JP2004162701A - Accumulator for common rail system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a common rail system for an internal combustion engine to enable very high inner pressure with the simplest means and dynamic load possible without setting requirements for space for the accumulator. <P>SOLUTION: This accumulator for a common rail system in an internal combustion engine comprises a base main body 2 of a tubular form provided with a wall 3 to part a boundary for an accumulation space 4 provided in the base main body 2 in which a medium is to be accumulated, and at least one hole 5 extended through the wall 3 for discharging the medium. At least one curved arch 6 is provided in an inner side surface 31 of the wall 3 to be extended into the accumulation space 4. The hole 5 is opened in the curved arch 6 into the accumulation space 4. <P>COPYRIGHT: (C)2004,JPO

Description

  The invention relates to an accumulator for a common rail system of an internal combustion engine according to the preamble of independent claim 1.

  The present invention specifically relates to an accumulator suitable for a common rail system of a large diesel engine. Large diesel engines are used, for example, as main drive units for ships or as stationary machinery for power generation. These are typically configured as low speed two-stroke crosshead engines or four-stroke engines. According to more recent developments, optional auxiliary systems, such as for fuel injection, gas exchange, water injection, and oil level adjustment, are implemented in modern large diesel engines using a common rail system. A fluid, for example, a fuel for injection, a hydraulic medium for operating the outlet valve, or a hydraulic medium for controlling the injection, respectively, is transported under high pressure by a pump into an accumulator, also called a pressure reservoir. Next, a high-pressure fluid is supplied from an accumulator and / or a valve to all the cylinders of the internal combustion engine, and the fuel injection device is controlled.

  Typically, the accumulators are each designed as a tubular component, closed at both ends, and extend along the engine at approximately the height of the cylinder head. The tubular base body of the accumulator typically has a plurality of holes through which the accumulator storage space can be connected to the supply or actuating device of each individual cylinder.

  The maximum pressure usually occurs in the common rail system for fuel injection. The pressure in the associated accumulator can reach, for example, 2000 bar. In operation, it is dynamic loads, for example, caused by pressure fluctuations, which in particular place great mechanical demands on the accumulator. The high pressure of the accumulator is also limited, especially by radial holes. This radial hole may increase strain, eg, equivalent stress, by three to four or more factors.

  In order to further increase the high pressure of the accumulator of the common rail injection system, DE-A-199 49 962 discloses that the interior space of the base body serving as a storage space is formed flat in the area of the opening of the hole. It has been proposed to reduce the maximum strain in the overlay region between the hole and the base body. These planar areas are later created by a local process of removing material.

  The object of the present invention is to enable very high internal pressures with the simplest possible means and dynamic loading without external dimensions which have been enlarged to allow for very high internal pressures, and therefore without space requirements for accumulators. The present invention provides an accumulator for a common rail system of an internal combustion engine. The accumulator is particularly suitable for common rail systems of large diesel engines, and in particular for fuel injection systems.

  An accumulator satisfying this object is characterized by the features of independent claim 1.

  Thus, according to the present invention, an accumulator for a common rail system of an internal combustion engine has a tubular base body with walls defining a storage space provided inside the base body in which the medium is to be stored. And has at least one hole extending through the wall for ejection of the media. At least one curved arch is provided on an interior side of the wall, the wall extending into the accumulator and configured to open a hole in the storage space inside the curved arch.

  It has been found that the increase in strain caused by the holes can be significantly reduced by the arch having a finite curvature and extending into the inner surface. Due to the optimized internal shape of the accumulator, with suitable fatigue-strength material for producing the base body, the permissible internal pressure for dynamic loads can be greatly increased or, for example, the walls can be made thinner The external dimensions of the accumulator, in particular its diameter, can be reduced. It is important to understand here that we design a region where the holes open into the storage space with a finite curvature, that is, especially a curvature that is not planar.

  In a preferred embodiment, the area has a curvature with the opposite sign to that of the remaining portion of the inner surface of the wall delimiting the substantially cylindrical storage space.

