EP2167810B1 - High-pressure fuel accumulator - Google Patents

Description

State of the art

In internal combustion engines, such as self-igniting internal combustion engines fuel injection systems shown, today, among other things, high-pressure accumulator injection systems (common rail) are used. The high-pressure accumulator injection system comprises a high-pressure feed pump with which a system pressure level is built up and maintained in a high-pressure accumulator body (common rail). Fuel is injected into the combustion chambers of the self-igniting internal combustion engine via a plurality of fuel injectors connected to the high-pressure accumulator body, which are in communication with the high-pressure accumulator body (common rail) via high-pressure lines. From the fuel injectors leakage and repelled amount via a return system usually fed back into the tank of the fuel injection system, from where it is fed again, possibly with the interposition of an electric fuel pump, the high-pressure pumping unit.

The high-pressure storage body is so far from a rod-shaped except for the threaded connections blank, which is a master or forming part, produced by machining. In the range of intersections of a introduced into the rod-shaped deep hole, which defines the fuel volume within the high-pressure accumulator body, and the radial bores in the wall of the high-pressure accumulator body to the individual high pressure connections occur in operation under pressure load of the high-pressure accumulator body, the maximum voltages. These intersections represent the point relevant to failure and determine the strength and thus the design of the high-pressure accumulator body (common rail) substantially. A reduction of the stress load in the region of the points of intersection of the deep hole bore with the individual radial bores to the high pressure ports can be achieved by increasing the outer diameter of the high pressure reservoir body while maintaining the inner diameter of the high pressure reservoir body. This reduction of Stress in the intersecting areas, however, asymptotically approaches a threshold. The associated with this solution material and weight would be disproportionately large.

To improve the high pressure resistance of high-pressure accumulator bodies is out
DE 199 48 338 A1 a method for processing a high-pressure fuel storage, a high-pressure fuel storage with connecting pieces and the application of the method for processing known. The common rail fuel injection system according to
DE 199 48 338 A1 includes a body equipped with multiple ports. The main body is deformed in the area of the connection openings. In the region of the connection openings in each case a through hole is provided which has two sections with different inner diameters. The connecting pieces are designed such that the outer diameter of the connecting piece at its end facing the high-pressure fuel accumulator end substantially corresponds to the inner diameter of the portion of the through-hole in the high-pressure fuel high-pressure accumulator.

Out DE 199 36 533 A1 a high-pressure fuel storage is known, which is particularly suitable for use in a common rail fuel injection system of an internal combustion engine. The high-pressure fuel accumulator comprises a tubular base body having a longitudinally extending blind hole and a plurality of terminals. In order to improve the high-pressure resistance of the high-pressure fuel accumulator and to extend its service life, a sealing plug is arranged in the closed end of the blind bore.

DE 39 32 672 A1 refers to a blank for producing a fuel supply manifold for an injection system of an engine. In an tubular part, an axial fuel passage is formed. Several sleeves are laterally from the tubular part. Each sleeve communicates with the axial fuel passage and forms a seat for a fuel metering and atomizing valve in its interior. An extension extends radially at one end of the tubular member and forms a seat for a pressure regulator. There are two blind holes provided whose axis is perpendicular to the axial fuel passage. The blank is made of molten metal by injection molding.

DE 199 45 316 A1 refers to a high-pressure fuel storage, the interior of which is arranged eccentrically in the base body relative to the longitudinal axis of the base body is. The high-pressure resistance of the high-pressure fuel accumulator is primarily limited by the intersections between the connection openings and the main body. During operation, the highest forces act on the transitions between the connection openings for the high-pressure lines to the individual fuel injectors to be supplied with fuel under system pressure and the main body. By a relative displacement of the interior in a first plane of the base of the fracture endangered transition region of the intersections is relieved or stabilized, so that an increase in the high pressure resistance of the high-pressure fuel storage by the solution DE 199 45 316 A1 can achieve. In a particular embodiment of the high-pressure fuel storage according to DE 199 45 316 A1 the base body is provided in cross-section with a substantially elliptical outer contour, wherein the connection openings are arranged in the longitudinal direction of the main axis of the ellipse. The substantially elliptical outer contour leads under high pressure loading of the interior of the tubular base body to the fact that the interior of the tubular body expands transversely to the main axis of the ellipse. The resulting strains in the main body ensure that the fracture-prone area of the intersections is relieved.

