DE102017105251A1 - Gas supply, internal combustion engine and method for switching off a gas-powered internal combustion engine - Google Patents

Abstract

The invention relates to a gas feed line (1) for passing a gas (50) from a gas reservoir (41) to an internal combustion engine (40), comprising a line element (2) having a low pressure section (3) and a high pressure section (5), the low pressure section (3) and the high pressure section (5) are fluidly connected by a pressure reducer (10), the low pressure section (3) having a motor end (4) and the high pressure section (5) having a reservoir end (6), the motor end (4) being fluid communicating a first shut-off valve (13) and at the motor end (4) of the low-pressure section (3) at least one injection valve (13) 15) is arranged, and wherein in the and / or at the low-pressure section (3) a compensation volume (20) for compensating a pressure increase of the gas (50) in the low-pressure section (3) is arranged. Furthermore, the invention relates to a gas supply line (1) with a thermal insulation (30), an internal combustion engine (40) with a gas supply line (1) and a method for switching off a running with a gas (50) internal combustion engine (40).

Description

The present invention relates to a gas supply line for conducting a gas from a gas reservoir to an internal combustion engine. Furthermore, the invention relates to a gas-operated internal combustion engine and a method for switching off a gas-powered internal combustion engine.

Modern internal combustion engines can often also be operated with a gaseous energy carrier, for example hydrogen or compressed natural gas (CNG). The gas is kept under high pressure, for example at 250 bar or higher, in a gas reservoir. A pressure reducer in a gas supply, which is arranged for conducting the gas between the gas reservoir and the internal combustion engine, reduces the pressure of the gas to a value suitable for the internal combustion engine, for example to about 7 bar. The pressure reducer divides the gas supply into a high-pressure section and a low-pressure section. By blowing valves at an engine end of the gas supply, the gas is introduced into the internal combustion engine.

Under certain conditions, such a large increase in the pressure of the gas may occur in the low-pressure section of the gas supply that opening of the injection valves against this internal pressure is no longer possible. This can occur, for example, when the engine is switched off after a phase of engine operation under high load. The gas in the low pressure section of the gas supply line has a very low temperature in these cases, often well below 0 ° C, and is heated by the shutdown of the engine, which usually has a temperature well above 100 ° C, through this. This can, for example, due to the so-called Joule-Thomson effect, form a large pressure of the gas in the low pressure section of the gas supply, which blocks an opening of the injection valves. As a result, a restart of the internal combustion engine is prevented. Another cause of such pressure increase may be due to a leakage of the pressure reducer. A shut-off valve in the high-pressure section of the gas supply line between the gas reservoir and the pressure reducer, which as a rule is leak-free, prevents a backflow of gas from the gas reservoir in the closed state. However, immediately after the closing of the shut-off valve between the shut-off valve and the pressure reducer, a high-pressure gas is entrapped which, over time, relaxes through the pressure reducer into the remaining gas supply line, in particular into the low pressure section of the gas supply line. This can lead to such a large gas pressure in the low pressure section of the gas supply line, in particular in the case of a long standstill of the internal combustion engine or in bifuel internal combustion engines during a longer phase in which the internal combustion engine is not operated with gas, that opening of the injection valves is blocked and thereby in turn a restart of the engine is prevented. In these cases, a complex repair of the gas supply is necessary in each case, in which in particular the low-pressure section of the gas supply must be vented usually manually. It should also be noted that simply venting the gas from the low pressure section into the environment is not possible due to safety requirements or environmental protection conditions. This also makes it difficult to repair the gas supply.

It is therefore an object of the present invention to at least partially overcome the disadvantages described above. In particular, it is an object of the present invention to provide gas supply lines for conducting a gas from a gas reservoir to an internal combustion engine, an internal combustion engine and a method for switching off a gas-powered internal combustion engine, in a particularly simple and cost-effective manner, a high pressure of the gas in a Prevent low pressure section of the gas supply, in particular, an opening of a Einblasventil can be ensured at an engine end of the gas supply at any time.

The above object is achieved by a gas supply line for conducting a gas from a gas reservoir to an internal combustion engine with the features of independent claim 1. Further, the object is achieved by a gas supply line for passing a gas from a gas reservoir to an internal combustion engine having the features of independent claim 10 , an internal combustion engine with the features of the independent claim 12 and by a method for switching off a gas-fueled internal combustion engine with the features of independent claim 13. Further features and details of the invention will become apparent from the dependent claims, the description and the drawings. In this case, features and details that are described in connection with the individual gas supply lines according to the invention apply, of course, also in connection with the internal combustion engine according to the invention and the method according to the invention and in each case vice versa, so that with respect to the disclosure of the individual aspects of the invention is always reciprocally referred to or become can.

According to a first aspect of the invention, the object is achieved by a gas feed line for conducting a gas from a gas reservoir to an internal combustion engine, comprising Conduit member having a low pressure section and a high pressure section, wherein the low pressure section and the high pressure section are fluidly communicating by a pressure reducer, the low pressure section having a motor end and the high pressure section having a reservoir end, the motor end being fluidly communicating with the engine and the reservoir end fluidly communicating with the gas reservoir, wherein furthermore a first shut-off valve is arranged in the high-pressure section and at least one blow-in valve is arranged at the motor end of the low-pressure section, and wherein a compensation volume for equalizing a pressure increase of the gas in the low-pressure section is arranged in and / or at the low-pressure section.

