Pressure coaster device

Abstract

Revealed is a fuel supply system for a dual-fuel internal combustion engine. The fuel supply system comprises a first injector for a first fuel, a second injector for a second fuel, a pump for supplying the first fuel to the first injector, and a hydraulically operated delivery device using the first fuel for supplying the second fuel to the second injector. Furthermore, a fuel supply system for a dual-fuel internal combustion engine is disclosed, wherein a fuel can be supplied to an injector by means of pressure reduction. A dual-fuel internal combustion engine with the aforementioned fuel supply systems is also disclosed. Furthermore, a method for converting a mono-fuel internal combustion engine that can be operated with a fuel that can be conveyed by a pump into a dual-fuel internal combustion engine is disclosed. Furthermore, a method for operating a dual-fuel internal combustion engine is disclosed.

Description

[0001] The present disclosure relates to a pressure-reducing device. In particular, the present disclosure relates to a pressure-reducing device for so-called dual-fuel internal combustion engines.

[0002] Dual-fuel engines are internal combustion engines that can run on two different fuels. This means that these engines can use two different fuels to generate torque. These engines are typically relatively large and are used, for example, in ships or power plants. However, the use of dual-fuel engines is not limited to ships or power plants.

[0003] EP 2 585 704 B1 describes an injection unit for injecting a first fuel and a second fuel into a combustion chamber. The injection unit receives the first fuel from a first fuel source where this fuel is at high pressure, and the second fuel from a second fuel source where this second fuel is at a lower pressure than the first fuel. An actuator, which triggers a process for injecting at least the second fuel into the combustion chamber, and an injection nozzle, configured for injecting at least the second fuel into the combustion chamber, are provided. The injection unit includes a pressure booster device configured to increase the pressure of the second fuel to a higher value than the pressure in the second fuel source, using the pressure of the first fuel, before the second fuel is injected into the combustion chamber through the injection nozzle.

[0004] German patent DE 10 2011 108 469 A1 describes a fuel injection system for an internal combustion engine in a vehicle. The first fuel is a gaseous fuel at normal pressure and a temperature above 10°C, and the second fuel is a liquid fuel at normal pressure and a temperature above 10°C. In the vehicle's first operating mode, the first fuel is supplied to a high-pressure pump at a first pressure, which then pumps the first fuel to the internal combustion engine. In the vehicle's second operating mode, the second fuel is pumped to the internal combustion engine. When switching from the first to the second operating mode, the second fuel is pumped to the high-pressure pump at a second pressure, which is higher than the first pressure.

[0005] DE 10 2014 016 927 B3 describes a dual-fuel fuel injector with a first injector unit, which is provided with a first main fuel for a first injector operating mode, a second injector unit, which is provided with a second main fuel for a second injector operating mode, and an injector reservoir (55). The dual-fuel fuel injector is configured to fill the injector reservoir with either the first or the second main fuel, depending on the respective injector operating mode.

[0006] DE 10 2019 219 441 A1 describes a two-component injector for injecting two different media, comprising two coaxially arranged, nested nozzle needles for opening and closing injection ports, wherein each nozzle needle is assigned a control chamber pressurized with a control medium, which can be relieved depending on the switching position of a control valve, so that a control pressure applied to the nozzle needle can be varied in order to actuate the respective nozzle needle. A pressure intensification device is arranged in a supply path of the first medium, so that the pressure in the supply path of the first medium can be increased.

[0007] For the dual-fuel combustion engines disclosed here, all common fuels, especially liquid fuels, used in combustion engines (particularly large engines) are suitable as the primary fuel. In particular, all common diesel fuels are suitable. This includes, for the purposes of this document, paraffinic diesel fuels (e.g., Coal-to-Liquid / CtL, Gas-to-Liquid / GtL, Biomass-to-Liquid / BtL, Power-to-Liquid / PtL, E-fuels, Hydrotreated Vegetable Oil / HVO, Fatty Acid Methyl Esters (FAME), Biodiesel, etc.).

[0008] For the dual-fuel combustion engines revealed here, methanol or ammonia are particularly suitable as a second fuel. However, the use of (other) so-called power-to-X (PtX) fuels is also possible, such as ethanol, hydrogen, methane, syngas (a mixture of hydrogen and carbon monoxide), etc.

[0009] A preferred combination of fuels for dual-fuel combustion engines is diesel and methanol or ammonia.

[0010] In the case of diesel as one of the two fuels for the dual-fuel engine (first fuel), the combustion process requires that the diesel be introduced into the combustion chamber of the engine under high pressure. This means that the diesel is fed from a container (e.g., a tank), in which it is preferably stored at ambient pressure and temperature, through a supply system (supply subsystem) that includes a means of conveying the fuel (e.g., a pump), to an injector of the engine, pressurizing the diesel to the pressure level required for the combustion process.

[0011] In other words, if diesel is one of the two fuels for the dual-fuel engine, the engine includes means for pressurizing the diesel.

[0012] Examples of devices used to pressurize a system include pumps. The pumps transport the diesel fuel from the reservoir to the injector, thereby increasing the pressure of the delivered diesel.

[0013] Other examples of pressurization methods include a combination of one or more pumps and an intermediate storage tank (pressure accumulator or intermediate pressure accumulator). In this case, the one or more pumps deliver the diesel fuel from the tank to the intermediate storage tank, where the diesel is stored under (high) pressure for injection into the combustion chamber by means of one or more injectors.

