Combustion engine for operation with gaseous fuel, especially hydrogen, and high-pressure valve for introducing gaseous fuel into the combustion engine

Abstract

An internal combustion engine for operation with gaseous fuel, in particular hydrogen, is provided, which has a high-pressure valve (4) with cylindrical surfaces and control edges (5.1) or with conical elements (5.2) for supplying hydrogen to a cylinder (3) by means of a control valve piston (5). The control valve piston (5) is electromagnetically actuated, achieves short control times / high switching frequencies, is sealed in the housing (6) in at least two stages and without elastomers, and prevents or at least largely avoids backflow of gaseous fuel, in particular hydrogen, thus preventing back-ignition, and is designed in a weight-reduced lightweight construction.

Description

The invention relates to an internal combustion engine for gas operation, in particular hydrogen operation, and to a high-pressure valve for introducing gaseous fuel into such an internal combustion engine.In the field of operation of internal combustion engines with gaseous fuel, in particular hydrogen, a great deal of prior art has been published because of the many years in which the industry and assemblies have dealt with this topic, especially from an ecological point of view. In addition to the most frequently used liquid fuels, gaseous fuels such as natural gas or hydrogen are increasingly also used for operating vehicles. The injection nozzles, also called injectors, for liquid fuels are largely perfected in their development, but a number of problems not occurring in liquid fuels arise in gaseous fuels. The known injectors for liquid fuels are therefore only conditionally suitable.Gaseous fuels have different energy densities and volumes from liquid fuels.One problem with the use of hydrogen or gaseous fuels is that, on the one hand, a relatively large quantity with a significantly larger volume of fuel compared to liquid fuels must be introduced into the combustion chamber of an internal combustion engine in a relatively short time, and, on the other hand, the introduction must also be realized very accurately and very accurately with regard to the metering of the fuel quantity introduced into the combustion chamber. This is necessary so that no excessive consumption and minimal pollutant emission occur during the operation of internal combustion engines used with natural gas or hydrogen or with other gaseous fuels. For this purpose, it is precisely necessary that as accurately as possible metered gas quantities are introduced into the cylinder per injection process and at a defined time of the injection process, which is matched to optimized combustion in the cylinder.In principle, two basic injection methods for gaseous fuels, in particular hydrogen, are known. One possibility for introducing gaseous fuel is that this fuel is introduced into the combustion chamber of the internal combustion engine in the end region of the inlet line, preferably directly upstream of the inlet region of the inlet line. A further possibility is that the gaseous fuel is injected directly into the combustion chamber with the correspondingly developed injectors which are suitable and optimized for gaseous fuels, wherein this is also referred to as "injected". The injection or injection of gaseous fuels is realized in such a way that all the fuel required for a combustion cycle is introduced in one injection process or also in a plurality of injection processes per combustion cycle. In addition to the need to be able to inject a specific maximum fuel quantity in a predefined time period, it must also be additionally possible to introduce defined small quantities or smallest quantities into the cylinder in an exact metering. A further general requirement for the gas injectors or injection valves is that they must be sealed off exactly and reliably with respect to the combustion chamber into which the gas, preferably hydrogen, is introduced, in order to avoid back-ignition in the region in front of the combustion chamber.Christian Schneimler, Diesel combustion process with hydrogen for passenger car applications, dissertation at the Technical University of Graz, 2011, compiles the specifics and peculiarities required in the hydrogen operation of internal combustion engines from investigations carried out. Both charge exchange and combustion differ from conventional operation of internal combustion engines with liquid fuels and require special technology for introducing hydrogen or other gaseous fuels into the combustion chamber of these internal combustion engines.Examples of prior art, in which gaseous fuel is introduced into the intake tract of an internal combustion engine via a corresponding gas valve, are EP 3 225 827 A1, according to which the valve element of the gas valve is actuated by means of a magnetic actuator for supplying the gaseous fuel and in which two sealing regions are provided, DE 10 2004 049 589 A1, which describes a hydrogen engine with an optimized fuel injection device, by means of which hydrogen opens into the intake duct via a hydrogen duct and is introduced from there into the combustion chamber of the hydrogen engine, and DE 3904480 A1, in which gaseous fuel, for example hydrogen, is introduced intermittently into an intake pipe of an internal combustion engine, wherein the valve element can be actuated electrically.Examples in the prior art for injecting gaseous fuel, in particular hydrogen, into the combustion chamber of an internal combustion engine are mentioned in DE 4308775 C1, in which the valve is designed as a piston valve, has the shape of a poppet valve in the opening region and is actuated by means of liquid via a control hydraulic system, U.S. Pat. No. 7,117,849 B1, in which a fuel injector introduces a gaseous fuel at high pressure via a fuel line by means of the nozzle forming the main part of the fuel injector directly into the combustion chamber of the internal combustion engine by means of a needle controlled with respect to its movement, DE 10 2009 012 688 B3, according to which a valve for injecting gas is introduced into the combustion chamber of an internal combustion engine at high pressure, wherein a closing element and an adjusting element are driven by means of a magnetic coil and are arranged movably in the housing, and EP 3 267 028 A1, in which an injection valve for injecting high-pressure natural gas can be introduced into the combustion chamber of an internal combustion engine using a controlled needle, wherein two valve seats are intended to ensure the corresponding tightness.Furthermore, EP 3 153 701 A1, DE 10 2017 218 267 A1 and DE 103 53 011 A1 likewise describe a valve for controlling a gas to be introduced into the combustion chamber of an internal combustion engine, wherein the need for a reliable seal is pointed out in these documents of the prior art. EP 3 153 693 A1 describes a high-pressure valve for gaseous fuel, which ensures a corresponding tightness with respectively arranged bellows devices. DE 10 2014 224 348 A1, DE 10 2014 224 340 A1, DE 10 2014 224 341 A1 and DE 10 2015 201 293 A1 describe high-pressure valves which all refer to two or more sealing seats for securing the tightness of such a fuel suitable for hydrogen, wherein elastomer seals are recommended in some cases which, although having good tightness, can easily damage during operation of the internal combustion engine at full load and at the same time at high temperatures, for which reason a thermal insulation element is obviously provided at one of two sealing seats in DE 10 2015 201 392 A1, wherein one of the two sealing seats consists of an elastomer sealing element, in order to keep the temperature load of the elastomer sealing element within limits. DE 10 2014 224 343 A1 describes a reliable sealing and protection of a sealing seat by means of an additional thermal protection device, and DE 10 2014 224 339 A1 describes that work is performed by means of a shielding element and a cooling ring in order to reduce the temperature load on the sealing regions.DE 10 2014 224 344 A1 describes a gas injector for injecting a gaseous fuel directly into a combustion chamber of an internal combustion engine for better and more uniform distribution of the gaseous fuel in the combustion chamber, having an additional control element in order to shape the gas jet to be injected in accordance with the geometry of the combustion chamber for better mixture formation and combustion. Finally, DE 10 2014 205 454 A1 describes a gas injector for injecting gaseous fuels, in which a double valve needle is provided, wherein an outer needle is designed as a hollow needle and an inner needle is arranged in a hollow region of the outer needle.DE 10 2016 212 075 A1 discloses a valve for injecting gaseous fuel. The valve has a first and a second sealing seat, wherein the second sealing seat is arranged axially offset with respect to the first sealing seat. Both sealing seats close or open a fluid path between a pressure chamber that can be filled with gaseous fuel and injection openings via which the fuel reaches the combustion chamber of an internal combustion engine. At least one sealing seat is flexible.DE 10 2014 200 756 A1 shows a gas injector which has a valve needle with a conical tip, which is arranged on the valve seat, and at the same time has control edges, which form a gas control region, in a lateral surface region of the valve needle. During a stroke of the valve needle, a change in the first cross-sectional area at the valve seat is different from a change in