EP2705242B1 - Fuel distributor - Google Patents

Description

State of the art

The invention relates to a fuel distributor, which is used in particular for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines. Specifically, the invention relates to the field of fuel injection systems designed as medium-pressure systems.

In automotive fuel injection systems, it is conceivable that a fuel rail used for high pressure steel or aluminum applications may be used. As a result, a compressive strength for pressures of, for example, 20 MPa (200 bar) can be achieved. However, this massive design of the suitable for high pressure applications Rails is associated with high production costs.

Fuel rail manifolds may also be used for low pressure applications at 0.3 MPa (3 bar) to 0.5 MPa (5 bar) for such applications. Here, for example, thin-walled steel tubes can serve to produce the fuel distributor. However, the scope of such fuel rail for low pressure applications is limited to the low pressure range mentioned.

From the US 5,390,638 A is already a fuel distributor, in particular for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines, known, comprising a tubular body. An inner wall of the tubular base body defines an elongated fuel space, wherein the tubular base body is formed of a plastic and wherein on the tubular base body at least one through hole is provided, which is eccentric to a longitudinal axis extending centrally through the elongated fuel space on the inner wall of the tubular base body in the Fuel room opens. The passage openings open in each case the inner wall contour of the tubular body according to a concave inner contour. An improvement in strength in the area of the passage openings by a contour change on the main body of the fuel distributor is not provided.

Disclosure of the invention

The fuel distributor according to the invention with the features of claim 1 has the advantage that a compressive strength of the fuel distributor is improved. Specifically, a suitable for a medium pressure fuel distributor can be created with relatively low production costs.

The measures listed in the dependent claims advantageous developments of the fuel distributor specified in claim 1 are possible.

It is provided that on the inner wall of the tubular base body in the region of the passage opening, a non-concave surface is configured, in which the passage opening is at least partially. Since the non-concave surface is provided only in the region of the passage opening, the configuration of the non-concave surface can be realized by only a slight thickening of the wall of the tubular base body. This demolding technology can thus be easily realized, with the cycle time, in particular cooling time, only slightly extended during injection molding. Although the tension can also be reduced and laid outside the weld line due to a large area, the wall thickness increases more strongly, which adversely affects the cycle time and thus increases the production costs. It is therefore also advantageous that an expansion of the non-concave surface in a longitudinal direction along the longitudinal axis of the elongate fuel chamber projects beyond the opening width of the through-opening in the longitudinal direction on both sides and that an expansion of the non-concave surface in the circumferential direction with respect to the longitudinal axis of the elongated fuel chamber on both sides within the opening width of the through hole is in the circumferential direction. As a result, the strength can be increased locally, especially in the weakened by the Bindenaht local area of the tubular body formed of plastic. In addition, by this measure, the maximum voltage itself as well as the volume in which the high voltage is applied, reduced. Thus, the component load capacity increases.

The non-concave surface on the inner wall could be designed as an at least approximately flat surface. Due to the planar configuration of the non-concave surface, a certain increase in the material thickness or wall thickness can be achieved, which, however, is insignificant in terms of cooling and thus extends the cycle time, in particular the cooling time, during injection molding only insignificantly. Thus, the component load capacity can be improved without increasing the manufacturing cost. This is particularly the case with a small flat surface, which is smaller than the exit surface of the through hole.

However, the planar configuration of the non-concave surface on the inner wall is not claimed in the present application, ie the appended claims are directed only to a manifold with a convex surface on the inner wall of the tubular base body in the region of the passage opening.

Advantageously, the tubular base body is formed as an injection molded part, wherein an injection direction is parallel to the longitudinal axis of the tubular base body. Due to the eccentric arrangement of the through hole, the stress level under load can be reduced overall. By the injection direction along the longitudinal axis results in the injection direction behind the passage opening a Bindenaht. Due to the eccentric arrangement of this Bindenaht is positioned obliquely. Since the strength is thereby improved, the tubular base body can be manufactured in terms of a desired load capacity, in particular a pressure level, of plastic with a reduced wall thickness. As a result, the cycle time, which depends essentially on the cooling time during injection molding, can be reduced.

