CN108699992B - Method for operating a fuel supply system and fuel supply system - Google Patents
Method for operating a fuel supply system and fuel supply system Download PDFInfo
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- CN108699992B CN108699992B CN201780009495.6A CN201780009495A CN108699992B CN 108699992 B CN108699992 B CN 108699992B CN 201780009495 A CN201780009495 A CN 201780009495A CN 108699992 B CN108699992 B CN 108699992B
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- 239000000446 fuel Substances 0.000 title claims abstract description 156
- 238000000034 method Methods 0.000 title claims abstract description 22
- 238000003860 storage Methods 0.000 claims abstract description 86
- 230000001105 regulatory effect Effects 0.000 claims abstract description 47
- 239000007788 liquid Substances 0.000 claims abstract description 44
- 238000002485 combustion reaction Methods 0.000 claims abstract description 35
- 238000002347 injection Methods 0.000 claims abstract description 23
- 239000007924 injection Substances 0.000 claims abstract description 23
- 230000001276 controlling effect Effects 0.000 claims abstract description 7
- 238000012432 intermediate storage Methods 0.000 claims description 5
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 62
- 239000003345 natural gas Substances 0.000 description 31
- 239000002283 diesel fuel Substances 0.000 description 22
- 230000009977 dual effect Effects 0.000 description 7
- 238000007789 sealing Methods 0.000 description 5
- 239000007789 gas Substances 0.000 description 4
- 230000000875 corresponding effect Effects 0.000 description 2
- 239000003949 liquefied natural gas Substances 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 230000000712 assembly Effects 0.000 description 1
- 238000000429 assembly Methods 0.000 description 1
- 239000012752 auxiliary agent Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 239000003638 chemical reducing agent Substances 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000002596 correlated effect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003502 gasoline Substances 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 230000002452 interceptive effect Effects 0.000 description 1
- 239000012528 membrane Substances 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000243 solution Substances 0.000 description 1
Images
Classifications
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D41/0027—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures the fuel being gaseous
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0602—Control of components of the fuel supply system
- F02D19/0605—Control of components of the fuel supply system to adjust the fuel pressure or temperature
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0639—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels
- F02D19/0642—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions
- F02D19/0647—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed characterised by the type of fuels at least one fuel being gaseous, the other fuels being gaseous or liquid at standard conditions the gaseous fuel being liquefied petroleum gas [LPG], liquefied natural gas [LNG], compressed natural gas [CNG] or dimethyl ether [DME]
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
- F02D19/0673—Valves; Pressure or flow regulators; Mixers
- F02D19/0678—Pressure or flow regulators therefor; Fuel metering valves therefor
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/0025—Controlling engines characterised by use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D41/00—Electrical control of supply of combustible mixture or its constituents
- F02D41/30—Controlling fuel injection
- F02D41/38—Controlling fuel injection of the high pressure type
- F02D41/3809—Common rail control systems
- F02D41/3836—Controlling the fuel pressure
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
- F02M21/00—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form
- F02M21/02—Apparatus for supplying engines with non-liquid fuels, e.g. gaseous fuels stored in liquid form for gaseous fuels
- F02M21/0218—Details on the gaseous fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
- F02M21/0248—Injectors
- F02M21/0275—Injectors for in-cylinder direct injection, e.g. injector combined with spark plug
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
- F02D19/0686—Injectors
- F02D19/0689—Injectors for in-cylinder direct injection
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
- F02D—CONTROLLING COMBUSTION ENGINES
- F02D19/00—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures
- F02D19/06—Controlling engines characterised by their use of non-liquid fuels, pluralities of fuels, or non-fuel substances added to the combustible mixtures peculiar to engines working with pluralities of fuels, e.g. alternatively with light and heavy fuel oil, other than engines indifferent to the fuel consumed
- F02D19/0663—Details on the fuel supply system, e.g. tanks, valves, pipes, pumps, rails, injectors or mixers
- F02D19/0686—Injectors
- F02D19/0694—Injectors operating with a plurality of fuels
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/10—Internal combustion engine [ICE] based vehicles
- Y02T10/30—Use of alternative fuels, e.g. biofuels
Abstract
The invention relates to a method for operating a fuel supply system, by means of which an internal combustion engine can be supplied with gaseous and liquid fuel, wherein the gaseous fuel is removed from a first storage line (1) and is injected directly into a combustion chamber of the internal combustion engine by means of an injection valve (2) connected to the first storage line (1), and wherein the pressure in the first storage line (1) is regulated by means of a pressure regulating device (3) comprising at least one hydraulically controlled valve (4,5) as a function of the pressure in a further storage line (6) for the liquid fuel. According to the invention, for hydraulically controlling the valves (4,5), a reduced pressure relative to the pressure in the further storage line (6) is used as the control pressure, wherein for reducing the pressure a throttle (7) is used which is arranged in a branch line (8) connecting the valves (4,5) to the further storage line (6). Furthermore, the invention relates to a fuel supply system which is suitable for carrying out the method.