By means of a gas feed line according to the invention, an internal combustion engine, in particular an internal combustion engine of a vehicle, can be supplied with a gas to be combusted. For example, hydrogen or compressed natural gas (CNG) can be used as the gas. The gas can be used both as a sole source of energy or, for example, in Bifuel internal combustion engines, as an alternative to a liquid energy carrier such as gasoline or diesel in the internal combustion engine. The gas is passed through a duct element from a gas reservoir in which the gas is stored under high pressure, for example 250 bar or higher, to the internal combustion engine. In order to supply the internal combustion engine with gas with a suitable pressure, for example a pressure of 7 bar, a pressure reducer is arranged in the line element, which divides the line element into a low-pressure section and a high-pressure section. In this case, the low-pressure section has a motor end, which is designed to make the line element communicate with the internal combustion engine in a manner that communicates with the fluid. At the engine end, at least one injection valve is arranged, through which an introduction of the gas to the internal combustion engine can be controlled. At the other end of the line element, the high-pressure section has a reservoir end, which is designed to form a fluid-communicating connection of the line element with the gas reservoir. In the high-pressure section, a first shut-off valve is further arranged, which is designed for a preferably hermetically sealed shut off of the high-pressure section. With a closed first shut-off valve, therefore, no gas can flow from the gas reservoir into the line element beyond the first shut-off valve. The first shut-off valve may be formed, for example, as part of the pressure reducer. During operation of the internal combustion engine, with the first shut-off valve open, high-pressure gas flows from the gas reservoir through the high-pressure portion of the conduit member to the pressure reducer. There, the pressure of the gas is reduced to a value suitable for the internal combustion engine. The gas at this lower pressure is then passed through the low pressure section to the engine end and controlled via the at least one injection valve into the internal combustion engine.

The arranged at the motor end at least one injection valve is usually opened against the pressure of the gas in the low pressure section of the conduit element. During operation, the pressure of the gas in the low pressure section is adjusted by the pressure reducer such that a controlled opening of the at least one injection valve is possible at any time. In particular, when stopping the internal combustion engine, it may happen that the pressure of the gas in the low pressure section increases to such a high value that an opening of the injection valve difficult or even completely prevented. For example, such limit pressure is achieved at about 11 bar in the case of injection valves, which are often used as gas when using CNG. In this case, a restart of the engine in gas mode is no longer possible.

As already described above, such an increase in pressure can occur, for example, when the internal combustion engine is switched off, in particular after a prolonged operation of the internal combustion engine under high load. By heating the cold gas in the low-pressure section by the waste heat of the parked internal combustion engine, the temperature and thereby simultaneously a pressure of the gas in the low-pressure section increase. Also, as described above, in longer periods in which the engine is not operated by gas, such an increase of the pressure of the gas may occur particularly by leakage of the pressure reducer in the low pressure portion. In either case, the pressure of the gas in the low pressure section of the conduit member may increase to levels that prevent opening of the at least one inflation valve.

To remedy this problem, a gas supply line according to the invention has a compensation volume, which is arranged in and / or at the low pressure section. In this case, according to the invention, a compensation volume in the low-pressure section is understood in particular to mean a compensating volume which is formed by the conduit element in the low-pressure section itself. An equalization volume, which is arranged at the low-pressure section, in the sense of the invention, on the other hand, is an additional component which, at least at times, can be connected in a fluid-communicating manner to the low-pressure section of the line element. By such a compensating volume, a pressure increase in the low-pressure section can be compensated or at least be reduced. By the compensation volume, the gas can be made available in particular a sufficiently large space in which the gas can flow at a pressure increase. The gas can thereby occupy a larger space, whereby an overall increase in pressure can be reduced. Alternatively or additionally, the compensation volume may also be a volume which increases the low-pressure section overall and at any time. Due to this larger volume of the low pressure section, a pressure increase of the gas can also be absorbed and at least partially compensated, since the pressure increase can be distributed over an overall larger volume. An increase in a pressure of the gas in the low pressure section over a limiting pressure, from which an opening of the at least one injection valve would no longer be possible, can be safely avoided. Starting the internal combustion engine in the gas mode can thus be ensured at all times.

In this case, a gas supply line according to the invention may be designed such that the compensation volume is arranged in and / or at the low-pressure section remote from the motor end and / or close to the pressure reducer. The compensating volume can be designed, for example, as an additional volume, which is arranged on the low-pressure section and can be connected to it in a fluid-communicating manner, or by an extension of the line element itself in the low-pressure section. It is essential that the compensation volume in and / or at the low-pressure section is arranged in such a way by the respectively realized location of the arrangement that a heat input from the internal combustion engine into the gas in the compensation volume is reduced, preferably minimized. This can often be provided particularly simply by arranging the equalizing volume directly adjacent to and adjacent to the pressure reducer in the low-pressure section. By means of this arrangement of the compensation volume, it can be achieved in most cases, in particular, that the compensation volume can be arranged as far as possible from the internal combustion engine. Heating of the gas by the heat of the internal combustion engine can be reduced. A triggered by this heating pressure increase can thus be particularly easily reduced. Furthermore, apart from the internal combustion engine, in the vicinity of which a space available for a compensating volume is often limited, a sufficiently large compensating volume can be provided by this arrangement, in which a gas which is at high pressure between one end of a gas operation of the internal combustion engine first shut-off valve and the pressure reducer is included, can relax. Thus, a pressure increase caused by this relaxation can be particularly easily reduced.

