WO2012007540A1

WO2012007540A1 - Injection system for an intake line of an internal combustion engine

Info

Publication number: WO2012007540A1
Application number: PCT/EP2011/062039
Authority: WO
Inventors: Stefan Fischer; Jochen Reudenbach
Original assignee: Twintec Ag
Priority date: 2010-07-16
Filing date: 2011-07-14
Publication date: 2012-01-19
Also published as: DE102010027292A1

Abstract

The invention relates to an injection system (36) for a liquid fuel (33) for arranging in at least one intake line (8) of an internal combustion engine (2), wherein the injection system (36) has at least the following: - at least one dosing device (4), - at least one partially thermally insulated line (35) which can be connected to the dosing device (4) and which leads from the latter into an intake line (8) and which has at least one heat-transmitting nozzle (24), - at least one separate heat-transmitting structure (29) which can be connected to at least one heat source (38) situated outside the at least one intake line (8) and to the at least one heat-transmitting nozzle (24).

Description

Injection system for a suction line

The invention relates to an injection system for an intake pipe of a liquid fuel internal combustion engine. In particular, the device is a system for retrofitting a motor vehicle for operation with LPG (Liquefied Petroleum Gas). Such retrofit systems are used in motor vehicles, which are regularly set up for operation with a conventional fuel, for example. With gasoline or diesel fuel.

Such retrofit systems typically consist of an additional fuel tank system (such as LPG), a piping system, an additional fuel distribution device, and a suitable control system for controlling the supply of additional fuel. Motor vehicles are normally designed and equipped by motor vehicle manufacturers for use with petrol or diesel. Due to the attractive price and the increasing availability of alternative fuels, in particular of LPG, it is increasingly desired to equip motor vehicles in addition in such a way that they can be operated in addition to the operation with gasoline or diesel with LPG. For this purpose, motor vehicles can be provided with appropriate retrofit systems. This can sometimes be done directly by the motor vehicle manufacturer in new vehicles.

Injection systems for intake manifolds of internal combustion engines typically include a plurality of injectors for injecting the additional fuel into the individual intake manifolds to the combustion chambers of the internal combustion engine. Injection systems for operation with LPG or LPG are positioned in or on the suction lines. The liquefied gas expands at the outlet of the injection nozzle into the suction lines. Due to the evaporation of the liquid gas arise at the nozzle exit area sometimes very deep Temperatures that can lead to ice formation at the nozzle outlet. This can cause not only a reduction in the injection quantity, but also a noticeable fuel supersaturation in the combustion chamber in the event of a detachment of ice. The fuel supersaturation may also be in the form of torque fluctuations. Sometimes this can lead to damage to the cylinder and piston. In addition, so far technically relatively complicated holding devices for such injection systems have been proposed, in particular in order to achieve a dense and stable arrangement even in the retrofitting of motor vehicles. This often leads to a difficult assembly and high costs.

In particular, in retrofit systems is also important that the injection system can be easily adapted to different types of vehicles or types of internal combustion engines.

Based on this prior art, the present invention has the object, a particularly advantageous injection system for intake manifolds of a combustion engine for liquid fuel, in particular for the injection of LPG, indicate. The injection system is intended, at least in part, to solve the problems described with reference to the prior art, that is to say, in particular, also be simple and flexible, cost-effective to manufacture and assemble. Furthermore, in particular an impairment of the injection process by ice formation at the injection nozzle should be avoided.

These objects are achieved with an injection system according to the features of claim 1. Further advantageous embodiments and fields of application of the injection system according to the invention are specified in the dependent formulated claims. The features listed individually in the claims are combinable with each other in any technologically meaningful manner and can be supplemented by explanatory facts from the description, wherein further embodiments of the invention are shown. The invention relates to an injection system for a liquid fuel for arrangement on at least one intake line of an internal combustion engine, wherein the injection system comprises at least one metering device,

at least one line which can be connected to the metering device and leads from the latter into a suction line, and which has at least one heat-transmitting nozzle,

at least one separate heat-transferring structure that can be connected to at least one heat source located outside the at least one intake line and to the at least one heat-transferring nozzle.

The at least one line which can be connected to the metering device is preferably thermally insulated (at least in part), in particular if it is exposed to a warm environment. This means, in particular, that the line minimizes or prevents heat transfer from the outside to the fuel conveyed in the line. The insulating properties of the conduit may be defined relative to the heat transfer characteristics of the heat transferring structure. Preferably, the heat transfer coefficient of the material of the heat-transferring structure is greater than the heat transfer coefficient of the material of the heat-insulated pipe, in particular at least twice as large and more preferably at least ten times as large.