It is advantageous that an edge of the passage opening in the region of the weld line to the weld line is not configured concave. A non-concave embodiment here comprises a somewhat rectilinear configuration and a convex configuration. The arrangement of the weld line at the non-concave portion of the edge of the passage opening, the weld line is in the range of lower mechanical stresses. Specifically, the weld line is arranged away from occurring stress peaks in the region of concave curves of the edge of the passage opening. Since the local material strength is reduced in the region of the weld line, but at the same time the stress distribution in the tubular body is influenced so that the stresses on the weld line are reduced, the strength of the tubular body can be improved overall.

It is also advantageous here for an edge of the passage opening to have a straight section in the region of the weld line. Specifically, it is advantageous that the passage opening is designed as a slot-shaped passage opening and that the slot-shaped passage opening is aligned in a circumferential direction with respect to the longitudinal axis. With respect to a circular passage opening with the same flow cross-section, the slot-shaped passage opening allows the arrangement of the weld line in the region of the straight edge section, so that the weld line is removed from the stress peaks in the region of the curves of the slot-shaped passage opening.

However, it is also advantageous that an edge of the passage opening in the region of the weld line is convex toward the weld line. As a result, the stresses occurring in the region of the weld line in the plastic can also be reduced. It is also advantageous that an opening width of the passage opening in the circumferential direction with respect to the longitudinal axis is greater than an opening width of the passage opening in a longitudinal direction along the longitudinal axis. In particular, an oval configuration can be realized in which, in the region of the weakest curvature of the oval passage opening, the weld line adjoins the passage opening. This also results in a reduced local mechanical stress on the weld line, so that the strength is improved overall.

Brief description of the drawings

• Fig. 1 einen Brennstoffverteiler in einer schematischen Schnittdarstellung zur Veranschaulichung möglicher Ausgestaltungen der Erfindung, wobei die Schnittebene senkrecht zu einer Längsachse des Brennstoffverteilers liegt, und
• Fig. 2 einen Brennstoffverteiler in einer schematischen Schnittdarstellung zur Veranschaulichung möglicher Ausgestaltungen der Erfindung, wobei die Längsachse des Brennstoffverteilers in der Schnittebene liegt.

Preferred embodiments of the invention are explained in more detail in the following description with reference to the accompanying drawings, in which corresponding elements are provided with corresponding reference numerals. It shows:

• Fig. 1 a fuel distributor in a schematic sectional view to illustrate possible embodiments of the invention, wherein the sectional plane is perpendicular to a longitudinal axis of the fuel distributor, and
• Fig. 2 a fuel distributor in a schematic sectional view to illustrate possible embodiments of the invention, wherein the longitudinal axis of the fuel distributor is in the sectional plane.

Embodiments of the invention

Fig. 1 shows a fuel distributor 1 in an excerptional, schematic sectional view for explaining possible embodiments of the invention, wherein a sectional plane perpendicular to a longitudinal axis 2 (FIG. Fig. 2 ) is oriented. The fuel distributor 1 has a tubular base body 3. Specifically, the tubular base body 3 may be configured substantially hollow cylindrical. However, other embodiments are possible. For example, those with an oval cross-section. Other elements of the fuel distributor 1 are not shown for simplicity of illustration. Such elements may, inter alia, be cups which serve to connect the fuel distributor 1 to fuel injection valves.

The fuel distributor 1 can be designed in the form of a fuel distributor strip 1. The fuel distributor 1 is particularly suitable for fuel injection systems of mixture-compressing, spark-ignited internal combustion engines. In particular, the fuel distributor 1 is suitable for a medium-pressure system. The mean pressure for such a medium-pressure system can be in the range of 3 MPa to 10 MPa or 30 bar to 100 bar. In particular, the mean pressure may be in the range of 5 MPa to 7 MPa or 50 bar to 70 bar. However, the fuel distributor 1 according to the invention is also suitable for other applications.

The tubular base body 3 has an inner wall 4, which is designed substantially cylinder jacket-shaped. The inner wall 4 of the tubular body 3 defines a fuel chamber 5 of the fuel distributor 1. The fuel chamber 5 is designed here as an elongated fuel chamber 5. In operation, fuel is fed into the fuel chamber 5 via a suitable connection of the fuel distributor 1, preferably under a medium pressure. The stress of the tubular body 3 is greater than a stress in low pressure applications. However, the stress is also lower than in high pressure applications requiring compression strength of, for example, 20 MPa (200 bar) in spark-ignited spark-ignited internal combustion engines.