[0014] Intermediate storage systems can be so-called common rails. A common rail can be designed either as a container (of a certain size) or as an ordinary (pressure-resistant) pipe with a volume sufficient for intermediate storage.

[0015] Common rail systems are common in diesel and dual-fuel engines, but are not strictly necessary.

[0016] If the other of the two fuels for the dual-fuel engine is a PtX fuel (second fuel), it is also necessary for the combustion process to introduce this fuel under pressure into the combustion chamber of the engine. This means that the PtX fuel is fed from a container (e.g., a tank) in which the PtX fuel is stored, preferably and for logistical reasons, under increased pressure, through a feeding system (feeding subsystem) comprising a conveying device, to one (another or the same) injector of the engine, pressurizing the PtX fuel to the pressure level required for the combustion process.The pressure level required for injection of the PtX fuel into the combustion chamber is higher than the pressure level in the (storage) container for the PtX fuel, but (significantly) lower than the pressure level required for injection of the diesel fuel into the combustion chamber.

[0017] In other words, if a PtX fuel, especially methanol or ammonia, is one of the two fuels for the dual-fuel engine, the engine includes means for pressurizing the PtX fuel (but to a lower pressure level than, for example, diesel fuel).

[0018] The present disclosure is not limited to a combination of diesel and PtX fuel, in particular methanol or ammonia. The following pressure reduction concept is, in principle, applicable to any combination of two fuels in a dual-fuel engine, in which one of the two fuels is supplied to the combustion chamber of the engine at high pressure, and the other fuel is supplied to the combustion chamber of the engine at a (significantly) lower pressure.

[0019] According to the invention, the (large) pressure difference between the two fuels is to be used advantageously in a dual-fuel internal combustion engine.

[0020] In particular, the invention aims to reduce pressure. However, the present invention is not limited to this.

[0021] A fuel supply system according to the invention comprises a first injector, a second injector, a pump for a first fuel and a conveying device for a second fuel.

[0022] The fuel supply system is particularly, but not exclusively, suitable or intended for a dual-fuel internal combustion engine.

[0023] The pump is designed to supply the initial fuel to the first injector. The pump can deliver the initial fuel from a reservoir to the first injector, which can then inject the initial fuel into a combustion chamber of the internal combustion engine.

[0024] The conveying device is designed to supply the second fuel to the second injector. The conveying device can pump the second fuel from an (additional) container to the second injector, which can then inject the second fuel into the combustion chamber of the internal combustion engine.

[0025] The conveying device for the second fuel can be hydraulically operated using the first fuel. In other words, the conveying device is driven by the first fuel, which is preferably a liquid. However, a general fluid as the first fuel would also be conceivable, which would then also be covered by the hydraulic drive of the conveying device.

[0026] The injectors are configured to inject the respective fuel into a combustion chamber of the internal combustion engine for combustion. The first and second injectors can be designed as separate injectors (injection media) spatially separated from one another. However, the injectors can also be integrated. In other words, the injectors can be combined into a single injector, where one part (functionally) corresponds to the first injector for the first fuel (first part of the combined injector, first injector section), and another part (functionally) corresponds to the second injector for the second fuel (second part of the combined injector, second injector section). Preferably, such a combined injector can be designed such that the first injector (first injector section) is arranged essentially centrally, and at least two second injectors are arranged radially to the outside.Several second injectors surround the first injector (second injector section).

[0027] The fuel supply system can be divided into fuel supply subsystems, of which a first fuel supply subsystem is designed to supply the first fuel to the internal combustion engine and a second fuel supply subsystem is designed to supply the second fuel to the internal combustion engine. The fuel supply subsystems comprise their respective required and optional components.

[0028] Preferably, the conveying device for the second fuel is a pressure reduction device. Even more preferably, the conveying device is driven by the first fuel, which has a higher pressure than the second fuel being conveyed by the conveying device. In other words, a pressurized working fluid is introduced into the conveying device to deliver a further fluid at a pressure lower than the input pressure of the working fluid.

[0029] Preferably, the conveying device is configured to receive the first fuel as a working fluid at a working fluid pressure and to discharge the second fuel at a pressure that is lower than the working fluid pressure.

[0030] Accordingly, a pressure differential between the two fuels is exploited in such a way that the second fuel is conveyed by means of the (already) existing higher pressure of the first fuel, which is required for the combustion of the first fuel.

[0031] This circumstance can be advantageous in that (existing) pumps for the first fuel can be combined and / or retrofitted with the conveying device for the second fuel.

[0032] Retrofitting can mean converting a so-called mono-fuel engine, i.e., an engine designed to run on only one fuel, into a dual-fuel engine, or adding or replacing supply equipment (e.g., pumps and conveying devices) to an existing dual-fuel engine.

[0033] For example, in an existing dual-fuel engine, a separate pump for the first fuel and a delivery system for the second fuel can be replaced by a combined delivery system for both fuels. This can be achieved by attaching a module containing a delivery system for the second fuel to the existing pump for the first fuel. Alternatively, it can be done by using a new combined delivery system for both fuels instead of the existing separate systems.

[0034] Preferably, the conveying device comprises a work chamber and a compression chamber. Even more preferably, the conveying device may comprise more than one work chamber and more than one compression chamber.

[0035] The working chamber can be filled with the first fuel. Within the working chamber, the first fuel can act on a working piston surface. In other words, the first fuel in the working chamber can exert pressure on the working piston surface.

