DE102020203194B4 - INTERNAL COMBUSTION ENGINE FOR OPERATION WITH GASEOUS FUEL, ESPECIALLY HYDROGEN, AND HIGH-PRESSURE VALVE FOR INTRODUCING GASEOUS FUEL INTO THE INTERNAL COMBUSTION ENGINE - Google Patents

Abstract

An internal combustion engine for operation with gaseous fuel, in particular hydrogen, is provided, which has a high-pressure valve (4) which, with cylindrical surfaces and control edges (5.1) or with conical elements (5.2), implements the supply of hydrogen to a cylinder (3) by means of a control valve piston (5). The control valve piston (5) is electromagnetically actuated, implements 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 avoids to a great extent a backflow of gaseous fuel, in particular hydrogen, so that backfiring is avoided, 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 a high-pressure valve for introducing gaseous fuel into such an internal combustion engine.

In the field of operating internal combustion engines with gaseous fuel, particularly hydrogen, a great deal of state-of-the-art technology has been published due to the many years in which industry and associations have dealt with this topic, particularly from an ecological perspective. In addition to the most commonly used liquid fuels, gaseous fuels such as natural gas or hydrogen are increasingly being used to operate vehicles. The injection nozzles, also known as injectors, for liquid fuels have been largely perfected in their development, but gaseous fuels have a number of problems that do not occur with liquid fuels. The known injectors for liquid fuels are therefore only suitable to a limited extent.

Gaseous fuels have different energy densities and volumes than liquid fuels.

One problem with the use of hydrogen or gaseous fuels is that, on the one hand, a relatively large amount of fuel - a significantly larger volume than liquid fuels - has to be introduced into the combustion chamber of an internal combustion engine in a relatively short space of time, and, on the other hand, the introduction has to be carried out very precisely and with very precise dosing of the amount of fuel introduced into the combustion chamber. This is necessary so that when internal combustion engines are operated with natural gas, hydrogen or other gaseous fuels, excessive consumption does not occur and pollutant emissions are kept to a minimum. This requires that the gas quantities metered as precisely as possible are introduced into the cylinder per injection process and at a defined time of the injection process that is coordinated with optimized combustion in the cylinder.

In principle, two basic injection methods for gaseous fuels, in particular hydrogen, are known. One way of introducing gaseous fuel is to introduce this fuel into the combustion chamber of the internal combustion engine in the end area of the intake line, preferably immediately before the intake area of the intake line. Another possibility is to blow the gaseous fuel directly into the combustion chamber using the appropriately developed injectors that are suitable and optimized for gaseous fuels, which is also referred to as "injected". The injection of gaseous fuels is carried out in such a way that the entire fuel required for a combustion cycle is introduced in one injection process or in several injection processes per combustion cycle. In addition to the need to be able to inject a certain maximum amount of fuel in a given period of time, it must also be possible to introduce defined small amounts or very small amounts into the cylinder in precise dosages. Another general requirement for gas injectors or injection valves is that they must be precisely and reliably sealed against the combustion chamber into which the gas, preferably hydrogen, is introduced, in order to avoid backfiring in the area in front of the combustion chamber.

In Christian Spuller's Diesel combustion process with hydrogen for car applications, dissertation at the Technical University of Graz, 2011, the specifics and special features required for hydrogen operation of internal combustion engines are compiled from studies carried out. Both the charge exchange and the combustion differ from the 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 the state of the 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 for supplying the gaseous fuel is actuated by means of a magnetic actuator and in which two sealing areas are provided, DE 10 2004 049 589 A1 , which describes a hydrogen engine with an optimized fuel injection device, by means of which hydrogen flows into the inlet channel via a hydrogen channel 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 intermittently introduced into an intake manifold of an internal combustion engine, wherein the valve member is electrically actuable.

Prior art examples of injecting gaseous fuel, in particular hydrogen, into the combustion chamber of an internal combustion engine are mentioned in DE 4308775 C1 , at in which the valve is designed as a piston valve, has the shape of a poppet valve in the opening area and is actuated by means of a control hydraulic system using liquid, US 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 blowing gas into the combustion chamber of an internal combustion engine is introduced at high pressure, wherein a closing member and an actuator are driven by means of a magnetic coil and are movably arranged 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, with two valve seats ensuring the appropriate tightness.

Furthermore, EP 3 153 701 A1 , DE 10 2017 218 267 A1 and DE 103 53 011 A1 also describe a valve for controlling a gas to be introduced into the combustion chamber of an internal combustion engine, whereby these prior art documents point out the need for a reliable seal. In EP 3 153 693 A1 , a high-pressure valve for gaseous fuel is described, which ensures a corresponding tightness with bellows devices arranged in each case. In 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 High-pressure valves are described, all of which refer to two or more sealing seats to ensure the tightness of such a fuel suitable for hydrogen, whereby in some cases elastomer seals are recommended, which do have good tightness, but which can easily be damaged during operation of the internal combustion engine at full load and at high temperatures, which is why obviously in DE 10 2015 201 392 A1 a thermal insulation element is provided on one of two sealing seats, one of the two sealing seats consisting of an elastomer sealing element, in order to limit the temperature load on the elastomer sealing element. DE 10 2014 224 343 A1 describes a reliable sealing and protection of a sealing seat by means of an additional thermal protection device, in DE 10 2014 224 339 A1 It is described that a shielding element and a cooling ring are used to reduce the temperature load on the sealing areas.

DE 10 2014 224 344 A1 describes a gas injector for directly injecting a gaseous fuel into a combustion chamber of an internal combustion engine for better and more even distribution of the gaseous fuel in the combustion chamber with an additional control element to shape the gas jet to be injected according to the geometry of the combustion chamber for better mixture formation and combustion. And finally describes DE 10 2014 205 454 A1 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, the second sealing seat being 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 through which the fuel enters the combustion chamber of an internal combustion engine. At least one sealing seat is designed to be flexible.

In DE 10 2014 200 756 A1 a gas injector is shown which has a valve needle with a conical tip which is arranged on the valve seat and at the same time has control edges in a lateral surface area of the valve needle which form a gas control area. When the valve needle is lifted, a change in the first cross-sectional area on the valve seat is different from a change in the second cross-sectional area on the gas control area, with an elastomer being 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 manifold via at least one second injection valve.

Out of DE 10 2014 212 549 A1 A gas injector for injecting gaseous fuel is known, which comprises a gas damping device with a gas-filled damping chamber, which is delimited by a movable injector component and is connected to the injector chamber via a first connecting path, so that gaseous fuel is also present 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 usually only in relation to one or a maximum of two defi specific operating conditions which should be covered by the respective design.

In this case, for use under two different operating conditions, it is usually always necessary to make compromises in the technical design for both operating conditions; i.e. an optimal design was not technically envisaged.

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, optimal gas operation, very short switching cycles and control with regard to optimized properties also of the combustion.

This object is achieved by an internal combustion engine for hydrogen operation with 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. Appropriate further developments are defined in the dependent claims.