By "outside the intake pipe" is meant, in particular, that the heat source is not (only) formed by the intake air and thus does not lie (only) in the flow-through area of the intake pipe, but the heat source can be located in a region delimited by the through-flow area of the intake pipe In the case of the motor vehicle, the external heat source can thus be, for example, an electric heating element, a heat-emitting consumer (generator, pump, etc.), a cooling water aggregate, the engine block, the combustion chamber of an internal combustion engine or the like. The injection system is supplied for example via an additional tank with a liquid fuel. The injection system can, for. Example, from a single injection unit (ie a (single) injection line with a (single metering device and a (single) line with nozzle), which is connected to a single intake manifold of an internal combustion engine In one embodiment, four (4) injection units are used on a four-cylinder internal combustion engine, or several injection units or dosing units per cylinder may be provided the single injection unit is used to supply the four intake manifolds of the four-cylinder internal combustion engine with a liquid fuel In all cases, in the following, the umbrella term injection system for the one or more injection used to staple. It is further preferred that the injection system or the injection units are supplied by a common source of liquid fuel, so for example, the liquid fuel from a (single) tank is supplied by means of a (single) pump. Optionally, a return for unneeded liquid fuel may be provided so that liquid fuel can be directed from the injection system back into the tank as needed.

Via the intake line, the at least one combustion chamber of an internal combustion engine is supplied with a mixture of fuel and air corresponding to the desired mixture composition, which is suitable for the operation of the internal combustion engine. In this case, the mixture does not necessarily have to be sucked in, but in principle can also be conveyed by means of pressure, so that the "intake line" is used as the generic term for this type of lines / or partially controlled by the injection system. The internal combustion engine is a conventional internal combustion engine with intake manifolds and designed for operation with gasoline or diesel fuel. The internal combustion engine can therefore be a conventional reciprocating engine or piston engine (eg Otto engine or diesel engine), rotary engine or rotary engine (Wankel engine). Also, the operation with other internal combustion engines is conceivable, which are based on the closed cycle process. Accordingly, an intake pipe is understood to mean, in particular, a flow channel upstream of the at least one combustion chamber of the internal combustion engine, which in particular also includes a channel in the cylinder head. This may be part of the internal combustion engine itself (eg as a kind of bore in the engine block) and / or as a separate line. In particular, the injection system is positioned at a maximum distance of 30 centimeters, in particular a maximum of 20 centimeters, to the combustion chamber in the direction of flow of the intake air.

The injection system according to the invention is particularly advantageous when the injection system injects LPG as liquid fuel.

When LPG is used as a fuel, it is advantageous if it is supplied to the intake line predominantly in liquid form. The addition of liquid fuel results in a simpler and more accurate delivery and metering of the fuel. In addition, the LPG vaporizes as soon as it encounters warm intake air or parts of the intake line, or as soon as it exits the nozzle, the pressure drops in the vicinity of the fuel. The liquid supply of fuels such as LPG into the suction line has considerable advantages over the gaseous feed. In the gaseous feed, the intake air is partially displaced due to the volume of the gas supplied. This effect is eliminated in the liquid feed. Therefore, more mixture of fuel and air can be conveyed into the combustion chamber of the internal combustion engine. In addition, the LPG deprives the environment of Suction line Heat energy required as the enthalpy of vaporization of the LPG. This leads to a cooling of the intake air LPG mixture. In this way, the amount of fuel-air mixture supplied to a combustion chamber can be further increased, so that higher power densities are possible through the use of liquid LPG than with the use of gaseous LPG.

The metering of the liquid fuel is taken over by the metering device. The metering device is preferably assigned in each case one (individual) line for the fuel to the intake line; so that it is very particularly preferred that the number of metering devices coincides with the number of injection units. Nevertheless, of course, a concerted operation is possible, for. B. by means of a common control device. Consequently, a single metering device or a plurality of metering devices can be used for the entire injection system. In particular, a metering device per intake line of the internal combustion engine can be used. The metering device preferably comprises a (single) valve, for example a pressurized switching valve. The metering device is suitable for realizing a predetermined switching time or opening time. It is, for example, also possible for the metering device to throttle the applied pressure of the liquid fuel toward the heat-insulated line, so that an individually required pressure can be set for each injection point in time. The metering device designed as a valve can be in communication with a fuel reservoir in which the fuel is available with the pressure applied to the metering device. This fuel reservoir can be designed in the manner of a fuel rail. The pressure in the fuel reservoir can be generated by a common fuel pump for all metering devices. Another possible embodiment of the metering device is a pump device or a metering pump. In this case, it may be possible to dispense with a pressurized fuel reservoir or a fuel rail and possibly also a common fuel pump for all metering devices. The required injection pressure is generated directly in the metering device. The metering device together with the supply line and the nozzle represents a pump-nozzle unit. Furthermore, the metering device can be designed, for example, so that the remaining fuel in the partially heat-insulated line is withdrawn in order to prevent an increased amount of fuel from evaporating present in the fuel-air mixture. Also, vaporization of the liquid fuel at an uncontrolled time in the initial intake operation in overlap with the (still) open exhaust valve to displace the exhaust gases with the subsequent fresh air, by a proportion of fuel in the fresh air drive out this portion unused.

In order, inter alia, to prevent premature evaporation of the liquid fuel on the way to the suction line, an at least partially heat-insulated line is connected to the metering device, which leads from this into a suction line. In the case of a single metering device for an internal combustion engine with several intake lines, for example, a plurality of partially heat-insulated lines can lead from one metering device to one intake line each. If, on the other hand, there is a metering device per intake line, then it is advantageous to use one partially heat-insulated line per metering device-intake line pairing. Also, an intake pipe can be supplied with liquid fuel via a plurality of partially heat-insulated pipes. In this case, in each case different or equal numbers of partially heat-insulated lines can be used with the same number or different number of metering devices and suction lines thereof, eg. B. single, double or triple. The partially thermally insulated pipe should at least extend from the metering device into the intake pipe, so that the pipe guided therethrough liquid fuel remains liquid even under operating conditions up to the suction line.