[0036] The first fuel acts as the working fluid.

[0037] The compression chamber can be filled with the second fuel. Within the compression chamber, a compression piston surface can act upon the second fuel. In other words, the compression piston surface can exert pressure on the second fuel located in the compression chamber.

[0038] The compression piston area is larger than the working piston area. This achieves a pressure reduction from the higher pressure level of the first fuel to the lower pressure level of the second fuel.

[0039] The conveying device further comprises a working piston and a compression piston. The two pistons can be integrated into a single piston. The single piston can preferably be designed as a (cup-shaped) hollow piston. Alternatively, the working piston and the compression piston can be two independent, separate pistons.

[0040] In the embodiment comprising a common piston as a pot-shaped hollow piston, the inner surface of the hollow piston (the inner bottom surface of the pot) constitutes the working piston surface, and the outer surface of the hollow piston (the outer bottom surface of the pot) constitutes the compression piston surface. In this way, the hollow piston simultaneously functions as both a working piston and a compression piston. In other words, the hollow piston is designed as an integrated working and compression piston. Due to this integrated design, any pressure change in the working chamber or compression chamber is transmitted directly to the other chamber via the hollow piston.

[0041] In the alternative embodiment, which includes independent working and compression pistons, the working piston comprises the working piston area, and the compression piston comprises the compression piston area. The working piston and the compression piston are mechanically connected or coupled to each other. In particular, the two pistons are coupled by means of a piston rod. Due to the separate design, any pressure change in the working chamber or compression chamber affects the respective other chamber via the associated piston, the mechanical coupling (piston rod), and the other piston.

[0042] Preferably, the fuel supply system includes a position sensor for determining the position of at least one of the pistons. In principle, it is sufficient for position determination if only one sensor is provided on one of the pistons. That is, it is sufficient if either the working piston, the compression piston, or the (combined) hollow piston is equipped with a position sensor. Because the pistons are coupled or integrated, the position of one piston can be inferred from the position of another. Providing only one position sensor improves the control of the fuel supply system with only a slightly higher system complexity.To improve precision, for example with regard to (elastic) deformations, especially of the piston rod (but also the pistons), or for redundancy reasons, it can be advantageous to provide more than one position sensor. For example, if several pairs of working and compression chambers are provided in the fuel supply system, it can be advantageous to equip each pair of working and compression pistons with a position sensor, each piston of the fuel supply system with a position sensor, or only some pistons with a position sensor.

[0043] Even more preferable are the use of position sensors for end position detection, which allow pistons to be driven independently of each other in a power-appropriate manner in order to reduce pressure pulsations in the fuel supply system.

[0044] In the fuel supply system, the pump is arranged upstream of the conveying device in the direction of flow of the first fuel. Preferably, means for pressure regulation or a pressure regulating device is provided between the pump and the conveying device. A particularly preferred means for pressure regulation is a pressure regulating valve. This allows the pressure of the first fuel flowing from the pump to the conveying device to be regulated or reduced to a suitable (variable) pressure level.

[0045] Preferably, the pump can include a storage tank. Even more preferably, this storage tank is built into or integrated with the pump, i.e., an internal storage tank. The outlet of the storage tank is connected to the delivery device and the first injector. The respective connection can be direct (i.e., without any intervening components of the fuel supply system) or indirect (i.e., with intervening components of the fuel supply system).

[0046] Even more preferably, a common rail can be arranged between the storage tank and the first injector. This fuel supply system configuration is particularly recommended when diesel is used as the primary fuel. Alternatively or additionally, pressure regulation means or a pressure regulating device are provided between the storage tank and the delivery system. The pressure regulating device can preferably be a pressure regulating valve.

[0047] In general, the flow direction of the fuels in the fuel supply system is from the respective containers for storing the fuels towards the respective injectors for injecting the fuels into the combustion chamber of the internal combustion engine.

[0048] Preferably, a valve is arranged upstream of the conveying device in the flow direction of the first fuel. The valve allows the flow of the first fuel into the conveying device (especially into the working chamber) and out of the conveying device (especially out of the working chamber). Thus, the valve serves as a control device for the working fluid of the conveying device.

[0049] Even more preferably, the valve is a switching valve. In particular, the valve can be an electromagnetic switching valve, which is advantageous from the perspective of controlling the fuel supply system and from the perspective of lower complexity compared, for example, to a hydraulically actuated switching valve. Regardless of whether the switching valve is designed as an electromagnetic switching valve, in a particularly preferred embodiment it can be a 3 / 2-way valve or a 4 / 2-way valve. Preferably, the switching valve can also be a 3 / 3-way valve or a 4 / 3-way valve, wherein the respective additional third switching position can, for example, be a switching position in which the valve closes all three or four ports, respectively. This can, for example, represent a safety function. Particularly preferably, the switching valve can be configured such that in its rest position, it is in the third switching position (e.g., biased).

[0050] According to the invention, the pump and the conveying device are integrated. This allows two different fuels to be conveyed simultaneously with a single pump / conveying assembly. The conveying device is mounted, or can be mounted, on the pump. The integrated design of the pump and conveying device makes the assembly particularly compact and the fuel supply system less complex. This results in advantages regarding space requirements, costs, maintenance, and repair. A conveying device that can be mounted on a pump also offers the possibility of retrofitting existing pumps.This can be done both as part of converting a so-called mono-fuel engine to a dual-fuel engine, and as part of converting a dual-fuel engine equipped with a separate pump and a separate delivery system to a dual-fuel engine with an integrated pump and delivery system assembly in order to achieve the aforementioned advantages.