The hydrogen-powered 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 conical control valve piston guided in a housing. By means of the control valve, hydrogen is blown or injected directly into the combustion chamber or indirectly via an inlet line of the internal combustion engine into the combustion chamber shortly before an inlet valve. The term "injection" is used here equally for the introduction of a gaseous fuel in the form of hydrogen into the cylinder. The control valve piston of the high-pressure valve, which is also designed according to the invention, is electromagnetically actuated, which is one of the reasons for this and therefore achieves short control times and high switching frequencies, so that the inlet cross sections of the injection element for the hydrogen in the combustion chamber are quickly released in accordance with optimized mixture formation and combustion in the combustion chamber. The control valve piston has a first, closing and opening elastomer-free sealing area and a second, always closing elastomer-free sealing area in the housing between the combustion chamber and a damping pad, which are designed in such a way that a backflow of a fundamentally possible small amount of combustion gas in the form of hydrogen when it comes into contact with oxygen does not cause backfiring. This means that the high-pressure valve has a high and reliable sealing effect on both the combustion chamber and the damping pad when it is closed. In order to achieve short control times and high switching frequencies of the high-pressure valve, it is designed to be lightweight and reduced in weight. The seal is therefore designed in such a way that only such small amounts of hydrogen flow back, if at all, that when these small amounts of hydrogen come into contact with oxygen, no backfiring occurs, which can also be referred to as explosions.

For the hydrogen operation of an engine, the gaseous fuel in the form of hydrogen is stored in filled hydrogen bottles at around 350 bar. This storage pressure does not, of course, correspond to the injection pressure for liquid fuels, as is achieved today with common rail systems, for example, and as is used, in particular, for the internal mixture formation. For this reason, the supply pressure must be queried by means of sensors upstream of the valve or injection nozzle or injection valve in the cylinder, and the opening time or 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 of it. However, it is also possible that a pressure reduction is achieved before the gaseous fuel is supplied under the previously specified high pressure, so that the opening time or opening path of the supply is essentially constant in the same operating state. Depending on the operating conditions, 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 the fine metering of combustion gas or hydrogen into the combustion chamber. With such a preferred design of the internal combustion engine, there are therefore two introduction elements for combustion gas or hydrogen into the combustion chamber. The high-pressure valve is primarily intended for the introduction of larger quantities of gaseous fuel or hydrogen into the cylinder, whereas the injector enables the fine metering of smaller quantities of gaseous fuel or hydrogen into the combustion chamber at defined and quite short points in time or time intervals.

Furthermore, the injector is preferably designed in such a way that an intermittent or multi-stage supply of hydrogen can be carried out directly into the combustion chamber. Intermittent supply is to be understood as It should be noted that the introduction of hydrogen is not possible in a continuous manner, ie at precisely defined and controllable intervals, so that a direct improvement or optimization of the combustion in the combustion chamber can be achieved through fine dosing.

Preferably, the high-pressure inlet valve is designed to inject larger quantities of, for example, hydrogen into the combustion chamber than the injector, which introduces smaller quantities of hydrogen into the combustion chamber to optimize combustion. Larger quantities preferably mean a multiple of the smaller quantities of gaseous fuel injected by the injector.

Preferably, in the interests of lightweight construction of the high-pressure valve, in particular its control valve piston is hollow, wherein the wall thickness and shape are designed with a high rigidity, so that the lightweight construction is realized by reducing the weight of the control valve piston in particular, without the required strength of the components suffering.

Instead of making the high-pressure valve and injector out of steel, it can therefore preferably be provided that the high-pressure valve and/or the injector are made of ceramic or of ceramic-coated light metal. In addition, the moving parts in the high-pressure valve and injector can be hollow and ceramic-coated in the sense of a lightweight construction.

According to a further embodiment, the high-pressure valve can preferably comprise other metal alloys. This ensures that the moving parts in the high-pressure valve and in the injector have a corresponding strength and rigidity, but are nevertheless designed to be lighter in weight and therefore have a reduced mass due to the significantly lower density of light metal alloys compared to a steel alloy.

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 determine the times of supply of gaseous fuel in the form of hydrogen and the size of the supply cross-sections and thus the amount of gaseous fuel that is introduced into the cylinder, but on the other hand also close the supply cross-sections at defined times after the desired amount of gaseous fuel has been injected.

According to a further preferred embodiment, injection holes arranged in a ring shape are formed on a surface of the high-pressure valve facing the combustion chamber, which are arranged concentrically in the axial direction in the high-pressure valve. This means that the essentially flat ring surface of the high-pressure valve has injection or blow-in holes arranged on an imaginary circular line in this ring-shaped ring surface. These injection holes are arranged concentrically in the axial direction in the outer ring of the high-pressure valve. The concentrically arranged injection holes therefore make it possible to introduce a relatively large gaseous quantity of fuel into the cylinder in short units of time.

The high-pressure valve of the internal combustion engine also preferably has a gaseous damping cushion into which the control valve piston in the housing is immersed in the area of its end positions to prevent impacts or to dampen impacts. This prevents the control valve piston from hitting corresponding counter surfaces in the housing with its corresponding piston surface in its end position. When dimensioning the control of the control valve piston or the high-pressure valve as a whole, the existing damping cushion is included in the control concept so that the slight delay in the movement of the control valve piston that occurs in the end positions does not have a detrimental effect on the introduction of gaseous fuel, in particular hydrogen, into the combustion chamber.

According to a further embodiment, the internal combustion engine according to the invention for gaseous fuels in the form of hydrogen has a high-pressure valve that is preferably arranged vertically in the cylinder head with respect to the axial alignment of the combustion chamber, wherein the control valve piston uses its control edges to open or close injection lines for the hydrogen that are arranged radially in the housing of the high-pressure valve, depending on the piston position, introduction cross-sections or injection cross-sections. The vertical arrangement of the high-pressure valve has the advantage that the already limited space in the cylinder head can be used to arrange an additional valve in addition to the inlet and outlet valves that are already arranged in the cylinder head.

1. a) ein Gehäuse;
2. b) einen in dem Gehäuse geführten Steuerventilkolben mit zylindrischen Kolbenseitenflächen begrenzenden Steuerkanten, welche mit im Gehäuse ausgebildeten Führungsflächen zusammenwirken, oder mit einer mit einer kegelförmigen Sitzfläche im Gehäuse zusammenwirkenden Kegelform;
3. c) mittels der Führungsflächen und der Steuerkanten oder der Kegelform und der kegelförmigen Sitzfläche bei entsprechender axialen Bewegung des Steuerventilkolbens freigebbare oder wiederverschließbare Ausströmquerschnitte;
4. d) eine elektromagnetische Betätigung für den hohe Schaltfrequenzen realisierenden Steuerventilkolben;
5. e) bei verschlossenen Ausströmquerschnitten zumindest zweistufig im Gehäuse zur Abdichtung des Steuerventilkolbens im Gehäuse vorgesehene elastomerfrei ausgebildete erste und zweite Dichtbereiche;
6. f) eine derart dichtend vorgesehene Ausbildung der Dichtbereiche, dass allenfalls nur solche Kleinstmengen an Wasserstoff-Rückströmung durchgelassen werden, dass keine Rückzündungen auftreten; und
7. g) den in gewichtsreduzierender Leichtbauweise ausgebildeter, ein bewegliches Element des Hochdruckventils darstellender Steuerkolben.

