EP1674711A1 - Supercharged diesel engine with Common-Rail injection - Google Patents

Abstract

A second chamber (6) has a first passage through which a high-pressure fuel line and a high-pressure fuel reservoir (7) communicate with one another, and a second passage through which fuel injection lines and fuel connections of a cylinder head (3) communicate. A lid (12) encloses the high-pressure fuel reservoir, fuel injection lines and fuel connections such that when leakage occurs, lid allows leaking fuel to flow into the second chamber. At least one charged air conduit (4) for distributing charged air includes a first chamber (5) for conveying charged air, and second chamber with a removable lid. Air inlet openings of at least one cylinder head are connected to the first chamber in a gastight manner. A high-pressure fuel reservoir is secured in the second chamber via mounting straps.

Description

The invention relates to a supercharged diesel internal combustion engine with a common rail injection system according to the preamble of claim 1.

For better fuel utilization and optimization of pollutant emissions in diesel internal combustion engines come increasingly common rail injection molding systems used. The achievable in such fuel injection systems of load and speed achievable very high system pressure allows optimal control of the injection process. In conjunction with a corresponding characteristic of the charge, this results in an optimization of combustion in all load ranges.

However, the above-described advantages of common-rail injection systems is counteracted by the disadvantage that the already mentioned very high injection pressures, which today amount to between 1500 bar and 2000 bar and will even be higher in future systems, must be mastered. This means that, especially in the high-pressure fuel area, ie in the high-pressure fuel storage and in the injection lines of the injection system, an extremely high material stress is given. If engines are used with such injection systems in safety-related areas, it is essential to ensure that in case of breakage or leakage in the high pressure area of the injection system under high pressure possibly emerging as a fine mist fuel is safely collected without entering the environment to an ignition and thus to avoid an explosive combustion.

To achieve this, it is already known from DE 197 16 513 C2 to provide an encapsulation of the fuel accumulator and the injection lines. The encapsulation is carried out so that the high-pressure fuel accumulator is arranged received in a channel which is at least partially formed by walls of the crankcase. Although the system described allows safe encapsulation of the vulnerable region of the injection system, but has significant disadvantages in practical use. An arrangement in or on the crankcase requires a corresponding design of the crankcase, so that interventions in the structural design of this complex, very expensive and often maintained over several engine generations or used for a series of different engines with different injection systems component are inevitable. In particular, a possible retrofitting of an engine already produced in series with an encapsulation would result in a costly redesign of the crankcase. In addition, the range of the crankcase vibration technology is extremely unfavorable for the attachment of the high-pressure accumulator, because this leads by the large masses moved in the crankcase to increased vibration load of the high-pressure fuel accumulator and the associated injection lines, which is due to the already high material stress necessarily avoided. Furthermore, the known arrangement makes collection, discharge and detection of escaping fuel more difficult, because a number of different regions are formed in which leaked fuel can collect.

From EP 0 690 221 A1 a fuel injection device is furthermore known in which a high-pressure fuel accumulator supplied by a high-pressure fuel pump is integrated into the wall of a cylinder head cover arranged on an internal combustion engine. From the fuel high pressure accumulator lead injection lines to the arranged in the cylinder head injectors. It should be advantageous that the high-pressure fuel storage is arranged protected against vibration and damage. However, the described arrangement has the significant disadvantage that in a disassembly of the cylinder head cover, which must be relatively frequently for maintenance purposes, all connections of the high-pressure fuel storage to the injection lines or to the high-pressure fuel pump must be solved. However, this is because of the sensitivity of the compounds, both in terms of the voltage conditions occurring when screwed into the lines as well as because of the high demands on the purity of the system, to avoid. In addition, a complete encapsulation of the injection lines is not possible because of Connection of the injection lines must be done with already mounted cylinder head cover, so appropriate mounting holes are inevitable. A further disadvantage in the described arrangement is that it can not be used in single-cylinder heads, as they frequently occur in diesel internal combustion engines.

Another known from DE 75 15 413 U1 arrangement shows an internal combustion engine, in which all necessary for fuel supply lines are arranged in an extruded profile parallel to each other. The extruded profile can be integrated in an engine cowling or in a cooling air duct. Advantage of this arrangement should be that a clear, reliable, easy to install and space-saving arrangement of the fuel pipes is created. It is disadvantageous, however, that even in this case in the necessary for maintenance disassembly of the engine cowling all fuel connections to the engine must be solved, which, as already stated above, especially at the high pressure connections of common-rail injection systems must be avoided. An insert in conjunction with single cylinder heads is also eliminated. In addition, an extruded profile is not suitable for a high-pressure fuel storage, the strength values of such an extruded profile rich in terms of the pressures to be controlled by far from.