Furthermore, it can be provided in a gas supply line according to the invention that the compensating volume is reversibly connected by a valve arrangement fluidkommunizierend with the low pressure section. By means of such a valve arrangement, a reversible fluid-communicating connection of the compensation volume and the low-pressure section of the line element can be controlled particularly easily. It can be provided, for example, that during normal operation of the internal combustion engine, the valve assembly is closed, whereby the compensating volume is not traversed by the gas during this time. An influence of the compensation volume on this normal operation of the internal combustion engine can thus be particularly easily avoided by a valve arrangement. Furthermore, as a result, a temperature of the gas present in the compensating volume can also be significantly higher than a temperature of the gas in the low-pressure section, for example even as high as the temperature of the internal combustion engine. An increase in pressure due to heating thus falls for the gas already present in the compensation volume significantly smaller than for the gas in the low pressure section, which then can flow in a controlled manner through the valve assembly in the compensating volume. Thus, by opening the valve arrangement with a pressure increase, it can be ensured in a particularly simple manner that the compensating volume for compensating the pressure increase is connected in a fluid-communicating manner with the low-pressure section of the line element. A compensation of the pressure rise can thus be provided without or at least with only slight influence on a normal operation of the internal combustion engine.

Also, a gas supply line according to the invention can be further developed such that the valve arrangement comprises two countercurrently flow-through valves, in particular non-return valves and / or prestressed diaphragm valves, and / or a double-acting valve. These embodiments of a valve arrangement represent preferred embodiments, wherein alternative valve arrangements can be used. These preferred embodiments of usable valve assemblies have the common feature that they can be influenced and / or regulated by them both flow directions of the gas, ie both from the low pressure section of the conduit element in the compensating volume and in the opposite direction. A particularly good control over a flow of the gas can be provided thereby. In addition, these embodiments of a valve assembly are also designed for automatic, for example pressure-controlled, control of the fluid-communicating connection between the low-pressure section and the compensating volume. A automatic, so in particular without additional necessary control units and / or sensors, avoiding a detrimental increase in pressure in the low pressure section of the conduit element can be provided thereby.

Alternatively or additionally, it can be provided in the case of a gas supply line according to the invention that the compensation volume is connected to the low-pressure section in a fluid-communicating manner by a flap arrangement. In this case, such a flap arrangement preferably has two flaps, which are opened in the opposite direction under pressure control. As a trigger pressure from which the flaps are opened, it is possible to select a pressure which is slightly above the pressure set in the low-pressure section during normal operation of the internal combustion engine. Thereby, at a higher pressure of the gas in the low pressure section, a flow of the gas through the first flap in the compensation volume and vice versa at a higher pressure of the gas in the compensation volume, a flow of gas through the second flap from the compensation volume in the low pressure section can be made possible. For the respective closing of the flaps, a return element, for example a spring element or a bi-metal element, can be provided. This results in a hysteresis for the opening of the flaps, so that the respective flap remains open, as long as the corresponding pressure condition is met. With such a flap arrangement, there is thus no gas exchange between the line element and the compensating volume in normal operation. A particularly simple and in particular automatic control of a fluid-communicating connection between the low-pressure section of the line element and the compensating volume can thus be provided by a flap arrangement.

Furthermore, in a further alternative or additional embodiment, a gas supply line according to the invention can be designed such that the compensation volume has an elastic membrane, wherein a pressure increase of the gas in the low-pressure section can be formed by an elastic deformation of the membrane, a bubble to increase the compensation volume. The membrane is made of a suitable material having, for example, a required flexibility and / or heat resistance. Preferably, the elastic deformation occurs only from a certain pressure of the gas in the low-pressure section of the conduit element, for example, from a limit pressure, from which opening of the at least one injection valve would no longer be possible. Due to the bubble formed, the compensation volume is increased, sometimes even completely formed, so that an increase in pressure of the gas can be reduced. About a geometry and / or a thickness of the membrane, the limit pressure or a working range of the membrane can be set. Overall, a particularly demand-adapted compensation volume can be provided by such a membrane.

According to a preferred further development of a gas supply line according to the invention, it can further be provided that a housing element for receiving the bubble is arranged at the low-pressure section. By means of such a housing element, the bubble resulting from an elastic deformation of the membrane can preferably be completely surrounded. Protection against external influences, in particular damage to the membrane, can be provided particularly easily by means of such a housing.

Also, a gas supply line according to the invention can be further developed such that the housing element has compensation openings for a fluid-communicating gas exchange with an environment. By such compensation openings can be ensured that when forming the bubble air that is located within the housing, can be displaced in an environment of the housing. When the bubble regresses, the air flows back through the equalization ports into the interior of the housing. A complete filling of the housing through the bladder can be made very easy.

Alternatively, a gas supply line according to the invention may be designed such that the housing element is formed sealed against the environment. In this way, during the formation of the bubble, an air cushion is created between the elastically deformed membrane and the housing. An even better protection of the membrane can thereby be provided. In particular, it may be provided that this air cushion is taken into account in a design of the membrane. By a suitable choice of an air pressure in the housing element while the shaping of the bubble can be influenced by the elastic membrane targeted. Instead of using air, the housing element can also be filled with another suitable gas. An even more accurate adjustment of a working area of the membrane can thereby be provided.