The announcements EP1811165A2 (Article 54 (3) EPC), DE19913793A1 and FR2816668 show other similar high-pressure storage body.

Disclosure of the invention

According to the invention, it is proposed to modify the geometry of the high-pressure storage body (common rail) in such a way that, by increasing the axial elongation acting in the axial direction, a tapering of the outer diameter between the individual high-pressure connections in combination with a locally reduced reduction of the transverse expansion by a material reduction on the side the high-pressure storage body, which is opposite to the respective Verschneidungsstelle, a more uniform stress distribution in the region of the intersection is achieved. For this purpose, the material reduction is designed as a wall thickness reduction in the form of a flat flattening. By inventively proposed solution can be achieved in an advantageous manner that in the same applications, ie at a same system pressure to be generated, a material with low strength can be used. This offers the possibility of reducing the costs by allowing a more cost-effective material to be used when the solution proposed according to the invention is used as well as reduced machining requirements in the area of the point of intersection. There other surface qualities and roughness values can be permitted. On the other hand, the solution proposed according to the invention, while maintaining the selected material and with otherwise identical operating conditions due to the improvement of the high pressure resistance, offers the possibility of increasing the system pressure level.

As a result of the tapering of the outer diameter of the high-pressure storage body, which essentially has a tubular appearance, the material expenditure and thus the weight of the high-pressure storage body can advantageously be reduced considerably at the same time for reducing the stress. On the one hand, this leads to a lower weight of the high-pressure storage body with increased high-pressure resistance; on the other hand, the amount of material used is reduced, which contributes to a not insignificant reduction in material costs in mass production.

The inventively proposed, substantially tubular high-pressure storage body has in one-piece form high-pressure connections and between these a tapered outer diameter. A suitable diameter ratio d / D is in the range between 0.4 and 0.75, where D denotes the diameter of the high-pressure storage body without a taper and d the diameter of the high-pressure storage body at the taper. A width b of the dome in the region of the sections remaining in the cylindrical basic shape of the high-pressure storage body in the region of the high-pressure connections is between 0.6 and 0.85 relative to the diameter of the basic cylindrical shape, ie. a transition radius r from the outer surface to the dome-shaped elevation in the region of the high-pressure ports is formed to be smaller than the difference of d, the diameter of the body at the taper point, and D, the original diameter of the high-pressure reservoir body, i. r <(D - d).

The essentially high-pressure storage body, which is essentially cylindrical in its basic form, has flattenings in one-piece form on the cylinder half opposite the bore intersection. These flats serve the purpose of reducing the bending strength of the cross-section at the side opposite the bore intersection.

In a particularly advantageous embodiment, a flat flattening is formed which contacts the taper diameter and the circular transition from the taper diameter to the base diameter in the plane of symmetry.

Brief description of the drawings

With reference to the drawing, the invention will be described below in more detail.

Figur 1

einen aus dem Stand der Technik bekannter Hochdruckspeicherkörper,

Figur 2

die Draufsicht auf den erfindungsgemäß vorgeschlagenen Speicherkörper in perspektivischer Wiedergabe,

Figur 3

eine schematische Wiedergabe der spannungsoptimierten Außengeometrie in Seitenansicht,

Figur 4

eine Schnittdarstellung einer nicht erfindungsgemäßen Außengeometrie,

Figur 5

eine nicht erfindungsgemäße Geometrie zur Reduktion der Biegesteifigkeit an der der Verschneidungsstelle zwischen Querbohrung und Hohlraum des Hochdruckspeicherkörpers gegenüberliegenden Seite,

Figuren 6.1, 6.2 und 6.3

eine Ausführungsvariante (6.1) und zwei nicht erfindungsgemäße Geometrien (6.2 und 6.3) zur Reduktion der Biegesteifigkeit des erfindungsgemäß vorgeschlagenen Hochdruckspeicherkörpers.

It shows:

FIG. 1

a high-pressure storage body known from the prior art,

FIG. 2

the top view of the inventively proposed storage body in perspective playback,

FIG. 3

a schematic representation of the stress-optimized outer geometry in side view,

FIG. 4

a sectional view of a non-inventive outer geometry,

FIG. 5

a geometry not according to the invention for reducing the flexural rigidity at the side opposite the point of intersection between the transverse bore and the cavity of the high-pressure storage body,

Figures 6.1, 6.2 and 6.3

an embodiment (6.1) and two non-inventive geometries (6.2 and 6.3) for reducing the bending stiffness of the present invention proposed high-pressure storage body.