Based on this prior art, it is an object of the invention to design a supercharged internal combustion engine with common rail injection system so that the high-pressure region of the injection system safely encapsulated and vibrationally low, without regard to the arrangement and encapsulation of the high pressure accumulator and the injection lines constructive in Engage crankcase or cylinder head and without the encapsulation in the assembled state negatively affects the maintenance or repair of the internal combustion engine.

The problem is solved by the characterizing features of claim 1, advantageous embodiments of the invention are characterized in the subclaims.

In the solution of the problem was based on the consideration that an arrangement of the high-pressure fuel accumulator on or in the crankcase or on or in the cylinder head because of the then necessary structural interventions in these components in particular then is not suitable if these components are to be used for a number of different engines with different injection systems, or if engine concepts used over several engine generations are to be converted without changing these components. Based on this consideration, it has been found that an arrangement in an additional chamber formed on the charge air tube combines a number of advantages. In particular, any intervention on the crankcase or on the cylinder head is avoided, only the charge air duct, as a relatively inexpensive attachment is adapt. Furthermore, the charge air duct, by the structural separation of the strongly oscillating areas of the internal combustion engine, a relatively low-vibration area. By arranging the charge air pipe on the cold side of the internal combustion engine to the intake ports of the cylinder head, it is further advantageously possible to make the injection lines very short, whereby high vibration amplitudes are avoided. Next belongs to the charge air duct to the maintenance and repair least affected areas of the engine so that unnecessary disassembly of high-pressure fuel storage and injection lines can be avoided. Thus, assuming a continuous cylinder head, this could be dismantled without first the high-pressure fuel accumulator or the injection lines would have to be dismantled. Next form the charge air duct, high-pressure fuel storage and injection lines a preassembled unit which can minimize the assembly effort in the final assembly of the internal combustion engine advantageous. By providing a removable lid with which the second chamber of the charge air tube can be closed, the high-pressure fuel storage and the injection lines remain fully accessible, so that maintenance or repair work can be carried out unhindered. To be considered particularly advantageous is further that the inventive arrangement both in-line engines and V-engine, each with single cylinder heads or continuous cylinder heads, so therefore can be used in a variety of engines and retrofitting already mass-produced engines without any intervention on the engine block is possible.

By attaching the high-pressure fuel accumulator in the second chamber of the charge air pipe, these can be advantageously designed and sealed so that certain areas of the high-pressure fuel storage, which are not very vulnerable to breakage or should remain accessible even when attached to the second chamber lid, are excluded from the enclosure ,

In order to avoid that any escaping fuel can accumulate at different points, the second chamber is designed in a simple and thus advantageous manner so that any outflowing fuel collects at all occurring during normal operation of the engine operating positions at a point geodetically lowest lies.

The provision of a drain opening, particularly advantageous at the geodesic lowest point, allows the safe discharge of leaked fuel from the second chamber. This can be of particular importance if, for security reasons -. B. in marine engines - the Berieb the engine despite z. B. a broken injection line must be maintained.

The provision of a fuel sensor in the second chamber of the charge air tube, particularly advantageous at the geodesic lowest point, allows a safe detection of leaked fuel, even at very small amounts and thus creates the prerequisite to be able to perform an alarm when this event occurs.

The second chamber of the charge air pipe is advantageously sealed from the environment in the areas and with respect to the passages, which are arranged so that escaping or leaked fuel in the assumed operating positions of the internal combustion engine could escape uncontrollably from the second chamber.

Fig. 1

Eine schematische Darstellung der wesentlichen Bauteile in ihrer räumlichen Zuordnung zueinander

Fig. 2

Eine Darstellung eines Ladeluftrohres senkrecht zu seiner Längsachse gesehen

Fig. 3

Eine Darstellung des Ladeluftrohres aus Fig. 2 parallel zu seiner Längsachse gesehen

In addition to the advantages mentioned above, there are further advantages and advantageous embodiments of the invention in conjunction with the examples, which are described in more detail below with the aid of the drawings. Show it:

Fig. 1

A schematic representation of the essential components in their spatial relationship to each other

Fig. 2

An illustration of a charge air tube seen perpendicular to its longitudinal axis

Fig. 3

An illustration of the charge air tube of Fig. 2 seen parallel to its longitudinal axis