  The arch preferably extends over most of the length of the storage space, particularly preferably over the entire length of the storage space. As a result, the inner cross section of the storage space, which is a cross section perpendicular to the longitudinal axis, is the same over the entire length of the storage space. Accordingly, local internal processing of the accumulator can be omitted, thereby greatly reducing manufacturing. The base body with storage space can be manufactured in a simple manner, for example by extrusion, casting or broaching with a correspondingly shaped working tool.

  A further advantageous method is to provide at least two, for example three, curved arches extending into the storage space, each extending over a majority of the length of the storage space, on the inner surface of the wall, with respect to the circumferential direction of the inner surface of the wall. In various positions. Accordingly, a plurality of arches are provided distributed in the circumferential direction of the inner surface, and preferably each extend over the entire length of the storage space. Thus, holes are provided that extend in different directional scans, thereby greatly improving the accumulator's adaptability to connectability.

  For strain minimization, one or more holes extend radially such that their central axis is perpendicular to the longitudinal axis of the base body. Furthermore, it is known that each hole is open in the storage space so that it is at the center of the arch relative to the circumferential direction of the inner surface of the wall, i.e. the center axis of the hole is located at the center of the arch. Is advantageous. Of course, the holes can also be arranged eccentrically or offset from one another. It is important that the hole is open in the storage space on the inside surface of the arch.

  Embodiments have shown that each arch preferably has a radial height corresponding to 5% to 30% of the inner diameter of the storage space. This height is the maximum value at which the arch projects beyond the other points, for example beyond the circular contour of the cross section of the storage space, into the storage space.

  An arch according to the invention that extends into the storage space is particularly preferably realized in that the storage space comprises at least two substantially cylindrical longitudinal holes arranged such that the cross sections of the holes overlap. Can be done. A particularly preferred variant comprises a storage space realized by two cylindrical longitudinal holes, the axes of which run parallel and are spaced apart from one another so that the cross section of the longitudinal holes is It is designed to overlap. This means that the distance between the axes of the longitudinal holes is smaller than the sum of the radii of the two longitudinal holes. As a result of this dimension, the storage space will have a shape with an inner cross-section (cross-sectional area perpendicular to the longitudinal axis) of eight. The area where this 8 has a "constriction" forms two curved arches that extend into the storage space contemplated by the present invention.

  The realization of a configuration in which the storage space has at least two overlapping longitudinal holes offers the advantage, inter alia, of simple production. It is only necessary to form two (or more) longitudinal holes in the tubular structure from which the base body is made.

  A further advantageous feature is that the wall of the base body has at least one flat on the outer surface of the wall, and the flat is configured and designed to perforate in a plane on the outer surface of the wall. is there. By this means it is possible to provide an actuating or supply device directly on the external side of the wall to be filled with medium from an accumulator, for example a slide valve for fuel injection. This has the advantage that high voltage resistant supply lines can be omitted.

  A further advantageous variant is that, on the other side extending substantially the entire length of the tubular base body, the wall of the base body has at least one planar strip. This makes it possible, for example, to provide a heating element on the outer surface of the high-pressure accumulator to apply heat to the medium in the storage space. The flat strip can also serve as a contact area for fixing the accumulator, for example.

  The accumulator according to the invention is particularly suitable for common rail systems for large diesel engines, and in particular for fuel injection common rail systems.

  Further advantageous measures and preferred embodiments of the invention result from the dependent claims.

  The invention is explained in more detail below with reference to examples and the drawings. They are shown schematically.

  FIG. 1 shows a cross-sectional view of a first embodiment of an accumulator according to the invention, indicated generally by the reference numeral 1. This cross-sectional view is taken along section line II of FIG. FIG. 2 shows a longitudinal section of the same embodiment taken along section line II-II in FIG.

  The common rail system, especially for large diesel engines, and in particular for fuel injection of large diesel engines, is well-known for its design and function and is therefore described in further detail below. I will omit such things in a simple explanation.

  The accumulator 1 has a tubular, for example cylindrical base body 2 with a wall 3. The inner side 31 of the wall 3 delimits a storage space 4 for a medium, for example fuel under high pressure. The base body 2 and the storage space 4 extend in the direction of the longitudinal axis L. Furthermore, at least one hole 5 is provided, which extends radially through the wall 3 and perpendicular to the longitudinal axis L and connects the storage space 4 to the outer surface 32 of the wall 3. The medium can be removed from the storage space 4 by the holes 5.