It is also advantageous that the at least partially thermally insulated line also extends into the suction line. For a cost-effective one-piece design, the entire partially insulated line can be made of heat-insulating material. Regardless of a one-piece longitudinal embodiment, the partially thermally insulated conduit may be constructed of multiple (coaxial) layers. In this case, an inner layer which is in contact with the liquid fuel, in particular can be chemically and / or thermally inert with respect to the fuel used. A middle layer may in particular be suitable for providing mechanical stability. In particular, this middle layer can facilitate the formability and adaptability to the variety of different constructive conditions of the respective internal combustion engines in a manner favorable for retrofitting. An outer layer can in particular take on the task of thermal insulation. It is also conceivable interchanging the middle and outer layer, as well as the combination of several layers in a material. Also, the properties of the above-described layers may be adopted by one or more materials, and / or, in the entirety, an above-mentioned property may not be satisfied if it is not necessary in the embodiment. At least one layer can also be designed as a coating. In addition, a layer can be designed as a sheath or as an insert and / or insertable tube. In the simplest embodiment, the at least partially heat-insulated conduit is (completely) formed from a (single) plastic, in particular from polytetrafluoroethylene (PTFE) or a similar material.

At the transition into the suction line or in the suction line, the at least one heat-transmitting nozzle is to be arranged. The nozzle accomplishes a good distribution of the fuel in the intake (and in particular at a distance from the wall of the intake), so that z. In the Interaction with turbulence in the intake takes place a good mixing of the fuel with the intake air. The nozzle can cause various effects by different geometries. These effects can sometimes be to motivate a wide fanning, a wide atomization and / or an expansion of the liquid gas. In particular, the nozzle may be suitable for causing a targeted beam to a desired position. For the purpose of heat transfer, the nozzle is made of a thermally conductive material, in this case, an embodiment with metal is preferred, for example comprising copper, brass or similar highly thermally conductive materials. Also conceivable is a nozzle that generates heat as a result of its ohmic resistance and an applied high current density and transmits at the outlet of the nozzle to the fuel. The nozzle itself thus represents, in particular, an electrical heater. Alternatively or additionally, a separate resistance heating element for generating heat may also be provided on the nozzle. The nozzle then also forms the heat-transmitting structure. The heat source is either the electrically heated nozzle and / or the separate resistance heating element. The heat source may in this case be formed within the intake pipe or in an inner region of the intake pipe which is delimited by the intake air. The sucked air in the intake line is (in essence) no heat removed in such a device. In this respect, the heatable nozzle or the resistance heating element is also an external heat source. The nozzle can be made in one piece or in several pieces and also several nozzles can be connected to the heat-insulated line.

Furthermore, the injection system has a separate heat-transmitting structure. "Separately" means, inter alia, that the structure before or for installation in the internal combustion engine is an independent (one-part or multi-part) component , Shrinkage-bonded connection and / or adhesive bond are also materially bonded, eg soldered and / or welded, to the heat-transferring nozzle. to be bound. The heat-transmitting structure can be designed both with bendable and / or rigid sheets and / or rods, as well as a power line to the electrically heatable nozzle and / or as an electrical heating element with power supply. Also, the heat-transferring structure may be a tubular structure, which flows around and / or flows through a heat-transferring fluid. The heat-transferring structure can also be designed in several parts per suction line or per heat-transferring nozzle. The heat transferring structure may be connected to a heat source located outside the at least one intake passage. The heat source is thus provided outside of the suction line. The heat source can deliver the heat to the heat transferring structure by convection, conduction and / or radiation. For heat transfer by convection, the heat transferring structure and the heat source are to be regularly positioned so that a flow (eg of ambient air) is formed from the heat source to the heat transferring structure in operation. For heat conduction, appropriate (direct or indirect) contact of the heat transferring structure and the heat source must be provided. For example, waste heat from the internal combustion engine can also be transmitted via radiation to the heat-transferring structure, for example onto a metal sheet of the heat-transferring structure. In this case, no direct firm connection between the heat source and the heat transferring structure is required. Only sufficiently large areas are required that reliably ensure the transport of heat through radiation. Again, the heat-transferring structure can be materially connected both to the heat source, as well as screwed, clamped, shrunk and / or glued. For the respective purpose or the type of heat transfer and the geometries of the heat source and the nozzle so adapted connecting sections are provided for the interaction of these components during operation. With such an injection system, it can be ensured for the first time that the addition of liquid fuel into the intake line can take place precisely and without interference even under particularly cool and / or moist conditions. In particular, in the installed state of the injection system, targeted (external) heat is provided to the nozzle, which reliably avoids ice formation with the negative aspects explained in the introduction. This relatively independent from the ambient conditions at the nozzle heat supply allows possibly even a needs-based and controlled heat. In any case, however, the design of the injection system can be such that sufficient heat always reaches the nozzle (s). It is very particularly preferred that during operation with this injection system, even at outside temperatures of less than 15 ° C or even less than 5 ° C, heating of the nozzle to at least 0 ° C can be achieved.