According to a second aspect of the invention, the object is achieved by a gas supply line for passing a gas from a gas reservoir to an internal combustion engine, comprising a line element having a low pressure section and a high pressure section, the low pressure section and the high pressure section being fluidly communicated by a pressure reducer, the low pressure section a motor end and the high-pressure section having a reservoir end, wherein the motor end fluidkommunizierend with the internal combustion engine and the reservoir end fluidkommunizierend with the gas reservoir are connectable, wherein further in the high pressure section a first shut-off valve and at the motor end of the low-pressure section at least one injection valve is arranged, and wherein the low pressure section at least partially thermal insulation having.

With regard to fields of application and the problems arising, reference is made to a gas supply line according to the first aspect of the invention, as described in detail above. Essential to the invention is provided in a gas supply line according to the second aspect of the invention that the low pressure section at least partially has a thermal insulation. This thermal insulation is preferably arranged at the low-pressure section of the line element, particularly preferably adjacent to the internal combustion engine. Also, the thermal insulation may preferably be arranged on the entire low-pressure section. By such insulation, a heat input can be prevented in particular by the engine in the gas in the low pressure section or at least slowed down. For example, after a shutdown of the internal combustion engine, in particular after a prolonged operation under high load, the maximum reached temperature of the gas can be significantly reduced. As a result, a maximum pressure which the gas can assume as a result of this temperature increase automatically also decreases. It can be achieved by a suitable embodiment of the thermal insulation, that the maximum achievable pressure is lower than a limiting pressure, from which opening of the at least one injection valve is no longer possible. An opening of the at least one injection valve can thus be ensured by a thermal insulation arranged at least in sections on the low-pressure section of the conduit element.

With a gas supply line according to the invention according to the second aspect of the invention, it may be particularly preferred that the gas supply line is additionally designed according to the first aspect of the invention. Accordingly, such a further developed gas supply line according to the second aspect of the invention brings the same advantages as have been explained in detail with respect to a gas supply line according to the invention according to the first aspect of the invention.

According to a third aspect of the invention, the object is achieved by an internal combustion engine, wherein the internal combustion engine is operable with a gas and wherein the internal combustion engine is fluid-communicating with a gas reservoir through a gas supply line. An internal combustion engine according to the invention is characterized in that the gas supply line according to the first or the second aspect of the invention is formed. Accordingly, an internal combustion engine according to the invention according to the third aspect of the invention brings the same advantages as have been explained in detail with reference to a gas supply line according to the invention according to the first and second aspect of the invention. An internal combustion engine according to the invention can preferably be used in a vehicle. Also, an internal combustion engine according to the invention can be designed as a so-called bi-fuel internal combustion engine, which can be operated both with gas and alternatively with a liquid energy carrier such as gasoline or diesel in the internal combustion engine.

• a) Schließen eines Absperrventils im Hochdruckabschnitt,
• b) Weiterbetreiben des Verbrennungsmotors zum Vermindern eines Gasdrucks im Niederdruckabschnitt, und
• c) Beenden des Betriebs des Verbrennungsmotors.

According to a fourth aspect of the invention, the object is achieved by a method for switching off a gas-operated internal combustion engine, wherein the internal combustion engine is fluid-communicating with a gas reservoir through a line element of a gas supply, the line element having a low-pressure section and a high-pressure section, wherein in the high-pressure section Shut-off valve and at least one injection valve is arranged at the motor end of the low-pressure section. A method according to the invention is characterized by the following steps:

• a) closing a shut-off valve in the high-pressure section,
• b) continuing to drive the internal combustion engine to reduce a gas pressure in the low-pressure section, and
• c) stop the operation of the internal combustion engine.

Even in a gas-fueled internal combustion engine, the problems described above with respect to a gas supply line according to the first aspect of the invention may occur. Thus, for example, after operation under, in particular, high load, the internal combustion engine may have a very high temperature, for example 130 ° C. or higher, and the gas contained in the low-pressure section may have a very low temperature, for example -30 ° C. or lower. A heating of the gas in the low-pressure section of the line element by a residual heat of the switched-off internal combustion engine could cause such a large pressure increase in the gas that an opening of the at least one injection valve could be blocked. Also could be at a longer downtime, a gas that has the high pressure of the gas reservoir, for example 250 bar or higher, and after closing the shut-off valve between the shut-off valve and the pressure reducer or a pressure-reducing element of the pressure reducer, relax by the leak-prone pressure reducer into the low-pressure section of the line element. As a result, such a high gas pressure can arise in the low pressure section that an opening of the at least one injection valve could be blocked. In both cases, a restart of the internal combustion engine would then no longer be possible.