the second cross-sectional area at the gas control region, wherein an elastomer is used as the sealing element.DE 10 2008 001 111 A1 describes a method and a device for operating an internal combustion engine, wherein the liquid fuel can be injected directly into the combustion chamber via at least one first injection valve and into an intake pipe via at least one second injection valve.DE 10 2014 212 549 A1 discloses a gas injector for injecting gaseous fuel, which comprises a gas damping device with a gas-filled damping chamber, which is bounded by a movable injector component and is connected to the injector chamber via a first connecting path, so that gaseous fuel is also located in the damping chamber.The known injectors or gas or hydrogen injection valves for internal combustion engines have been adapted to different operating conditions, but as a rule only with respect to one or at most two defined operating conditions, which should be covered with the respective construction.For use under two different operating conditions, it is normally always necessary here for compromise to be made for both operating conditions in the technical design; that is, an optimum design was not technically targeted.It is therefore the object of the present invention to provide an internal combustion engine with a high-pressure valve and a high-pressure valve for an internal combustion engine for gas operation, preferably hydrogen operation, which realizes improved operating conditions, an optimum gas operation, very short switching cycles and control with regard to optimized properties of the combustion as well.This object is achieved by an internal combustion engine for hydrogen operation having the features according to claim 1 and by a high-pressure valve for hydrogen operation provided for this internal combustion engine according to claim 9. Practical further developments are defined in the dependent claims.The hydrogen-operated internal combustion engine according to the invention has, in a manner known per se, a cylinder in which a combustion chamber is formed and a piston is guided therein. According to the invention, the internal combustion engine has a high-pressure valve which has control edges or a control valve piston which has a conical shape and is guided in a housing. By means of the control valve, hydrogen is injected or injected directly into the combustion chamber or indirectly via an inlet line of the internal combustion engine shortly before an inlet valve into the combustion chamber. The term "injecting" is used herein to equally apply a gaseous fuel in the form of hydrogen to the cylinder. The control valve piston of the high-pressure valve, which is likewise designed according to the invention, is actuated electromagnetically, for which reason short control times and high switching frequencies are realized, among other things, so that the inlet cross sections of the injection element for the hydrogen into the combustion chamber are quickly released in accordance with an optimized mixture formation and combustion in the combustion chamber. The control valve piston has in the housing between the combustion chamber and a damping cushion a first, closing and opening elastomer-free and a second, always closing elastomer-free sealing region, which are designed in such a way that a return flow of a fundamentally possible small quantity of the combustion gas, in the form of hydrogen upon contact with oxygen, does not cause a back ignition to occur. This means that the high-pressure valve has a high and reliable sealing effect both with respect to the combustion chamber and with respect to the damping cushion in the closed state. In order that short control times and high switching frequencies of the high-pressure valve can be realized, this is designed to be light-weight-reduced in construction. The seal is therefore designed in such a way that only very small amounts of hydrogen flow back, if any, such that, when these very small amounts of hydrogen are in corresponding contact with oxygen, no restriking occurs, which can also be referred to as explosion.For the hydrogen operation of an engine, the gaseous fuel in the form of hydrogen is stored in filled hydrogen cylinders at about 350 bar. This pressure of the reservoir naturally does not correspond to the injection pressure in the case of liquid fuels, as is currently implemented, for example, with common rail systems and as is used, in particular, for internal mixture formation. For this reason, the supply pressure must be interrogated by means of sensors upstream of the valve or the injection nozzle or the injection valve into the cylinder and the opening time or the opening path of the supply of gaseous fuel, in particular hydrogen, must be regulated on the basis of this pressure information or as a function thereof. However, it is also possible for a pressure reduction to be implemented before the gaseous fuel is supplied under the above-specified high pressure, so that the opening time or the opening travel of the supply is substantially constant in the same operating state in each case. Depending on the operating condition, the pressure range for the gaseous fuel can be between 20 and 350 bar.In addition to the high-pressure valve, the internal combustion engine preferably has an injector for finely metering combustion gas or hydrogen into the combustion chamber. In such a preferred embodiment of the internal combustion engine, two introduction elements for combustion gas or hydrogen are thus present into the combustion chamber. The high-pressure valve is primarily provided for the introduction of relatively large amounts of gaseous fuel or hydrogen into the cylinder, whereas the injector enables the fine metering of relatively small amounts of gaseous fuel or hydrogen into the combustion chamber at defined and entirely short times or time intervals.Further preferably, the injector is designed such that an intermittent or multistage supply of the hydrogen can be carried out directly into the combustion chamber. Intermittent feeding is to be understood to mean that the introduction of hydrogen is possible in a non-continuous manner, i.e. at precisely defined and controllable intervals, so that a direct improvement or optimization of the combustion in the combustion chamber can be achieved by the fine metering.The high-pressure inlet valve is preferably designed for blowing in larger amounts of, for example, hydrogen than the injector which introduces smaller amounts of hydrogen into the combustion chamber for optimizing combustion. Preferably, larger amounts mean multiples of the smaller amounts of gaseous fuel injected with the injector.Preferably, in the sense of the lightweight construction of the high-pressure valve, in particular its control valve piston is of hollow design, wherein the wall thickness and shape are formed with a high rigidity, so that the lightweight construction is realized by a weight reduction, in particular of the control valve piston, without the required strength of the components suffering.Instead of a design of high-pressure valve and injector from steel, it can therefore preferably be provided that the high-pressure valve and / or the injector are designed from ceramic or from ceramic-coated light metal. In addition, the moving parts in the high-pressure valve and in the injector can be formed hollow and ceramic-coated in the sense of a lightweight construction.According to a further exemplary embodiment, the high-pressure valve can preferably comprise other metal alloys. This ensures that the parts moving in the high-pressure valve and in the injector have a corresponding strength and rigidity, but are nevertheless reduced in weight and therefore reduced in mass as compared with a steel alloy because of the significantly lower density of light metal alloys.According to a preferred embodiment, the control valve piston of the high-pressure valve is provided in its housing with a guide piston on which the control edges are formed, which interact with a hydrogen supply line. The control edges release the points in time of the supply of gaseous fuel, in the form of hydrogen, and the size of the supply cross sections and thus of the quantity of gaseous fuel which is introduced into the cylinder, but on the other hand also close the supply cross sections at defined points in time after the desired quantity of gaseous fuel has been injected.According to a further preferred exemplary embodiment, injection bores which are arranged in the form of a ring are formed on a surface of the high-pressure valve facing the combustion chamber and are arranged concentrically in the axial direction in the high-pressure valve. This means that the substantially planar ring surface of the high-pressure valve has injection or injection bores arranged on an imaginary circular line in this ring surface of annular design. These injection holes are concentrically arranged in the outer rim of the high-pressure valve in the axial direction. The concentrically arranged injection holes therefore make it possible to introduce a relatively large gaseous quantity of fuel into the cylinder in short time units.The high-pressure valve of the internal combustion engine furthermore preferably has a gaseous damping cushion, into which the control valve piston dips in the housing in the region of its end positions for stop avoidance or for stop damping. This prevents the control valve piston in its end position from striking with its corresponding piston surface on corresponding counter surfaces in the housing. When dimensioning the control of the control valve