  According to the invention, an arch 6 is provided on the inner side 31 of the wall 3 and extends in the direction of the axis L over most of the storage space 4, preferably over the entire length of the storage space 4. In the display of FIG. 2, the arch 6 is the difference between the upper part 3a of the wall 3 and the lower part 3b. In particular, as shown in FIG. 1, the arch 6 is continuously curved and has no flat area. The curvature of the arch 6 has the opposite sign to the curvature of the remaining part of the inner surface 31 of the wall 3. For a better understanding, the contour K obtained from a precise circular cross section of the storage space 4 is shown completely by the dashed line in FIG.

  The transition area 61 between the arch 6 and the rest of the inner face 31 of the wall 3 is rounded, with no edges present, so that the stress in these areas can also be kept low. ing.

  The arch 6 is configured such that the hole 5 opens in the storage space 4 symmetrically at the center of the arch 6 in the circumferential direction.

  Several variants are possible for the design of the arch 6, in particular for the curvature of the arch 6 and the center position of the curvature. The curvature of the arch 6 also need not be constant. It is important, however, that the curvature is a finite value and has a different sign than the curvature of the rest of the inner surface 31, that is, the arch 6 must extend into the storage space 4. Furthermore, it is important that the hole 5 is open entirely in the storage space 4 in the arch 6, ie that the opening of the hole 5 into the storage space 4 must be completely covered by the arch 6. .

  With respect to the height H of the arch 6, which means the maximum deviation from the radial contour K, it has proven practically advantageous for this height to be between 5% and 30% of the inner diameter D of the storage space 4. I have.

  Usually, the accumulator 1 has a plurality of holes 5. As described above, in the first embodiment, they are arranged in order such that each hole 5 opens into the storage space 4 at the center of the arch 6.

  The accumulator 1 has an internal shape optimized for strain by the arch 6 of the present invention. Important to the strain, due to the design of the arch 6 projecting into the storage space 4 in the area where the holes 5 are open, this area remains within the range of the pressure strain when applying pressure. In known accumulators, the tangential strain, ie the tensile strain, occurs directly when pressure is applied. In an embodiment of the invention, the transition of the tensile strain into the region occurs only at much higher loads. Therefore, the accumulator 1 can also be exposed to a considerably high internal pressure with a dynamic load. Due to the internal shape of the accumulator 1 of the present invention, the accumulator of the present invention can be exposed to various internal pressures as compared with a known accumulator. On the other hand, with the same internal pressure and the same volume of storage space as known accumulators, the accumulators according to the invention can be made much slimmer, ie with thinner walls 3.

  The arch 6 preferably extends over the entire length of the storage space 4, and the inner cross-section, which means the cross-section of the storage space 4, is identical over the entire length of the base body 2. This will greatly simplify the manufacturing process. The base body 2 of the accumulator 1 of the present invention can be manufactured in a simple manner by extrusion, casting, or broaching with a tool that matches the desired cross section. Subsequent local internal working on the inner side 31 of the arch 6 is no longer necessary.

  A further advantage is that the holes 5 can be drilled in any desired position in the longitudinal direction, which greatly increases their adaptability to different environments.

  A further advantageous measure is that a flat 7 is provided on the outer surface 32 of the wall 3 of the base body 2, the flat being designed and designed such that the hole 5 opens in a plane at the outer surface 32. This means that the device 10 (shown in dashed lines in FIGS. 1 and 2), which should have the medium supplied from the accumulator, for example the components of the fuel injection system, is fixed directly to the base body 2 and the connection line is eliminated. There is an advantage that can be.

  As shown in conjunction with the second embodiment of FIG. 5, the flat portion 7 extends over the entire length of the base body, and the flat portion 7 forms a flat strip extending substantially over the entire length of the base body 2. Of course, it is also possible. At this time, the hole 5 opens in this planar strip.

