EP4146926B1 - Injection nozzle and device for charging a fuel with gas - Google Patents

Description

The invention relates to an injection nozzle and an apparatus/device directly or indirectly connected to it for loading the fuel by diffusion/permeation with gas, hereinafter referred to as diffusion device, preferably air or air and exhaust gas.

State of the art

In the patent DE 314 252 A An open nozzle is described in which the fuel is transported by air through a storage space and a dividing area into the cylinder chamber. The air is used to discharge the fuel.

Furthermore, US 5 150 836 A An open injection nozzle is known in which the fuel is pumped to the engine by means of an individual gas quantity through a pulse. The pressure and the gas quantity are sufficient to pump the fuel out of the nozzle at almost the speed of sound.

In GB 1 459 097 A A gas atomization nozzle is shown in which the liquid and gas are brought together at a focal point via spiral channels.

In DE 44 44 417 A1 A controllable throttle valve is disclosed in front of a mechanically driven fuel pump, whereby the pressure in the fuel line to the fuel nozzles can be regulated.

It is also known from DE 198 15 042 A1 that, in particular for the operation of a starting aid system for engines that operate in particular with vegetable oils, diesel fuel is evaporated via an evaporator tube containing a glow plug and mixed with intake air. Diesel operation should only take place until the engine's operating temperature is reached.

DE 197 13 377 A1 introduces a nozzle in which a fluid, in particular fuel, is guided through channels in such a way that a swirling fluid flow is created which enters a second fluid, in particular combustion air, and thereby leads to a fine distribution of the fuel.

The aforementioned devices and methods have in common that either air is used to discharge the fuel or diesel fuel is atomized by collision of the fluids.

In EN 10 2013 213 349 B4 An internal combustion engine is described which is operated in a first operating state with different liquid fuels (diesel, etc.) and in a second operating state with gas.

EN 11 2006 000 809 T5 describes an injector that has openings in two levels, whereby the fuel is ejected through these openings and thus mixed.

In EP 3 058 208 A1 A liquid injector is used to produce atomized liquid, whereby the pressurized liquid and the gas are directed to adjacent focal points and collide.

In the three aforementioned intellectual property rights, fuel and gas are each guided in a different way so that they interact with each other and the distribution of the fuel is thereby improved.

It is also known EN 601 10 544 T2 , EN 10 2007 017 561 A1 and EN 20 2012 100 107 U1 to operate the internal combustion engine (diesel engine) in mixed operation with gas fuel and diesel fuel in such a way that both energy sources are used in a mixed manner. The positive properties of homogeneous combustion of gas fuel are combined with the inhomogeneous combustion of diesel fuel.

Also known is EP 1 647 685 A2 an internal combustion engine which operates with two types of fuel, wherein at least a first type of fuel is supplied, then a second type of fuel is alternately supplied and a fuel mixing ratio is set depending on the volume of fuel supplied.

The specific formulation of the use of diesel and petrol is also known EN 10 2012 112 337 A1 , where first the fuel gasoline is loaded in the classic way and after compression diesel fuel is injected.

These systems require two fuels to produce combustion with the desired properties. The costs are considerable for all of these designs and two fuels must always be carried. The known devices and processes do not lead to complete combustion of the fuel, which is why exhaust gas purification systems are required.

Aim of the invention

The aim of the invention is to homogenize the fuel distribution and distribution density in the diesel process and thereby influence the combustion process so that the fuel burns as completely as possible and little or no soot is produced. At the same time, the fuel is better converted into mechanical energy.

Inventive solution

This object is achieved by the injection nozzle according to the main claim and the method according to claim 8; advantageous developments of the invention are described in the subclaims.

The invention consists of an injection nozzle and a diffusion device connected directly or indirectly to it for loading the fuel, usually diesel fuel, with gas, preferably with air or exhaust gas, as well as air and exhaust gas. The fuel is loaded with gas in the diffusion device via gas filters, preferably membranes made of sintered metal (sintered metal filter) or ceramic filters. The membrane (semi-permeable membrane) has a pore size that allows the gas to pass through and the fuel to be retained in the idle state. In the working state, the gas is subjected to a higher pressure than the pressure in the fuel.

The flow resistance of the membrane depends on the pore size and pore length. The aforementioned fuels and gases exhibit almost purely viscous behavior. The viscosity ratio is therefore decisive for the flow through the respective components. Under the same pressure conditions, the viscosity ratio of diesel to air under normal conditions is greater than 10 ⁴ . Under these conditions, no diesel will flow through the membrane.