Description
Technical Field
The invention relates to a method for operating a fuel supply system. The invention further relates to a fuel supply system for supplying an internal combustion engine with gaseous and liquid fuel. The fuel supply system is particularly suitable for carrying out the proposed method.
Background
The gaseous fuel is in particular Natural Gas (NG, Natural Gas).
Natural Gas is itself gaseous at high pressure at normal temperatures (Compressed Natural Gas, CNG, or "Compressed Natural Gas"). For the injection of compressed natural gas into the combustion chambers of an internal combustion engine, special injection valves or injectors are required, which differ from each other in the direct injection of gasoline or diesel fuel. Because liquid Natural Gas (LGN), which is a "Liquefied Natural Gas," has a significantly smaller volume than gaseous Natural Gas, for mobile applications, the Natural Gas is typically maintained in a liquid form. For this purpose, the natural gas is cooled down to a temperature of about-160 ℃.
The natural gas introduced into the combustion chamber of the internal combustion engine is ignited by the auxiliary agent or auxiliary medium. For example, liquid diesel fuel can be used as a secondary medium, since it is not normally self-igniting in the given conditions as natural gas. In this case, there are two different fuel types to be introduced into the combustion chamber of the internal combustion engine.
In order to introduce two different fuel types into the combustion chamber of an internal combustion engine, so-called dual fuel injectors may be used. In such dual fuel injectors, the two fuels are separately directed in order to prevent mixing outside the combustion chamber. However, mixing can occur through leakage, which is particularly dangerous or harmful if the gaseous fuel reaches the region of the liquid fuel. To reliably prevent this, the gas pressure in the dual fuel injector must be kept lower than the pressure of the liquid fuel.
From the publication DE 112006001271T 5 a method for controlling the injection pressure of a gaseous fuel is known, which takes this principle into account when using a single fuel injection valve for injecting the gaseous fuel and a liquid auxiliary fuel for igniting the gaseous fuel. Here, the pressure for the gaseous fuel inside the fuel injection valve is defined as the injection pressure. In order to reduce this injection pressure, the supply of gaseous fuel to the fuel rail which feeds the fuel injection valve can be interrupted or delayed by means of a valve in the fuel supply line until the injection pressure for the gaseous fuel drops to a predetermined value. In this way, the pressure of the gaseous fuel can be regulated such that it is lower than the pressure of the liquid fuel. Preferably, the injection pressure adjustment of the gaseous fuel is performed in reaction to the pressure of the auxiliary fuel. In this case, a valve can be used which is designed as a pressure regulating valve and has a control chamber which is connected to a fuel rail for auxiliary fuel. In this arrangement, the pressure for the gaseous fuel is controlled by the pressure for the auxiliary fuel.
Disclosure of Invention
Starting from the prior art described above, the object of the present invention is to provide a method for operating a fuel supply system for gaseous and liquid fuels, which method makes it possible to regulate the pressure in a storage line for gaseous fuel as a function of the pressure in a further storage line for gaseous fuel in such a way that a pressure difference is maintained. It is thereby ensured that the pressure in the storage line for gaseous fuel is always lower than the pressure in the further storage line for liquid fuel. Furthermore, a fuel supply system is to be specified, which is capable of carrying out the method.