These problems can be solved by an inventive method for switching off a gas-fueled internal combustion engine. In this case, a method according to the invention can preferably be carried out after a switch-off request made by a user of the internal combustion engine. In this case, in a step a) of a method according to the invention, a shut-off valve in the high-pressure section is closed. The shut-off valve is preferably a hermetically sealed shut-off valve. This first shut-off valve may be formed, for example, as part of the pressure reducer or as the first shut-off valve in the high-pressure section of the line element. By means of this closing, it can be ensured in particular that a further gas supply from the gas reservoir into the line element of the gas supply line is prevented. In the following step b), the internal combustion engine continues to operate. These are, for example, a short operation of the internal combustion engine, in which, for example, only a few cylinder strokes of the internal combustion engine are preferably carried out. Gas is consumed by this fired wake of the internal combustion engine, whereby gas is only consumed from the low-pressure section, in particular since there is no subsequent flow of gas out of the gas reservoir due to the closed shut-off valve. This automatically reduces a pressure of the gas in the low-pressure section of the conduit element. The continued operation of the internal combustion engine in step b) of a method according to the invention is preferably carried out so long that the pressure reduction in the low pressure section is sufficient to a possible pressure increase by heating the gas by a Nachwärme of the engine or by a relaxation of gas through the leak-prone pressure reducer compensate. Blocking of the at least one injection valve by a high pressure in the low-pressure section of the line element can be safely avoided. This can be achieved by a suitably late performed step c) of a method according to the invention, in which the operation of the internal combustion engine is terminated. Overall, it can thus be ensured by a method according to the invention that a starting of a gas-fueled internal combustion engine, which requires opening of the at least one injection valve, can be made possible at any time, in particular blocking the at least one injection valve by an excessively high gas pressure in the low pressure section of the conduit element is prevented.

Particularly preferably, a method according to the invention can be further developed in that the method is carried out by an internal combustion engine according to the third aspect of the invention. Accordingly, an inventive method according to the fourth aspect of the invention brings the same advantages as have been explained in detail with reference to an internal combustion engine according to the invention according to the third aspect of the invention. An internal combustion engine according to the invention is further characterized in that the gas supply line used in the internal combustion engine according to the first or the second aspect of the invention is formed. Accordingly, a method according to the invention according to the fourth aspect of the invention also entails the same advantages as have been explained in detail with reference to a gas feed line according to the invention according to the first or second aspect of the invention.

Further advantages, features and details of the invention will become apparent from the following description in which, with reference to the drawings, embodiments of the invention are described in detail. The features mentioned in the claims and in the description may each be essential to the invention individually or in any desired combination. Elements with the same function and mode of action are provided with the same reference numerals.

They show schematically:

1 an internal combustion engine according to the invention with a gas supply line according to the invention and various gas pressure profiles in this gas supply line,

2 A first embodiment of a low-pressure section of a gas supply line according to the invention,

3 A second embodiment of a low-pressure section of a gas supply line according to the invention,

4 a third embodiment of a low-pressure section of a gas supply line according to the invention, and

5 A fourth embodiment of a low-pressure section of a gas supply line according to the invention.

1 shows in the uppermost figure an internal combustion engine according to the invention 40 , via a gas supply line according to the invention 1 with a gas reservoir 41 connected in a fluid-communicating manner. There is an engine end for that 4 a conduit element 2 the gas supply 1 with the internal combustion engine 40 and a reservoir end 6 of the conduit element 2 with the gas reservoir 41 connected. gas 50 flows, represented by an arrow, with an opened first shut-off valve 13 under high pressure in a high pressure section 5 of the conduit element 2 one. Some possible courses of the gas pressure 51 in the conduit element 2 the gas supply line according to the invention 1 are in 1 shown in the pictures below. The high pressure section 5 ends at a pressure reducer 10 which in this embodiment is a diaphragm valve 12 and also a shut-off valve 11 having. In the pressure reducer 10 becomes the pressure of the gas 50 in the gas reservoir 41 and in the high pressure section 5 Often values of 250 bar or higher may be reduced to a pressure that is appropriate for the internal combustion engine 40 is appropriate, for example, 7 bar. This gas 50 low pressure will be following the pressure reducer 10 in a low pressure section 3 of the conduit element 2 to the internal combustion engine 40 directed. At the engine end 4 are for a controlled providing of the gas 50 for the internal combustion engine 40 injection valves 15 arranged. Another, in particular optional, second shut-off valve 14 in the low pressure section 3 allows a hermetically sealed shut off the low pressure section 3 ,

In the lower pictures of the 1 , denoted by A to E in the figure, are schematically various possible courses of a gas pressure 51 of the gas 50 in such a gas supply line 1 shown. The individual elements of the gas supply line 1 or the internal combustion engine 40 and the gas reservoir 41 are preferred in each case as in the top figure of 1 educated. In each of the gas pressure curves A to E is additionally a limit pressure 52 drawn from which the injection valves 15 can not be opened anymore.

Thus, in the course of gas A is a course of the gas pressure 51 shown as it during normal operation or shortly after completion of an operation of the internal combustion engine 40 is present. From the gas reservoir 41 becomes a gas 50 with a high gas pressure 51 provided by the pressure reducer 10 is reduced. After the pressure reducer 10 becomes gas 50 with a low gas pressure 51 forwarded and the internal combustion engine 40 fed. The gas pressure 51 after the pressure reducer 10 is lower than the limit pressure 52 so that the injection valves 15 can be opened in a controlled manner at any time.

After completion of an operation of the internal combustion engine 40 , in particular an operation under high load and / or for a long time, is the internal combustion engine 40 very heated and can have temperatures of well above 100 ° C, sometimes even 130 ° C or higher. At the same time is the gas 50 in the low pressure section 3 due to physical processes in the pressure reduction in the pressure reducer 10 very cold, mostly well below 0 ° C, often even -30 ° C or colder. Due to the spatial proximity of the low pressure section 3 to the internal combustion engine 40 becomes this and the gas in it 50 by the waste heat of the internal combustion engine 40 heated. An increase in gas pressure 51 in the low pressure section 3 is the consequence. This is shown in the gas pressure curve B. Here is also clearly visible that the gas pressure 51 It can rise so much that he the limit pressure 52 exceeds. A controlled opening of the injection valves 15 and thus restarting the internal combustion engine 40 is thereby prevented.