piston or of the high-pressure valve overall, the existing damping cushion is correspondingly incorporated into the control concept so that the slight delay of the movement of the control valve pistons occurring in the end positions has no adverse influence on the introduction of gaseous fuel, in particular hydrogen, into the combustion chamber.According to a further exemplary embodiment, the internal combustion engine according to the invention for gaseous fuels, in the form of hydrogen, has a high-pressure valve which is arranged preferably standing in the cylinder head with respect to the axial alignment of the combustion chamber, wherein introduction cross sections or injection cross sections are opened or closed by the control valve piston by means of its control edges, injection lines for the hydrogen which are arranged radially in the housing of the high-pressure valve, as a function of a piston position. The stationary arrangement of the high-pressure valve has the advantage that the space which is already present in the cylinder head in any case to a limited extent can be accommodated in terms of space for the arrangement of an additional valve which is arranged in addition to the inlet and outlet valves which are already arranged in the cylinder head.According to a further aspect of the invention, a high-pressure valve for an internal combustion engine has the following: a) a housing; b) a control valve piston guided in the housing, having control edges which delimit cylindrical piston side surfaces and cooperate with guide surfaces formed in the housing, or having a conical shape cooperating with a conical seat surface in the housing; c) outflow cross sections which can be released or re-closed by means of the guide surfaces and the control edges or the conical shape and the conical seat surface when the control valve piston is moved axially in a corresponding manner; d) a control valve piston which implements electromagnetic actuation for the high switching frequencies; e) first and second sealing regions which are formed without elastomer and are provided at least in two stages in the housing for sealing the control valve piston in the housing when the outflow cross sections are closed; f) a formation of the sealing regions provided in such a sealing manner that only very small amounts of hydrogen return flow are allowed to pass through in such a way that no back ignitions occur; and g) the control piston formed in a weight-reducing lightweight construction and constituting a movable element of the high-pressure valve.The elements defining the high-pressure valve according to the invention form a high-pressure valve which is designed for hydrogen and with the synergy present between the individual features a high-pressure valve is provided for the first time, which high-pressure valve fully meets the requirements for operating an internal combustion engine with hydrogen and not only locally for individual requirements, as was previously only the case in the prior art.Further advantages, details and possible applications of the present invention will now be described with reference to exemplary embodiments with reference to the following drawing. In the drawing, the following are shown: FIG. 1 : a first exemplary embodiment of a high-pressure inlet valve according to the invention in the closed position with a poppet valve; FIG. 2 : shows a high-pressure inlet valve according to FIG. 1 in the open position; FIG. 2a shows a control valve piston of the high-pressure inlet valve of lightweight construction; FIG. 3 : a sectional view through the housing and the shaft of the control valve piston according to a further exemplary embodiment; FIG. 4 : shows a further exemplary embodiment of the high-pressure inlet valve according to the invention, having a control valve piston with two cylindrical guide pistons which are guided in guide surfaces in the interior of the valve housing, wherein a multiplicity of axial injection bores for introducing the gaseous fuel into the combustion chamber is provided in the manner of a ring; FIG. 5 : shows the high-pressure inlet valve according to FIG. 4, but in the passage position for supplying gaseous fuel through the high-pressure inlet valve into a combustion chamber of an internal combustion engine; FIG. 6 shows an exemplary embodiment according to FIGS. 4 and 5, but with injection bores which have a diverging direction with respect to the longitudinal axis of the control valve piston; FIG. 7 shows an exemplary embodiment according to FIG. 6, but with injection bores which have a converging direction with respect to the longitudinal axis of the control valve piston; FIG. 8 shows a further exemplary embodiment of a high-pressure inlet valve in the closed position according to the invention with inlet and outlet for gaseous fuel in planes arranged offset with respect to one another; FIG. 9 : shows the exemplary embodiment of the high-pressure inlet valve according to the invention according to FIG. 8, but in the open position; FIG. 10 is a detailed sectional view of the arrangement of the high-pressure inlet valve according to the invention in the cylinder head of an internal combustion engine in the passage position for introducing gaseous fuel into the inlet line; FIG. 11 is a detailed sectional view of a cylinder and a cylinder head with a built-in high-pressure inlet valve according to the invention in the open position; FIG. 12 a : shows a high-pressure inlet valve according to the invention with a poppet valve as first pressurization region and with a cylindrical guide piston with an annular surface as second pressurization region and with additional piston for opening and closing the valve; FIG. 12 b : shows the high-pressure inlet valve according to FIG. 12 a, but in the open position for entry of gaseous fuel into the cylinder through the interior of the additional piston and the poppet valve seat region; FIG. 12 c : a sectional view through the stem of the control valve piston of the high-pressure inlet valve according to the invention, with a view of the additional piston in section A-A (cf. FIG. 12 b ); FIG. 13 : shows a high-pressure inlet valve according to a second exemplary embodiment, in which the second pressurizing region in the form of a cylindrical guide piston is dimensioned larger with respect to the effective annular surface than the effective annular surface of the first pressurizing region in the form of a poppet valve; FIG. 14 shows a high-pressure inlet valve for the method according to the invention in a sectional illustration with a closed state; FIG. 15 : the high-pressure inlet valve according to FIG. 14 in the open state; FIG. 16 : shows a detailed sectional view of a cylinder and a cylinder head with an installed high-pressure inlet valve according to the invention in the passage position and with an injector in the closing position, each with a direct inlet into the combustion chamber of the cylinder; FIG. 17 : a detailed sectional view of a cylinder and a cylinder head with an injector according to the invention installed in its closed position in a sectional plane for illustrating the inlet valve, but not the high-pressure inlet valve; and FIG. 18 : shows a detailed sectional view of a cylinder and a cylinder head with an injector according to the invention installed and a corresponding sectional plane, with a high-pressure inlet valve, not shown, but with an injection nozzle provided for dual fuel operation of the internal combustion engine.In the following description of the figures, hydrogen is generally described as fuel. It is understood that other gaseous fuels are also possible.FIG. 1 shows a cross-section of a high-pressure inlet valve 4 according to the invention. The valve has a housing 6, within which a control valve piston 5 is guided. For this purpose, the control valve piston 5 has a region which is designed as a cylindrical guide piston 5.3 and is guided in the housing 6 so as to slide on a guide surface 16 which is designed to be congruent in shape with the cylindrical guide piston 5.3. The diameter of the cylindrical guide piston 5.3 of the control valve piston 5 is greater than that of a shank 5.4 which extends from the cylindrical guide piston 5.3 downwards in the direction of an inlet opening in the form of a hydrogen inlet 20 in the direction of a combustion chamber 1 (see for example FIG. 11 ). On the side of the cylindrical guide piston 5.3 opposite thereto, an extension of the shaft 5.4 of the control valve piston 5 is provided with an insert in which a spring 22 is arranged, which serves for closing the high-pressure inlet valve 4, with which pre-compressed hydrogen is introduced into the combustion chamber 1 of an internal combustion engine. A pressure force F N( see the vertically downward pointing arrow in the top of FIG. 2 ), presses the control valve piston 5 downward by an opening stroke 21 of the high-pressure inlet valve 4, so that the outflow cross section 18 is fully open, i.e. the high-pressure inlet valve 4 is in the passage position 4.2.FIG. 1 illustrates the closing position 4.1 of the high-pressure inlet valve 4. In the outflow cross section 18 (see FIG. 2 ), a closing plate 5.5 closes in the manner of a poppet valve with a conical seat surface 17 (see FIG. 2 ) formed in the housing 6 and thereby prevents a passage of hydrogen, the hydrogen inlet 20 of which is provided on the left side through an inlet opening. The hydrogen itself is indicated by the horizontally right-pointing arrow. In the closed position 4.1 of the high-pressure inlet valve 4, the control valve piston 5 is immersed with