In order to solve the object, a method according to the invention and a fuel supply system according to the invention are provided. A method for operating a fuel supply system for supplying an internal combustion engine with gaseous and liquid fuel is proposed. In the method, gaseous fuel is taken from a first storage line and injected directly into a combustion chamber of the internal combustion engine by means of an injection valve connected to the first storage line. The pressure in the first storage line is regulated by a pressure regulating device comprising at least one hydraulically controlled valve as a function of the pressure in the further storage line for the liquid fuel. According to the invention, for hydraulically controlling the valve, a reduced pressure relative to the pressure in the further storage line is used as the control pressure. In order to reduce the pressure, a throttle is used, which is arranged in a branch line connecting the valve with the further storage line.
In the proposed method, the pressure in the first storage line for gaseous fuel is correlated with the pressure in the further storage line for liquid fuel. In this case, it is ensured by a throttle arranged in the branch line which conducts the liquid fuel that the pressure in the first storage line is lower than the pressure in the further storage line. The control pressure or the pressure difference between the pressure in the first storage line and the pressure in the further storage line can be set by the design of the throttle.
Preferably, the throttle is designed such that the control pressure or the pressure of the liquid fuel after the throttle is 150 to 500bar in order to adjust the pressure of the gaseous fuel in the first storage line to the respective pressure. The pressure in the further storage line for liquid fuel is preferably 200 to 600bar and is furthermore preferably 10 to 100bar higher than the control pressure or the pressure in the first storage line for gaseous fuel.
In addition, the return line is preferably supplied with liquid fuel taken from a further storage line for hydraulically controlling the at least one hydraulically controlled valve. The fuel quantity of the liquid fuel used for the control can therefore be pressure-loaded again and supplied to the further storage line.
Since the pressure in the return line is lower than the control pressure in the branch line, it is also proposed that the control pressure is maintained and/or adapted by an electrically controlled further valve of the pressure regulating device, which is arranged downstream of the throttle and the at least one hydraulically controlled valve in the branch line. The further valve is preferably designed as a valve which opens when no current is present, so that in the event of a fault, a pressure reduction can be achieved in the branch line. It is also ensured that the pressure in the branch line is never higher than the pressure in the additional storage line for liquid fuel.
The gaseous fuel is preferably stored in an intermediate storage, which is connected to the first storage line and/or the return line for the gaseous fuel via at least one hydraulically controlled valve of the pressure regulating device. The pressure regulating device may comprise, for example, a first hydraulically controlled valve which connects the intermediate reservoir to a first storage line for gaseous fuel and closes in the absence of a control pressure. The closing of the valve can be brought about by means of a spring which loads the valve element of the valve in the closing direction. In order to reliably keep the valve closed in the absence of a control pressure, the pressure in the intermediate reservoir is preferably selected to be higher than the pressure in the first storage line for gaseous fuel. Preferably, the pressure in the intermediate reservoir is 520 to 550 bar. The high pressure in the intermediate reservoir contributes to the closing of the valve in the event of a lack of control pressure or a drop in control pressure. The control pressure acting can thus regulate the flow through the valve in the direction of the first storage line for gaseous fuel and thus the pressure in the first storage line.
Furthermore, the pressure regulating device may comprise a further hydraulically controlled valve which connects the intermediate reservoir to a line for returning gaseous fuel and which opens in the absence of a control pressure. The opening of the valve can be brought about by means of a spring which loads the valve element of the valve in the opening direction. In the event of a fault, the further hydraulically controlled valve can therefore effect a pressure reduction in the first storage line. Since the pressure in the return line is preferably less than 16 bar. The pressure in the first storage line for gaseous fuel can be regulated by means of a further hydraulically controlled valve in such a way that: this pressure corresponds approximately to the applied control pressure.