[0051] The integration of the pump and the conveying system into a single assembly can preferably be done modularly.

[0052] The integrated design and, in particular, the modular integration can offer advantages with regard to assembly, maintenance and repair work, in that no long-term work needs to be carried out on site that leads to the shutdown of the entire internal combustion engine or the fuel supply system, but only the entire assembly or individual modules can be replaced.

[0053] The integrated design also offers advantages, particularly for retrofitting, due to its compact size, as the space available for the pump in existing internal combustion engines can be limited. By integrating the pumping unit with the pump itself, the resulting assembly is hardly larger than the previously used pump and can therefore be installed relatively easily within the existing, limited installation space.

[0054] Modular integration is particularly advantageous for mounting more than one pumping device on the pump. This allows the volume or mass flow rate of the second fuel delivered by the fuel supply system to be increased relatively easily (as needed). As long as the pressure difference or pressure gradient between the first and second fuels is sufficiently high, any number of pumping devices can be mounted on the pump.

[0055] The pump and the conveying unit can also be housed in a single casing. Simply installing the pump and conveying unit in a common casing may not result in the same compactness of the assembly as with an integrated design, but it can be advantageous, for example, for maintenance and repair purposes. For instance, this slightly less compact design offers more space during installation and maintenance / repair work. Individual components of the assembly may also be easier to replace.

[0056] Preferably, the fuel supply system comprises more than one first injector. Additionally or alternatively, the fuel supply system can comprise more than one second injector. The multiple injectors can also be integrated together. It is particularly preferred to integrate a single first injector with several second injectors to form a single injector. This offers similar advantages to those of integrating the pump and the delivery system.

[0057] In addition to the aforementioned details of the present invention, an inventive concept consists in providing a dual-fuel internal combustion engine in which a fuel (for example, a second fuel) can be supplied to an injector by means of pressure reduction.

[0058] Preferably, one (second) fuel can be supplied to its assigned injector by means of pressure reduction of the other (first) fuel of the dual-fuel internal combustion engine.

[0059] The dual-fuel engine or the fuel supply system of the dual-fuel engine preferably comprises a common rail. The first fuel can preferably be supplied to the first injector via the common rail.

[0060] Preferably, the dual-fuel engine is operable in two operating modes. Even more preferably, the dual-fuel engine is operable in three operating modes.

[0061] In the first operating mode, the internal combustion engine is operated exclusively with the first fuel for torque generation and operation. In other words, only the first fuel is burned in the first operating mode. Put another way, in the first operating mode, only the first fuel is supplied to the combustion chamber of the internal combustion engine (via the fuel supply system) for combustion. The engine's power output is therefore derived solely from the chemical energy provided by the first fuel.

[0062] In the case of diesel as the primary fuel, a diesel pump can be operated in 100% diesel mode in the first operating mode.

[0063] In the second operating mode, only the second fuel is used to generate torque. Preferably, in this second operating mode, a (relatively small) amount of the first fuel is also used as pilot fuel to ignite the second fuel. In other words, in the second mode, the second fuel is (preferably primarily) burned, preferably together with an amount of the first fuel required for its ignition. Put another way, in the second operating mode, the combustion chamber of the internal combustion engine is supplied (through the fuel supply system) mainly (or exclusively) with the second fuel for combustion and to generate the main energy input, and preferably with a small proportion of the first fuel, the first fuel being supplied as pilot fuel to ignite the second fuel and not (primarily) for generating torque in the internal combustion engine.The power output of the internal combustion engine is therefore primarily (almost exclusively) due to the chemical energy provided by the second fuel.

[0064] In the second operating mode, a pump for the first fuel can be reduced to a pilot injection pressure and then supplies a delivery unit for the second fuel with the required amount of working fluid. Preferably, in combination with an adjustable pressure control, the pressure of the second fuel can then be varied during operation while the pilot injection pressure remains constant.

[0065] The quantity control of the second fuel side can be hydraulically force-balanced using the reduction principle.

[0066] In the case of diesel as the primary fuel, the diesel side can be regulated by means of suction throttle control.

[0067] In the third operating mode, the internal combustion engine is operated using both the first and second fuels to generate torque and power the engine. In other words, in the third operating mode, both the first and second fuels are burned. Put another way, in the third operating mode, both the first and second fuels are supplied to the combustion chamber of the internal combustion engine (via the fuel supply system) for combustion and power generation. The engine's power output is therefore derived from the chemical energy provided by both fuels. Which of the two fuels contributes the majority of the energy can be variably set, controlled, or regulated.

[0068] The present invention also includes a method for converting an internal combustion engine, in particular a diesel internal combustion engine (or mono-fuel internal combustion engine), to a dual-fuel internal combustion engine.

[0069] The internal combustion engine can be operated with a primary fuel that is supplied by a pump.

[0070] The conversion or retrofit procedure includes providing an injector, providing a conveying device, connecting the conveying device to the injector, and connecting the conveying device to the pump.

[0071] The provided injector is an injector for a second fuel, in particular methanol or ammonia. However, other second fuels mentioned above are also possible. Providing the injector includes providing an additional injector alongside the existing injector for the first fuel. Alternatively, providing the injector includes providing an integrated injector for both the first and second fuels (as described above) to replace the existing injector for the first fuel.