According to a further aspect of the invention, a high-pressure valve for an internal combustion engine comprises:

1. (a) a housing;
2. b) a control valve piston guided in the housing with control edges defining cylindrical piston side surfaces which interact with guide surfaces formed in the housing, or with a conical shape interacting with a conical seat surface in the housing;
3. c) discharge cross-sections that can be opened or reclosed by means of the guide surfaces and the control edges or the cone shape and the conical seat surface with corresponding axial movement of the control valve piston;
4. d) an electromagnetic actuation for the control valve piston realising high switching frequencies;
5. e) in the case of closed outflow cross-sections, first and second sealing areas, free of elastomers, provided in at least two stages in the housing for sealing the control valve piston;
6. f) the sealing areas are designed to be so sealed that only such small amounts of hydrogen backflow are allowed to pass through that no backfires occur; and
7. g) the control piston, which is designed in a weight-reducing lightweight construction and represents 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 existing between the individual features, for the first time a high-pressure valve is provided which fully meets the requirements for operating an internal combustion engine with hydrogen and not only selectively for individual requirements, as has only been the case so far in the prior art.

• 1: ein erstes Ausführungsbeispiel eines erfindungsgemäßen Hochdruckeinlassventils in Schließposition mit Tellerventil;
• 2: ein Hochdruckeinlassventil gemäß 1 in Durchlassposition;
• 2a: einen Steuerventilkolben des Hochdruckeinlassventils in Leichtbauweise;
• 3: eine Schnittansicht durch Gehäuse und Schaft des Steuerventilkolbens gemäß einem weiteren Ausführungsbeispiel;
• 4: ein weiteres Ausführungsbeispiel des erfindungsgemäßen Hochdruckeinlassventils mit einem Steuerventilkolben mit zwei zylindrischen Führungskolben, welche in Führungsflächen im Inneren des Ventilgehäuses geführt sind, wobei kranzartig eine Vielzahl von axialen Einblasbohrungen zum Einbringen des gasförmigen Kraftstoffes in den Brennraum vorgesehen ist;
• 5: das Hochdruckeinlassventil gemäß 4, jedoch in Durchlassposition zum Zuführen von gasförmigem Kraftstoff durch das Hochdruckeinlassventil in einen Brennraum einer Verbrennungskraftmaschine;
• 6: ein Ausführungsbeispiel gemäß den 4 und 5, jedoch mit Einblasbohrungen, welche, bezogen auf die Längsachse des Steuerventilkolbens, eine divergierende Richtung aufweisen;
• 7: ein Ausführungsbeispiel gemäß 6, jedoch mit Einblasbohrungen, welche, bezogen auf die Längsachse des Steuerventilkolbens, eine konvergierende Richtung aufweisen;
• 8: ein weiteres Ausführungsbeispiel eines Hochdruckeinlassventils in Schließposition gemäß der Erfindung mit Einlass und Auslass für gasförmigen Kraftstoff in versetzt zueinander angeordneten Ebenen;
• 9: das Ausführungsbeispiel des erfindungsgemäßen Hochdruckeinlassventils gemäß 8, jedoch in Durchlassposition;
• 10: eine Detailschnittansicht der Anordnung des erfindungsgemäßen Hochdruckeinlassventils im Zylinderkopf einer Verbrennungskraftmaschine in Durchlassposition zum Einbringen von gasförmigem Kraftstoff in die Einlassleitung;
• 11: eine Detailschnittansicht eines Zylinders und eines Zylinderkopfes mit eingebautem erfindungsgemäßem Hochdruckeinlassventil in Durchlassposition;
• 12a: ein erfindungsgemäßes Hochdruckeinlassventil mit einem Tellerventil als erstem Druckbeaufschlagungsbereich und mit einem zylindrischen Führungskolben mit Ringfläche als zweitem Druckbeaufschlagungsbereich und mit zusätzlichem Kolben zum Öffnen und Schließen des Ventils;
• 12b: das Hochdruckeinlassventil gemäß 12a, jedoch in geöffneter Position zum Eintritt von gasförmigem Kraftstoff in den Zylinder durch das Innere des zusätzlichen Kolbens und dem Tellerventilsitz-Bereich;
• 12c: eine Schnittansicht durch den Schaft des Steuerventilkolbens des erfindungsgemäßen Hochdruckeinlassventils mit Ansicht des zusätzlichen Kolbens im Schnitt A-A (vgl. 12b);
• 13: ein Hochdruckeinlassventil gemäß einem zweiten Ausführungsbeispiel, bei welchem der zweite Druckbeaufschlagungsbereich in Form eines zylindrischen Führungskolbens bezüglich der wirksamen Ringfläche größer dimensioniert ist als die wirksame Ringfläche des ersten Druckbeaufschlagungsbereichs in Form eines Tellerventils;
• 14: ein Hochdruckeinlassventil für das erfindungsgemäße Verfahren in geschnittener Darstellung bei geschlossenem Zustand;
• 15: das Hochdruckeinlassventil gemäß 14 bei geöffnetem Zustand;
• 16: eine Detailschnittansicht eines Zylinders und eines Zylinderkopfes mit eingebautem erfindungsgemäßen Hochdruckeinlassventil in Durchlassposition und mit Injektor in Schließposition mit jeweils direktem Einlass in den Brennraum des Zylinders;
• 17: eine Detailschnittansicht eines Zylinders und eines Zylinderkopfes mit eingebautem erfindungsgemäßen Injektor in seiner Schließposition in einer Schnittebene zur Darstellung des Einlassventils, nicht aber des Hochdruckeinlassventils; und
• 18: eine Detailschnittansicht eines Zylinders und eines Zylinderkopfes mit eingebautem erfindungsgemäßen Injektor und entsprechender Schnittebene, nicht gezeigtem Hochdruckeinlassventil, jedoch vorgesehener Einspritzdüse für dualen Kraftstoffbetrieb der Verbrennungskraftmaschine.

