shown in the attached figures, which are described below and which may contain further inventive features. Fig. 1 a principle arrangement of only the elements or components necessary for understanding the invention, while Fig. Figure 2 shows a cross-sectional view of a possible air separator-pressure accumulator assembly according to the invention. The individual elements described are designated by the same terms as in the explanations preceding the description of the figures.

[0017] First on Fig. 1 With reference to FIG. 1, reference numeral 1 denotes a high-pressure fuel pump of an internal combustion engine (not shown), which functions as the drive unit of a motor vehicle (likewise not shown). This high-pressure fuel pump 1 not only compresses the fuel to be supplied to the internal combustion engine, but also mixes water with it at selected operating points of the internal combustion engine. The present invention relates to a device for supplying water generally to a supply device for an internal combustion engine, wherein in the present exemplary embodiment, the high-pressure fuel pump 1 functions as such a supply device, which is why reference numeral 1 is also used below for the term or object "supply device".

[0018] The water to be supplied to the supply device 1 (or high-pressure fuel pump 1) is taken from a storage tank 2 carried in the motor vehicle by means of a conveying device 3a (= pump), to whose discharge outlet a supply line 4 ultimately leads to the supply device 1 is connected. In this supply line 4, a tank shut-off valve 3b is provided very close to the conveying device 3a and the storage tank 2. Further downstream in the supply line 4 (viewed in the conveying direction of the conveying device 3a), this is followed by a fine filter 5 and then, already relatively close to the supply device 1, an air separator-pressure accumulator assembly 10. Starting from this assembly 10, the supply line 4 continues to a so-called engine shut-off valve 6a assigned to the internal combustion engine, which is followed by a metering valve 6b, from which the supply line 4 then opens into the supply device 1.An air line branch 7 branches off from the air separator pressure accumulator assembly 10 and opens into the environment U via a ventilation valve 8 and a filter element 9 connected upstream or downstream of the latter.

[0019] Now on Fig. 2 With reference to Figure 2, a possible embodiment of an air separator pressure accumulator assembly 10 according to the invention is shown in more detail. This assembly 10 initially consists of an approximately circular-cylindrical housing 11 with an internal volume 12. This assembly 10 is shown in the figure in the installed position or in the installed state in the motor vehicle, i.e. the vehicle's vertical axis runs vertically in the plane of the drawing and the roadway on which the vehicle is standing is located significantly below this assembly 10. In its internal volume 12, in the upper region (for example at 75% of the height of the internal volume 12), a partition wall 13 is provided which extends essentially completely across the (horizontal) cross-section of this internal volume 12. This partition wall here has the shape of a cone with a relatively large cone angle (on the order of 160°, for example) and in whose cone tip a relatively narrow passage opening 14 is provided.A water drainage opening 15 is provided in a narrow edge area above the (outer) circumference of the partition wall 13.

[0020] The supply line 4 coming from the conveying device 3a opens essentially tangentially into the internal volume 12 of the structural unit 10 relatively far below the partition wall 13 via an inlet opening 16 provided in the cylinder wall or in the housing 11 of the structural unit 10, i.e. the supply line 4 opens essentially tangentially into the internal volume 12, so that the water supplied through the supply line 4 with a certain pressure in the internal volume 12 carries out a vortex-like rotational flow around the cylinder axis of the essentially cylindrical internal volume 12. From the lowest area or point of the structural unit 10, i.e. the area furthest down viewed in the vertical direction of the vehicle, a line section 17 branches off from the internal volume 12 of the structural unit 10, through which line the water supplied through the inlet opening 16 is discharged again from the structural unit 10.This line section 17, which is located centrally in the area of ​​the cylinder axis at the bottom of the essentially circular cylindrical housing 11 of the assembly 10, goes into the motor shut-off valve 6a (cf. . Fig. 1) leading supply line 4 over or forms this section of the supply line 4. In the internal volume 12 of the structural unit 10, a filter element or filter 18 is also provided, viewed in the vertical direction or vertical axis direction, between the inlet opening 16 and the beginning of the line section 17, extending over the entire (horizontal) cross section of the internal volume, through which filter element or filter 18 the water supplied through the inlet opening 16 must pass in order to reach the line section 17. Due to its design with capillary action, this filter 18 ensures particularly effective separation of any air or air bubbles contained in the water.