For a better understanding of the arrangement according to the invention, an overview of the spatial allocation of the individual components to each other will be given first with the aid of FIG. The internal combustion engine 1 shown in FIG. 1 with its crankcase 2 and the cylinder head 3 arranged thereon is, in the case of the selected example, an in-line engine with a continuous cylinder head, which direction of view is parallel to the longitudinal axis. As already stated above, the arrangement according to the invention is not limited to this engine type, it could also be a V-engine and instead of the continuous cylinder head shown in the example separate cylinder heads or cylinder heads comprising a plurality of cylinders could also be arranged on the crankcase. According to the illustration according to FIG. 1, a charge air pipe 4 is arranged on the cylinder head 3, next to the cylinder head cover 3a, which comprises a first chamber 5 which carries the charge air and has a second chamber 6, in which a high-pressure fuel accumulator 7 with injection lines 8 connected thereto is arranged. The injection lines 8 connect the high-pressure fuel accumulator 7 with fuel ports 9 on the cylinder head 3, the charge air leading, parallel to the longitudinal axis of the engine 1 extending first chamber 5 is connected via transversely extending intake ports 10 with corresponding intake ports (not shown) in the cylinder head 3. Parallel to the longitudinal axis of the charge air pipe 4 extending and with a part of its walls immediately adjacent to this, a coolant pipe 11 is arranged, which is connected to coolant channels (not shown) in the cylinder head 3. In order to allow access to the second chamber 6 of the charge air pipe 4, this has on its side facing away from the cylinder head 3, a cover 12 on. The charge air is supplied to the first chamber 5 by means of a charge air connection 13 shown in FIG. 2, which is connected to a charging device, not shown in the drawings, of the internal combustion engine 1.

The charge air pipe 4 shown schematically in FIG. 1 is shown in more detail in FIG. 2, in a plan view perpendicular to its longitudinal axis, looking in the direction of the cover side. The cover 12 is removed in this illustration, the position of the cylinder head 3 and the cylinder head cover 3a arranged thereon is indicated by a dot-dash line.

From the recognizable in the upper part of the illustration, provided with a charge air connection 13 first chamber 5 extending, down, running back, the intake ducts 10, the arcuate in the lying in Fig. 2 behind the charge air pipe 4 cylinder head 3 open. For attachment of the charge air pipe 4 on the cylinder head 3, as well as conventional charge air tubes, through holes 14 in the cylinder head 3 adjacent wall of the charge air pipe 4 are arranged corresponding with corresponding threaded holes (not shown) in the cylinder head 3, the actual attachment is made in the Drawing not shown screws. For reasons of clarity, only some of the through-holes 14 and only part of the intake ducts 10 are provided with reference numerals in FIG. 2.

Below the first chamber 5, easily recognizable by the circumferential sealing collar 15, the second chamber 6 of the charge air pipe 4. The lower part of the second chamber 6 is designed so that certain parts of the arranged there high-pressure accumulator 7 protrude beyond the sealing collar 15, So are accessible from the outside with attached lid. Where the high-pressure fuel accumulator 7 extends through the wall of the second chamber 6, not shown in the drawing seals can be provided. The attachment of the high-pressure fuel accumulator 7 in the lower part of the second chamber 6 via integrally formed on the high-pressure fuel accumulator 7 mounting tabs 16 which are provided with through holes 17 and held by screws 18 in corresponding threaded holes (not shown) of the charge air pipe 4.

For connection of the high-pressure fuel accumulator 7 with the cylinder head 3 are on the high-pressure accumulator 7, projecting into the free part of the second chamber 6 in, compression fittings 19 are provided which connect by means of the injection lines 8, 8a arranged on the cylinder head 3 fuel connections. For reasons of clarity, only two of the total of six injection lines are shown in FIG. Accessible are arranged on the cylinder head 3 fuel connections 9 via corresponding openings 20 in the cylinder head 3 facing wall of the second chamber 6 of the charge air pipe 4. The sealing of the openings 20 through the underlying parts of the cylinder head 3 and optionally around the openings 20 extending seals (not shown).

For design reasons, it can not always be realized that the second chamber 6 comprises all the fuel connections 9, such a case is shown on the left in FIG. The outside of the second chamber 6 of the charge air pipe 4 lying on the cylinder head 3 arranged fuel port 9a is connected by means of a double-walled injection line 8a via one of the connection fittings 19 with the high-pressure fuel storage 7. The space formed in the double-walled injection line 8a between the inner actual injection line and the surrounding outer tube opens, as shown in simplified form in Fig. 2, via a port 21 in the second chamber 6 of the charge air pipe 4, so that possibly in this space leaking fuel into the second chamber 6 is derived. Double-walled injection lines and their connections are well known in automotive engineering, so that it can remain in the schematic representation shown in FIG.