In order to improve the load capacity of the fuel distributor 1 with respect to low-pressure applications and at the same time to reduce the production costs in relation to high-pressure applications, the tubular base body 3 is made of a plastic, which is preferably designed as an injection molded part. An injection direction 6 ( Fig. 2 ) is selected here at least approximately parallel to the longitudinal axis 2 of the tubular base body 3. In addition, for reasons of stability, an eccentric configuration of passage openings 7, 8 is provided on the tubular base body 3. The passage openings 7, 8 illustrate possible embodiments for a plurality of passage openings, which are configured, for example, along the axis 2 one behind the other on the tubular base body 3 in order to enable a connection with a corresponding number of cups of the fuel distributor 1. However, such through-holes can also serve for other purposes.

The passage openings 7, 8 have centrally through the passage opening 7, 8 extending axes 20, 21. However, the axes 20, 21 do not point to the longitudinal axis 2, since the passage openings 7, 8 are eccentric to the longitudinal axis 2 extending centrally through the elongate fuel chamber 5 on the inner wall 4 of the tubular body 3 open into the fuel chamber 5. The axes 20, 21 are in each case oriented eccentrically to the longitudinal axis 2. As a result, the load capacity of the tubular base body 3 in the region of the passage openings 7, 8 and thus improved overall.

The inner wall 4 is configured substantially concave with respect to a circumferential direction 22 from the longitudinal axis 2 and the fuel chamber 5, respectively. The circumferential direction 22 here refers to the longitudinal axis 2. However, the inner wall 4 in the region of the passage openings 20, 21 at least partially not concave. Such non-concave surfaces 23, 24 are provided at the passage openings 7, 8. By the non-concave surfaces 23, 24, the load capacity in the region of the through holes 7, 8 is further improved. The non-concave surface 23 is here as flat surface 23 configured. The flat surface 23 extends along a longitudinal direction 25, which in this embodiment is the same as the injection direction 6, on both sides via the passage opening 7. However, an extension 26 of the flat surface 23 in the circumferential direction 22 with respect to the longitudinal axis 2 of the elongated fuel chamber 5 is inside both sides an opening width 27 of the passage opening 7 in the circumferential direction 22. Thus, a wall thickness 28 in the region of the passage opening 7, although somewhat increased, this increase is in relation to the cycle time, in particular cooling time, during injection molding but only slightly. Thus, the strength improves in the region of the through hole 7. The improved local strength in this case relates specifically to a weld line, which is also based on the Fig. 2 is described.

The non-concave surface 24 at the passage opening 8 is configured as a convex surface 24. In the circumferential direction 22, however, an extension 29 of the convex surface 24 is smaller than an opening width 30 of the passage opening 8. As a result, the magnification occurring in the region of the passage opening 8 is Wall thickness 28 optimized in terms of volume. Specifically, in relation to the occurring increase in volume in the region of the passage opening 8, the wall thickness 28 at a weld line can be set comparatively large, without this adversely affecting the cycle time, in particular cooling time, during injection molding.

Fig. 2 shows a fuel distributor 1 in an excerpt, schematic sectional view, wherein a longitudinal axis 2 of the fuel distributor 1 is in the sectional plane. By way of example, passage openings 9 to 15 corresponding to possible embodiments of the invention are shown. As based on the Fig. 1 described, the through-holes 9 to 15 according to the passage openings 7, 8 are preferably also or additionally eccentrically to the centrally through the elongated fuel chamber 5 extending longitudinal axis 2 on the inner wall 4 of the tubular body 3 in the fuel chamber 5 out.