its upper annular surface 25 oriented in the direction of the spring insert in a chamber 23, which is connected to the outside via a venting bore 24. When the control valve piston 5 dips with its upper annular surface 25 of the cylindrical guide piston 5.3, non-compressed air is forced out of the chamber 23 provided there (see FIG. 2 ) via the venting bore 24.An essential criterion for the mode of operation of the high-pressure inlet valve 4 according to the invention is that the annular surface 25 facing the passage channel forms a second pressurizing region 26 and the closing plate 5.5 of the poppet valve, which faces the passage region 28 for the hydrogen, forms a first pressurizing region 27. The first pressurizing portion 27 forms a projected area formed perpendicular to the longitudinal axis of the control valve spool 5, and has a size approximately equal to the projected area of the annular surface 25 on the cylindrical guide spool 5.3 of the control valve 5, i.e., approximately equal to or equal to the projected area of the second pressurizing portion 26. Due to this surface equality of the projected surfaces, no relevant resulting axial forces are present, namely independently of the level of the pressure of the hydrogen provided for the inlet into the combustion chamber 1 of an internal combustion engine. The control valve piston 5 itself is pressed by means of a cam, a camshaft or another drive device or, for example, an electromagnetic actuating device against the spring force F N from its closed position 4.1 into its open position 4.2 and, when the cam is released, is brought rapidly back into the closed position 4.1 by the action of the spring force F N corresponding to its strength, in which the closing plate 5.5 of the poppet valve strikes against the conical seat surface 17 and seals it there (see also FIG. 13 ). In Fig. 1, the stem 5.4 of the control valve piston 5 of the high pressure inlet valve 4 comprises a control valve piston having a cavity, i.e. having a hollow stem (see Fig. 2a). For simplicity, the axially extending bore provided in the stem of the control valve piston 5 is not shown in FIG. 2 and in FIG. 3. The cavity in the interior of the shaft 5.4 of the control valve piston 5 extends substantially over the greatest possible length of the shaft 5.4. On the one hand, this achieves the effect that a significant weight reduction is realized for use in hydrogen operation. In conjunction with the electromagnetic drive 9 shown schematically, very short reaction times and thus also high switching frequencies can be realized because of the reduced weight of the control valve piston 5, which are required in particular for hydrogen operation. In addition, in the lower end of the control valve piston 5 facing the combustion chamber, a ceramic coating is provided, especially in the first pressurization region 27. For reasons of further weight savings, it is also possible for the entire control valve piston 5 to consist of ceramic.FIG. 2 illustrates the high-pressure inlet valve 4, in which the control valve piston 5 is however in the passage position 4.2, which is indicated by the arrow in the outflow cross section 18. When the outflow cross section 18 is open, the passage region 28 for the hydrogen is opened, so that the hydrogen flows at high pressure and thus also at high flow speed between the sealing seat 17 and the closing plate 5.5 and reaches the combustion chamber 1 (not shown) of the internal combustion engine. The chamber 23 formed with the spring 22 on the upper side of the cylindrical guide piston 5.3 when the control valve piston 5 is pressed downward by the opening stroke 21 is clearly visible. This chamber 23 is provided with a venting bore 24, so that when closing takes place the upper annular surface of the cylindrical guide piston 5.3 dips into this chamber 23 and the non-compressed air located there presses outwards via the venting bore 24. The diameter of this venting bore 24 is selected such that no appreciable throttling effects occur, so that when the cylindrical guide piston 5.3 dips into the chamber 23 (when the valve is closed), no pressure cushion which forms a high resistance arises, but rather only a certain damping cushion arises.In FIG. 2 a, the control valve piston 5 is designed hollow for weight reduction and has a hollow space 44 in the interior of the shaft and of the plate. To achieve a further weight reduction, the guide piston 5.3 is provided on its end faces 25, 26 with weight-reducing recesses 43. These recesses 43 make it possible for the guide piston 5.3 to be relatively long in its longitudinal extension even with a greatly reduced mass, which results in an improved sealing effect between the piston side surface 15 and the guide surface 16 (see FIG. 1, for example).FIG. 3 shows a sectional view through a sectional plane through the valve parallel to the valve disk plane, which shows guide webs 29 running radially from the shaft 5.4 between the shaft 5.4 and the housing 6. These guide webs 29 ensure additional stability for exact axial and additionally radial guidance of the control valve piston 5 in the housing 6, which is important for reliable sealing of the cylindrical piston side surfaces 15 of the cylindrical guide piston 5.3 on the similarly cylindrically correspondingly configured accurately fitting guide surfaces 16 in the housing 6.FIG. 4 shows a further exemplary embodiment of the high-pressure inlet valve 4 according to the invention, in which the control valve piston 5 has two cylindrically formed guide pistons 5.3, which are guided in corresponding guide surfaces 16 of complementary shape. For this purpose, three cylindrical guide surfaces 16 of a shape-matching configuration are provided in the interior of the housing 6. FIG. 4 shows the closed position 4.1 of the control valve piston 5 within the housing 6.In the closed position 4.1 shown in FIG. 4, the cylindrical guide piston 5.3, which is larger in its axial length and is shown in the lower part of the high-pressure inlet valve 4 shown, is provided for opening and closing the actual axial hydrogen injection bore 13. For this purpose, in the housing 6 in the closed position 4.1 shown in FIG. 4, the feed lines are covered with the cylindrical guide surfaces 16 by injection bores 13 arranged in the manner of a ring in the circumference of the end face 25 of the high-pressure inlet valve 4 which is supplied to the combustion chamber, so that passage of the hydrogen from the hydrogen inlet line 20 is blocked.Below the piston top side, a chamber 23 is formed, into which the lower cylindrical guide piston 5.3 dips in order to open the axial injection holes 13. In order that no counterpressure forms in the air present in the chamber 23, a venting bore 24 is provided in the interior along the longitudinal axis of the control valve piston 5 and radially in the housing 6. Given appropriate dimensioning of the venting bore 24, throttling can be avoided to the greatest possible extent, but it can nevertheless still be ensured that a certain damping function is built up. The damping function prevents a hard strike of the upper side, in the case of the illustration according to FIG. 4, of the upper cylindrical guide piston 5.3 from occurring in the interior of the housing 6 at the bottom of the chamber 23. The annular surfaces 25 facing the passage region 28, i.e. the first and second pressurization regions 27, 26 of the cylindrical guide pistons 5.3 of the control valve piston 5, are dimensioned such that they are of the same size. This ensures that no additional resulting axial forces are generated independently of the pressure at which the hydrogen enters the passage region 28 in the interior of the housing 6 of the high-pressure inlet valve 4. Thus, independently of the pressure of the hydrogen to be introduced into the combustion chamber 1, the high-pressure inlet valve 4 can be opened against the action of the spring 22 merely by means of a corresponding drive, for example a cam or a camshaft or an electromagnetic actuation 9, and can be closed using the spring 22.FIG. 5 shows how this opening force F N applied by a cam or an electromagnetic actuation dips the control valve piston 5 into the chamber 23, with the result that the radially directed feed regions leading to the axial injection bores 13 are open in the manner of an annular chamber and the hydrogen can be introduced from the outflow cross section 18 into the cylinder or combustion chamber 1 of the internal combustion engine. By opening the high-pressure inlet valve 4, the chamber 23 is formed on the upper cylindrical guide lobe 5.3 for guiding the control valve piston 5 in the housing 6 on the corresponding guide surface 16. This chamber 23 is also connected to a venting bore 24, so that when the closing movement is carried out by the control valve 5, i.e. when it is moved upward in the drawing, the air located in the chamber 23 can escape via the venting bore 24. The axial injection bores 13 are preferably arranged equidistantly; however, an irregular arrangement can also be provided, in particular if the air flow into the combustion chamber 1 is to be used thereby to improve the mixture formation.FIG. 6 shows a detailed sectional view of the region of the axial injection bores 13, i.e. of the lower region of the high-pressure inlet valve 4, in which, in contrast to the embodiment according to FIGS. 4 and 5, the injection bores 13 are arranged divergingly with respect to the longitudinal axis of the control valve piston 5. The other geometric conditions correspond to those of FIGS. 4 and 5.FIG. 7 shows an exemplary embodiment in