Instead of the two valves described above, the pressure regulating device may also comprise only a single hydraulically controlled valve. The valve can be embodied, for example, as a top-loaded (domeplasted), reduced-pressure valve, which combines the previously described functions of the two valves. A compact and space-saving arrangement can be achieved by using a single hydraulically controlled valve. Furthermore, piping and connection costs are reduced.
In order to solve the aforementioned object, a fuel supply system for supplying an internal combustion engine with gaseous and liquid fuel is also proposed. The fuel supply system comprises a first storage line for gaseous fuel and an injection valve connected to the first storage line for injecting gaseous fuel directly into a combustion chamber of the internal combustion engine. The system further comprises a pressure regulating device for regulating the pressure in the first storage line as a function of the pressure in the further storage line for the liquid fuel, wherein the pressure regulating device comprises at least one hydraulically controlled valve having a control chamber connected to the further storage line for the liquid fuel. According to the invention, the connection of the control chamber to the further storage line is established by a throttle arranged in the branch line. The throttle causes a pressure reduction in the branch line, so that a control chamber of the at least one hydraulically controlled valve is acted upon with a control pressure which is lower than the pressure in the further storage line for the liquid fuel. The control of the valve is therefore effected in dependence on the pressure in the further storage line, wherein it is ensured by the throttle that the pressure in the first storage line for gaseous fuel is always lower than the pressure in the further storage line for liquid fuel. Thus, if fuel is injected into the combustion chamber of the internal combustion engine through the dual fuel valve, it is ensured that no gaseous fuel penetrates into the region of the liquid fuel through leakage.
The proposed fuel supply system is particularly suitable for carrying out the method according to the invention described above, since it has the system components required for this purpose. The advantages described above in connection with the method thus apply analogously to the fuel supply system according to the invention. As regards the pressure prevailing in the region of the fuel supply system in which the fuel is guided, the same values as have already been explained in connection with the method described above preferably apply.
According to a preferred embodiment of the invention, the pressure regulating device of the fuel supply system comprises at least one further valve, which is electrically controlled. The branch line, in which the throttle is arranged, can be connected to the return line via the electrically controlled further valve. The control variable returned via the return line can therefore be pressure-loaded again and supplied to the storage line for the liquid fuel. An electrically controlled further valve serves to maintain and/or adapt the control pressure in the branch line and thus in the control chamber of the hydraulically controlled valve. The electrically controlled further valve is therefore arranged downstream of the throttle and the at least one hydraulically controlled valve. Preferably, the electrically controlled further valve is designed as a valve which opens when no current is present, so that in the event of a fault, a pressure reduction in the branch line can be achieved. In addition, it is thereby ensured that the pressure in the branch line is never higher than the pressure in the storage line for the liquid fuel. The electrically controlled further valve may in particular relate to a pressure regulating valve.
It is further proposed that the fuel supply system comprises an intermediate reservoir for gaseous fuel, which can be connected to the first storage line and/or the return line for gaseous fuel via at least one hydraulically controlled valve of the pressure regulating device. The supply of gaseous fuel in the direction of the first storage line or the return via the return line can therefore be regulated by at least one hydraulically controlled valve in order to adapt the pressure in the first storage line to a predefined value. The pressure in the intermediate reservoir can be used as a counter pressure against which the valve opens in the case of a control pressure. The pressure in the intermediate storage is therefore preferably selected to be higher than the pressure in the first storage line and preferably lies between 520 and 550 bar. In contrast, the pressure in the first storage line can be 150 to 500bar depending on the control pressure applied. Furthermore, the valve preferably comprises a valve element which is acted upon in the closing direction by the spring force of a spring.
The pressure regulating device of the fuel supply system according to the invention may comprise two hydraulically controlled valves, in particular a pressure reducing valve and a pressure regulating valve or a top-loaded pressure reducing valve. If two valves are provided, they are connected in series in such a way that a connection of the intermediate reservoir to the first storage line for gaseous fuel can be established via the first valve, which preferably reduces the pressure, so that the supply of gaseous fuel can be regulated via this connection. The second valve, which preferably regulates the pressure, is preferably used to connect the intermediate reservoir or the first storage line to the return line, so that a pressure adaptation in the first storage line for gaseous fuel can be achieved by this connection. If the pressure in the first storage line exceeds a predetermined value, the valve is opened or the flow through the valve is increased, so that the pressure is reduced.