As already stated above, the high-pressure fuel accumulator 7 is arranged in the second chamber 6 of the charge air pipe 4 that certain parts of the high-pressure fuel accumulator 7 are outside the second chamber 6. On the one hand, this is an overpressure valve 22 shown on the right in FIG. 2 and the associated outlet nozzle 23 and, on the other hand, the high-pressure port 24 of the high-pressure fuel accumulator 7 illustrated on the left in FIG. 2. The outlet port 23 of the overpressure valve 22 is connected via a line connection 25 connected to a collecting container 26 for fuel recirculated from the injection system, the high-pressure port 24 has a connection via a high-pressure fuel line 27 to a high-pressure fuel pump 28 which generates the high-pressure fuel. Also in the case of the high-pressure fuel line 27, as shown in simplified form in FIG. 2, it is a double-walled line. The gap between the actual high-pressure line and the surrounding outer tube is, as indicated by the arrow designated 29, also connected to the second chamber 6 of the charge air tube 3. For detecting the pressure conditions in the high-pressure fuel accumulator 7, a pressure sensor 31 may be arranged thereon, the electrical connections (not shown) of which are guided at a suitable point through the wall of the second chamber 6. Depending on the location, such a cable bushing may need to be sealed.

For fixing the cover 12, not shown in FIG. 2, 6 threaded holes 30 are arranged in the second chamber, these correspond with arranged in the cover 12 Through holes (not shown), so that the cover by means of screws (not shown) can be screwed onto the charge air pipe and closes the second chamber 6 along the sealing collar 15, it can be provided between lid 12 and sealing collar 15 is a soft material seal (not shown).

The controlled discharge of fuel spilled out of the high-pressure region of the injection system and into the second chamber 6 of the charge-air pipe 4 has been explained below in conjunction with FIG. FIG. 3 shows the arrangement described in conjunction with FIG. 2 in a side view as viewed from the right, the cover 12 is mounted, the arrangement is shown broken away in the cover area.

As can be seen from the illustration in FIG. 3, a drain pipe 32 is arranged on the cover 12. This has a return line 33 to a connection with the collecting container 26, so that, in the event of leakage of fuel from the high pressure system of the injection system, the leaked fuel flows into the collecting container 26. In the example, the collecting container 26 is the collecting container, into which the fuel normally returning from the injection system is also introduced, but in deviation from the example shown, it may also be a separate collecting container. The discharge nozzle 32 is arranged at the geodetically lowest point of the second chamber 6, so that no fuel can accumulate in the second chamber 6. For the sake of completeness it should be mentioned that the second chamber 6 is of course designed so that the inner contour of its wall steadily falls towards the outlet nozzle. If the permissible and actual positions of use of the internal combustion engine deviate very strongly from the horizontal, assuming that the charge air pipe 4 or at least the second chamber 6 is horizontal in the horizontal position of use, the inner wall of the second chamber 6 is under such circumstances form so that there is a funnel running towards the outlet nozzle. Such conditions are present, for example, when the internal combustion engine in a watercraft or in a vehicle used in extreme terrain, for. B. a snowcat, is installed.

To detect emerging from the high-pressure region of the injection system fuel, a fuel sensor 34 is disposed in the outlet pipe 32 and connected via lines 35 with an evaluation circuit 36, which may be part of an engine control system. The evaluation circuit 36 acts on an alarm device 37, which causes the alarm in the event of leakage of fuel from the high pressure region of the injection system. Of course, in such a case, an emergency shutdown of the internal combustion engine can also be carried out by means of the evaluation circuit 36, if this is permissible.

Notwithstanding the example described above is in the double-walled lines, ie the injection line 8a and the high-pressure fuel line 27, also the possibility not to connect the space between the respective actual high-pressure line and the outer tube with the second chamber 6 of the charge air pipe 4, but with the Return line 33 merge. In such a case, the fuel sensor should be located downstream of this merge. Furthermore, it is also possible, of course, to provide separate fuel sensors for the injection line 8a and the high-pressure fuel line 27 or their respective intermediate spaces or downstream lines and to connect the said intermediate spaces directly to the collecting container 26.

Furthermore, the embodiment described in connection with the drawings can be varied so that, in order to save material, weight and space, parts of the wall of the second chamber 6 are formed by adjacent components. In question comes here z. B. the area of the second chamber 6, which is directly adjacent to the coolant pipe 11. In this area, the wall of the chamber 6 can be omitted and replaced by the wall of the coolant tube 11. After this area closes the second chamber 6 of the charge air pipe 4 upwards, additional sealing measures are unnecessary.

Of course, the above-described embodiments can be embodied in a variety of ways with specialist knowledge available to the person skilled in the art, without departing from the basic inventive idea; thus, these exemplary embodiments are only exemplary in nature.