In a further advantageous embodiment, the at least one separate heat-transferring structure is made in one piece and can be connected to a plurality of heat-transferring nozzles. "Integral" here means, in particular, that the injection system uses only one-piece structure, eg, a sheet assembly or a rod assembly, Basically, a structure is also considered "one-piece" if it has multiple butted individual rows, but it is preferred an embodiment in which the structure is formed with only one material and / or without joints. In addition, this is to be expressed in particular also that for several thermally insulated lines, a single structure is used, the z. B. each protrudes into the majority of the suction lines.

In a further embodiment, the at least one heat source is an area of the internal combustion engine. As a heat source here is a range suitable having a temperature above the freezing temperature of water. Preferably, the temperature of the heat source is in the range of room temperature, but below the ignition temperature of the fuel-air mixture. Most preferably, this region of the heat source has a temperature of about 50 ° C to 100 ° C.

The spatial area of the internal combustion engine may be any area that meets the temperature specifications. For design reasons, it may be useful to choose an area that is freely accessible on the one hand and on the other hand is close to the partially insulated line. Also suitable are those areas of the internal combustion engine which can be disassembled with little effort and / or, for example, have a fastening means which itself or by slight changes is suitable for securing the separate heat-transferring structure. Such an area is, for example, the connection between the (separate) intake pipe and the internal combustion engine.

In a further advantageous embodiment, the at least one partially thermally insulated line can be aligned and held by means of the at least one heat-transmitting structure in a predetermined position in the suction line.

The predetermined position of the line is usually suitable for injecting the liquid fuel as possible in such a way that a high mixing of the fuel with the intake air in the intake line is achieved by flow processes during intake. It is therefore clear that this predetermined position (in particular position and / or orientation and / or orientation) is dependent both on the geometry of the suction line and in particular on the design of the nozzle. This predetermined position can also be dependent on the heat-transferring structure or other internals in the intake line and their flow influence. The function of the alignment may be, for example, that the predetermined position during the Installation or retrofitting by a deformability or by an adjustability z. B. can be adjusted by Einstellgewinde the heat-transmitting structure. In addition, the alignment may also include that the heat-transferring structure already has the shape that substantially retains it in the assembled state and also z. B. continue to support easy installation. This can be z. Example, be achieved by guide means for facilitating insertion of the partially thermally insulated line in the heat transfer structure together with the partially thermally insulated line. With the function of holding the predetermined position is meant in particular that the partially thermally insulated line does not deviate in the just predetermined position even with the applied mechanical influences during operation of the injection system from the predetermined position in a disturbing manner. This holding can, as already mentioned above, be achieved by a screw connection, clamping connection, shrink connection, adhesive connection and / or cohesive connections.

In a further advantageous embodiment, the at least one separate heat-transferring structure promotes a mixing of a fuel and sucked air in the at least one intake line.

This can be achieved in many ways. In one embodiment, for example, the sucked air can be redirected by the heat-transferring structure such that it quickly absorbs and discharges the escaping fuel in the nozzle exit region by an increased relative speed of the air with respect to the partially heat-insulated conduit. Also conceivable is an embodiment in which the heat-transferring structure promotes swirling of the intake air in the intake line and thus leads to a higher mixing of fuel and intake air in the intake line. Depending on the configuration of the suction line, it may also be advantageous to design the heat-transmitting structure in such a way that it forms a flow shadow with respect to the intake paths of the air, which can only be achieved by the Injection is influenced by the partially thermally insulated line. Also, flow guides through the heat-transmitting structure, which represent a combination of the above-mentioned flow guides, conceivable as well as reversing guides and / or accelerators and the like. For this purpose, it will be provided in most cases that the heat-transmitting structure is at least partially also flows or flows around the sucked air. Optionally, it is also provided that the heat-transmitting structure subdivides the suction line in sections or in a cross-section of the intake into different flow channels.

In a further advantageous embodiment, the at least partially heat-insulated line of the injection system comprises at least the following sections:

at least one thermally insulated supply line, which can be connected to the metering device and forms an outlet opposite,

at least one heat-transmitting nozzle, which is arranged at the outlet of the at least one heat-insulated feed line and which has a nozzle opening for discharging the fuel into the at least one suction line.