Further advantages, details and possible applications of the present invention will now be described with reference to embodiments based on the following drawing. In the drawing:

• 1 : a first embodiment of a high-pressure inlet valve according to the invention in the closed position with poppet valve;
• 2 : a high pressure inlet valve according to 1 in pass-through position;
• 2a : a lightweight high-pressure inlet valve control valve piston;
• 3 : a sectional view through the housing and shaft of the control valve piston according to a further embodiment;
• 4 : a further embodiment of the high-pressure inlet valve according to the invention with a control valve piston with two cylindrical guide pistons which are guided in guide surfaces in the interior of the valve housing, wherein a plurality of axial injection bores are provided in a ring-like manner for introducing the gaseous fuel into the combustion chamber;
• 5 : the high pressure inlet valve according to 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;
• 6 : an embodiment according to the 4 and 5 , but with injection holes which have a diverging direction with respect to the longitudinal axis of the control valve piston;
• 7 : an embodiment according to 6 , but with injection holes which have a converging direction with respect to the longitudinal axis of the control valve piston;
• 8 : a further 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 from one another;
• 9 : the embodiment of the high-pressure inlet valve according to the invention according to 8 , but in the pass-through position;
• 10 : 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;
• 11 : a detailed sectional view of a cylinder and a cylinder head with installed high-pressure inlet valve according to the invention in the passage position;
• 12a : a high-pressure inlet valve according to the invention with a poppet valve as the first pressurization area and with a cylindrical guide piston with an annular surface as the second pressurization area and with an additional piston for opening and closing the valve;
• 12b : the high pressure inlet valve according to 12a , but in open position for the entry of gaseous fuel into the cylinder through the interior of the additional piston and the poppet valve seat area;
• 12c : a sectional view through the shaft of the control valve piston of the high-pressure inlet valve according to the invention with a view of the additional piston in section AA (cf. 12b) ;
• 13 : a high-pressure inlet valve according to a second embodiment, in which the second pressurization region in the form of a cylindrical guide piston is larger in terms of the effective annular area than the effective annular area of the first pressurization region in the form of a poppet valve;
• 14 : a high-pressure inlet valve for the method according to the invention in a sectional view in the closed state;
• 15 : the high pressure inlet valve according to 14 when opened;
• 16 : a detailed sectional view of a cylinder and a cylinder head with built-in high-pressure inlet valve according to the invention in the passage position and with injector in the closing position, each with direct inlet into the combustion chamber of the cylinder;
• 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 showing the inlet valve, but not the high-pressure inlet valve; and
• 18 : a detailed sectional view of a cylinder and a cylinder head with built-in injector according to the invention and corresponding sectional plane, high-pressure inlet valve not shown, but provided injection nozzle for dual fuel operation of the internal combustion engine.

In the following figure description, hydrogen is generally described as a fuel. It goes without saying that other gaseous fuels are also possible.

In 1 a high-pressure inlet valve 4 according to the invention is shown in cross-section. The valve has a housing 6, within which a control valve piston 5 is guided. For this purpose, the control valve piston 5 has an area designed as a cylindrical guide piston 5.3, which is slidably guided in the housing 6 on a guide surface 16 designed to be congruent with the cylindrical guide piston 5.3. The cylindrical guide piston 5.3 of the control valve piston 5 is larger in diameter than a shaft 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 1 combustion chamber 1 not shown (see for example 11 ). On the opposite side of the cylindrical guide piston 5.3, 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 to close the high-pressure inlet valve 4, with which pre-compressed hydrogen is admitted into the combustion chamber 1 of an internal combustion engine. A pressure force F _N (see vertically downward pointing arrow in 2 above) presses the control valve piston 5 downwards by an opening stroke 21 of the high-pressure inlet valve 4, so that the outflow cross-section 18 is fully open, ie the high-pressure inlet valve 4 is in the passage position 4.2.

1 represents the closing position 4.1 of the high pressure inlet valve 4. In the outlet cross section 18 (see 2 ) closes a closing plate 5.5 in the manner of a disk valve with a conical seat surface 17 formed in the housing 6 (see 2 ) and thereby prevents the 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 arrow pointing horizontally to the right. In the closed position 4.1 of the high-pressure inlet valve 4, the control valve piston 5 is immersed with its upper ring surface 25, which is directed towards the spring insert, in a chamber 23, which is connected to the outside via a vent hole 24. When the control valve piston 5 is immersed with its upper ring surface 25 of the cylindrical guide piston 5.3, uncompressed air is released from the chamber 23 provided there (see 2 ) is pushed out through the vent hole 24.

An essential criterion for the functioning of the high-pressure inlet valve 4 according to the invention is that the ring surface 25 facing the passage channel forms a second pressurization area 26 and the closing plate 5.5 of the plate valve, which faces the passage area 28 for the hydrogen, forms a first pressurization area 27. The first pressurization area 27 forms a projected area which is formed perpendicular to the longitudinal axis of the control valve piston 5 and has a size which is approximately equal to the projected area of the ring surface 25 on the cylindrical guide piston 5.3 of the control valve 5, i.e. almost equal to or equal to the projected area of the second pressurization area 26. Due to this equality of area of the projected areas, no relevant resulting axial forces are present, regardless of the level of the pressure of the hydrogen which is required for the inlet in 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 passage position 4.2 and, when the cam is released, is quickly brought back into the closed position 4.1 by the effect of the spring force F _N according to its strength, in which the closing plate 5.5 of the plate valve strikes the conical seat surface 17 and seals there (see also 13 ). In 1 the shaft 5.4 of the control valve piston 5 of the high pressure inlet valve 4 has a control valve piston with a cavity, ie has a hollow shaft (see 2a) For the sake of simplicity, the axially extending bore provided in the shaft of the control valve piston 5 is 2 and in 3 not shown. The cavity inside the shaft 5.4 of the control valve piston 5 extends essentially over as long a length of the shaft 5.4 as possible. This means that a significant weight reduction is achieved for use in hydrogen operation. In conjunction with the schematically shown electromagnetic drive 9, very short reaction times and thus high switching frequencies can be achieved due to the reduced weight of the control valve piston 5, which are particularly necessary for hydrogen operation. In addition, a ceramic coating is provided in the lower end of the control valve piston 5 facing the combustion chamber, especially in the first pressurization area 27. For reasons of further weight savings, it is also possible for the entire control valve piston 5 to be made of ceramic.

2 represents the high-pressure inlet valve 4, in which the control valve piston 5 is 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 area 28 is released for the hydrogen, so that the hydrogen flows at high pressure and thus also at a high flow rate between the sealing seat 17 and the closing plate 5.5 and reaches the combustion chamber 1 (not shown) of the internal combustion engine. Clearly visible is the chamber 23 formed on the top of the cylindrical guide piston 5.3 in the direction of the spring insert with the spring 22 when the control valve piston 5 is pressed downwards by the opening stroke 21. This chamber 23 is provided with a vent hole 24 so that when the valve closes, the cylindrical guide piston 5.3 dips into this chamber 23 with its upper ring surface and pushes the uncompressed air located there outwards via the vent hole 24. The diameter of this vent hole 24 is now selected so that no significant 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 forming a high resistance is created, but only a certain damping cushion.

In 2a the control valve piston 5 is hollow to reduce weight and has a cavity 44 inside the shaft and the plate. To achieve a further reduction in weight, the guide piston 5.3 is provided with weight-reducing recesses 43 on its front sides 25, 26. These recesses 43 make it possible for the guide piston 5.3 to be made relatively long in its longitudinal extension even with a greatly reduced mass, which improves the sealing effect between the piston side surface 15 and the guide surface 16 (see for example 1 ) results in.

In 3 a sectional view is shown through a cutting plane through the valve parallel to the valve plate 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 precise 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 precisely fitting guide surfaces 16 in the housing 6, which are also cylindrically designed. The precise design of these two surfaces 15, 16 sliding relative to one another ensures or further improves the tightness of the valve on the inside.