Claims (20)

Charged diesel engine with at least one charge air pipe for the charge air distribution where - The internal combustion engine (1) has at least one cylinder bank with a plurality of cylinders arranged in series, - The cylinder bank is associated with at least one cylinder head (3), - The at least one cylinder head (3) are associated with one or more cylinders, - The air inlet openings of the at least one cylinder head (3) with a charge air leading first chamber (5) of the charge air pipe (4) are connected in a gastight manner, - The internal combustion engine (1) has a common rail injection system which has at least one high-pressure fuel accumulator (7), each associated with a plurality of cylinders and on the one hand via a high-pressure fuel line (27) with a high-pressure fuel pump (28) and on the other Injection lines (8) arranged on the cylinder head (3), each associated with a cylinder fuel connections (9) is connected, characterized in that the charge air pipe (4) has at least one second chamber (6) separated from the first chamber (5), the second chamber (6) has a removable lid (12), in the second chamber (6) fastening means are provided, by means of which the high-pressure fuel accumulator (7) in the second chamber (6) can be fastened, - In the second chamber (6) a first passage is provided, through which the first high-pressure fuel line (27) and the high-pressure fuel storage (7) are connectable to each other, - in the second chamber (6) facing the cylinder head (3), at least one second passage is provided, through which the injection lines (8) with the cylinder head (3) arranged fuel connections (9) are connectable, - The second chamber (6) with the lid closed (12) the high-pressure fuel storage (7), the injection lines (8) and the fuel connections (9) so encloses that, in the case of leaks in the high-pressure fuel storage (7) and / or the injection lines and / or the fuel connections (9), escaping fuel flows into the second chamber (6). Diesel internal combustion engine according to claim 1, characterized in that the charge air pipe (4) is attached to the at least one cylinder head (3). Diesel engine according to one of the preceding claims, characterized in that the first passage is formed by an opening in the second chamber (6), which extends through a part of the high-pressure fuel accumulator (7). Diesel engine according to one of the preceding claims, characterized in that the second chamber (6) is designed so that it has a geodetically lowest point in all operating positions of the internal combustion engine (1) occurring in normal operation. Diesel engine according to one of the preceding claims, characterized in that an opening is provided at the second chamber (6) for discharging fuel leaking into the second chamber (6) during leakage. Diesel internal combustion engine according to claims 4 and 5, characterized in that the opening for discharging leakage of leaking fuel is disposed at the geodesic lowest point. Diesel engine according to one of the preceding claims, characterized in that in the second chamber (6) a fuel sensor (34) is arranged, by means of which the presence of free fuel in the second chamber (6) is detectable. Diesel engine according to claims 4 and 7, characterized in that the fuel sensor (34) is arranged at the geodetically lowest point. Diesel internal combustion engine according to claims 5 to 8, characterized in that the fuel sensor (34) is arranged in the opening for discharging fuel leaking at leakage. Diesel engine according to one of the preceding claims, characterized in that the first passage is sealed off from the space surrounding the charge air pipe (4). Diesel engine according to one of the preceding claims, characterized in that the at least one second passage (openings 20) is sealed off from the space surrounding the charge air pipe (4). Diesel engine according to claim 11, characterized in that the sealing surface of the second passage (openings 20) is formed by parts of the at least one cylinder head (3). Diesel engine according to one of the preceding claims, characterized in that at least one wall of the second chamber (6) of the charge air pipe (4) by a the charge air pipe (4) adjacent to the cylinder head (3) mounted component is formed. Diesel engine according to claim 13, characterized in that the further component is a coolant pipe (11) which leads to the cooling of the internal combustion engine (1) used coolant. Diesel engine according to one of the preceding claims, characterized in that in the second chamber (6) at least one third passage is provided, through which a pressure relief valve (22) of the high-pressure fuel accumulator (7) is accessible from the outside. Diesel internal combustion engine, according to claim 15, characterized in that the at least one third passage is sealed relative to the space surrounding the charge air pipe (4). Diesel internal combustion engine according to one of the preceding claims, characterized in that in the second chamber (6) at least one cable feedthrough is provided by which at least one in the second chamber (6) arranged sensor with a outside of the second chamber (6) arranged control means is connectable , Diesel engine according to claim 16, characterized in that the at least one cable duct is sealed off from the space surrounding the charge air pipe (4). Diesel engine according to one of claims 7 to 9, characterized in that the fuel sensor (34) is connected to an evaluation device (36). Diesel engine according to claim 19, characterized in that the evaluation device (36) is connected to an alarm device (37).

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