[0072] The provided conveying device is for the second fuel. Preferably, the conveying device operates on the principle of pressure reduction.

[0073] The conveying device is connected to the pump in such a way that the second fuel can be conveyed by the conveying device, using the first fuel as a working fluid, to the injector for the second fuel. According to an unclaimed comparative example, the conveying device can be mounted and connected separately (next to the pump in the fuel supply system), or alternatively or additionally, it can be installed with the pump in a common housing. According to the invention, the conveying device (preferably in a modular design) is mounted to the existing pump. In other words, connecting the conveying device to the pump involves mounting the conveying device to the pump.

[0074] In particular, several conveying devices can be connected to the pump in the manner described in order to increase the volume or mass flow rate of the conveyed second fuel. Specifically, more than one conveying device can be mounted, and even more preferably, (modular) conveying devices can be stacked (laterally) on or (on top of) the pump.

[0075] The present invention also comprises a method for operating a dual-fuel internal combustion engine according to one of the embodiments described above. The dual-fuel internal combustion engine can be operated with a first and a second fuel.

[0076] In the method according to the invention, the first fuel is supplied to the first injector. The supply of the first fuel to the first injector is preferably carried out by means of a common rail.

[0077] The second fuel is fed to the second injector. This feeding of the second fuel to the second injector is achieved via a reduction gear. The first fuel, which has a (significantly) higher pressure than the second fuel, is used as the working fluid for this reduction gear.

[0078] In summary, a fuel supply system for a dual-fuel internal combustion engine is disclosed. The fuel supply system comprises a first injector for a first fuel, a second injector for a second fuel, a pump for supplying the first fuel to the first injector, and a hydraulically operated conveying device for supplying the second fuel to the second injector.

[0079] Furthermore, a fuel supply system for a dual-fuel internal combustion engine is disclosed, wherein a fuel can be supplied to an injector by means of pressure reduction.

[0080] A dual-fuel internal combustion engine with the aforementioned fuel supply systems is also disclosed.

[0081] Furthermore, a method for converting a mono-fuel internal combustion engine, which can be operated with a fuel that can be conveyed by a pump, into a dual-fuel internal combustion engine is disclosed.

[0082] Furthermore, a method for operating a dual-fuel internal combustion engine is disclosed.

[0083] The features and embodiments of the fuel supply system, the pressure reduction principle, the dual-fuel internal combustion engine with the fuel supply system, the method for converting an internal combustion engine, and / or the method for operating a dual-fuel internal combustion engine described herein can be combined with one another as desired, provided that the resulting combinations are technically feasible and / or produce at least one of the advantageous effects described herein or other advantageous effects. In particular, individual features of the (preferred) embodiments described above and below can be taken from individual embodiments and used in other embodiments.

[0084] Further embodiments of the present invention are described in detail below. Fig. Figure 1 shows an external view of a diesel pump with a methanol delivery module mounted on it. The figure illustrates an integrated design of the diesel pump and the delivery system. Fig. Figure 2 is a schematic sketch of the fuel supply system according to the invention. It shows in particular an upper part of the diesel pump, the methanol delivery device or the methanol delivery device module in an embodiment in which a series arrangement of pistons has been selected, two injectors and a common rail. Fig. Figure 3 shows a sectional view in top view of, for example, the integrated diesel pump and delivery system. Fig. 1. It shows in particular an embodiment of the conveying device or the conveying device module in which four hollow pistons were selected as integrated working and compression pistons in a parallel arrangement.

[0085] The following embodiments are described for the case of diesel as the first fuel and methanol as the second fuel. However, these embodiments are not limited to these two fuels. In particular, the fuels described above, as well as other fuels in any combination, can be used.

[0086] Fig. Figure 1 shows an oblique side view of an integrated assembly 100 from the outside. A (conventional) diesel pump 11 is visible in the lower section. A methanol conveying device 31 is mounted on the diesel pump 11. The conveying device 31 is of modular design.

[0087] It is conceivable to mount several modules of the conveying device 31, for example stacked on top of each other, onto the diesel pump 11. This allows the amount of methanol conveyed to be increased particularly easily and economically.

[0088] Thanks to its modular design, the assembly, maintenance and repair of the integrated assembly 100 is particularly easy and economical.

[0089] As described above, the diesel pump 11 can be a conventional diesel pump 11, in particular one already installed in an internal combustion engine (or, even more preferably, a used diesel pump 11). The delivery device 31 can then be retrofitted relatively easily, in particular by mounting it to the diesel pump 11 as an additional module 31.

[0090] Fig. 2 shows an example of the in Fig. 1 shown integrated assembly 100 together with two injectors 10, 30 and a common rail 13.

[0091] In the lower area of Fig. Figure 2 shows the upper end of diesel pump 11.

[0092] Above this, a storage tank 12 for diesel is visible. This storage tank 12 can, for example, be part of the (existing or newly provided) diesel pump 11. However, the storage tank 12 can also be mounted as a separate component, in particular as a separate module 80, on an existing or new diesel pump 11, as shown in Fig. The embodiment shown in Figure 2 is shown. However, the storage unit 12 can also be integrated into the (modular) conveying device 31.

[0093] Storage tank 12 is an intermediate storage tank for the diesel fuel delivered by diesel pump 11. The pressure of the diesel fuel stored in storage tank 12 can be, for example, approximately 100 MPa.