  FIG. 3 shows a variant of the first embodiment, with a display similar to that of FIG. In this variant, the outer shape of the base body 2 is not cylindrical, but has two planar strips 8 that extend over substantially the entire length of the tubular base body 2. The flat strips 8 are configured such that the holes 5 open into the outer surfaces 32 outside these flat strips 8.

  Additional devices 9 can be arranged on these strips 8. In large diesel engines, heavy oil is usually used as fuel. Heavy oil must be heated until the required viscosity is reached. For this purpose, a heating device can be provided as an additional device 9 in one of the planar strips 8 to apply heat to the heavy oil in the storage space 4.

  FIG. 4 shows a cross section of a second embodiment of the accumulator 1 according to the invention, with a representation similar to FIG. In the following, only differences from the first embodiment will be dealt with. The description related to the first embodiment basically applies to the second embodiment in the same manner. In particular, the reference numbers have the same meaning.

  In the embodiment shown in FIG. 4, a plurality of, for example three in this case, arches 6 according to the invention are provided on the inner side 31 of the wall 3. Each arch 6 extends over most of the storage space 4, preferably over its entire length. The arches 6 are evenly distributed around the inner surface 31. A plurality of holes 5 are provided, each opening into the storage space 4 at one center of the arch 6. A flat portion 7 is provided on the outer side surface 32, and the hole 5 is configured to open in a plane on the outer side surface 32. It is naturally also possible to distribute the arches unevenly in the circumferential direction.

  In this embodiment, holes 5 for removing the medium from the storage space 4 are distributed around the pressure reservoir 1. Therefore, more holes 5 can be provided. Further, the medium can be guided in various directions without much effort.

  In the variant of FIG. 5, the flats 7 extend over the entire length of the base body 2, such that the flats 7 form planar strips 8 each extending substantially the entire length of the base body 2. At this time, the holes 5 are respectively opened in one of the planar strips 8.

  FIG. 6 shows a variant in which the outer surface 32 of the wall 3 forms a cylindrical jacket.

  Many variants are possible for connecting the accumulator 1 to such devices and devices to which the medium is to be supplied. For example, the device 10 (FIGS. 1 and 2) can be fixed directly to the outer surface 32 of the wall 3 as described above. It is also possible to provide holes 5 with internal threads, to apply pressure in the internal threads or to screw in connecting parts. Furthermore, it is also preferred that the flange can be fixed to one of the flat parts 7 or to one of the flat strips 8. In general, all known connections and fastening possibilities are suitable.

  In the following, an implementation for the arch 6 according to the invention, which extends into the storage space 4, will be described with reference to a third embodiment of the invention, which is particularly preferred in practice. The description of the first and second embodiments applies basically in the same way to this third embodiment, and the individual means described are likewise combined with or applicable to the third embodiment. I want to be understood.

  FIG. 7 shows a cross section of the third embodiment. The difference from the first and second embodiments lies in the design of the storage space 4. In this embodiment, the storage space 4 consists of two cylindrical longitudinal holes 41, 42 extending parallel to each other in the direction of the axis L. The axes L1, L2 of the longitudinal holes 41, 42 have an interval E therebetween, and the interval E is dimensioned such that the cross sections of the longitudinal holes 41, 42 overlap. The inner cross-section shown in FIG. 7 is thus substantially in the shape of eight. The eight constrictions thus form two curved arches 6 according to the invention, which extend into the interior space of the storage space 4. According to this display, the hole 5 is open in the upper arch 6. This indication, of course, allows additional or alternative holes to be drilled in the lower arch 6.

  In this embodiment, the difference between the diameter of the longitudinal holes 41 or 42 and the length of the common secant of the two circular cross sections of the longitudinal holes 41 and 42 is understood as the height H of the arch.

  Each spacing of axis L1 or L2 from axis L may be, for example, about 40% of the radius of the associated longitudinal bore 41 or 42, respectively. The distance from the center (axis L) of the longitudinal holes 41, 42 is defined by the diameter of the radial holes 5 and the permissible fatigue strength. In the embodiment shown in this figure, the two longitudinal holes 41 and 42 are located symmetrically with respect to the axis L. However, this is not necessary.

  The longitudinal holes preferably have the same radius. However, different radii can be used.