A slightly different course of the gas pressure 51 , shown in the gas pressure curve C, results when an existing second shut-off valve 14 in the low pressure section 3 closed is. The closer to the internal combustion engine 40 arranged portion of the low pressure section 3 of the conduit element 2 experiences even greater heating, so that in this section the gas pressure 51 increases to even higher values. However, the gas too 50 in the remaining low pressure section 3 by the residual heat of the internal combustion engine 40 heated up, so that there too the gas 50 a gas pressure 51 may be higher than the limit pressure 52 ,

Another problem with regard to a gas pressure 51 in the low pressure section 3 results from the fact that, as shown in the gas pressure curve A, after stopping the engine 40 between a closed shut-off valve 11 that's here as part of the reducer 10 is formed, and a diaphragm valve 12 of the pressure reducer 10 a gas 50 with a high gas pressure 51 that the gas pressure 51 in the gas reservoir 41 corresponds, is included. Because the diaphragm valve 12 mostly leaking, this trapped gas becomes 50 over a period of time through the diaphragm valve 12 of the pressure reducer 10 in the low pressure section 3 of the conduit element 2 relax. Also, thereby, as shown in the gas pressure curve D, in the low-pressure section 3 a gas pressure 51 occur, which is higher than the limit pressure 52 , A controlled opening of the injection valves 15 is no longer possible in this case.

A method according to the invention represents a possibility of remedying the problems explained with regard to the gas pressure curves B, C and D. It is, for example, at a present request for a shutdown of the internal combustion engine 40 by a user, in a first step a) a shut-off valve 11 . 13 , here designed as a shut-off valve 11 inside the pressure reducer 10 , closed. An afterflow of gas 50 from the gas reservoir 41 in the gas supply line 1 This can be safely avoided. in a second step b), the internal combustion engine 40 continue to operate. This continued operation is carried out only for a short time, for example, only for a few cylinder strokes of the engine 40 , In this short operation of the internal combustion engine 40 but it will still be gas 50 consumed, due to the closed shut-off valve 11 of the pressure reducer 10 , only from the low pressure section 3 of the conduit element 2 can be provided. This will be the low pressure section 3 deflated, causing the low pressure section 3 a very low gas pressure 51 can be generated. This is shown in the gas pressure curve E. This gas pressure 51 in the low pressure section 3 can be set so low that the gas pressure 51 after a final stop of an operation of the internal combustion engine 40 , the step c) of a method according to the invention, even by the mechanisms described in particular with respect to the gas curves B and D no longer about the limit pressure 52 is increased. A controlled opening of the injection valves 15 and thus a restart of the internal combustion engine 40 can thus be provided by an inventive method at any time.

In the 2 to 5 is each a low pressure section 3 a conduit element 2 a gas supply line according to the invention 1 shown. In each case, devices are shown in the individual figures, by the also, in addition or as an alternative to a method according to the invention, with respect to the gas pressure curves B and D, see 1 , described problems can be solved. The internal combustion engine 40 , the gas 50 itself and its gas pressure 51 are not shown in each case.

So is in 2 on the one hand on the line element 2 a thermal insulation 30 arranged, in particular close to the engine end 4 of the conduit element 2 and thus immediately adjacent to an internal combustion engine 40 (not shown). This can cause a heating of the gas 50 (not shown) in the low pressure section 3 by a waste heat of the internal combustion engine 40 be avoided or at least significantly reduced. A pressure increase of the gas 50 in the low pressure section 3 can be prevented or at least significantly reduced. In particular, this can increase the gas pressure 51 about a limit pressure 52 (each not shown), from the opening of a blow-in valve 15 (not shown) by the gas pressure 51 is blocked, safely prevented. Furthermore, in the illustrated line element 2 a compensation volume 20 intended. The compensation volume 20 can, as shown, in addition to the thermal insulation 30 to be available. Alternatively, depending on only one of these devices, the compensation volume 20 or the thermal insulation 30 , be provided. The compensation volume 20 is here as part of the conduit element 2 educated. It is clearly visible that the compensation volume 20 away from the engine end 4 and close to the pressure reducer 10 in the low pressure section 3 of the conduit element 2 is arranged. This allows an arrangement of the compensation volume 20 be provided outside of an area caused by waste heat of the internal combustion engine 40 is heated or will. A heating of gas 50 in the equalization volume 20 by the waste heat of the internal combustion engine 40 This can be particularly easily and effectively reduced or even completely avoided. Through the equalization volume 20 can thus the entire volume of the low pressure section 3 increases and thereby an increase in pressure in the remaining low-pressure section 3 , for example near the engine end 4 to be compensated. In particular, by such a compensation volume 20 an increase in gas pressure 51 about a limit pressure 52 , from the opening of a blow-in valve 15 by the gas pressure 51 is blocked, safely prevented.