The representation according to FIG. 1 is a high pressure storage body according to the prior art can be seen.

FIG. 1 shows a high pressure storage body 10, on the lateral surface 14, a number of domes 12 is formed. The dome 12 each represent high pressure ports 28, in which FIG. 1 not shown high-pressure lines are connected, via which the system pressure generated in the high-pressure accumulator body 10 to in FIG. 1 also not shown fuel injectors a high-pressure accumulator injection system (common rail) is applied. On the end faces of the tubular high-pressure accumulator body 10 there is, on the one hand, a pressure regulating valve 16 and, on the opposite front side, a stopper identified by reference numeral 18. Along its entire length 22, the high-pressure storage body 10 has a constant outer diameter 20. Laterally on the lateral surface 14 a plurality of fastening points 24 are provided, with which the high-pressure accumulator body 10 is fixed in the cylinder head area of the fuel to be supplied to the internal combustion engine. Each of the attachment points 24 includes a bore 26; the dome 12 on the lateral surface 14 of the Prior art high pressure accumulator bodies 10 serve as high pressure ports 28 and typically include a threaded portion.

embodiments

FIG. 2 shows an embodiment of the inventively proposed high-pressure storage body with regions which are formed in a tapered diameter relative to a basic shape.

FIG. 2 can be taken that the there reproduced in perspective view high-pressure storage body 10 (common rail) on its lateral surface 14 is also provided with a number of domes 12, which serve as high pressure ports 28. Analogous to in FIG. 1 illustrated high-pressure storage body 10 includes the in FIG. 2 represented according to the invention proposed high-pressure accumulator body 10 at its end faces the control valve or the plug 18th

Unlike in FIG. 1 illustrated high-pressure accumulator body 10 are located at the invention proposed high-pressure accumulator body 10 between individual high-pressure connections 28 sections 42 in which the high-pressure accumulator body 10 is formed with a tapered diameter 46, on which the lateral surface 14 compared to the diameter 44 of a basic shape 40, which corresponds to the cylindrical shape 52, returns.

The suitable diameter ratio of the diameters 46 to 44 is between 0.4 and 0.75. By the tapering portions 42, which extend in the axial direction between the high-pressure ports 28 on the high-pressure accumulator body 10, an increase in a longitudinal expansion 60, see illustration according to FIG FIG. 3 , can be achieved in combination with a local reduction in lateral strain by material reduction on the side of the high-pressure storage body 10 which is opposite to a point of intersection 56, as in FIG FIG. 4 shown. This offers the advantage that with the same application, for example with the same system pressure, a material with lower strength can be used as the material for the high-pressure storage body 10, so that the costs are reduced by choosing the less expensive material or reduced requirements in the area of the Verschneidungsstelle 56 can be. On the other hand, in the high pressure storage body 10 proposed according to the invention, an increase in pressure with respect to the system pressure can be achieved if the material is retained and only the outer geometry of the high-pressure accumulator body 10, as proposed according to the invention, is changed.

FIG. 3 shows a representation of the inventively proposed high-pressure storage body in the region of a dome for a high pressure port.

Out FIG. 3 shows that the Verschneidungsstelle 56 of a transverse bore 58 which passes through the dome 12, with the longitudinal bore produced as a cavity 54 of the cylinder produced in the form of 52 high-pressure accumulator 10 is formed. On the lateral surface 14 of the high-pressure accumulator body 10, the dome 12 rises in the transition radius 50. A width in which the dome 12 together with high pressure ports 28 on the lateral surface 14 of the invention proposed high-pressure accumulator 10 is designated by reference numeral 48.

At the opposite side of the high pressure port 28 68, as proposed by the invention, a flat 64 is formed. This results in a reduced circumferential expansion in the intersection region 56 due to the constrictions obtained. The width 48 in which the sections of the high-pressure accumulator body 10 remaining in the cylindrical basic shape 40, 52 are executed, in particular in the area of the high-pressure connections 28, lies between 0.6 and 0 , 85, based on the diameter of the basic shape 44. The transition radius 50 of the basic shape 40, ie the cylindrical shape 52 on the sections 42 formed in tapered outer diameter 46 is preferably chosen to be smaller than the difference in the diameters of the basic body, i. of the diameter 44, and the diameter of the tapered portions 42, i. the diameter 46.