4 shows a further embodiment of the high-pressure inlet valve 4 according to the invention, in which the control valve piston 5 has two cylindrically designed guide pistons 5.3, which are guided in corresponding shape-congruent guide surfaces 16. For this purpose, three shape-congruent cylindrical guide surfaces 16 are provided in the interior of the housing 6. 4 shows the closing position 4.1 of the control valve piston 5 within the housing 6. The 1 and 2 The basic structure with the spring insert explained is identical and will therefore not be repeated here.

In the 4 In the illustrated closing position 4.1, the cylindrical guide piston 5.3, which is larger in its axial length and is shown in the lower part of the illustrated high-pressure inlet valve 4, is provided for opening and closing the actual axial hydrogen injection bore 13. For this purpose, the housing 6 in the 4 In the closed position 4.1 shown, the supply lines cover the injection bores 13 arranged in a ring around the circumference of the front side 25 of the high-pressure inlet valve 4 facing the combustion chamber with the cylindrical guide surfaces 16, so that the passage of hydrogen from the hydrogen inlet line 20 is blocked.

A chamber 23 is formed beneath the top of the piston, into which the lower cylindrical guide piston 5.3 is immersed to release the axial injection holes 13. To ensure that no counterpressure is formed in the air present in the chamber 23, a vent hole 24 is provided inside along the longitudinal axis of the control valve piston 5 and radially in the housing 6. With appropriate dimensioning of the vent hole 24, throttling can be largely avoided, but it can still be ensured that a certain damping function is built up. The damping function prevents a hard impact of the top, in the case of the illustration according to 4 , of the upper cylindrical guide piston 5.3 inside the housing 6 at the bottom of the chamber 23. The annular surfaces 25 facing the passage area 28, i.e. the first and second pressurization areas 27,26 of the cylindrical guide pistons 5.3 of the control valve piston 5, are dimensioned such that they are the same size. This ensures that regardless of the pressure with which the hydrogen enters the passage area 28 inside the housing 6 of the high-pressure inlet valve 4, no additional resulting axial forces are caused. This means that regardless of the pressure of the hydrogen to be admitted into the combustion chamber 1, the high-pressure inlet valve 4 can be opened against the action of the spring 22 and closed using the spring 22 using only an appropriate drive, for example a cam or a camshaft or an electromagnetic actuator 9.

In 5 it is shown how this opening force F _N applied by a cam or an electromagnetic actuation immerses the control valve piston 5 in the chamber 23, so that the radially directed feed areas leading to the axial injection holes 13 are opened in the manner of an annular chamber and the hydrogen from the outflow cross-section 18 can be introduced 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 piston 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 vent hole 24, so that when the control valve 5 executes the closing movement, ie in the drawing when it moves upwards, the air in the chamber 23 can escape via the vent hole 24. The axial injection holes 13 are preferably arranged equidistantly; However, an irregular arrangement may also be provided, in particular if the air flow into the combustion chamber 1 is to be used to improve the mixture formation.

6 shows a detailed sectional view of the area of the axial injection holes 13, ie the lower area of the high-pressure inlet valve 4, in which, in deviation from the embodiment according to 4 and 5 the injection holes 13 are arranged divergently with respect to the longitudinal axis of the control valve piston 5. The other geometric conditions correspond to those of the 4 and 5 .

In 7 is an embodiment in the form of a detailed area according to 6 shown, but the injection holes 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, with respect to the longitudinal axis of the control valve piston 5, both diverging and converging injection holes 13 are provided.

8 shows a further embodiment of a high-pressure inlet valve 4 according to the invention, the basic structure of which with regard to the housing 6 and spring insert corresponds to the previous embodiments, so that these parts will not be described 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 difference to the previous embodiments is that the hydrogen inlet line and the outflow cross-section 18 are arranged in different planes with respect to the longitudinal axis of the housing 6 of the high-pressure inlet valve 4. The hydrogen is under high pressure 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 area 28, so that no hydrogen can enter the passage area 28 and finally into the combustion chamber 1 (see 10 ) of the cylinder. Two ring surfaces 25 are facing the passage area 28, which have the same size, so that no resulting axial forces are present regardless of the pressure of the hydrogen supplied. A displacement of the control valve piston 5 can therefore only be applied against the force of the spring 22. The chamber 23 is located below the front of the large cylindrical guide piston 5.3, so that when displacing of the control valve piston 5 is immersed in the chamber 23 and thus ultimately when the opening stroke 21 is carried out, the 9 shown passage position 4.2 of the control valve piston 5 is reached. In the passage position 4.2, the hydrogen can flow via the hydrogen inlet line 20 from the lower level to the upper level of the recess of the passage area 28 in 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 into the chamber 23 on guide surfaces 16 of congruent shape. In the closed position 4.1 according to 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 between the lower level is arranged on the hydrogen inlet line 20 and the passage region 28 in the upper level on the outflow cross-section 18. And finally, the smaller cylindrical guide piston 5.3, the upper one, which is arranged in the direction of the spring insert, is slidably guided on a third guide section 16.

While 8 the high pressure inlet valve 4 in its closed position 4.1 is in 9 its passage position 4.2 is shown.

10 shows an 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 (not shown), 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, when the cam engages, the spring 22 present in the spring insert can be compressed. The compression of the spring 22 and thus the opening of the high-pressure inlet valve are equally achieved by an electromagnetic actuator 9. By compressing the spring 22, the hydrogen, which is led via the high-pressure line 32 to the hydrogen inlet line 20 and from there via the illustrated passage position 4.2 through the high-pressure inlet valve 4 in its passage area 28 to the outflow cross-section 18, passes through the inlet line 7 and the inlet valve 8 at high pressure into the combustion chamber 1. This is indicated by the arrows, which characterize the hydrogen flow of the hydrogen under high pressure and also the combustion air. On the left at the top of the 10 an exhaust valve 33 is shown which is in the closed state so that the gaseous fuel cannot escape into the exhaust line. A piston 2 is shown in the cylinder 3, which is connected to a crankshaft (not shown) by means of a piston pin 34 and a connecting rod 35. 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 bottom dead center to top dead center, individual amounts of hydrogen can be filled into the cylinder in a timely manner in conjunction with the control of the inlet line valve 46.

And finally, 11 a cylinder 3 with cylinder head 30 according to 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 blown 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 passage position 4.2 of the injector 10, supplies hydrogen indirectly into the combustion chamber 1 via the inlet line 7 in targeted quantities at desired times to directly influence the subsequent mixture formation and combustion in the combustion chamber 1, is arranged in the cylinder head. The piston 2 in the cylinder 3 is connected to a crankshaft (not shown) by means of its connecting rod 35 and via the piston pin 34.