Since the viscosity ratio of diesel fuel to air is very high, air/gas can be added to the diesel fuel by diffusion via the semi-permeable wall.

The parameters permeation area and thickness, gas pressure and fuel pressure are designed so that the required amount of gas is absorbed by the fuel by diffusion.

After the injection of the loaded diesel fuel, the dissolved gas causes the droplets emerging from the injection nozzle to spontaneously burst due to the gas pressure within the droplet after the pressure in the compression chamber has been released, which leads to a very fine and even distribution of the fuel.

This creates a homogeneous temperature distribution during the subsequent combustion, which minimizes the amount of soot during combustion. Homogeneous combustion also reduces the excess air during combustion and the formation of _NOx through exhaust gas recirculation.

The diffusion of the gas into the fuel is a surface and time process, therefore the surface-to-volume ratio of the fuel is designed to be as large as possible as it flows through the diffusion device.

The required gas pressure is determined by the pressure loss for the gas to pass through the membrane (viscous pressure loss) and the required and specified pressure for the diffusion of the gas (diffusion pressure gradient). The saturation volume for gas is proportional to the diffusion pressure over a wide range (Dalton's law). The overpressure to the injection pressure is selected depending on the gas requirement in the fuel.

The present invention is implemented both in the inventive design of the injection nozzle and in the independent method for injecting fuel, whereby this can advantageously also be implemented as a method for operating the inventive injection nozzle. Analogous to the further developments of the injection nozzle, associated operating modes and methods of operation of the nozzle are considered to be disclosed as a further development of the inventive method.

A particularly elegant and effective variant of the method according to the invention results from the injection of the loaded fuel into a compression chamber or injection chamber, which has or forms a vacuum at least at the time of injection. The concrete realization of such a vacuum for the injection chamber results from the German utility model publication DE 20 2020 002 930 U1 , which is to be considered as part of the invention in the present disclosure with regard to the structural realization of this vacuum in the compression or injection chamber and the realization of the fuel injection; the present loading of the fuel according to the invention in conjunction with the vacuum leads to a further improved fuel distribution including further reduced droplet diameters after injection. The result is a further improved combustion with a positive influence on the emission behavior.

Example

• Fig. 1 zeigt in schematischer Darstellung die Einspritzdüse mit unmittelbar verbundener Diffusionseinheit.
• Fig. 2 zeigt ebenso in schematischer Darstellung die Einspritzdüse mit mittelbarer Anbindung der Diffusionseinheit.
• Fig. 3 zeigt in schematischer Darstellung den Schnitt durch die Diffusionsvorrichtung bei Diffusion des Gases in den Kraftstoff von einer Seite.
• Fig. 4 zeigt den Schnitt durch einen Bereich der Diffusionsvorrichtung mit Zuführung des Gases in den Kraftstoff von zwei Seiten.

The invention is described in more detail below using exemplary embodiments and the associated drawings relating to the exemplary embodiments. This description also reveals further advantages, features and details of the injection nozzle according to the invention and the method according to the invention.

• Fig.1 shows a schematic representation of the injection nozzle with directly connected diffusion unit.
• Fig.2 also shows a schematic representation of the injection nozzle with indirect connection to the diffusion unit.
• Fig.3 shows a schematic representation of the section through the diffusion device during diffusion of the gas into the fuel from one side.
• Fig.4 shows the section through a region of the diffusion device with supply of the gas into the fuel from two sides.

As from Fig.1 As can be seen, the injection nozzle 1 is directly connected to the diffusion device 2; they form a structural unit. The supply line 3 supplies the gas at the required pressure and line 4 supplies the fuel to the nozzle via the diffusion device 2. The advantage of this arrangement is that the loading of the fuel with gas can be dynamically adapted to specific requirements.

Figure 2 shows the injection nozzle 5, which is connected to the diffusion device 6 via a line 9. The supply lines 7 and 8 on the diffusion device 6 provide the gas and the fuel. The line 9 supplies the gas-enriched fuel to the nozzle. The advantage here is that there is a larger amount of the gas-enriched fuel in the line 9, which ensures a stable supply to the nozzle in the event of dynamic fuel requirements.

The supply of fuel to the nozzle by a diffusion device in which gas is supplied by diffusion can also be carried out in such a way that more than one diffusion device in Fig. 1 and Fig. 2 not shown, supply the nozzle with gas-enriched fuel and in the same way a diffusion device can supply several nozzles with the gas-enriched fuel.