the form of a detailed region according to FIG. 6, wherein, however, the injection bores 13 are arranged convergingly with respect to the longitudinal axis of the control valve piston 5. However, it is also possible that in a single embodiment, both diverging and converging injection bores 13 are provided with respect to the longitudinal axis of the control valve piston 5.FIG. 8 shows a further exemplary embodiment of a high-pressure inlet valve 4 according to the invention, the basic design of which with respect to housing 6 and spring insert corresponds to the previous exemplary embodiments, so that these parts will not be described again in more detail here. The high-pressure inlet valve 4 shown is in its closed position 4.1 of the control valve piston 5. The hydrogen under high pressure is present at the hydrogen inlet line 20, coming from a high-pressure line, not shown. In the closed position 4.1, the lower cylindrical guide piston 5.3 covers this passage region 28, so that no hydrogen can enter the passage region 28 and finally the combustion chamber 1 (see FIG. 10 ) of the cylinder. Facing the passage region 28 are two annular surfaces 25 which have the same size, so that no resulting axial forces are present irrespective of the pressure of the hydrogen fed in. A displacement of the control valve piston 5 is therefore to be applied merely against the force of the spring 22. Below the front side of the large cylindrical guide piston 5.3 is again the chamber 23, so that when the control valve piston 5 is displaced, it dips into the chamber 23 and thus ultimately, when the opening stroke 21 is carried out, the open position 4.2 of the control valve piston 5 shown in FIG. 9 is reached. In the open position 4.2, the hydrogen can flow via the hydrogen inlet line 20 from the lower plane to the upper plane of the recess of the passage region 28 into the housing 6 and finally to the outflow cross section 18, from where the hydrogen can flow directly into the combustion chamber 1 of the internal combustion engine (not shown) or indirectly via an inlet line into the combustion chamber 1.In order to ensure reliable guidance of the control valve piston 5 in the housing 6, the lower larger cylindrical guide piston 5.3 is guided on guide surfaces 16 of shape-matching design into the chamber 23. In the closed position 4.1 according to FIG. 8, this cylindrical guide piston 5.3 is then guided in the lower region and in the intermediate region on corresponding guide surfaces 16, wherein the intermediate region is arranged between the lower plane on the hydrogen inlet line 20 and the passage region 28 in the upper plane on the outflow cross section 18. And finally, the smaller cylindrical guide piston 5.3 is the upper one, which is arranged in the direction of the spring insert, guided in a sliding manner on a third guide section 16.While FIG. 8 shows the high-pressure inlet valve 4 in its closed position 4.1, FIG. 9 shows its through-position 4.2.FIG. 10 shows an exemplary embodiment of how a high-pressure inlet valve 4 according to the invention can be arranged in the cylinder head 30 of an internal combustion engine in its inlet line 7. The high-pressure inlet valve 4 is driven by means of a cam, which is not shown and which preferably belongs to a camshaft, but can of course also be driven by an electromagnetic actuator, so that in the case of a camshaft drive, the spring 22 present in the spring insert can be compressed when the cam is engaged. The compression of the spring 22 and thus the opening of the high-pressure inlet valve are likewise achieved by an electromagnetic actuator 9. By compressing the spring 22, the hydrogen, which is guided via the high-pressure line 32 to the hydrogen inlet line 20 and from there reaches the outflow cross section 18 through the high-pressure inlet valve 4 via the illustrated passage position 4.2 and via the passage region 28 thereof, reaches the combustion chamber 1 via the inlet line 7 and the inlet valve 8 at high pressure. On the left of the top side of FIG. 10, an outlet valve 33 is shown, which is in the closed state, so that the gaseous fuel cannot escape into the exhaust line. In cylinder 3 a piston 2 is shown which is connected by means of a piston pin 34 and a connecting rod 35 to a crankshaft, not shown. The high-pressure inlet valve 4 can now preferably be controlled in such a way that, basically at almost any position during the movement of the piston 2 from the bottom dead center to the top dead center, individual amounts of hydrogen can be filled into the cylinder in a time-directed manner in conjunction with the control of the inlet line valve 46.Finally, FIG. 11 shows a cylinder 3 with a cylinder head 30 according to FIG. 10, but with both a high-pressure inlet valve 4 and an injector 10. The high-pressure inlet valve 4 is arranged in the cylinder head 30 in its passage position 4.2 such that hydrogen can be injected directly into the cylinder 3 together with the combustion air from the inlet line 7 via the outflow cross section 18 in relatively large quantities. In addition, the injector 10, to which a high-pressure line for hydrogen is connected and which in the open position 4.2 of the injector 10 indirectly feeds hydrogen into the combustion chamber 1 via the inlet line 7 in targeted amounts at desired times for direct influencing of the later mixture formation and combustion in the combustion chamber 1, is arranged in the cylinder head. The piston 2 in the cylinder 3 is connected by means of its connecting rod 35 and via the piston pin 34 to a crankshaft (not shown).In Fig. 12a, a further embodiment of the high pressure inlet valve 4 according to the invention is shown. In FIG. 12 b, this high-pressure inlet valve 4 is shown in the open position. The closed position of the high-pressure inlet valve 4 shown in FIG. 12a is reached in the position of the control valve piston 5, in which the hydrogen inlet line 20 closes off in the interior of the housing 6, hydrogen being supplied at high pressure when it is opened, namely a valve disk or closing disk 5.5 of a poppet valve seated sealingly in a valve seat and thus likewise arranged sealingly to supply hydrogen into the combustion chamber 1. The closing plate 5.5 of the poppet valve merges continuously into the shaft 5.4 in the usual manner for such valves which are used in the cylinder head 30 of internal combustion engines. In the region of the shaft 5.4 located in the housing 6, the control valve piston 5 has a cylindrical guide piston 5.3 or a guide surface 16, which forms an annular surface 25 which points in the direction of the passage region 28. On a side opposite the annular surface 25, the shaft 5.4 has a closing plate 5.5 of the poppet valve, which preferably forms a sealing seat 17 or valve seat 17 with the housing 6 at an angle of 45 degrees.The sealing force of this valve seat 17 is ensured by the spring 22, which is held under prestress in the housing 6 by means of a yoke-like support ring 37. The annular surface 25 and the effective surface of the poppet valve closing plate 5.5 projected into a plane perpendicular to the longitudinal axis of the control valve piston 5 are both of the same size, so that the pressure of the hydrogen which reaches the passage region 28 for introduction into the cylinder 1 when the high-pressure inlet valve 4 is open (see FIG. 12 b ) loads the pressurizing surfaces 27 and 26 against one another without any significant resultant surfaces. As a result, without additional forces to the compression spring 22, a displacement of the control valve piston 5 in the housing 6 is realized. In the region of the shaft 5.4, the control valve piston 5 has an additional piston 38 which likewise has a cylindrical guide surface 15 on its outer periphery, which guide surface is guided on corresponding guide portions 16 of shape-conforming configuration in the housing 6. The axial dimension of this additional piston 38 is now such that in the position as shown in Fig. 12a, i.e. in which the supply of hydrogen is blocked, the additional piston 38 interrupts the cross section of the supply line of the high pressure hydrogen. For this purpose, the additional piston 38 as well as the guide pistons 5.3 or guide surfaces 15, 16 are ground in in order to ensure a corresponding sealing force and tightness. A second sealing surface is formed in the valve seat 17 of the poppet valve, the sealing force being determined by the spring force of the spring 22. Between the upper side of the guide piston 5.3 shown in FIG. 12a, which points to the side with the spring 22 from high pressure of a valve, a pressure chamber is formed, which can be vented via a venting bore 24 when the control valve piston 5 is compressed accordingly, i.e. when it moves upward.In the case of a corresponding force acting against the spring force of the spring 22 for adjusting the slide valve piston 5 in the housing 6, air is sucked in again via this venting bore 24, so that no appreciable negative pressure arises in the pressure chamber 23 present between the upper side of the cylindrical guide piston 5.3 and the housing 6.In Fig. 12b, the high pressure inlet valve 4 according to Fig. 12a is shown, but in the open position. For this purpose, the control valve piston 5 is displaced downwards in the illustration shown counter to the action of the spring force of the spring 22, so that the additional piston 38 releases the cross section of the hydrogen inlet line 20 via the passage region 28 at the seat region 17 of the closing plate 5.5 of the poppet valve and hydrogen can be forced into the combustion chamber 1 (not shown) at