[0094] The memory module 12 shown has two outputs. One (in Fig. The left outlet (2) is fluidically connected to the diesel injector 10. In the illustrated embodiment, the storage tank 12 is connected to the diesel injector 10 via a common rail 13. The diesel fuel delivered by the diesel pump 11 thus initially flows into the storage tank 12, and then into the common rail 13. In the common rail 13, the diesel fuel is prepared for injection. From the common rail 13, the diesel fuel then flows on to the diesel injector 10 or to several diesel injectors 10.

[0095] Another (in Fig. The outlet of the reservoir 12 (2, right) is fluidically connected to the pumping device 31. In the illustrated embodiment, the reservoir 12 is connected to two working chambers 34 of the pumping device 31 via a pressure regulating valve 50 and a switching valve 60. The diesel fuel pumped by the diesel pump 11 thus initially flows into the reservoir 12 and then to the pressure regulating valve 50. If necessary, the pressure of the diesel fuel is regulated (reduced) by the pressure regulating valve 50 to a pressure level required for use as a working fluid in the pumping device 31. The diesel fuel then flows to the switching valve 60.

[0096] The switching valve 60, in the embodiment shown, is a 4 / 2-way valve, which is an electromagnetic switching valve. By means of the switching valve 60, the diesel fuel from the storage tank 12 can selectively flow into one of the two working chambers 34 and simultaneously flow from the other of the two working chambers 34 into a drain 61. A 4 / 3-way valve (not shown), for example with a safety position or shut-off position (especially in the rest position), is also conceivable in the present embodiment.

[0097] The outlet 61 can be fluidically connected to a container (tank) for the diesel or be part of the container.

[0098] The 4 / 2-way valve shown represents a relatively simple way of controlling the inflow and outflow of a working fluid into the two working chambers 34 of the conveying device 31.

[0099] In the conveying device 31, two working chambers 34 are provided in the embodiment shown. A working cylinder with two working piston surfaces 36 can move back and forth within the two working chambers 34. The stroke volume of the two working chambers 34 is limited by the respective walls of the working cylinder and the corresponding working piston surface 36.

[0100] In the embodiment shown, the working cylinder is mechanically coupled or connected to two compression pistons by means of a continuous or two separate opposing piston rods 38 in series.

[0101] Each compression piston has a compression piston area 37 and can move back and forth within a compression chamber 35. The displacement of the two compression chambers 35 is limited by the respective walls of the compression cylinder and the corresponding compression piston area 37.

[0102] With the two working chambers 34 and the two compression chambers 35 or the arrangement of a working piston connected to two compression pistons, the delivery volume of the methanol can be increased and the mass flow of the methanol delivered can be made more uniform.

[0103] Each of the compression chambers 35 has an outlet connected to a methanol injector 30. The compression chambers 35 can be connected to multiple methanol injectors 30.

[0104] In addition, each of the compression chambers 35 has an inlet for methanol (in Fig. 2 not shown). Through the inlet, methanol at a relatively low pressure can flow into the compression chamber 35.

[0105] During operation, diesel fuel flows from the storage tank 12 or the diesel pump 11 alternately into one of the working chambers 34 via the pressure regulating valve 50 and the switching valve 60. In each working chamber 34, the high-pressure diesel fuel exerts pressure on the respective working piston surface 36, causing the working piston to move. This, in turn, sets the compression piston, which is connected to the working piston via the piston rod 38, also in motion. The compression piston, with its compression piston surface 37, compresses the methanol flowing into the compression chamber 35. Due to the relative sizes of the working piston surface 36 and the compression piston surface 37, the methanol in the compression chamber 35 is compressed to a (significantly) lower pressure level than the pressure level of the diesel fuel in the working chamber 34. The compressed methanol then flows through the outlet of the compression chamber 35 towards the methanol injector 30.

[0106] The pressure of the methanol flowing towards the methanol injector 30 can be approximately 15 MPa, for example.

[0107] After the compressed methanol has left the compression chamber 35, the switching valve 60 is opened, allowing the working fluid (the diesel) to flow from the associated working chamber 34 to the outlet 61, thus reducing the pressure in the working chamber 34. Simultaneously, methanol flows into the compression chamber 35 via the inlet, increasing the pressure in the compression chamber 35. Due to the pressure differential between the compression chamber 35 and the associated working chamber 34, the piston assembly moves in the opposite direction to the compression of the methanol. In other words, the methanol exerts pressure on the compression piston surface 37, causing the compression piston to move. The working piston, connected to the compression piston via the piston rod 38, also moves and, with its working piston surface 36, forces the remaining diesel out of the working chamber 34 towards the outlet 61.

[0108] Once the diesel has flowed out of the working chamber 34 and the compression chamber 35 has filled with methanol, the switching valve 60 is switched again and a new compression cycle begins.

[0109] In the manner described, the methanol can be conveyed and compressed for combustion using the high-pressure diesel fuel.

[0110] The described operating method of the conveying device 31 corresponds to a pressure reduction.

[0111] Fig. Figure 3 shows an alternative embodiment of the conveying device 31 in a top view as a sectional representation.

[0112] In the embodiment shown, four pairs of working chambers 34 and associated compression chambers 35 are provided. This can, on the one hand, increase the volume of methanol produced and, on the other hand, improve the uniformity of the methanol produced compared to an arrangement with, for example, one or two pairs of associated working chambers 34 and compression chambers 35.