In 12a another embodiment of the high pressure inlet valve 4 according to the invention is shown. In 12b This high pressure inlet valve 4 is shown in the open position. The 12a The closed position of the high-pressure inlet valve 4 shown is achieved in the position of the control valve piston 5, in which the hydrogen inlet line 20 closes off inside the housing 6, whereby hydrogen is supplied under high pressure when it is opened, namely in a valve plate or closing plate 5.5 of a plate valve which is sealingly seated on a valve seat and thus also sealingly arranged for the supply of hydrogen into the combustion chamber 1. The closing plate 5.5 of the plate 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. The control valve piston 5 has a cylindrical guide piston 5.3 or a guide surface 16 in the area of the shaft 5.4 located in the housing 6, which has a Ring surface 25 is formed, which points in the direction of the passage area 28. On a side opposite the ring surface 25, the shaft 5.4 has a closing plate 5.5 of the plate 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 pre-tension in the housing 6 by means of a yoke-like support ring 37. The ring surface 25 and the effective surface of the closing plate 5.5 of the plate valve 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 enters the passage area 28 for introduction into the cylinder 1 when the high-pressure inlet valve 4 is open (see 12b) , the pressure application surfaces 27 and 26 are loaded against each other without significant resulting surfaces. As a result, a displacement of the control valve piston 5 in the housing 6 is realized without additional forces to the compression spring 22. In the area of the shaft 5.4, the control valve piston 5 has an additional piston 38, which also has a cylindrical guide surface 15 on its outer circumference, which is guided on corresponding shape-congruent guide sections 16 in the housing 6. The axial dimension of this additional piston 38 is now such that in the position as shown in 12a is shown, ie 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 and guide surfaces 15,16 are ground in order to ensure an appropriate sealing force and tightness. A second sealing surface is created in the valve seat 17 of the disk valve, whereby the sealing force is determined by the spring force of the spring 22. Between the in the 12a On the upper side of the guide piston 5.3 shown, which points to the side with the spring 22 of high pressure of a valve, a pressure chamber is formed which can be vented via a vent hole 24 upon corresponding compression, ie upon upward movement of the control valve piston 5.

When a corresponding force acts against the spring force of the spring 22 to adjust the slide valve piston 5 in the housing 6, air is sucked in again via this vent hole 24, so that no significant negative pressure is created in the pressure chamber 23 between the top of the cylindrical guide piston 5.3 and the housing 6.

In 12b The high pressure inlet valve 4 is 12a shown, but in the open position. For this purpose, the control valve piston 5 is moved downwards against the effect of the spring force of the spring 22 in the illustration shown, so that the additional piston 38 releases the cross-section of the hydrogen inlet line 20 via the passage area 28 at the seat area 17 of the closing plate 5.5 of the plate valve and hydrogen can be pressed into the combustion chamber 1 (not shown) at high pressure. The other elements and functions are the same as those 12a identical and are therefore not described again here. It is 12b It can be seen that the additional piston 38 is slidably displaced on the ground cylindrical guide surfaces 16 formed in the interior of the housing 6, ie in the interior of the passage area 28, so that the hydrogen under high pressure can ultimately flow into the cylinder 1.

And finally, in 12c a sectional view through the control valve piston 5 in its lower part of the shaft 5.4 looking along the section AA (cf. 12b) on the additional piston 38. The piston 38 has a cylindrical piston side surface 15 on its outer circumference, which is ground in and cooperates in a sealing manner with the corresponding guide surfaces 16 formed in the housing 6. The interior of the piston 38 is made sufficiently stable by webs 39, between which there are openings 40, and thus enables the hydrogen to flow through when the hydrogen inlet is released, in order to then flow past the area of the valve seat 17 of the closing plate 5.5 of the plate valve into the combustion chamber 1. This is shown by the arrows which indicate the flow path. In addition, the control valve piston 5 is reliably and precisely guided by the cylindrical piston side surfaces 15 in the upper part of the housing 6, since these areas are also ground in.

And finally, 13 a further embodiment in which the effective pressure application areas 27,26 facing the passage area 28 in the interior of the housing 6 have a different size. In 13 a state of the high-pressure inlet valve 4 is shown in which the supply of hydrogen into the combustion chamber 1 does not take place through the control valve piston 5. Due to the fact that the second pressurization area 26, designed as an annular surface 25, is larger than the first pressurization area 27 at the transition of the closing plate 5.5 of the plate valve to its shaft 5.4, the housing 6 is designed in two parts so that the control valve piston 5 and the guide piston 5.3 can be installed in the interior of the housing 6. The guide piston 5.3 must be installed on the inside of the housing 6 by additional assembly in an assembly embodiment not shown in more detail. the control valve piston 5. Otherwise, the basic structure is analogous to that in 12 described. Because the area of the second pressurization area 26 is larger than that of the first pressurization area 27, in conjunction with the high pressure of the hydrogen, a greater closing force of the closing plate 5.5 of the plate valve in the area of its seat 17 is ensured. In this respect, the imbalance based on the different sized effective areas benefits. The great force achieved in this way ensures a significantly improved sealing performance of the valve seat 17 during operation of the engine. The principle of operation of such a high-pressure valve 4 is similar to that of a pneumatic cylinder.

In addition to the presentation in 12 is in 13 A retaining ring 41 is also shown, which prevents the support ring 42 from coming loose during operation, since the support ring 42 is placed on the upper shaft part of the control valve piston 5, so that the spring tension is set. The 13 The control valve piston 5 shown is sealed against the chamber 23 with its guide piston 5.3. In the direction of the valve plate 5.5. there is a conical area inside the housing 6. The other sealing area is the conical seat formed directly on the plate valve. The latter ensures a secure sealing of the hydrogen supply line against the combustion chamber 1, whereas the guide piston 5.3 forms an additional sealing surface between the hydrogen supply area and the chamber 23. In principle, it is also possible for the guide piston 5.3 in the second pressurization area 26 to be smaller than the first pressurization area 27.

14 and 15 show in sectional view two positions of the high pressure inlet valve 4 according to the invention for realizing the function in a further embodiment of the invention in the closed state ( 14 ), whereas in 15 this high-pressure inlet valve 4 is shown 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 an area with a recess opposite the outer maximum diameter of the piston 200. In the position according to 14 the piston 200 forms a valve chamber 90 within the housing 300 on its front face or piston top, which is opposite the piston tappet 100, which is closed on the front face of the high-pressure inlet valve 4 by means of a cover plate 60. Between the cover plate 60 and the front face of the piston 200, the valve chamber 90 forms an air cushion, so to speak, into which the piston 200 moves with its stroke 101, so that during the short times required for the inlet processes for hydrogen into the cylinder, it is prevented that the piston 200 could hit the cover plate 60.