Also in 3 is a low pressure section 3 a conduit element 2 a gas supply line according to the invention 1 as well as a compensation volume 20 shown. In contrast to 2 is this compensation volume 20 at the low pressure section 3 arranged, through a valve assembly 21 a reversible fluid communicating connection of the low pressure section 3 and the compensation volume 20 is possible. The valve arrangement 21 For example, it may preferably comprise, for example, two valves which can be flowed through in opposite directions, in particular non-return valves and / or prestressed diaphragm valves, and / or a double-acting valve. This can be achieved that, if in the low-pressure section 3 a gas pressure 51 of the gas 50 rises too high values, the valve assembly 21 correspondingly establishes the fluid-communicating connection and gas 50 to compensate for the high gas pressure 51 into the equalization volume 20 can flow. Conversely, if the gas pressure 51 in the low pressure section 3 again dropped to low enough levels, through one through the valve assembly 21 prepared corresponding fluid-communicating compound gas 50 from the equalization volume 20 back to the low pressure section 3 stream. Making the fluid communicating connection through the valve assembly 21 can be controlled, for example, by a control device, as well as automatically, for example, pressure controlled, done. A particularly safe Avoidance of too high a gas pressure 51 in the low pressure section 3 , in particular by opening a blow-in valve 15 could be blocked.

Another embodiment of a gas supply line according to the invention 1 in which a compensation volume 20 at a low pressure section 3 a conduit element 2 is arranged in is 4 shown. The fluid communicating connection between the low pressure section 3 and the equalization volume 20 is in this embodiment by a flap assembly 22 provided. A flap arrangement 22 represents a mechanically particularly simple way to produce such a reversible fluid-communicating compound. The flap arrangement 22 can, as shown, have two flaps, wherein one of the flaps in the open state, a flow of gas 50 from the low pressure section 3 into the equalization volume 20 , the others a stream of gas 50 in the opposite direction. The opening of the flaps can be made, for example, under pressure control, wherein as a trigger pressure, for example, a gas pressure 51 can be selected, which is a little above the normal operation of the internal combustion engine 40 in the low pressure section 3 set gas pressure 51 lies. At a higher gas pressure 51 of the gas 50 in the low pressure section 3 This is done by a flow of gas 50 through the first flap in the compensation volume 20 and vice versa at a higher gas pressure 51 of the gas 50 in the equalization volume 20 a flow of the gas 50 through the second flap from the compensation volume 20 back to the low pressure section 3 , For the respective closing of the flaps, a return element, for example a spring element or a bi-metal element, can be provided. As a result, the respective flap remains open and thus the fluid-communicating connection is established, as long as the corresponding pressure condition is met. In such a flap arrangement 22 takes place at a gas pressure 51 in the low pressure section 3 below the trigger pressure no gas exchange between the line element 2 and the equalization volume 20 instead of. A particularly simple and, in particular, automatic control of a fluid-communicating connection between the low-pressure section 3 of the conduit element 2 and the equalization volume 20 can thus by a flap assembly 22 to be provided. Also in this way can thus a particularly safe avoidance of too high a gas pressure 51 in the low pressure section 3 , in particular by opening a blow-in valve 15 could be blocked.

5 shows a further embodiment of a gas supply line according to the invention 1 , The low pressure section 3 of the conduit element 2 again has a compensation volume 20 on, in this embodiment, an elastic membrane 23 having. When exposed to a sufficiently large gas pressure 51 (not shown) the membrane deforms 23 elastic and forms a bubble 24 through which the equalization volume 20 enlarged or even completely formed. In the upper figure is shown a state in which the gas pressure 51 of the gas 50 in the low pressure section 3 has a low value, for example, a value that is important for the operation of the internal combustion engine 40 fitting through a pressure reducer 10 (not shown). This value is preferably smaller than a gas pressure 51 , from which the elastic membrane 23 to a bubble 24 deformed. Now increases the gas pressure 51 in the low pressure section 3 on, for example after an operating end of the internal combustion engine 40 by heating the gas 50 in the low pressure section 3 by a waste heat of the internal combustion engine 40 or by a leakage of the pressure reducer 10 , so will the elastic membrane 23 by the gas pressure 51 deformed and a bubble 24 forms. This is shown in the picture below. The compensation volume 20 is thereby increased or formed and the gas 50 in the low pressure section 3 This provides an additional space, thereby increasing the gas pressure 51 is limited or even decreases again. In this way it can be ensured that not too high a gas pressure 51 in the low pressure section 3 prevails, in particular by opening a Einblasventils 15 would be blocked. In addition, in 5 a housing element 25 shown that to pick up the bubble 24 at the low pressure section 3 is arranged. A protection of the elastic membrane 23 and in particular by the elastic membrane 23 formed bubble 24 , For example, from mechanical damage, can be provided by it. It can be provided that the housing element 25 is formed sealed against an environment. This forms inside the housing element 25 in the formation of the bladder 24 an air cushion, which is the bubble 24 additionally protects. By a suitable choice of air pressure in the housing element 25 may also be shaping the bladder 24 through the elastic membrane 23 be set. Instead of air can thereby the housing element 25 also be filled with another suitable gas. Alternatively, the housing element 25 also have compensation openings (not shown) through which a fluid-communicating gas exchange with the environment is possible. When forming the bubble 24 displaces these in the housing element 25 existing air through the compensation openings and can in this way, for example, the housing element 25 completely complete. A particularly good utilization of an existing installation space can be provided thereby.