In Fig.3 The diffusion device 10 is shown schematically in section. The gas is introduced into the area 12 inside this device. The tubular geometry 11 shows the microporous wall (semipermeable wall). The outer tubular geometry 14 is arranged around this tube, with the fuel flowing in the space 13 between the outer wall 14 and the outer geometry of the microporous wall.

The microporous wall, in the example made of sintered stainless steel, CrNi steel, has, depending on the dimensions and operating conditions, a porosity that allows the necessary gas components to pass through, but on the other hand prevents the fuel, preferably diesel fuel, from diffusing through the microporous wall. This is impossible due to the higher gas pressure compared to the fuel pressure and the significantly higher viscosity of the fuel compared to the diffusing gases, air or exhaust gas.

To increase the diffusion into the fuel, as in Fig.4 As shown, the gas supply to the fuel in the region 18 takes place via the microporous walls 17 and 19. The provision of the gas for diffusion is realized by the regions 16 and 20.

In order to achieve the best possible ratio of surface area to volume of the fuel for diffusion, the thickness of the flowing fuel is kept small, which increases the pressure loss of the flow. However, the speed of the flow in the diffusion device is relatively low, so that the flow pressure losses are small. To optimize diffusion, the microporous wall can also be designed in such a way that the surface area becomes larger due to a selected topography, for example with the same radius, achieved by making the surface corrugated, interlocked or in some other way increasing the surface area.

The design of the diffusion device is not limited to tubular geometries, but other cross-sections, such as rectangular geometries or elliptical cross-sections, can also be used.

Within the scope of the present invention, diesel fuel is a preferred form of implementation of the fuel according to the invention, but the invention is not limited thereto; rather, any fuels that can be loaded with the gas according to the invention are suitable within the scope of the invention, including gasoline or petrol of various octane numbers, synthetic fuels, methanol, ethanol, biodiesel, vegetable oils and suitable mixtures of these.

Although the gas supplied to the fuel by diffusion is advantageously air and/or exhaust gas, the gas according to the invention is not limited to this. Rather, almost any other gases or gas mixtures are also possible, which can be introduced into the fuel in accordance with the invention and then lead to the spontaneous bursting of the droplets after injection into the compression chamber, with the advantageous effect according to the invention on the fuel distribution and droplet size. For example, hydrogen, alcohol, methane, ammonia, oxygen, nitrogen, carbon dioxide, various noble gases, propane, butane, biogas are therefore also used, alone, in combination or in combination with air and/or exhaust gas. It is advantageous if gas mixtures of different compositions are supplied to the fuel as gas. The loading of fuel with hydrogen as gas according to the invention would then offer an advantageous way of elegantly introducing hydrogen, which is otherwise difficult to convey and handle, into the fuel according to the idea of a carrier material. This means that not only does the hydrogen itself contribute energetically to fuel combustion, but the hydrogen’s contribution to combustion energy also does not produce any additional _CO2 .

Claims (9)

1. Injector (1) for fuel, preferably diesel fuel, whereby a diffusion device (2) with a gas filter that feeds gas to the fuel by means of diffusion is connected to the injector, characterised in that gas is fed to the fuel by means of diffusion via semi-permeable areas of the diffusion device, whereby the diffusion device is connected directly to the injector and the injector and the diffusion device form a structural unit.
2. Injector according to claim 1, characterised in that the semi-permeable areas of the diffusion device are a semi-permeable diaphragm (11; 17; 19).
3. Injector according to claim 2, characterised in that the semi-permeable diaphragm of the diffusion device is made of sintered metal.
4. Injector according to claim 2 or 3, characterised in that the semi-permeable diaphragm of the diffusion device is made of CrNi steel.
5. Injector according to claim 2, characterised in that the semi-permeable diaphragm of the diffusion device is made of ceramic.
6. Injector according to one of claims 1 to 5, characterised in that air or exhaust gas, or air and exhaust gas, is or are fed to the fuel in the diffusion device.
7. Injector according to one of claims 1 to 6, characterised in that gas of different compositions is fed to the fuel.
8. Procedure for injecting fuel into a compression chamber, in particular a procedure for operating the injector according to one of claims 1 to 7, characterised by the steps:

   - feeding fuel to a diffusion device,

   - enriching the fuel with a gas by means of diffusion in the diffusion device,

   - feeding the enriched fuel to an injector, in particular to the injector according to one of claims 1 to 7, and

   - injecting the enriched fuel into a compression chamber and/or injection chamber.
9. Procedure according to claim 8, characterised in that the enriched fuel is injected into the compression chamber or injection chamber, which has or forms a vacuum.

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