The representation according to FIG. 4 is a cross section through a not according to the invention proposed high-pressure body in the range of a high-pressure connection can be seen.

As already related to FIG. 3 explained, created at the interface of the transverse bore 48 with the high-pressure storage body 10 in the axial direction traversing cavity 54, the Verschneidungsstelle 56, which represents the most critical component site. The transverse bore 78 extends through the dome 12, on the outside of the threaded portion 58 extends. At this high pressure connection 28 to be connected high-pressure fuel line is connected to the high-pressure accumulator body 10. At the point of intersection 56 opposite side, ie in the region of the bottom 68 of the high pressure storage body 10, this has a flattening 64 on. Through this, the Reduces flexural rigidity of the cross section of the high-pressure accumulator body 10 at the directly opposite the Verschneidungsstelle 56 side and simultaneously reduces the strain in the circumferential direction in the intersection region 56. From the illustration according to FIG. 4 shows that the flattening 64 is formed on the lateral surface 14 of the high pressure storage body 10 of the Verschneidungsstelle 56 directly opposite rounded. Due to the reduced elongation 70 in the circumferential direction, there is a support action indicated by reference numeral 66, which acts on the region of the transverse bore 58 above the intersection point 56 via the elongation 70 in the region of the rail bottom 68 and significantly improves the high-pressure strength in the intersection region 56, produced by lower elongation in FIG Circumferential direction, as in FIG. 4 shown. Together with the increased axial elongation 60, a homogenization and thus a significant reduction of the stress peaks in the intersection region 56 can be achieved.

From the illustration according to FIG. 4 also shows that the flattening 64 shown there is achieved by a material reduction in the region of the bottom 68 of the high-pressure accumulator body 10. The resulting at Systemdruckbeaufschlagung the cavity 54 deformation of the wall surface of the high-pressure accumulator body 10 leads to a reduced elongation 70 in the circumferential direction, above the Verschneidungsstelle 56 of transverse bore 78 and cavity 54, which is usually designed as a longitudinal bore, to a reduction of the voltage spikes in leads this area. As a result, a significant reduction of stress peaks in the area of the intersection point 56 from the cavity 54 and transverse bores 78 at each of the high-pressure ports 28 of a high-pressure accumulator body 10 can be achieved. In the FIG. 4 indicated, here rounded flattened 64 is formed on the inventively proposed high-pressure accumulator body 10 in the lateral surface 14, each having a transverse bore 78 of a high pressure port 28 opposite. By in connection with the FIGS. 3 and 4 illustrated optimization of the outer geometry of the inventively proposed high-pressure storage body 10, a reduction of the stresses can be achieved by an increased strain 60 in the axial direction and a reduced strain in the radial direction. The voltage optimization in the area of the Verschneidungsstelle 76 means there a reduction of the maximum voltage and in other areas an increase in the base voltages, ie in the non-critical area outside of the Verschneidungsstellen 56 between the transverse bores 78 and the cavity 74, the ground voltage level is increased.

FIG. 5 shows a schematic representation of a comparison of the diameter 44 formed as a cylinder 52 basic shape 40 of the high-pressure accumulator body 10. In FIG. 5 It is shown that the tapered diameter 46, which on the high-pressure storage body 10 in the region of a flat 64 (see FIG FIG. 4 ) is formed, gradually from the diameter 44 of the basic mold 40 can be reduced until this on the in FIG. 5 hatched shown residual wall thickness between the lateral surface 14 and the cavity 54 (longitudinal bore) can be returned. In the illustration according to FIG. 5 the flattening 64 is on the opposite side of the Verschneidungsstelle 56, that is formed in the bottom 68 of the high-pressure accumulator body 10. Deviating from the basic shape 40, which is designed as a cylinder 52, in the region of the diameter 44 of the high-pressure accumulator 10, the high-pressure accumulator 10 in the region of flattened areas 64 assumes an oval appearance due to the tapered diameter 46, as in connection with FIG FIG. 5 shown. The representations according to the Figures 6.1, 6.2 and 6.3 Different specifications of material reductions can be seen, which can be carried out on the opposite side of a respective Verschneidungsstelle on inventively proposed high-pressure storage body 10.