If only one valve is provided, which in this case is preferably designed as a top-loaded, pressure-reducing valve that combines the functions of the two valves described above, the pressure regulating device can be constructed compactly, which advantageously contributes to the installation space requirement.
In principle, valves suitable for the construction of the proposed pressure regulating device are known from the prior art. Thus, already existing components can be utilized, so that the solution can be implemented simply and cost-effectively.
The pressure control device proposed for the method and the fuel supply system provides a pressure control of the gaseous fuel which is hydraulically controlled by means of the pressure of the liquid fuel, wherein it is ensured by means of hydraulic/mechanical means that the pressure of the liquid fuel to be injected is always higher than the pressure of the gaseous fuel to be injected. The supply of gaseous fuel in the direction of the storage line can be regulated by means of a hydraulically controlled pressure reducing valve and a pressure regulating valve or a single hydraulically controlled valve combining both functions, wherein the hydraulic pressure of the liquid fuel downstream of a throttle, which is arranged in a branch line connected to the storage line for the liquid fuel, is used to control the valve. In this way, the pressure of the gaseous fuel is regulated in dependence on the pressure of the liquid fuel, wherein it is simultaneously ensured that the pressure of the gaseous fuel to be injected is always lower than the pressure of the liquid fuel to be injected. Thus, in the case of using a dual fuel injector for injecting both fuels, there is no risk of the gaseous fuel reaching the region of the liquid fuel through leakage.
Drawings
The invention is explained in detail below with reference to the drawings. The figures show:
figure 1 is a schematic illustration of a preferred first embodiment of a fuel supply system according to the invention,
figure 2 a schematic longitudinal section through a hydraulically controlled valve of a pressure regulating device of the fuel supply system of figure 1,
figure 3 a schematic longitudinal section through a further hydraulically controlled valve of the pressure regulating device of the fuel supply system of figure 1,
figure 4 is a schematic longitudinal section of a hydraulically controlled valve of the top load of a pressure regulating device of an alternative fuel supply system,
FIG. 5 is a schematic diagram of a regulator structure for a pressure regulating device of a fuel supply system according to the present invention, an
Fig. 6 is a graph showing the pressure trend over time.
Detailed Description
The fuel supply system shown in fig. 1 is used for supplying an internal combustion engine with gaseous and liquid fuel. The gaseous fuel is currently natural gas and the liquid fuel is diesel fuel. With the natural gas feed being carried out through the circuit located above. The lower circuit is arranged for feeding with diesel fuel. Thus, the two fuel types are isolated from each other.
The natural gas is stored in the storage tank 15 in liquid form. The natural gas, which is still in liquid form, is supplied to the evaporator 17 via the conveyor assembly 16 and then as gas to the intermediate storage 11. The pressure in the intermediate reservoir is 520 to 550 bar. The intermediate storage 11 can be connected to a storage line 1 via a supply line 18, in which a valve 4 is arranged, via which gaseous fuel is supplied to an injection valve 2 for injecting the gaseous fuel into a combustion chamber of the internal combustion engine. The pressure in the storage line 1 is 150 to 500bar and is thus below the pressure prevailing in the intermediate reservoir 11.
For operating the injection valve 2, an auxiliary medium, preferably diesel fuel, is often used, since the required switching force cannot be generated directly by means of electrical energy, for example by means of an electromagnet. The injection valve control is then effected by means of a hydraulic control chamber, the pressure of which can be varied by means of a solenoid valve, as in the known diesel common rail injectors. The secondary medium must be isolated with respect to the natural gas in order to avoid harmful and dangerous input of natural gas into the diesel fuel. The small amount of diesel fuel that enters the natural gas is not interfering and it is blown together into the combustion chamber and burned.