[0021] Furthermore, on the assembly 10 or on its housing 11 there is a connection 19 leading from the internal volume 12 above the partition wall 13 for the Fig. 1. Via this connection 19, the air separated in the assembly 10 is discharged into the air line branch 7, which then, as long as the ventilation valve 8 is closed, functions as an (additional) compressed air cushion for the pressure accumulator formed by the assembly 10 and described in detail before the description of the figures. Also not shown in the figures is an electronic control and computing unit, which, depending on the operating state or operating point of the internal combustion engine, appropriately controls the delivery device 3a, the tank shut-off valve 3b, the engine shut-off valve 6a, the engine metering valve 6b, and the ventilation valve 8. This occurs as described in detail above and is summarized below: When the internal combustion engine is switched off, there should be no water in the supply line 4 downstream (viewed in the conveying direction of the conveying device 3a) of the fine filter 5, as well as within this vertically installed fine filter 5 in an upper area thereof, while when the internal combustion engine is operating, the supply line 4 and the air separator pressure accumulator assembly 10 in the internal volume area below the partition wall 13 are completely filled with water taken from the storage tank 2, either under pressure or at a pressure above ambient pressure. To meet this requirement, when the internal combustion engine is switched off, the engine shut-off valve 6a is closed and the tank shut-off valve 3b, which may have previously been closed, is opened, whereby the conveying device 3a is not (continued) in operation.The result is that, due to the overpressure in the air separator pressure accumulator assembly 10 and in the supply line 4, some of the water contained in these latter components flows back into the storage tank 2. Once this overpressure has been reduced, which can be determined using a pressure sensor not shown in the figures, the aforementioned electronic control and computing unit opens the (previously closed) ventilation valve 8, whereby air from the environment can enter the system via the air line branch 7, i.e. through the assembly 10 into the supply line 4, which causes any water still contained therein to flow further out into the storage tank 2, which is located further down in the vehicle's vertical axis direction.In the concretely implemented exemplary embodiment, the area between the fine filter 5 and the engine shut-off valve 6a is completely emptied, and the fine filter 5 is half emptied. This, for reasons not further explained, is sufficient to prevent damage caused by water freezing during extended periods of inactivity of the motor vehicle and correspondingly low ambient temperatures. At the end of this described water removal process, which follows a shutdown of the internal combustion engine (for an extended period), during which water is pumped back into the reservoir 2, the tank shut-off valve 3b and the vent valve 8 are closed.

[0022] With the restart of the internal combustion engine, in those areas of the Fig. 1 or the system shown in Fig.1, where water may well freeze, an electric heating device (not shown) is first used to thaw the frozen water. The system shown can then be filled with water by starting up the conveying device 3a after the tank shut-off valve 3b has been opened. Since no air may reach the supply device 1, the motor shut-off valve 6a initially remains closed. The conveying device 3a now conveys water towards the closed motor shut-off valve 6a until the space in the internal volume 12 of the air separator-pressure accumulator assembly 10 is completely filled with water under a certain excess pressure, which can be determined by means of a suitably provided pressure sensor (already mentioned) not shown in the figure.During this filling process—as explained in detail before the description of the figures—the air previously contained in the supply line 4 passes through the narrow opening 14 in the partition wall 13 into the air line branch 7 and is buffered there. Upon completion of this described filling process, the motor shut-off valve 6a can be opened.

[0023] The further functioning of the assembly 10, in particular its ability to separate any air contained in the water supplied from the reservoir 2 during operation of the internal combustion engine with the engine shut-off valve 6a and the metering valve 6b open, has already been described above. It should also be mentioned that any small amounts of water that pass through the narrow passage opening 14 in the partition 13, which acts as a diaphragm, in the assembly 10 can, when there is no excess pressure in the supply line 4, flow back into the area of ​​the internal volume 12 located below the partition 13 via the water discharge opening 15.

Claims

[1] Device for supplying a liquid at risk of freezing into the combustion chambers of an internal combustion engine, in particular driving a motor vehicle, which is further designed to convey the liquid at risk of freezing back to the storage container (2) at least from a section of a supply line (4), through which the liquid passes from a storage container (2) to a supply device (1) to the internal combustion engine, characterized bythat a venting valve (8) is provided near the feed device (1) branching off from the feed line (4), via which valve the feed line (4) is connected to the environment (U) in the open state, and that downstream of this venting valve (8) as viewed in the direction of the storage container (2) there is provided an air separator-pressure accumulator assembly (10) connected to the feed line (4), which is designed to at least partially separate air components from the feed line (4) and from the liquid in the feed line (4) in a section which is at the top in the installed state and to act as a pressure accumulator acting on the liquid in the feed line (4). [2] Device according to claim 1, wherein the air separator pressure accumulator assembly (10) is designed in the form of a container, in the inner volume (12) of which a partition wall (13) provided with a narrow passage opening (14) is provided in a section which is located at the top in the installed state in the vehicle. [3] Device according to claim 2, wherein the partition wall (13) is conical and the passage opening (14) is located in the cone tip. [4] Device according to one of the preceding claims, wherein a water discharge opening (15) is provided in an edge section of a partition wall (13). [5] Device according to one of the preceding claims, wherein an inlet opening (16) of the air separator pressure accumulator assembly (10) connected to the supply line (4) opens tangentially into a or the at least approximately circular-cylindrical interior (12) of this assembly (10). [6] Device according to one of the preceding claims, wherein one or the inlet opening (16) of the air separator pressure storage unit (10) connected to the supply line (4) is provided in the installed state above a line section (17) which further conducts the liquid at risk of freezing from the unit (10), which acts as a component of the supply line (4) and branches off from the lowest point of the unit (10) in the installed state. [7] Device according to one of claims 5, 6, wherein a filter (18) with capillary action is provided in the volume of the structural unit (10) filled with liquid between the inlet opening (16) and a line section (17) which further conducts the liquid at risk of freezing from the structural unit (10) and thereby covers the cross section of said volume. [8] Device according to one of the preceding claims, wherein the air separator pressure accumulator assembly (10) is provided in the supply line (4) upstream of a shut-off valve (6a), viewed in the flow direction of the liquid towards the supply device (1), which is closed when the internal combustion engine is not in operation.

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