LIST OF REFERENCE NUMBERS

1

gas supply

2

line element

3

Low pressure section

4

engine end

5

High pressure section

6

reservoir end

10

pressure reducer

11

Shut-off valve (pressure reducer)

12

Diaphragm valve (pressure reducer)

13

first shut-off valve

14

second shut-off valve

15

injection valve

20

compensating volume

21

valve assembly

22

door assembly

23

elastic membrane

24

bladder

25

housing element

30

thermal insulation

40

internal combustion engine

41

gas reservoir

50

gas

51

gas pressure

52

limit pressure

Claims (14)

Gas supply line ( 1 ) for conducting a gas ( 50 ) from a gas reservoir ( 41 ) to an internal combustion engine ( 40 ), comprising a conduit element ( 2 ) with a low pressure section ( 3 ) and a high pressure section ( 5 ), the low pressure section ( 3 ) and the high pressure section ( 5 ) by a pressure reducer ( 10 ) are connected in a fluid-communicating manner, the low-pressure section ( 3 ) a motor end ( 4 ) and the high pressure section ( 5 ) a reservoir end ( 6 ), the engine end ( 4 ) in fluid communication with the internal combustion engine ( 40 ) and the reservoir end ( 6 ) in fluid communication with the gas reservoir ( 41 ) are connectable, wherein further in the high pressure section ( 5 ) a first shut-off valve ( 13 ) and at the engine end ( 4 ) of the low-pressure section ( 3 ) at least one injection valve ( 15 ) is arranged, and wherein in and / or at the low-pressure section ( 3 ) a compensation volume ( 20 ) for equalizing a pressure increase of the gas ( 50 ) in the low pressure section ( 3 ) is arranged. Gas supply line ( 1 ) according to claim 1, characterized in that the compensating volume ( 20 ) in and / or at the low-pressure section ( 3 ) away from the motor end ( 4 ) and / or close to the pressure reducer ( 10 ) is arranged. Gas supply line ( 1 ) according to claim 1 or 2, characterized in that the compensating volume ( 20 ) by a valve arrangement ( 21 reversibly fluid-communicating with the low-pressure section ( 3 ) connected is. Gas supply line ( 1 ) according to claim 3, characterized in that the valve arrangement ( 21 ) comprises two countercurrently flowable valves, in particular non-return valves and / or prestressed diaphragm valves, and / or a double-acting valve. Gas supply line ( 1 ) according to one of the preceding claims, characterized in that the compensating volume ( 20 ) by a flap arrangement ( 22 ) in fluid communication with the low pressure section ( 3 ) connected is. Gas supply line ( 1 ) according to one of the preceding claims, characterized in that the compensating volume ( 20 ) an elastic membrane ( 23 ), wherein at a pressure increase of the gas ( 50 ) in the low pressure section ( 3 ) by an elastic deformation of the membrane ( 23 ) a bubble ( 24 ) to increase the compensation volume ( 20 ) is bildbar. Gas supply line ( 1 ) according to claim 6, characterized in that at the low pressure section ( 3 ) a housing element ( 25 ) for picking up the bladder ( 24 ) is arranged. Gas supply line ( 1 ) according to claim 7, characterized in that the housing element ( 25 ) Has equalization openings for a fluid-communicating gas exchange with an environment. Gas supply line ( 1 ) according to claim 7, characterized in that the housing element ( 25 ) is formed sealed against the environment. Gas supply line ( 1 ) for conducting a gas ( 50 ) from a gas reservoir ( 41 ) to an internal combustion engine ( 40 ), comprising a conduit element ( 2 ) with a low pressure section ( 3 ) and a high pressure section ( 5 ), the low pressure section ( 3 ) and the high pressure section ( 5 ) by a pressure reducer ( 10 ) are connected in a fluid-communicating manner, the low-pressure section ( 3 ) a motor end ( 4 ) and the high pressure section ( 5 ) a reservoir end ( 6 ), the engine end ( 4 ) in fluid communication with the internal combustion engine ( 40 ) and the reservoir end ( 6 ) in fluid communication with the gas reservoir ( 41 ) are connectable, wherein further in the high pressure section ( 5 ) a first shut-off valve ( 13 ) and at the engine end ( 4 ) of the low-pressure section ( 3 ) at least one injection valve ( 15 ), and wherein the low-pressure section ( 3 ) at least in sections a thermal insulation ( 30 ) having. Gas supply line ( 1 ) according to claim 10, characterized in that the gas supply line ( 1 ) is additionally designed according to one of claims 1 to 9. Internal combustion engine ( 40 ), wherein the internal combustion engine ( 40 ) with a gas ( 50 ) and wherein the internal combustion engine ( 40 ) by a gas supply line ( 1 ) in fluid communication with a gas reservoir ( 41 ), characterized in that the gas supply line ( 1 ) is designed according to one of the preceding claims. Method for shutting off one with a gas ( 50 ) operated internal combustion engine ( 40 ), wherein the internal combustion engine ( 40 ) by a conduit element ( 2 ) a gas supply line ( 1 ) in fluid communication with a gas reservoir ( 41 ), the conduit element ( 2 ) comprising a low pressure section ( 3 ) and a high pressure section ( 5 ), wherein in the high pressure section ( 5 ) a shut-off valve ( 11 . 13 ) and at the engine end ( 4 ) of the low-pressure section ( 3 ) at least one injection valve ( 15 ), comprising the following steps: a) closing a shut-off valve ( 11 . 13 ) in the high pressure section ( 5 ), b) Continuing to drive the internal combustion engine ( 40 ) for reducing a gas pressure ( 51 ) in the low pressure section ( 3 ), and c) stopping the operation of the internal combustion engine ( 40 ). A method according to claim 13, characterized in that the method by an internal combustion engine ( 40 ) is carried out according to claim 12.

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