[0113] In the embodiment shown, the working piston and the compression piston are integrated into a single piston, which is designed as a hollow piston 32. The hollow piston 32 is cup-shaped. The inner surface of the hollow piston 32 (the inner cup base) corresponds to the working piston surface 36. The outer surface of the hollow piston 32 (the outer cup base) corresponds to the compression piston surface 37.

[0114] The hollow piston 32 is mounted on a rigid piston 33 (servo piston) and can move back and forth on it. The inner surface of the hollow piston 32 (the inner side walls of the pot), the working piston surface 36, and the rigid piston 33 define a working chamber 34.

[0115] The compression piston surface 37 and inner surfaces of the housing of the conveying device 31 define a compression chamber 35.

[0116] An inlet of the compression chamber 35 is equipped with an inlet valve 71. Through the inlet valve 71, methanol can flow from a container into the compression chamber 35 at a relatively low pressure.

[0117] An outlet of the compression chamber 35 is equipped with an outlet valve 72. Through the outlet valve 72, the compressed methanol from the compression chamber 35 can flow towards the methanol injector 30 at a higher pressure required for injection into the combustion chamber or combustion.

[0118] In the embodiment shown, the inlet valve 71 and the outlet valve 72 are designed as simple check valves, each allowing the flow of methanol in only one direction. This reduces the complexity of the conveying device 31. However, other types of inlet and outlet valves are also conceivable, for example, for more precise control of the methanol flows.

[0119] The working chamber 34 is connected to the switching valve 60 via a passage in the rigid piston 33 and a port 73. The port 73 is a combined inlet and outlet through which diesel fuel can flow into and out of the working chamber 34.

[0120] In the illustrated embodiment, each port 73 is connected to its own (schematically represented) switching valve 60. In this embodiment, the switching valve 60 can be a 3 / 2-way valve. In one position of the 3 / 2-way valve, diesel fuel from the diesel pump 11 or from the accumulator 12 can flow, if necessary via the pressure regulating valve 50, into the working chamber 34, while the connection to the drain 61 is interrupted. In another position of the 3 / 2-way valve, diesel fuel from the working chamber 34 can flow into the drain 61, while the connection to the diesel pump 11 or the accumulator 12 is interrupted.

[0121] Instead of the four exemplary 3 / 2-way valves, the arrangement shown could also be equipped with two 4 / 2-way valves, each of which alternately supplies two associated working chambers 34 with diesel (similar to the one in Fig. 2 embodiment shown). Further embodiments of the switching valves 60 connected to the ports 73 are possible.

[0122] For example, 3 / 3-way valves or 4 / 3-way valves with a safety position or shut-off position (especially in the rest position) are also conceivable in the present design.

[0123] During operation, diesel fuel flows from the storage tank 12 or the diesel pump 11, possibly via the pressure regulating valve 50, the switching valve 60, the connection 73, and the passage in the rigid piston 33 into the working chamber 34. In the working chamber 34, the high-pressure diesel fuel exerts pressure on the working piston surface 36, causing the hollow piston 32 to move. The hollow piston 32 compresses the methanol flowing into the compression chamber 35 by means of the compression piston surface 37. Due to the size ratio of the working piston surface 36 and the compression piston surface 37, the methanol in the compression chamber 35 is compressed to a (significantly) lower pressure level than the pressure level of the diesel fuel in the working chamber 34. The compressed methanol then flows via the outlet valve 72 towards the methanol injector 30.

[0124] After the compressed methanol leaves the compression chamber 35 via the outlet valve 72, the switching valve 60 is opened, allowing the working fluid (the diesel) to flow from the working chamber 34 through the passage in the rigid piston 33, the port 73, and the switching valve 60 to the outlet 61, thereby reducing the pressure in the working chamber 34. Simultaneously, methanol flows into the compression chamber 35 via the inlet of the compression chamber 35, which is equipped with the inlet valve 71, thus increasing the pressure in the compression chamber 35. Due to the pressure differential between the compression chamber 35 and the associated working chamber 34, the hollow piston 32 moves in the opposite direction to the compression of the methanol (towards the rigid piston 33). In other words, the methanol exerts pressure on the compression piston surface 37, causing the hollow piston 32 to move.The hollow piston 32, together with the working piston surface 36, pushes the remaining diesel out of the working chamber 34 in the direction of the outlet 61.

[0125] Once the diesel has flowed out of the working chamber 34 and the compression chamber 35 has filled with methanol, the switching valve 60 is switched again and a new compression cycle begins.

[0126] The switching cycles of the four parallel arrangements (the four parallel pairs of working chambers 34 and associated compression chambers 35) preferably take place staggered, so that a uniform conveying of the methanol is made possible.