In 15 it is shown that the valve chamber 90 is vented via a vent hole 70, which is guided through the piston part in the region of its longitudinal axis. Particularly at higher speeds of the internal combustion engine, the charge exchange in the cylinder must be carried out in very short periods of time in terms of absolute time. Therefore, the high-pressure inlet valve 4 and, as an essential core element thereof, its piston 200, must also carry out very fast movements to open and close, ie to control the supply of hydrogen. Lightweight construction is an essential feature for the realization of high 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 inertia of this component. The space on the top of the piston that changes during the movement of the piston 200, i.e. the valve chamber 90, leads to a dampening of the piston movement due to the compression of the air contained therein, which is why a vent hole 70 is provided inside the piston 200 in the area of its longitudinal axis. The diameter of the vent hole 70 is now designed such that during the rapid movement of the actual piston of the piston 200, at least most of the air is pressed out of the valve chamber 90 via the vent hole 70. The diameter of the vent hole 70 is only large enough to ensure that only so much air remains in the valve chamber 90 that, during the rapid movement of the piston 200 and its inertia, the top of the piston does not strike the inner closure of the high-pressure valve 4 formed by the cover plate 60 in this embodiment. On the other hand, the vent hole 70 must be able to interrupt the passage of hydrogen through the high-pressure inlet valve 4 during the backward movement of the piston away from the cover plate 60 in the direction of its position, and to enable a backflow to refill the valve chamber 90. The vent hole 70 therefore has a diameter such that essentially the air in the valve chamber 90 can be discharged or fed back into this chamber, and this while still having a certain small throttling function so that no vacuum or negative pressure can be created 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 a certain damping effect when the top of the piston moves in the direction of the cover plate 60, in which a certain damping cushion is formed, among other things due to the still existing throttling effect of the vent hole 70, whereby the top of the piston does not strike the inside of the cover plate 60 or at least counteracts a strike. The vent hole in the shaft of the piston 200 already represents a measure for reducing mass in the sense of supporting rapid or high switching frequencies.

On the side of the piston 200 opposite the front side 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 piston underside and the passage opening of the piston tappet 100 through the material of the housing 300, which also has a damping function analogous to that described on the piston top. For this purpose, a vent hole 70 is also provided from this damping chamber on the piston underside, which is designed and functions analogously to the vent hole 70, which runs longitudinally through the piston part and has a connection to the valve chamber 90.

In the upper area 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 to the top of the housing recess 131. The piston therefore works against the spring 80, which is compressed or stretched depending on the direction of movement within the piston stroke 100.

In the 14 In the position of the piston 200 shown, its control edge 45 is located above a channel arranged transversely to the direction of movement of the piston 200 for the supply 121 of hydrogen under high pressure to the cylinder, so that the hydrogen supply 111 is prevented by the valve. Only in the position shown in 15 In the position of the piston 200 shown, the control edge 45 is immersed in the channel for the hydrogen supply 121 to the cylinder, which 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 represents the inlet, so to speak, opposite 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 for the hydrogen supply 121 to the cylinder, the high-pressure hydrogen immediately passes through into the cylinder.

Since, when the piston 200 moves in the housing 300, the piston 200 only acts against the respective air cushions, i.e. with its upper side of the piston in the air cushion of the valve chamber 90 or with its lower side of the piston in the air cushion, taking into account the respective spring force acting, and since, on the other hand, the piston groove 50 has an equally large area at both ends in the longitudinal direction, no significant additional resulting axial forces arise which act on the piston 200. The piston 200 can therefore be easily adjusted to the high required speeds of a corresponding rotational speed of the internal combustion engine despite the high pressures of the hydrogen applied.

The high-pressure inlet valve 4 provided according to the invention thus offers the possibility of providing hydrogen under high pressure to a consumer, in this case the cylinder of an internal combustion engine. The pressures of the hydrogen provided are, for example, at a level of 20 to 350 bar.

Because the axial forces acting on the piston 200 are essentially balanced due to the same applied surfaces, there is no one-sided force component on the piston 200 or the piston tappet 100 to the detriment of the other direction of movement. This makes it possible to bring the piston into the respective switching states with little force. The respective switching states are the closed valve on the one hand and the open valve on the other.

The size of the opening in the open switching state can be varied by the size of the axial displacement of the piston 200. When the piston is displaced, 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 channels (hydrogen supply 111 and hydrogen supply 121) to the cylinder, which are arranged offset in the axial direction, are connected to 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 so that the flow rate, ie the mass flow of hydrogen to be introduced into the cylinder can be varied.

The cross-sections are now selected so that in the open state, large amounts of hydrogen can be supplied to a consumer, in this case the cylinder of an internal combustion engine, in a short time unit, ie high mass flows. If from an open state (see 15 ) back to a closed state (see 14 ), the piston 200 is accordingly 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 in accordance with the corresponding position of the piston 200 in the housing 300, it can be provided for in order to further improve the operating behavior of the engine that the closing process is delayed again by a predetermined amount so that a certain recharging effect can be realized in the cylinder. This recharging usually takes place in the cylinder at a time when the piston 200 in the cylinder of the internal combustion engine is already in its upward movement, i.e. in the compression phase. The advantage of using compressed hydrogen in conjunction with the high-pressure inlet valve 4, as described above, is, among other things, that after the corresponding cross-sections are released, the compressed hydrogen spreads quickly, since the compressed hydrogen expands quickly when the cross-section is free. This also supports the ability of the high-pressure inlet valve 4 according to the invention to pass through high amounts of hydrogen in a short unit of time.

The supply of hydrogen to a respective cylinder can now be carried out in such a way that all of the hydrogen for a cycle is introduced into the cylinder once in one intake process. In order to optimize, 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 in several pulses, so to speak. Each individual pulse of supplied hydrogen can be varied with regard to the length of the opening of the high-pressure inlet valve 4, so that the engine operation can be directly influenced by the amount of hydrogen introduced into the cylinder in a defined unit of time. Preferably, two such pulses are provided. A large number of pulses of supplied hydrogen can also be advantageous in terms of optimizing the overall process of operating the engine. If the hydrogen is introduced in partial quantities in several pulses during the movement of the piston 200 in the cylinder on its way from bottom dead center to top dead center during the compression stroke, the total amount of hydrogen corresponds to the total amount required for the respective cycle, with which a reliable mode of operation guaranteeing a high efficiency of the internal combustion engine can be achieved.

The sealing of the piston 200 within the housing 300 is achieved by a corresponding fit between the piston 200 and the bore in the housing 300.

The high-pressure inlet valve 4 is preferably made of high-strength and heat-resistant metal alloys or of light metal or light metal alloys such as magnesium or ceramic materials, whereby 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 optimal sliding and sealing properties of the piston 200 moving in the housing 300 at the high pressures of the hydrogen supplied. In addition to a selected coating, a different heat treatment of the parts moving against each other in the high-pressure inlet valve 4 is also conceivable. To reduce friction, lubrication can also be provided between the piston 200 and the housing 300, whereby a supply 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 place 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 designed using conventional technology. The high-pressure inlet valve 4 can of course also be used for other types of supply of gases to rooms of other facilities.

In order to realize correspondingly rapid opening and closing processes of the high-pressure inlet valve 4 so that optimal 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 with 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 approx. 20 to 350 bar. This is also possible because the compression of the hydrogen on the side of the hydrogen supply 111 to the valve is already relaxed in the valve. The relaxation 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, which automatically means that a larger amount of hydrogen is fed into B, cylinder 1, in the same unit of time, i.e. a larger mass flow.

Since the control valve piston 5 undergoes a controlled linear movement, the opening cross sections can be controlled in a simple manner via the time units for the open state of the high-pressure inlet valve 4.