The heat-insulated supply line can be designed in the manner mentioned above. The one end of the heat-insulated feed line, which lies on the side of the metering device, can be connected to the metering device in various ways. This means z. B. that the heat-insulated lead is clamped, plugged, shrunk, glued and / or screwed. Also, solder joints and other thermal joint connections are conceivable. At the end remote from the metering device, the heat-insulated supply line forms an outlet. This outlet can be formed by simply cutting the conductor material for the heat-insulated supply line (smooth front side) or else be specially prepared for the connection of a heat-transferring nozzle. For this purpose, for. As an insert, a sheath, a screw or be provided similar. Also, a widening or a taper of the heat-insulated lead at the outlet may be useful. The heat-transmitting nozzle may be designed according to the design of the outlet. Thus, the heat-transmitting nozzle can surround a portion of the outlet of the heat-insulated lead to firmly connect these two components together. This compound can be formed both cohesively and frictionally or in the manner of a screw connection. Also it can be dismantled or not dismountable. Also, the back of the heat-transferring nozzle, which faces the heat-insulated lead, with its end face to this end face of the outlet of the heat-insulated lead (directly) abut. In addition, the nozzle can also be arranged at a distance from the heat-insulated feed line. It can be z. B. by gluing or forming a solid (indirect) connection between heat-transmitting nozzle and heat-insulated lead can be achieved. The nozzle opening is located in the intake and shows in the above-mentioned manner in a predetermined position in the intake. The nozzle opening may be designed in various ways, which is adapted to the flow conditions and the viscosity or the expansion behavior of the fuel. In this way, it is achieved, in particular, that the injection line from the metering device to the exit point at the nozzle is formed both by heat-insulating material (heat-insulated line, heat-insulated feed line) and by a heat-conducting material (heat-transmitting nozzle), in particular in the sense that the liquid Fuel is first performed heat insulated and is guided before exiting with a thermally conductive material (axially one behind the other positioned pipe sections). Thus, a first preconditioning and / or a (partial) evaporation can be initiated already in the line, thereby further disrupting attachment mechanisms for ice in the nozzle and a significant expansion of the fuel can be achieved in the intake into it.

This idea can also be the subject of an injection system which, independent of the provision of a heat-transferring structure realized significant improvement of the known systems. Accordingly, this object can be formulated independently with the following features: Injection system for a liquid fuel for arrangement on at least one intake manifold of an internal combustion engine, wherein the injection system has at least one metering device and at least one partially thermally insulated line which can be connected to the metering device and from this leads into a suction line, further wherein the at least one partially thermally insulated line has at least one heat-insulated feed line which is connected to the metering device and forms an outlet opposite, and further comprises at least one heat-transmitting nozzle, which is arranged at the outlet of the at least one heat-insulated supply line and having a nozzle opening for discharging the fuel into the at least one suction line.

For the individual characteristics of the features and components listed here, please refer to the other versions throughout the description. In particular, sub-aspects or features which are disclosed in connection with the above invention, can be combined with the above subject accordingly.

In a further advantageous embodiment, the outlet of the at least one heat-insulated feed line at least partially encloses the at least one heat-transmitting nozzle.

By this is meant primarily that the nozzle comprises a connecting piece at the rear, which is suitable for (partial) introduction into the outlet of the heat-insulated supply line. Also conceivable are embodiments of the heat-transferring nozzle, wherein the heat-transferring nozzle is completely accommodated in the outlet region of the heat-insulated supply line. It may also be advantageous if the area which is enclosed by the heat-insulated supply line, by teeth, Wellun- conditions and / or undercuts a loss of the heat-transferring nozzle due to positive engagement and / or friction and / or traction prevented. Also, the inserted portion of the nozzle can cause expansion of the outlet of the heat-insulated lead, so that they are already firmly connected to each other. Also, this connection can be achieved by means of an adhesive and / or by shrinkage of the heat-insulated lead. Furthermore, the connection can also be achieved by clamping and / or screw connections as well as by solder. It is very particularly preferred that the outlet completely surrounds an element of the nozzle provided for insertion into the supply line, in the outer circumference.

In a further advantageous embodiment, the heat-transmitting nozzle of the injection system is integrally connectable to the at least one separate heat-transferring structure. By "coherent substance" it is meant in particular that the nozzle and the heat-transferring structure are welded, soldered and / or connected to one another by an adhesive (diffusing in) A sleeve is used to achieve, in particular, a frictional clamping connection between the heat-insulated feed line and the heat-transmitting nozzle, in particular by a coaxial gripping of nozzle and feed line being clamped by means of the sleeve a shrink tube are used, but also two-piece or multi-part sleeves, which screwed together or latched effect a clamping.Especially preferred is that the sleeve is formed either of heat-transferring material and with the nozzle in wä is rmeleitendem contact, and / or that this forms an outer layer in the region of the heat-insulating lead and is itself made of heat-insulating material. It is also possible that the Although cuff is made of a thermally conductive material, but is not in heat-conducting contact with the nozzle.