Claims

[1] Fuel supply system (1) for a dual-fuel internal combustion engine, the fuel supply system (1) comprising: a first injector (10) for a first fuel, a second injector (30) for a second fuel, a pump (11) for supplying the first fuel to the first injector (10), and a hydraulically operated conveying device (31) for supplying the second fuel to the second injector (30) by means of the first fuel, wherein the pump (11) and the conveying device (31) are integrated as a single assembly in such a way that the conveying device (31) can be mounted on the pump (11). [2] Fuel supply system (1) according to claim 1, wherein the conveying device (31) is a pressure reduction device; and / or the conveying device (31) is set up to receive the first fuel as working fluid at a working fluid pressure and to discharge the second fuel at a pressure lower than the working fluid pressure. [3] Fuel supply system (1) according to claim 1 or 2, wherein the conveying device (31) comprises: a working space (34) which can be filled with the first fuel and in which the first fuel can act on a working piston surface (36), and a compression chamber (35) which can be filled with the second fuel and in which a compression piston area (37) which is larger than the working piston area (36) can act on the second fuel, wherein the conveying device (31) preferably comprises more than one work chamber (34) and more than one compression chamber (35). [4] Fuel supply system (1) according to any of the preceding claims, wherein the conveying device (31) comprises: a working piston with a working piston area (36) on which the first fuel can act, and a compression piston with a compression piston area (37) that is larger than the working piston area (36) and that can act on the second fuel, wherein preferably the conveying device (31) comprises a pot-shaped hollow piston (32) whose inner surface is the working piston surface (36) and whose outer surface is the compression piston surface (37), so that the hollow piston (32) is designed as an integrated working piston and compression piston. [5] Fuel supply system (1) according to claim 4, further comprising a position sensor for determining a position of the working piston, the compression piston and / or the hollow piston (32), wherein preferably each piston of the conveying device (31) is provided with an associated position sensor. [6] Fuel supply system (1) according to any one of claims 1 to 3, wherein the conveying device (31) comprises: a working piston with a working piston area (36) on which the first fuel can act, and a compression piston with a compression piston area (37) that is larger than the working piston area (36) and that can act on the second fuel, wherein preferably the working piston and the compression piston are mechanically coupled to each other, in particular by means of a piston rod (38), and more preferably the fuel supply system (1) comprises at least one position sensor for determining a position of the pistons. [7] Fuel supply system (1) according to any one of the preceding claims, wherein the pump (11) is arranged upstream of the conveying device (31) in the flow direction of the first fuel, and preferably a pressure regulating device (50), in particular a pressure regulating valve (50), is arranged between the pump (11) and the conveying device (31). [8] Fuel supply system (1) according to any one of the preceding claims, wherein the pump (11) includes a storage tank (12), preferably an internal storage tank (12), and the storage tank (12) is located on the output side. indirectly connected to the conveying device (31) and / or indirectly to the first injector (10), and preferably a common rail (13) is arranged between the storage tank (12) and the first injector (10), and / or preferably the pressure regulating device (50), in particular the pressure regulating valve (50), is arranged between the storage tank (12) and the conveying device (31); or is directly connected to the conveying device (31) and / or directly to the first injector (10). [9] Fuel supply system (1) according to any one of the preceding claims 1 to 7, wherein the pump (11) includes a storage tank (12), preferably an internal storage tank (12), and the storage tank (12) is located on the output side. is directly connected to the conveying device (31) and indirectly to the first injector (10), wherein a common rail (13) is preferably arranged between the storage device (12) and the first injector (10); or is directly connected to the first injector (10) and indirectly to the conveying device (31), wherein the pressure regulating device (50), in particular the pressure regulating valve (50), is preferably arranged between the storage tank (12) and the conveying device (31). [10] Fuel supply system (1) according to any one of the preceding claims, wherein a switching valve (60), in particular an electromagnetic switching valve (60), is arranged upstream of the conveying device (31) in the flow direction of the first fuel, and the switching valve (60) is preferably a 3 / 2-way valve or a 4 / 2-way valve, more preferably a 3 / 3-way valve or a 4 / 3-way valve. [11] Fuel supply system (1) according to one of the preceding claims, wherein more than one conveying device (31) can be modularly mounted on the pump (11), and / or the pump (11) and the conveying device (31) are contained in a common housing. [12] Fuel supply system (1) according to any one of the preceding claims wherein the fuel supply system (1) comprises more than one first injector (10) and / or more than one second injector (30); and / or the first fuel is diesel and / or the second fuel is methanol or ammonia. [13] Dual-fuel internal combustion engine with the fuel supply system (1) according to one of the preceding claims, wherein the first fuel can preferably be supplied to the first injector (10) via a common rail (13), wherein the internal combustion engine is operable in a first operating mode in which only the first fuel is used to generate torque, and is operable in a second operating mode in which only the second fuel is used to generate torque and preferably the first fuel is used as a pilot fuel to ignite the second fuel, and wherein The internal combustion engine can be operated even more preferably in a third operating mode, in which the first and second fuels are used to generate torque. [14] Method for converting an internal combustion engine, in particular a diesel internal combustion engine, which can be operated with a first fuel supplied by a pump (11), into a dual-fuel internal combustion engine, the method comprising: Providing an injector (30) for a second fuel, in particular methanol or ammonia; Providing a conveying device (31) for the second fuel; Connecting the conveying device (31) to the injector (30); and Connecting the conveying device (31) to the pump (11) such that the second fuel can be conveyed through the conveying device (31) to the injector by means of the first fuel, which is used as the working fluid, wherein Connecting the conveying device (31) to the pump (11) includes mounting the conveying device (31) on the pump (11). [15] Method according to claim 14, wherein connecting the conveying device (31) to the pump (11) comprises mounting more than one conveying device (31) on the pump (11) and preferably stacking conveying devices (31) on or around the pump (11). [16] Method for operating a dual-fuel internal combustion engine according to claim 13, which is operated with a first and a second fuel, wherein the first fuel is supplied to the first injector (10), preferably by means of a common rail (13); and the second fuel is supplied to the second injector (30) by means of reduction using the first fuel as the working fluid.

Images