high pressure. The other elements and functions are identical to those of FIG. 12a and will therefore not be described again here. It can be seen from FIG. 12 b that the additional piston 38 is slidingly displaced on the ground-in cylindrical guide surfaces 16 formed in the interior of the housing 6, i.e. in the interior of the passage region 28, so that the hydrogen under high pressure can ultimately flow into the cylinder 1.Finally, FIG. 12 cshows a sectional view through the control valve piston 5 in its lower part of the shaft 5.4, viewed along the section A-A (cf. FIG. 12 b) onto the additional piston 38. The piston 38 has a cylindrical piston side surface 15 on its outer periphery, which is ground in and cooperates in a sealing manner in a manner conforming to the shape of the guide surfaces 16 correspondingly formed in the housing 6. The interior of the piston 38 is made stable enough by webs 39, between which openings 40 are located, and thus makes it possible to allow the hydrogen to flow through when the hydrogen inlet is released, in order subsequently to flow past the region of the valve seat 17 of the closing plate 5.5 of the poppet valve into the combustion chamber 1. This is shown by the arrows indicating the flow path. In addition, the control valve piston 5 is reliably and accurately guided by the cylindrical piston side surfaces 15 in the upper part of the housing 6, since these regions are also ground in.Finally, FIG. 13 shows a further exemplary embodiment in which the effective pressurization regions 27, 26 facing the passage region 28 in the interior of the housing 6 have a different size. FIG. 13 shows a state of the high-pressure inlet valve 4 in which the supply of hydrogen into the combustion chamber 1 does not take place by the control valve piston 5. Because the second pressurization region 26, which is designed as an annular surface 25, is designed larger than the first pressurization region 27 at the transition of the closing plate 5.5 of the poppet valve to its shaft 5.4, the housing 6 is designed in two parts, so that a corresponding assembly of the control valve piston 5 and of the guide piston 5.3 into the interior of the housing 6 can take place. The guide piston 5.3 must be mounted on the control valve piston 5 by an additional mounting in a mounting embodiment not shown in detail. Otherwise, the basic structure is analogous to that described in FIG. 12. Because the area of the second pressurizing portion 26 is larger than that of the first pressurizing portion 27, a greater closing force of the poppet valve closing plate 5.5 in the region of its seat 17 is ensured in conjunction with the high pressure of the hydrogen. In this respect, the imbalance on the basis of the effective areas of different sizes is profited. The high force thereby achieved ensures a significantly improved sealing performance of the valve seat 17 during operation of the engine. The principle of the operation of such a high pressure valve 4 is that which is similar to a pneumatic cylinder.In addition to the illustration in FIG. 12, FIG. 13 also shows a securing ring 41, which prevents the support ring 42 from being released during operation, since the support ring 42 is placed on the upper shaft part of the control valve piston 5, with the result that the spring tension is set. The control valve piston 5 shown in FIG. 13 is sealed with its guide piston 5.3 against the chamber 23. In the direction of the valve disk 5.5, a conically designed region is present in the interior of the housing 6. The further sealing region is the conical seat formed directly on the poppet valve. The latter ensures reliable sealing of the hydrogen supply line with respect to the combustion chamber 1, whereas the guide piston 5.3 forms an additional sealing surface between the hydrogen supply region and the chamber 23. It is also possible in principle for the guide piston 5.3 in the second pressurization region 26 to be smaller than the first pressurization region 27.FIGS. 14 and 15 show in a sectional illustration two positions of the high-pressure inlet valve 4 in a further embodiment of the invention in the closed state (FIG. 14 ) for realizing the function of the high-pressure inlet valve 4, whereas in FIG. 15 this high-pressure inlet valve 4 is illustrated in the open position.The high-pressure inlet valve 4 has a piston part formed from a piston tappet 100 and a piston 200 and guided in a housing 300. The piston 200 has a circumferential piston groove 50 forming a control edge 45, which has a region with a recess in relation to the outer maximum diameter of the piston 200. In the position according to FIG. 14, the piston 200 forms within the housing 300 on its end face or piston top side, which lies opposite the piston plunger 100, a valve chamber 90, which is closed on the end face of the high-pressure inlet valve 4 by means of a cover plate 60. Between the cover plate 60 and the end face of the piston 200, the valve chamber 90 forms, as it were, an air cushion into which the piston 200 moves with its stroke 101, so that at the short times required for the inlet processes for hydrogen into the cylinder, it is prevented that the piston 200 could strike the cover plate 60.In FIG. 15, it is shown that the valve chamber 90 is vented via a venting bore 70, which is guided through the piston part in the region of its longitudinal axis. Particularly at higher rotational speeds of the internal combustion engine, the charge change in the cylinder, based on absolute time scales, must be carried out in very short time periods. Therefore, the high pressure inlet valve 4 and, as an essential core element thereof, its piston 200 must also execute very fast movements for opening and closing, i.e., for controlling the supply of hydrogen. Lightweight construction is an essential feature for the realization of higher switching frequencies.At the dead points during the movement of the piston 200 of the high-pressure inlet valve 4, relatively large acceleration and deceleration forces occur due to the mass inertia of this component. The space changing on the piston top side during the movement of the piston 200, i.e. the valve chamber 90, leads to a damping of the piston movement due to the compression of the air located therein, for which reason a venting bore 70 is provided in the interior of the piston 200 in the region of its longitudinal axis. The diameter of the venting bore 70 is now designed such that during the rapid movement of the actual piston of the piston 200, the air is pressed out of the valve chamber 90 at least for the most part via the venting bore 70. The diameter of the venting bore 70 is only so large that only so much air remains in the valve chamber 90 that, during the rapid movement of the piston 200 and its inertia, a stop from its piston top side does not strike the inner termination of the high-pressure valve 4 formed by the cover plate 60 in this exemplary embodiment. On the other hand, upon rearward movement of the piston away from the top plate 60 toward its position, the vent bore 70 must be capable of interrupting the passage of hydrogen through the high pressure inlet valve 4 to permit return flow to refill the valve chamber 90. The vent hole 70 is therefore of such a diameter that substantially the air in the valve chamber 90 can be discharged or returned to this chamber, but in the presence of some slight throttling function, so that no vacuum or negative pressure occurs in this valve chamber 90 during the reciprocating movement of the piston 200 in the housing 300 of the high pressure inlet valve 4. The part of the air remaining in the valve chamber 90 serves at least during the movement of the piston top side in the direction of the cover plate 60 a certain damping effect in which, among other things, a certain damping cushion forms also because of the still present throttling effect of the venting bore 70, whereby a striking of the piston top side on the inner side of the cover plate 60 is prevented or a striking is at least counteracted. The venting bore in the shaft of the piston 200 already represents a measure for reducing mass in the sense of supporting fast or high switching frequencies.On the side of the piston 200 opposite the end face of the piston, on which the piston tappet 100 is arranged, a lower or rear valve chamber is arranged within the housing 300 between the lower side of the piston and the passage opening of the piston tappet 100 through the material of the housing 300, which chamber likewise has a damping function analogous to that described on the upper side of the piston. For this purpose, a venting bore 70 is also provided from this damping chamber on the piston bottom side, which is designed and functions analogously to the venting bore 70, which is guided through the piston part in the longitudinal direction and has a connection to the valve chamber 90.In the upper region of the housing 300 of the high-pressure inlet valve 4, the piston tappet 100 is surrounded by a spring which is arranged in a housing recess 130 and is held by a guide plate flanged upward onto the housing recess 131. The piston thus works against the spring 80 which is compressed or expanded depending on the direction of movement within the piston stroke 100.In the position of the piston 200 shown in FIG. 14, its control edge 45 is located above a channel for supplying 121 hydrogen under high pressure to the cylinder, which channel is arranged transversely to the direction of movement of the piston 200, so that the hydrogen supply 111 is prevented by the valve. Only in the position of the piston 200 shown in