By selecting the pressure of the natural gas to be slightly lower than the pressure of the diesel fuel, structurally induced leakage from the diesel fuel into the natural gas at the guide of the natural gas injection valve is avoided and leakage from the natural gas into the diesel fuel is minimized. To achieve this, the pressure of the natural gas is regulated in accordance with the pressure of the diesel fuel.
Diesel fuel is stored in a storage tank 19 and is supplied to the storage line 6 by means of a conveyor assembly 20, 21. In order to separate out particles that may be contained in the fuel, a fuel filter 22 is arranged between the conveyor assemblies 20, 21. The pressure in the storage line 6 can be variably set by the variable volume conveyor assembly 22 in a pressure range of 160 to 600bar and, in the event of a fault, is also kept below a predefined limit value by the pressure limiting valve 23. The overflow of the pressure-limiting valve 23 is led back to the storage tank 19 via the return line 9.
Diesel fuel can be used to run internal combustion engines or as an auxiliary fuel for igniting natural gas. In both cases, diesel fuel must be injected into the combustion chamber of the internal combustion engine. This can be achieved by means of a further injection valve 2 or by means of a so-called dual fuel injector (not shown), by means of which two different fuel types can be injected. In dual fuel injectors, the two fuel types must also be isolated from each other. This is achieved in a similar manner as in the hydraulically controlled natural gas injection valve 2.
For this purpose, the fuel supply system of fig. 1 has a pressure regulating device 3, which comprises a valve 4 in the circuit for natural gas and a further hydraulically controlled valve 5, and furthermore a throttle 7 in a branch line 8 of the circuit for diesel fuel and an electrically controlled valve 10. The valves 4,5 each have a control chamber 13,14 which can be acted upon with diesel fuel. Diesel fuel is taken out from a branch line 8 downstream of the throttle portion 7. Since the throttle 7 acts as a pressure reducer, a reduced pressure relative to the pressure in the storage line 6 occurs in the branch line 8 after the throttle 7, which pressure is used as a control pressure for hydraulically controlling the valves 4, 5. The control pressure can be maintained and/or adapted by an electrically controlled valve 10 which is also arranged in the branch line 8. The overflow of the valve 10 is supplied to the return line 9. The control pressure acting in the control chambers 13,14 of the valves 4,5 is therefore predefined by the design of the throttle 7 and the control flow acting on the valve 10. The valves 4,5 are designed such that in the absence of a control pressure, the valve 4 is closed and the valve 5 is open. In the event of a fault, the open valve 5 enables a pressure reduction in the storage line 1, since it connects the storage line 1 to the return line 12, in which the pressure lies below 16 bar.
Fig. 2 shows an exemplary embodiment of a hydraulically controlled valve 4. The valve has an actuator 24 which delimits the control chamber 13, so that a control pressure acts on the actuator 24, which control pressure corresponds to the pressure of the diesel fuel in the branch line 8 downstream of the throttle 7. The pressure is from 150 to 500 bar. A sealing ring 25 connected to the actuator 24 seals the control chamber 13 against a valve chamber 26, in which a spring 27 is received, by means of which the actuator 24 is biased in the closing direction of the valve 4. The sealing ring 25 seals the control chamber 13 against a valve chamber 26 through which natural gas is conducted. When the control pressure in the control chamber 13 is sufficiently high, the actuator 24 bears against a valve element 29 of the valve 4, which is acted upon by the spring force of a spring 30 against a valve seat 28. In the absence of a control pressure, the valve 4 is held closed by the spring 30 and by the pressure in the spring chamber 31, which corresponds to the pressure in the intermediate reservoir 11. Since the pressure in the intermediate reservoir 11 (520 to 550bar) lies above the control pressure (150 to 500 bar). The pressure in the valve chamber 26 corresponds substantially to the control pressure.