Furthermore, the inventive concept is subject to a vehicle having an internal combustion engine operable with a first fuel and a second fuel, wherein the injection system according to the invention is provided for adding the second fuel to at least one intake manifold of the internal combustion engine, and further wherein at least one separate heat-transferring structure with the at least a heat-transmitting nozzle on the one hand and a heat source located outside the at least one suction line is connected. Thus, in particular a preferred mounted version of the injection system is specified. With the first fuel in particular a conventional fuel such. As gasoline or diesel fuel, the usual way at a different location (closer to the combustion chamber of the internal combustion engine) is added. By the second fuel is meant in particular a liquefied gas or LPG. It is also possible to use natural gas as the first fuel. The injection system according to the invention is proposed here mainly for motor vehicles, which can be operated either with a conventional fuel or a second fuel. Nevertheless, the invention can of course also be used in monovalent motor vehicles. The addition of the second fuel takes place according to one of the above-mentioned manner with the injection system shown according to the invention. The second fuel is added to at least one suction line, which means in particular that the second fuel is introduced into a feed line of the intake pipes, also conceivable introduction into one of the branches or even close to or in the curve at the inlet valve of the combustion chamber internal combustion engine. This can be done via multiple or splitting fuel line. Furthermore, at least one separate heat-transmitting structure is provided which is preferred according to the above-mentioned manner not only a heat transfer, but also a mechanical alignment and holding function, can take over. In this case, the heat-transferring structure can be embodied in one piece for the entire internal combustion engine as well as in several parts and in particular in each case in multiple parts for an injection nozzle. The number of heat-transmitting nozzles depends primarily on the embodiment or position of the injection in the entire intake pipe. However, two, three or more heat-transferring nozzles may also be introduced into the intake line in each introduced region. The shape and type of the nozzle depends primarily on the nature of the second fuel, the position in the intake, but also according to other above-mentioned aspects. The heat source outside the intake pipe is any area of the internal combustion engine and also of the vehicle. In this case, it is preferably located outside the boundary of the suction line and, in particular, in the vicinity of the nozzle, in order, among other things, to save costs and material.

The invention and the technical environment will be explained in more detail with reference to FIGS. The figures show particularly preferred embodiments, to which the invention is not limited. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. Show it:

1 shows a motor vehicle which is equipped for operation with a first fuel and a second fuel, for example LPG, and has a device according to the invention for the second fuel,

2 shows a section through a detail of an embodiment of the

Injection system, a section through a detail of another embodiment of the injection system, 4 shows a section through an embodiment of the feed line and nozzle with a heat sheet,

5 shows a section through a variant of the supply line and

Nozzle connected by a cuff, and

6 shows a section through a variant of the supply line and

Nozzle, with the supply line enclosing the nozzle. 1 shows a motor vehicle 1 with an internal combustion engine 2, which is set up for operation with either (alternatively) a first fuel or a second fuel 33. The second fuel 33 may be LPG (Liquefied Petroleum Gas), while the first fuel is a conventional fuel such as gasoline or diesel. The second fuel 33 is metered in a motor vehicle 1 with a metering device 4 on a combustion chamber 11 of the internal combustion engine 2. In Fig. 1 is simplified, only a combustion chamber 11 of the internal combustion engine 2 is shown. The combustion chamber 11 is supplied via the suction line 8 with air 32 and with fuel. Exhaust gases pass out of the combustion chamber 11 via the exhaust pipe 9 also. In addition, there is a spark plug 18 in the combustion chamber 11 for igniting the ignitable mixture of fuel and air 32 present during operation of the internal combustion engine 2 in the combustion chamber 11. The intake line 8 can be closed with respect to the combustion chamber 11 with a valve 10. Likewise, the exhaust pipe 9 can be closed with respect to the combustion chamber 11 with a valve 10. During operation with the first fuel, the internal combustion engine 2 is controlled by the first control unit 5. A first fuel then passes through the gasoline or diesel injector 3 into the intake line 8 of the internal combustion engine 2. If the motor vehicle 1 to be operated with second fuel 33 (LPG), via the switch 7, a switch to the second fuel 33. The switch 7 is set in Fig. 1 such that a fuel supply with second fuel 33 takes place and the fuel supply the internal combustion engine 2 is interrupted with the first fuel. The fuel supply with second fuel 33 is thus controlled as shown in FIG. 1 by the second control unit 6, which in turn is addressed by the first control unit 5. For the second control unit 6 and the changeover switch 7, a simplified representation was selected here. The second control unit 6 and the changeover switch 7 can also be integrated with one another in one component. In particular, it is also possible that signals from the first control unit 5 to the gasoline or diesel injector 3 also pass through the second control unit 6 (optionally).

The second control unit 6 can receive and process different signals for controlling the injection of the second fuel 33. For example. a lambda input 13 is provided, via which a lambda value of the exhaust system (not shown) of the internal combustion engine 2 can reach the second control unit 6. If necessary, a temperature sensor 20 determines the engine temperature of the internal combustion engine 2. For this purpose, the temperature sensor 20 is preferably connected to a cooling circuit 12 of the internal combustion engine 2. Also, the signal of this temperature sensor 20 can be utilized by the second control unit 6. The second control unit 6 calculates from the first injection signal, which receives it from the first control unit 5 and which is actually intended to control the gasoline or diesel injector 3, in combination with the other second control unit 6 available signals, a second injection signal for the metering device 4, which injects the second fuel 33 (LPG) into the intake line 8 of the internal combustion engine 2.

One or more (LPG) metering devices 4 are provided per combustion chamber 11 of the internal combustion engine 2. The second control device 6 and the metering devices 4 are interconnected via signal lines.