In 16 a partial sectional view of a cylinder with a cylinder head is shown, in which an exhaust valve 33, a high-pressure valve 4 according to the invention and an injector 10 are arranged. The exhaust 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, the guide piston 5 being shown in the open position, in which hydrogen can be introduced into the cylinder on the one hand and combustion air from the inlet line 7 can be supplied via the outflow cross sections 18 on the other. The high-pressure valve 4 in its passage position 4.2 can supply 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. An injector 10 is also provided in the cylinder head, via which hydrogen can also be introduced directly into the combustion chamber 1 via a hydrogen pressure line 32. In the 16 In the illustration shown, the injector 10 is closed. The injector 10 is electromagnetically actuated, whereby high switching frequencies, ie the shortest switching times, can be achieved. The injector 10 is suitable for introducing hydrogen intermittently at selected times into the combustion chamber 1 in order to optimize mixture formation and combustion in the combustion chamber 1. In the cylinder, a piston 2 is guided on the cylinder wall 47, the piston 2 having a piston pin 34, on which a connecting rod 35 is connected in a manner known per se to a crankshaft (not shown).

17 shows a detailed view of a cylinder with cylinder head, similar to the one according to 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 in 17 in the passage position and allows combustion air to flow from the inlet line 7 into the combustion chamber 1 via the outflow cross sections 18. In the cylinder head 30, an outlet valve 33 is also arranged, 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 directly into the combustion chamber 1 via the hydrogen high-pressure line 32 when the injector 10 is open, ie in its passage position. In 17 The injector 10 is shown in its closed position. On the upper side of the guide piston 5.3 (see 1 ) there is an air-filled chamber 23 inside the housing 6, which serves as a damping cushion and from which, when the guide piston 5.3 is immersed in this chamber, air can be discharged via the vent line 24, whereby the vent line 24 is dimensioned in such a way that no or no significant throttling occurs when air flows out of the chamber. With the help of the inlet valve 8, only the supply of combustion air via the inlet line 7 is controlled. The engine structure of the piston 2 with the piston pin 34 and the connecting rod 35 corresponds to that in 16 described.

And finally, in 18 a detailed section view with an opposite 17 modified section through the cylinder and cylinder head, so that the 18 The structure described above still shows the injection nozzle. This injection nozzle can also be used to introduce gaseous fuel into the cylinder. The injection nozzle is also suitable for the introduction of liquid fuel, so that the 18 The embodiment of an internal combustion engine shown also enables a so-called duel-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 also be introduced into the combustion chamber 1 by means of the injector 10. The other structure corresponds to that according to the 16 and 17 and therefore does not need to be explained again here.

list of reference symbols

1

combustion chamber

2

Pistons

3

cylinder

4

high-pressure inlet valve/high-pressure valve

4.1

closed 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

locking plate, disc valve

6

Housing

7

intake line

8

intake valve

9

Electromagnetic actuation

10

injector

11

hydrogen supply line

12

surface of the high-pressure valve facing the combustion chamber

13

axial injection holes high-pressure valve

14

end position control valve piston

15

piston side surfaces

16

guide surfaces

17

Conical seat, sealing seat

18

discharge cross-section of the high-pressure valve

20

hydrogen inlet line

21

opening stroke

22

Feather

23

chamber

24

vent hole

25

front side/ring surface

26

second pressurization area

27

first pressurization area

28

hydrogen passage area

29

guide bridge

30

cylinder head

32

high-pressure line

33

outlet valve

34

piston pin

35

connecting rod

36

injection nozzle

37

support ring

38

additional piston

39

bridge of additional pistons

40

openings between the webs

41

retaining ring

42

support ring

43

Weight-reducing recesses

44

control valve piston cavity

45

control edge

47

cylinder inner surface

50

piston groove

60

cover plate

70

vent hole

80

Feather

90

valve chamber

100

piston tappet

101

piston stroke

111

hydrogen supply to the valve

121

hydrogen supply to the cylinder

131

housing recess

200

Pistons

300

Housing

H2

hydrogen

Claims (9)

Internal combustion engine for operation with gaseous hydrogen, with a cylinder (3) having a combustion chamber (1) and a piston (2) guided therein, with a high-pressure valve (4) with control edges (5.1) or a conical shape (5.2), guided in a housing (6), axially force-balanced with respect to the high pressure, and with which the hydrogen can be blown 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), is hollow on the inside in a lightweight construction or is made of ceramic or of ceramic-coated light metal or of light metal alloys, and in the housing (6) between the combustion chamber (1) and a chamber (23) forming a gaseous damping cushion, a first closing and opening elastomer-free sealing area (15, 16, 17) and a second always closing elastomer-free sealing area (15, 16) are provided, wherein the chamber (23) is provided with a vent hole (24) to the outside which only creates the damping pad and is designed with a throttle, the second sealing area (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 after claim 1 , which additionally has an injector (10) for fine dosing of the hydrogen into the combustion chamber (1). internal combustion engine after claim 2 in which the injector (10) carries out an intermittent or multi-stage supply of hydrogen directly into the combustion chamber (1). internal combustion engine after claim 2 or 3 , in which the high-pressure valve (4) is designed to inject larger quantities of hydrogen than the injector (10) which introduces small quantities of hydrogen into the combustion chamber (1) to optimize combustion. Internal combustion engine according to one of the Claims 1 until 4 , in which the high-pressure valve (4) is made of a magnesium alloy. Internal combustion engine according to one of the Claims 1 until 5 , in which the control valve piston (5) of the high-pressure valve (4) has guide pistons (5.3) in its housing (6), on which the control edges (5.1) are formed, which interact with a hydrogen supply line (11). Internal combustion engine according to one of the Claims 1 until 6 in which injection bores (13) arranged in a ring shape are formed on a surface (12) of the high-pressure valve (4) facing the combustion chamber (1), which are arranged concentrically with high-pressure valves (4) in the axial direction. Internal combustion engine according to one of the Claims 1 until 7 , in which the high-pressure valve (4) is arranged upright relative to the combustion chamber (1) and the control valve piston (5) uses its control edges (5.1) to open or close 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, depending on a piston position in the combustion chamber (1), inlet cross sections. High-pressure valve (4) for a hydrogen-powered internal combustion engine, which has: a) a housing (6); b) a control valve piston (5) guided in the housing (6), which is hollow on the inside in a lightweight construction or is made of ceramic or of ceramic-coated light metal or of light metal alloys and is axially force-balanced, with control edges (5.1) delimiting cylindrical piston side surfaces (15), which interact with guide surfaces (16) formed in the housing (6), or with a conical shape interacting with a conical seat surface (17) in the housing (6); c) outflow cross-sections (18) which, by means of the guide surfaces (16) and the control edges (5.1) or the conical shape and the conical seat surface (17), release or close the high-pressure valve (4) with a corresponding axial movement of the control valve piston (5); d) an electromagnetic actuation of the control valve piston (5); e) a first closing and opening elastomer-free sealing area (15, 16, 17) and a second always closing elastomer-free sealing area (15, 16) are provided between the combustion chamber (1) and a chamber (23) forming a gaseous damping cushion. The chamber (23) is provided with a vent hole (24) to the outside which only creates the damping cushion and is designed with a throttle, the second sealing area (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.

Images