So shows, for example, the Figure 6.1 the formation of a flat flattening 72 of the lateral surface 14 of the inventively proposed high-pressure storage body 10. As the schematic representation according to Figure 6.1 can be removed, in this embodiment, the flat flat 72 coincides with the tapered diameter 46. Furthermore, the in Figure 6.1 schematically shown flat flattening 72 the advantage of cost-effective manufacturability by means of a machining production of the inventively proposed high-pressure storage body 10. The sectional view according to Figure 6.1 It can be seen that, apart from the flattening 72, the basic shape 40 of the high-pressure accumulator body 10 is given by the cylindrical shape 52. The flat flattening 72 lies in the floor area (see position 68 in FIG FIG. 4 ) at the point of intersection 56 opposite side of the high-pressure accumulator body 10th

Figure 6.2 shows an alternative non-inventive geometry of a material reduction, in which on the circumference of the lateral surface 14 of the inventively proposed high-pressure storage body 10 lying in its plane of symmetry, a circular flattening 76 is formed. In the circular flattening 76 as shown in FIG Figure 6.2 this represents a transition from the tapered diameter 46 to the diameter 44 of the basic shape 40. This lies in the plane of symmetry of the inventively proposed high-pressure storage body 10, so that a symmetrical stress distribution and in particular a reduction of the maximum stress in the Verschipungsstelle 56 between the transverse bore 78 of the high-pressure ports 28 and the longitudinal direction of the high-pressure storage body 10 extending longitudinal bore, which represents the cavity 54 adjusts.

Figure 6.3 Finally, shows an arc-shaped flattening 74 in the bottom region of a non-inventively proposed high-pressure storage body 10, with the reduction of the maximum stress in the Verschneidungsstelle 56 between the transverse bore 78 of the high-pressure port 28 and formed as a longitudinal bore cavity 54 of the high-pressure accumulator body 10 can be achieved.

A particularly simple form of material reduction in terms of manufacturing technology can be achieved by the in Figure 6.1 illustrated flat flattening 72 and the in Figure 6.2 shown, lying in the plane of symmetry of the high-pressure accumulator body 10, circular trained flattening 76 on the respective intersection point 56 opposite side 68 of the high-pressure accumulator body 10 reach.

Claims (6)

1. High-pressure accumulator body (10) for a highpressure injection system for injecting fuel into combustion chambers of internal combustion engines, having a number of high-pressure ports (28) in a shell surface (14), having a cavity (54) which forms intersection points (56) with transverse bores (78) of the high-pressure ports (28), wherein, in sections (42) between the highpressure ports (28), the diameter (46) of the high-pressure accumulator body (10) is narrowed, and a material reduction (64, 72, 74, 76) is formed on said high-pressure accumulator body on the side (68) which is situated opposite the respective intersection points (56), wherein the material reduction (64, 72, 74, 76) is formed as a wall thickness reduction on the side (68), in particular of the base of the high-pressure accumulator body (10), characterized in that the material reduction is in the form of a planar flattened portion (72).
2. High-pressure accumulator body (10) according to Claim 1, characterized in that said high-pressure accumulator body has a substantially cylindrical (52) basic shape (40).
3. High-pressure accumulator body (10) according to Claim 1, characterized in that the ratio of the narrowed diameter (46) to the diameter (44) of the basic shape (40) lies between 0.45 and 0.75.
4. High-pressure accumulator body (10) according to Claim 2, characterized in that, in regions of the high-pressure regulator body (10) in which the cylindrical (52) basic shape (40) remains, the high-pressure ports (28) are formed as domes (12) of a width (48) which amounts to 0.6 to 0.8 times the diameter (44) of the basic shape (40).
5. High-pressure accumulator body (10) according to Claim 1, characterized in that a transition radius (50) from the diameter (44) of the basic shape (40) to the narrowed diameter (46) is smaller than the difference of the diameter (44) of the basic shape (40) and the narrowed diameter (46).
6. High-pressure accumulator body (10) according to one of the preceding claims, characterized in that the planar flattened portion (72) is tangent to the narrowed diameter (46).

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