The metering device 4 receives the second fuel 33 from the tank 16. The second fuel 33 is conveyed out of the tank 16 with the pump 17 and passes via the supply line 14 and the Zulaufverteilleitung 21 to the metering device 4. In the return line 15 is a pressure sensor 19th intended. The signal of the pressure sensor 19 also passes to the second control unit 6 and is used in this for calculating the second injection signal for the metering device 4 with. In the return line 15 is also a return valve 37, with which the pressure in the return line 15 and the metering device 4 can be regulated. In addition to the feed line 14 exists from the metering device 4 back to the tank 16, a return distribution line 22 and a return line 15 through which excess second fuel 33 is conveyed by the metering device 4 back into the tank 16. In particular, the return line 15 is also provided to promote, by heating and / or insufficient pressure in the feed line 14, gaseous second fuel 33 from the metering device 4 back into the tank 16; Namely, it is to be achieved that (only) liquid second fuel 33 is discharged via the metering device 4 to the internal combustion engine 2, or to the combustion chamber 11 of the internal combustion engine 2. The at least partially heat-insulated line 35 for the second fuel 33 (LPG) is connected to the metering device 4 and projects into the intake line 8. The gasoline or diesel injector 3 shown here is no longer shown in the following figures. Nevertheless, it is clear that the partially thermally insulated line 35 and the gasoline or diesel injector 3 represents two structurally and spatially separate units in the intake line 8. At this point, it should be emphasized once again that not only in the position shown in simplified in Fig. 1 must be arranged in front, but also next to or behind, as well as below or above the gasoline or diesel injector 3 may be arranged. Schematically indicated in Fig. 1, the heat-transferring structure 29, which transfers heat to the also indicated heat-transmitting nozzle 24. This will be explained in more detail with reference to the following figures.

Fig. 2 shows a section through a part of a first variant of the device according to the invention, installed in the suction line 8. Here, the heat-insulated feed line 23 is inserted into the suction line 8 and connected in series with the heat-transmitting nozzle 24 via a sleeve 30. In the illustrated case, the outlet 27 of the heat-insulated feed line 23 is spaced from the inlet 25 of the heat-transferring nozzle 24. The end face 28 of the outlet 27 and the inlet 25 are opposite. However, this is not absolutely necessary, but only a possible arrangement. The heat-insulated lead 23 together with the heat-transmitting nozzle 24 and the sleeve 30 thus form the partially heat-insulated pipe 35. The partially heat-insulated pipe 35 is aligned and held by the heat-transmitting structure 29. The heat-transferring nozzle 24 is connected to the heat transfer structure 29 z. B. materially connected. The heat transferring structure 29 exits the intake passage 8 in a portion of the intake passage far from the entrance portion of the heat-insulating passage 35, and is connected to a portion of the engine 2 via a screw connection 31. This area may, for example, be an engine block or a cylinder head of the internal combustion engine 2. In this case, the engine block or the cylinder head or the internal combustion engine 2 is a heat source 38, which is connected via the heat-transferring structure 29 with the heat-transferring nozzle 24.

As soon as the valve 10 is opened to the combustion chamber 11, air 32 is sucked through the suction line 8 by the negative pressure prevailing in the combustion chamber 11. At a point in time controlled by the metering device 4 (shown in FIG. 1), second combustion Substance 33 (eg, LPG) is injected via the partially heat-insulated conduit 35. In the intake 8 thus mixing takes place with the existing air 32. This mixture is conventionally sucked by the negative pressure into the combustion chamber 11 and the opened valve 10 and the chemical energy is converted into mechanical energy by combustion in a conventional manner. The resulting thermal energy is now transferred to a part of the heat transfer structure 29 to the heat transferring nozzle 24. In the heat-transmitting nozzle 24, in turn, the heat is transferred to the exiting second fuel 33. However, not on the heat-insulated lead 23 and not on the part of the second fuel 33 which is in this heat-insulated portion of the partially heat-insulated lead 35. The illustrated heat transferring structure 29 stably holds the partially heat-insulated pipe 35 in a predetermined position against vibrations inherent in flow forces and internal combustion engines.

Fig. 3 shows a similar arrangement as in FIG. 2, wherein the inlet 25 of the heat-carrying nozzle 24 is conical and the heat-insulated lead 23 surrounds the inlet 25 and the end face 28 of the outlet 27 of the heat-insulated lead 23 thus behind the Inlet 25 of the heat-transferring nozzle 24 is arranged. The heat-insulating lead 23 and the heat-transmitting nozzle 24 partially overlap. Again, the connection between the supply line 23 and the heat-transferring nozzle 24 is secured by a sleeve 30. In the embodiment shown here, the heat-transferring structure 29 is a heating ring 34, which comprises the heat-transferring nozzle 24. The heat source 38 is also formed by the heating ring 34. The heating ring 34 is powered by a power line 39 with electrical energy. Again, the heat is transferred through the heat-transmitting nozzle 24 to the exiting second fuel 33 (LPG) but not to the heat-insulated lead 23 and the second fuel 33 located therein. Fig. 4 shows a section through the partially heat-insulated line 35 and a heat-transmitting structure 29, which is designed in this illustration as a sheet metal. This sheet is connected to the heat-transferring nozzle 24. The sleeve 30 is connected to the heat-transmitting nozzle 24, for example via a screw connection on the side of the inlet 25 of the heat-transferring nozzle 24, for example screwed. The end face 28 of the outlet 27 of the heat-insulated feed line 23 abuts the inlet 25 of the heat-transferring nozzle 24. Thus, there is also a heat transfer to the second fuel 33 only in the region between the inlet 25 and the nozzle opening 26 instead; in no case in the heat-insulated lead 23 to the end face 28 of the outlet 27 of the heat-insulated lead 23rd