Fig. 3 shows an exemplary embodiment of a hydraulically controlled valve 5. The valve has an actuator 32 which delimits the control chamber 14, so that a control pressure acts on the actuator 32, which control pressure likewise corresponds to the pressure of the diesel fuel in the branch line 8 downstream of the throttle 7 (150 to 500 bar). The actuator 32 bears against a valve element 33 of the valve 5, which is acted upon by the spring force of a spring 35 against a valve seat 34. In the absence of control pressure, the spring 35 and the pressure in the storage line 1 keep the valve 5 closed. Since the pressure in the storage line 1 (150 to 500bar) lies above the pressure in the return line 9 (<16bar), the valve 5 is connected to the storage tank 15 via said return line. The seal between the gas-conducting region and the diesel fuel-conducting region can be realized, for example, by a sealing film 36 or a bellows 37.
Instead of the valves 4,5 shown in fig. 2 and 3, a single valve can also be provided, which can be designed as a top-loading, pressure-reducing valve as shown by way of example in fig. 4 and doubles the function of the valves 4, 5. The arrangement in the system can be made corresponding to the left-hand layout of fig. 4. A detailed description of the valve of fig. 4 is omitted, since valves of this type are known in principle. The sealing ring 25 only has to seal the natural gas between the valve chamber 26 and the return 12, where small leakages are harmless or not dangerous. In order to separate the regions for conducting the different fuels, a sealing membrane 36 is (exemplarily) provided.
Fig. 5 shows a regulator structure which leads to the pressure trend curve shown in fig. 6. In both figures, p_set represents a predefined pressure setpoint for the natural gas, which pressure setpoint needs to be achieved by a corresponding adjustment of the diesel pressure.
The setpoint value p _ set is dynamically corrected (fig. 5, block 37) to the setpoint value p _ setNG, which the gas pressure can also physically follow. From this setpoint value and from the current gas pressure p _ NG, a setpoint value for the diesel pressure p _ setD is calculated by means of a selectable difference p _ offset selected with respect to the maximum value, which setpoint value ensures that p _ setD is also always dynamically greater than the natural gas pressure p _ NG.
The actual pressure is subtracted from the two pressure target values and the difference of the regulation is supplied to a (preferably PID) regulating device (39,41) having a pilot control device (38,40) which calculates a regulating variable for the respective regulating valve (valve 10, contained in the conveyor assembly 21). In the case of natural gas, the manipulated variable is a control pressure p _ c, which is converted by its p/I characteristic curve into a control current I _ PCVD for the pressure control valve used. In the case of diesel fuel, the adjustment amount is the delivery amount of a diesel fuel pump (delivery unit 21). The pilot control unit 38 takes into account parameters that depend on the operation of the internal combustion engine, such as the rotational speed 42 and the injection quantity 43. The delivery quantity is converted into a control current I _ PumpD in accordance with a Q/I characteristic curve of a diesel fuel pump (delivery unit 21), for example, of a throttle (valve 10) used for flow control. Both control currents are usually represented by the PWM final stage of the current regulation of the controller used.
Claims (9)
1. Method for operating a fuel supply system, by means of which an internal combustion engine can be supplied with gaseous and liquid fuel, wherein the gaseous fuel is taken from a first storage line (1) and is directly injected into a combustion chamber of the internal combustion engine by means of an injection valve (2) connected to the first storage line (1), and wherein the pressure in the first storage line (1) is regulated by a pressure regulating device (3) comprising at least one hydraulically controlled valve (4,5) as a function of the pressure in a further storage line (6) for the liquid fuel, wherein, for hydraulically controlling the valve (4,5), a reduced pressure relative to the pressure in the further storage line (6) is used as a control pressure, and, for reducing the pressure, a throttle (7) is used, the throttle is arranged in a branch line (8) connecting the valves (4,5) to the further storage line (6),
characterized in that the control pressure in the branch line (8) downstream of the throttle (7) and the at least one hydraulically controlled valve (4,5) is maintained and/or adapted by means of an electrically controlled further valve (10) of the pressure regulating device (3).
2. The method of claim 1, wherein the first and second light sources are selected from the group consisting of,
characterized in that liquid fuel taken from the further storage line (6) for hydraulically controlling the valves (4,5) is supplied to a return line (9).
3. The method according to claim 1 or 2,
characterized in that the electrically controlled further valve is designed as a valve which is open in the absence of current.