FIG. 15 is the control edge 45 inserted into the channel for supplying hydrogen 121 to the cylinder, which channel extends transversely to the longitudinal axis of the piston and penetrates the housing 300 of the high-pressure inlet valve 4. When the control edge 45 has released this channel for the hydrogen supply 121 to the cylinder, the hydrogen supply 111 can flow via the piston groove 50, which runs around the piston 200 and constitutes the constriction, so to speak, with respect to the maximum diameter of the piston, in the direction of and through the channel for the hydrogen supply 121 to the cylinder. Due to the high pressure with which the hydrogen supply 111 to the valve is applied to the corresponding channel of the high-pressure inlet valve 4, after release and thus connection to the channel of the hydrogen supply 121 to the cylinder, the hydrogen under high pressure immediately passes into the cylinder.Since, during the movement of the piston 200 in the housing 300, the piston 200 acts only against the respective air cushions, i.e. with its upper side into the air cushion of the valve chamber 90 or with the lower side of the piston into the air cushion, taking into account the spring force acting in each case, and since, on the other hand, the piston groove 50 has formed an identically large surface at both ends in the longitudinal direction, no appreciable additional resulting axial forces are produced which act on the piston 200. Despite high applied pressures of the hydrogen, the piston 200 can therefore be easily adapted to the high required speeds of a corresponding rotational speed of the internal combustion engine.The high-pressure inlet valve 4 provided according to the invention thus offers the possibility of supplying hydrogen supplied under high pressure to a consumer, in this case the cylinder of an internal combustion engine. The pressures of the hydrogen provided are at a level of, for example, 20 to 350 bar.Because the axial forces acting on the piston 200 are substantially compensated for the same surfaces acted upon, no one-sided force component is produced on the piston 200 or the piston tappet 100 in favor of the respective other direction of movement. It is thus possible to bring the piston into the respective switching states with a low force effect. The respective switching states are, on the one hand, the closed valve and, on the other hand, the open valve.In this case, the size of the opening in the open switching state can be varied by the size of the axial displacement of the piston 200. During displacement of the piston, the control edge 45 of the piston 200 is displaced on the pressure side to such an extent that, with a corresponding width of the piston groove 50 as seen in the longitudinal direction of the piston 200, the supply and discharge ducts (hydrogen supply 111 and hydrogen supply 121) to the cylinder arranged offset with respect to one another in the axial direction are brought into communication with one another via the piston groove 50, which corresponds to the open state of the high-pressure inlet valve 4. By changing the position of the piston 200, the cross section of the hydrogen supply 121 to the cylinder can be varied such that the flow rate, i.e. the mass flow rate of the hydrogen to be introduced into the cylinder, can be varied.The cross sections are selected such that in the open state large amounts of hydrogen can be supplied to a consumer in a short unit of time, i.e. high mass flows, in the case of the cylinder of an internal combustion engine. Accordingly, when it is desired to transition from an open state (see FIG. 15 ) to a closed state (see FIG. 14 ), the piston 200 is displaced in the axial direction to such an extent that a connection of the hydrogen supply 111 to the high-pressure inlet valve 4 from a hydrogen source via the piston groove 50 to the hydrogen supply 121 to the cylinder is interrupted. Before the actual interruption has taken place according to the corresponding position of the piston 200 in the housing 300, it can be provided for a further improvement of the operating behavior of the engine that the closing process is delayed once again to a predefined extent, so that a certain recharging effect can be realized in the cylinder. This recharging generally occurs in the cylinder at a point in time when the piston 200 is already in its upward movement, i.e. in the compression phase, in the cylinder of the internal combustion engine. The advantage of using compressed hydrogen in conjunction with the high-pressure inlet valve 4 as described above is, among other things, also that after the corresponding cross sections have been released, the compressed hydrogen rapidly spreads, since the compressed hydrogen rapidly expands when the cross section is free. This also supports the capability of the high-pressure inlet valve 4 according to the invention that high amounts of hydrogen can be passed through in a small unit of time.The supply of hydrogen to a respective cylinder can now be effected in such a way that the complete hydrogen is carried out for a cycle with a single introduction into the cylinder in an inlet process. For the purpose of optimizing, for example, the compression work to be performed by the piston 200, the high-pressure inlet valve 4 can also be controlled in such a way that the supply of hydrogen into the cylinder takes place intermittently, so to speak, in a plurality of impacts. Each individual stroke of supplied hydrogen can be varied with respect to the length of the opening of the high-pressure inlet valve 4, so that the engine operation can be influenced directly, namely over the amount of hydrogen introduced into the cylinder in a defined unit of time. Preferably, two such impacts are provided. A plurality of pulses of supplied hydrogen may, however, also be advantageous for optimizing the overall process of operation of the engine. When the hydrogen is introduced in partial quantities in several strokes during the movement of the piston 200 in the cylinder on its path from the bottom dead center to the top dead center during the compression stroke, the hydrogen quantity in its sum corresponds to the total quantity required for the respective cycle, with which a reliable operation guaranteeing a high efficiency of the internal combustion engine can be achieved.The sealing of the piston 200 within the housing 300 is effected by a corresponding fit between the piston 200 and the bore in the housing 300.The high-pressure inlet valve 4 is preferably constructed from high-strength and heat-resistant metal alloys or from light metal or light metal alloys such as magnesium or from ceramic materials, wherein different materials can also be used for the piston 200 and the housing 300. It is also conceivable to select a specific base material with a coating of the respective parts in order to achieve optimum sliding and sealing properties of the piston 200 moved in the housing 300 at the high pressures of the supplied hydrogen. In addition to a selected coating, a different heat treatment of the parts moving relative to one another in the high-pressure inlet valve 4 is also conceivable. For reducing friction, lubrication can also be provided between the piston 200 and the housing 300, wherein a feed line, not shown in the figures, can be provided for supplying small amounts of lubricant.For hydrogen operation of the internal combustion engine, the high-pressure inlet valve 4 is expediently connected to the location of conventional inlet lines and inlet valves in the cylinder head 30 of an internal combustion engine, whereas the exhaust valves and the exhaust lines can remain formed in conventional technology. The high pressure inlet valve 4 is of course applicable to other ways of supplying gases to spaces of other devices.In order to realize correspondingly rapid opening and closing processes of the high-pressure inlet valve 4 in order that optimum engine operation can be carried out effectively, it is also possible for the control valve piston of the high-pressure inlet valve 4 to be actuated by mechanical components such as a camshaft or electromagnetically.Despite the comparatively small opening cross sections on the side of the hydrogen supply 111 to the valve, large amounts of hydrogen can be introduced into the combustion chamber due to the supply of hydrogen at high pressures of approximately 20 bar to 350 bar. This is also possible because the compression of the hydrogen on the side of the hydrogen supply 111 to the valve already expands in the valve. The expansion of the hydrogen already in the valve supports, so to speak, the "flow rate" of the hydrogen in the direction of the hydrogen supply 121 to the cylinder and into the cylinder, as a result of which a larger amount of hydrogen is thus automatically conveyed into the B, the cylinder 1, in the same unit time, i.e. a larger mass flow.Since the control valve piston 5 undergoes a controlled linear movement, the opening cross sections over the open state time units of the high pressure inlet valve 4 can be controlled in a simple manner.FIG. 16 shows a partial sectional view of a cylinder with a cylinder head, in which an outlet valve 33, a high-pressure valve 4 according to the invention and an injector 10 are arranged. The outlet valve 33 arranged in the cylinder head 30 is in the closed position, so that hydrogen can be introduced directly into the combustion chamber 1 via the high-pressure valve 4, wherein the guide piston 5 is shown in the open position, in which hydrogen can be introduced into the cylinder on the one hand and combustion air can