5 shows the same section as FIG. 4 in a somewhat different embodiment of the connection of heat-transferring nozzle 24 and heat-insulated supply line 23. In this case, the inlet 25 of the heat-transferring nozzle 24 is tubular and is enclosed by the sleeve 30. The inlet 25 of the heat-transferring nozzle 24 adjoins the end face 28 of the outlet 27 of the heat-insulated supply line 23. Again, heat transfer to the second fuel 33 takes place only in the region between the inlet 25 of the heat-transferring nozzle 24 and the nozzle opening 26.

FIG. 6, like FIGS. 4 and 5, likewise shows a section through an embodiment of the injection side of the partially heat-insulated line 35. Here, the inlet 25 of the heat-transferring nozzle 24 is partially conical. The heat-insulated inlet 23 encloses the inlet 25 and is easily performed by the flared shape of the inlet 25 and is fixed by a collar 30 in a cylindrical portion of the inlet 25 by a collar 30. Again, according to the invention, only a heat transfer in the region between the inlet 25 and the nozzle opening 26 of the heat-transferring nozzle 24 is effected. Again, the end face 28 of the outlet 27 of the heat-insulated feed line 23 is located behind the inlet 24 of the heat-transferring nozzle 24. The heat-transmitting nozzle 24 and the heat-insulating lead 23 partially overlap.

The injection system according to the invention for at least one intake line of a combustion engine for a liquid fuel is modular in addition to high stability and effective prevention of ice formation at the nozzle opening, so that it can be particularly easily adapted to different internal combustion engines with different numbers of combustion chambers. It thus represents a significant improvement over the prior art, particularly in the field of retrofit systems for additional fuels, such as LPG.

LIST OF REFERENCE NUMBERS

1 motor vehicle

2 internal combustion engine

3 gasoline or diesel injector

4 metering device

5 first control unit

6 second control unit

7 switches

8 suction line

9 exhaust pipe

10 valve

11 combustion chamber

12 cooling circuit

13 lambda input

14 supply line

15 return line

16 tank

17 pump

18 spark plug

19 pressure sensor

20 temperature sensor

21 supply distribution line

22 return distribution line

23 heat-insulated supply line

24 heat transfer nozzle

25 inlet

26 nozzle opening

27 outlet

28 face

29 heat transferring structure

30 cuff screw

air

second fuel

heating ring

partially insulated line

Injection system

Return valve

heat source

power line

Claims

claims

Injection system (36) for a liquid fuel (33) for arrangement on at least one intake line (8) of an internal combustion engine (2), wherein the injection system (36) has at least:

at least one metering device (4),

- At least one line (35) which is connected to the metering device (4) and leads from this into a suction line (8), and which has at least one heat-transmitting nozzle (24),

- At least one separate heat-transferring structure (29) which is connectable with at least one outside of the at least one suction line (8) located heat source (38) and the at least one heat-transmitting nozzle (24).

Injection system (36) according to claim 1, wherein the at least one separate heat-transferring structure (29) is made in one piece and connectable to a plurality of heat-transferring nozzles (24).

Injection system (36) according to one of the preceding claims, wherein the at least one heat source (38) is an area of the internal combustion engine (2).

An injection system (36) according to any one of the preceding claims, wherein the at least one partially thermally insulated pipe (35) can be aligned and held by the at least one heat transmitting structure (29) at a predetermined position in the suction pipe (8).

Injection system (36) according to one of the preceding claims, wherein the at least one separate heat-transferring Structure (29) promotes a mixing of a fuel and sucked air (32) in the at least one suction line (8).

An injection system (36) according to any one of the preceding claims, wherein the at least partially thermally insulated conduit (35) comprises at least:

at least one heat-insulated feed line (23) which can be connected to the metering device (4) and forms an outlet (27) opposite,

- At least one heat-transmitting nozzle (24) which is arranged at the outlet (27) of the at least one heat-insulated supply line (23) and which has a nozzle opening (26) for discharging the fuel (33) in the at least one suction line (8).

Injection system (36) according to claim 6, wherein the outlet (27) of the at least one heat-insulated supply line (23) at least partially encloses the at least one heat-transferring nozzle (24).

Injection system (36) according to one of the preceding claims, wherein the heat-transferring nozzle (24) is materially connectable to the at least one separate heat-transferring structure (29).

An injection system (36) according to any one of the preceding claims, wherein the heat transfer nozzle (24) and the heat insulated lead (23) are connected to a collar (30).

A vehicle (1) having an internal combustion engine (2) operable with a first fuel and a second fuel (33), wherein an injection system (36) according to one of the preceding claims for adding the second fuel (33) to at least one suction line (8 ) of the internal combustion engine (2) is provided, and further wherein at least one separate heat-transferring structure (29) is connected to the at least one heat-transmitting nozzle (24) on the one hand and to a heat source (38) located outside the at least one suction line (8).