4. The method according to claim 1 or 2,
characterized in that the gaseous fuel is held in an intermediate storage (11) which is connected to the first storage line (1) and/or a return line (12) via at least one hydraulically controlled valve (4,5) of the pressure regulating device (3).
5. A fuel supply system for supplying an internal combustion engine with gaseous and liquid fuel, comprising a first storage line (1) for gaseous fuel and an injection valve (2) connected to the first storage line (1) for injecting the gaseous fuel directly into a combustion chamber of the internal combustion engine, furthermore comprising a pressure regulating device (3) for regulating the pressure in the first storage line (1) as a function of the pressure in a further storage line (6) for the liquid fuel, wherein the pressure regulating device (3) comprises at least one hydraulically controlled valve (4,5) having a control chamber (13, 14) connected to the further storage line (6),
wherein the connection of the control chamber (13, 14) to the further storage line (6) is established by means of a throttle (7) arranged in a branch line (8),
characterized in that the branch line (8) is connectable with a return line (9) via an electrically controlled further valve (10) of the pressure regulating device (3), which is arranged downstream of the throttle (7) and the at least one hydraulically controlled valve (4, 5).
6. The fuel supply system according to claim 5,
characterized in that the electrically controlled further valve (10) of the pressure regulating device (3) is designed as a valve which is open in the absence of current.
7. The fuel supply system according to claim 5 or 6,
characterized in that the system comprises an intermediate reservoir (11) for the gaseous fuel, which can be connected to a first storage line (1) and/or a return line (12) for the gaseous fuel via the at least one hydraulically controlled valve (4,5) of the pressure regulating device (3).
8. The fuel supply system according to claim 5 or 6,
characterized in that the pressure regulating device (3) comprises two hydraulically controlled valves (4,5) or only one top-loaded, pressure-reducing valve.
9. The fuel supply system according to claim 8,
characterized in that the two hydraulically controlled valves (4,5) are a pressure-reducing valve (4) and a pressure-regulating valve (5).
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102016201511.7A DE102016201511A1 (en) | 2016-02-02 | 2016-02-02 | Method for operating a fuel supply system and fuel supply system |
| DE102016201511.7 | 2016-02-02 | ||
| PCT/EP2017/050030 WO2017133854A1 (en) | 2016-02-02 | 2017-01-02 | Method for operating a fuel supply system, and fuel supply system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN108699992A CN108699992A (en) | 2018-10-23 |
| CN108699992B true CN108699992B (en) | 2022-02-08 |
Family
ID=57737741
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201780009495.6A Active CN108699992B (en) | 2016-02-02 | 2017-01-02 | Method for operating a fuel supply system and fuel supply system |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP3411583A1 (en) |
| CN (1) | CN108699992B (en) |
| DE (1) | DE102016201511A1 (en) |
| WO (1) | WO2017133854A1 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102018202807A1 (en) * | 2018-02-23 | 2019-08-29 | Robert Bosch Gmbh | Valve arrangement for gas pressure regulation, fuel system with valve arrangement for gas pressure regulation |
| DE102018210899A1 (en) * | 2018-07-03 | 2020-01-09 | Robert Bosch Gmbh | Gas pressure regulator for regulating a gas pressure |
| DE102019204150A1 (en) * | 2019-03-26 | 2020-10-01 | Robert Bosch Gmbh | High pressure accumulator for fuels, fuel system |
| CN111677609A (en) * | 2020-06-09 | 2020-09-18 | 一汽解放汽车有限公司 | Dual-fuel system and vehicle |
| CN114992020B (en) * | 2022-05-10 | 2024-03-19 | 潍柴动力股份有限公司 | Method and device for determining fuel rail pressure of HPDI engine and controller of vehicle |
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Also Published As
| Publication number | Publication date |
|---|---|
| CN108699992A (en) | 2018-10-23 |
| DE102016201511A1 (en) | 2017-08-03 |
| WO2017133854A1 (en) | 2017-08-10 |
| EP3411583A1 (en) | 2018-12-12 |
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