be supplied from the inlet line 7 via the outflow cross sections 18 on the other hand. In its passage position 4.2, the high-pressure valve 4 can feed hydrogen alone or combustion air from the inlet line 7 alone or both together in the sense of a hydrogen-combustion air mixture to the combustion chamber 1. Furthermore, an injector 10 is provided in the cylinder head, via which additional hydrogen can be introduced directly into the combustion chamber 1 via a hydrogen pressure line 32. In the illustration shown in FIG. 16, the injector 10 is closed. The injector 10 is electromagnetically actuated, as a result of which high switching frequencies, i.e. shortest switching times, can be realized. The injector 10 is suitable for introducing hydrogen intermittently into the combustion chamber 1 at selected times in order to optimize mixture formation and combustion in the combustion chamber 1. A piston 2 is guided on the cylinder wall 47 in the cylinder, wherein the piston 2 has a piston pin 34, on which is connected at connecting rod 35 to a crankshaft, not shown, in a manner known per se.FIG. 17 shows a detailed view of a cylinder with a cylinder head, similar to that according to FIG. 16, but with the difference that instead of the high-pressure inlet valve 4 according to the invention, a conventional inlet valve is provided, which is shown in the open position in FIG. 17 and allows combustion air to flow from the inlet line 7 via the outflow cross sections 18 into the combustion chamber 1. Furthermore, an outlet valve 33 is arranged in the cylinder head 30, which is shown in the closed position. In the cylinder head 30 there is an injector 10, by means of which hydrogen can be introduced via the high-pressure hydrogen line 32 directly into the combustion chamber 1 when the injector 10 is open, i.e. in its passage position. In FIG. 17, the injector 10 is shown in its closed position. On the upper side of the guide piston 5.3 (see FIG. 1 ), there is located in the interior of the housing 6 an air-filled chamber 23, which serves as a damping cushion and from which, when the guide piston 5.3 dips into this chamber, air can be discharged via the venting line 24, wherein the venting line 24 is dimensioned such that no or no substantial throttling occurs when air flows out of the chamber. With the aid of the inlet valve 8, only the supply of combustion air via the inlet line 7 is controlled. The engine construction of the piston 2 with the piston pin 34 and the connecting rod 35 corresponds to that described in FIG. 16.Finally, FIG. 18 shows a detailed sectional view with a section through the cylinder and cylinder head that is modified in comparison to FIG. 17, so that the construction described in FIG. 18 still shows the injection nozzle. This injection nozzle can additionally be used to introduce gaseous fuel into the cylinder. The injection nozzle is also suitable for introducing liquid fuel, so that the exemplary embodiment of an internal combustion engine shown in FIG. 18 also enables a so-called dual-fuel operation. This means that both conventional liquid fuel can be introduced into the combustion chamber 1 of the internal combustion engine by means of the injection nozzle and hydrogen can additionally be introduced into the combustion chamber 1 by means of the injector 10. The other construction corresponds to that according to FIGS. 16 and 17 and therefore does not need to be explained again here.List of reference characters1 Combustion chamber 2 Piston 3 Cylinder 4 High-pressure inlet valve / high-pressure valve 4.1 Closing position 4.2 Passage position 5 Control valve piston 5.1 Control edge 5.2 Conical shape 5.3 Guide piston 5.4 Shaft 5.5 Closing plate, Poppet valve 6 Housing 7 Inlet line 8 Inlet valve 9 Electromagnetic actuation 10 Injector 11 Hydrogen supply line 12 Surface of the high-pressure valve 13 facing the combustion chamber axial injection bores High-pressure valve 14 End position Control valve piston 15 Piston side surfaces 16 Guide surfaces 17 Conical seat surface, Sealing seat 18 outflow cross section of high-pressure valve 20 hydrogen inlet line 21 opening stroke 22 spring 23 chamber 24 venting bore 25 end face / annular surface 26 second pressurizing region 27 first pressurizing region 28 passage region of hydrogen 29 guide web 30 cylinder head 32 high-pressure line 33 outlet valve 34 piston pin 35 connecting rod 36 injection nozzle 37 supporting ring 38 additional piston 39 web additional piston 40 openings between the webs 41 securing ring 42 supporting ring 43 weight-reducing recesses 44 cavity control valve piston 45 control edge 47 cylinder inner surface 50 piston groove 60 cover plate 70 venting bore 80 spring 90 valve chamber 100 piston tappet 101 piston stroke 111 hydrogen supply to valve 121 hydrogen supply to cylinder 131 housing recess 200 piston 300 housing H 2 hydrogen

Claims

Internal combustion engine for operation with gaseous hydrogen, having a cylinder (3) which has a combustion chamber (1) and a piston (2) guided therein, having a high-pressure valve (4) with control edges (5.1) or a control valve piston (5) which has a conical shape (5.2) and is guided in a housing (6) and is axially balanced with respect to the high pressure, and with which the hydrogen can be injected directly into the combustion chamber (1) or indirectly via an inlet line (7) shortly before an inlet valve (8) into the combustion chamber (1), wherein the control valve piston (5) has an electromagnetic actuation (9), A low-density construction, in which the chamber (6) is formed internally hollow or from ceramic or from ceramic-coated light metal or from light metal alloys, and between the combustion chamber (1) and a chamber (23) forming a gaseous damping cushion, a first closing and opening elastomer-free sealing region (15, 16, 17) and a second, always closing elastomer-free sealing region (15, 16) are provided, wherein the chamber (23) is provided with a venting bore (24) formed with a throttle and which merely gives rise to the damping cushion, the second sealing region (15, 16) is formed by the piston side surface (15) of a guide piston (5.3) and a guide surface (16) of the housing (6), and seals the chamber (23) in the housing (6) over the entire valve stroke.Internal combustion engine according to Claim 1, which additionally has an injector (10) for fine metering of the hydrogen into the combustion chamber (1).Internal combustion engine according to Claim 2, in which the injector (10) carries out an intermittent or multistage supply of the hydrogen directly into the combustion chamber (1).Internal combustion engine according to Claim 2 or 3, in which the high-pressure valve (4) is designed to blow in larger amounts of the hydrogen than the injector (10) which introduces small amounts of hydrogen into the combustion chamber (1) for optimizing combustion.Internal combustion engine according to one of Claims 1 to 4, in which the high-pressure valve (4) comprises a magnesium alloy as material.Internal combustion engine according to one of Claims 1 to 5, in which the control valve piston (5) of the high-pressure valve (4) has in its housing (6) guide pistons (5.3), on which the control edges (5.1) are formed, which interact with a hydrogen feed line (11).Internal combustion engine according to one of Claims 1 to 6, in which injection bores (13) which are arranged in the form of a ring are formed on a surface (12) of the high-pressure valve (4) which faces the combustion chamber (1), said injection bores being arranged concentrically with high-pressure valves (4) in the axial direction.Internal combustion engine according to one of Claims 1 to 7, in which the high-pressure valve (4) is arranged so as to stand in relation to the combustion chamber (1) and, by means of its control edges (5.1), the control valve piston (5) releases or closes an injection line (20), arranged radially in the housing (6) of the high-pressure valve (4), for the hydrogen and / or combustion air and / or hydrogen-combustion air mixture as a function of a piston position in the combustion chamber (1).High-pressure valve (4) for a hydrogen-operated internal combustion engine, which has: a) a housing (6); b) a control valve piston (5) which is guided in the housing (6) and is formed in a lightweight construction on the inside hollow or from ceramic or from ceramic-coated light metal or from light metal alloys and is axially force-balanced, having control edges (5.1) which delimit cylindrical piston side faces (15) and cooperate with guide faces (16) formed in the housing (6), or with a conical shape cooperating with a conical seat face (17) in the housing (6); c) outflow cross sections (18) which, by means of the guide faces (16) and the control edges (5.1) or the conical shape and the conical seat face (17), release from the high-pressure valve (4) or close the latter upon corresponding axial movement of the control valve piston (5); d) electromagnetic actuation of the control valve piston (5); e) a first closing and opening elastomer-free sealing region (15, 16, 17) and a second, always closing elastomer-free sealing region (15, 16) are provided between the combustion chamber (1) and a chamber (23) forming a gaseous damping cushion, wherein the chamber (23) is provided with a venting bore (24) formed with a throttle, which merely creates the damping cushion, the second sealing region (15, 16) is formed by the piston side surface (15) of a guide piston (5.3) and a guide surface (16) of the housing (6) and seals the chamber (23) in the housing (6) over the entire valve stroke.

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