  It is preferred, but not necessary, that the two longitudinal holes 41, 42 extend in parallel. They can also be slightly inclined with respect to each other.

  The third embodiment is characterized in particular by its simple manufacture. According to the invention, only two holes are required to establish the storage space 4 with the arch 6.

  FIG. 8 shows a cross section of a modification of the third embodiment. In this variant, the storage space 4 consists of three longitudinal holes 41, 42, 43, whose cross-sections are configured to overlap. Thus, as shown in FIG. 8, three arches 6 according to the invention are provided, each projecting into the storage space 4. A radial hole 5 opens in each of these arches. Of course, the radial holes 5 can also be drilled in only one or two arches 6.

  The longitudinal holes 41, 42, 43 are preferably arranged symmetrically with respect to the axis L.

  Embodiments with more than three longitudinal holes 41, 42, 43 are of course also possible.

  It is to be understood that the described embodiments and variations may be combined with one another in other ways than expressly described herein. Embodiments with two or more arches 6 are also possible. In the case of a plurality of arches 6, not all arches need to be designed identically, for example, the arches can have different curvatures.

  Although reference has been made with respect to this application in the field of application closely related to the implementation of large diesel engines, in general, the accumulator according to the invention basically applies to other diesel engines, for example, small diesel engines and internal combustion engines as well. It should be understood that it can be used.

FIG. 3 is a sectional view of the first embodiment of the accumulator according to the invention, taken along section line II in FIG. 2. 2 is a longitudinal sectional view of the embodiment of FIG. 1, taken along section line II-II of FIG. 1. FIG. 2 is a view of a modification of the first embodiment similar to FIG. 1. FIG. 4 is a sectional view of a second embodiment of the accumulator according to the present invention. FIG. 5 is a view of a modification of the second embodiment similar to FIG. 4. FIG. 5 is a view of another modification of the second embodiment similar to FIG. 4. FIG. 7 is a sectional view of a third embodiment of the accumulator according to the present invention. FIG. 8 is a view of a modification of the third embodiment similar to FIG. 7.

Claims (11)

  It has a tubular base body (2) with a wall (3) delimiting a storage space (4) provided inside the base body (2) in which the medium is to be stored, and for discharging the medium It has at least one hole (5) extending through the wall (3) and at least one curved arch (6) is provided on the inner side (31) of the wall (3) and in the storage space (4) An accumulator for a common rail system of an internal combustion engine, wherein the accumulator extends and is configured such that the hole (5) opens into the storage space (4) in the curved arch (6).   Accumulator according to claim 1, wherein the arch (6) extends over most of the length of the storage space (4), preferably over the entire length of the storage space (4).   At least two curved arches (6) extending into the storage space and each extending over most of the length of the storage space (4), preferably over the entire length of the storage space (4), have at least two curved arches (6). The accumulator according to claim 1 or 2, wherein the accumulator is provided at various positions with respect to a circumferential direction of the inner surface (31) of the wall (3).   The accumulator according to any of the preceding claims, wherein the one or more holes (5) extend radially.   5. The method according to claim 1, wherein each hole (5) opens into the storage space (4) at the center of the arch (6) relative to the circumferential direction of the inner surface of the wall. Accumulator as described.   6. The method according to claim 1, wherein each arch has a radial height corresponding to 5% to 30% of the inner diameter of the storage space. The accumulator according to 1.   7. The storage space (4) comprises at least two, preferably cylindrical, longitudinal holes (41, 42, 43), the cross sections of which are configured to overlap. An accumulator according to any one of the preceding claims.   The wall (3) of the base body (2) has at least one flat part (7) on the outer side of the wall, the flat part having a hole (5) flat on the outer side (32) of the wall (3). An accumulator according to any one of the preceding claims, wherein the accumulator is configured and designed to open into the accumulator.   The wall (3) of the base body (2) has at least one flat band (8) on the outer surface (32) of the wall, the flat band being substantially the entire length of the tubular base body (2). An accumulator according to any one of the preceding claims, extending over the accumulator.   10. The accumulator according to claim 9, wherein the holes (5) open into the planar strip (7; 8). A large diesel engine comprising a common rail system for fuel injection having an accumulator (1) according to any one of the preceding claims.