The passage opening 9 is configured at least approximately circular. In this way, an opening width 31 of the passage opening 9 in the circumferential direction 22 with respect to the longitudinal axis 2 is the same size as an opening width 32 of the passage opening 9 in the longitudinal direction 25 along the longitudinal axis 2. When injection molding the tubular base body 3 is formed behind the passage 9 designed as a transverse bow 9 a Bindenaht 33. In a corresponding manner also forms behind the through holes 10 to 15 each a weld line 34 to 39th

At the weld line 33, the stability of the tubular base body 3 is impaired. The passage opening 10 is designed in accordance with the passage opening 9 with a circular cross-section. However, the passage opening 10 is made smaller than the passage opening 9, so that the stability in the region of the weld line 34 is less affected than in the region of the weld line 33 at the through hole 9. The passage opening 10 is in this case with respect to the allowable pressure as small as possible executed.

The passage opening 11 is configured at least approximately oval. As a result, an opening width 40 of the passage opening 11 in the circumferential direction 22 with respect to the longitudinal axis 2 is greater than an opening width 41 of the passage opening 11 in the longitudinal direction 25 along the longitudinal axis 2. In the region of the weld line 35 has an edge 42 of the through hole 11 in this case its minimum curvature , Because the oval passage opening 11 is aligned with its larger opening width 40 in the circumferential direction 22. As a result, the mechanical stresses occurring in the region of the weld line 35 in the tubular base body 3 are reduced, so that the strength or load capacity of the fuel distributor 1 is improved.

The passage opening 12 is designed as a slot-shaped passage opening 12. Here, the slot-shaped passage opening 12 is aligned in the circumferential direction 22 with respect to the longitudinal axis 2. As a result, an edge 43 of the passage opening 12 has a straight section 44 in the region of the weld line 36. As a result, the stresses arising in the region of the weld line 36 are further reduced in comparison to the situation at the passage opening 11.

The situation described with reference to the passage opening 11, in which the opening width 40 in the circumferential direction 22 is greater than the opening width 41 in the longitudinal direction 25, is realized in a corresponding manner also in the passage openings 12 to 15.

In contrast to the configuration of the passage opening 12 in the region of the weld line 37, a convex section 45 of the rim 46 is configured on the passage opening 13. As a result, with the same opening cross-section, the mechanical stress acting locally on the weld line 37 in the tubular base body 3 can be further reduced in comparison to the situation described with reference to the passage opening 12.

The described with reference to the through holes 12 and 13 embodiments of the edge 43, 46 represent examples of through holes 12, 13, in the area of their Bindenaht 36, 37 are formed to the weld line 36, 37 out not concave. The straight portion 44 and the convex portion 45 are examples of non-concave portions 44, 45.

Thus, voltage peaks can be offset laterally in the tubular base body 3 and removed from the weld line 36, 37. Specifically, in the convex configuration of the through hole 13 to the Bindenaht 37 towards the Anrisspunkt the Bindenaht 37 can be laid in a completely stress-free area.

The passage openings 14, 15 are designed eccentrically. Here, the passage opening 14 is designed to be maximally eccentric, wherein a bulge 47 is provided on the tubular base body 3. As a result, the passage opening 14 can even be arranged eccentrically outside of the cylinder jacket-shaped remaining part of the inner wall 4.

When using the Fig. 1 described embodiment of the inner wall 4 by means of non-concave surfaces 23, 24 is an extension 50 (FIG. Fig. 2 ) of the non-concave surface in the longitudinal direction 25 of the elongated fuel chamber 5 is preferably larger than the opening width 32 of the through-hole 9 in the longitudinal direction 25, as it is based on the through-hole 9 in the Fig. 2 is illustrated. In this case, the extension 50 projects beyond the opening width 32 at least on the side of the weld line 33 and preferably on both sides.

The basis of the Fig. 1 and 2 described possible embodiments of the through holes 7 to 15 can be combined with each other in a meaningful way. Preferably, in the case of a through opening, the smallest possible cross section is always predetermined, as described with reference to the through opening 10. Furthermore, an eccentric configuration is always predetermined, as described with reference to the passage openings 7, 8, 14, 15.

Preferably, a non-concave surface 23, 24 is provided at the passage opening, as described with reference to the passage openings 7, 8, 9.

In addition, an opening width 41 in the longitudinal direction 25 is preferably smaller than an opening width 40 in the circumferential direction 22, as described with reference to the through holes 11 to 13.

The invention is not limited to the described embodiments.

Claims (8)

1. Fuel distributor (1), in particular for fuel injection systems of mixture-compressing, spark-ignition internal combustion engines, having a tubular main body (3), an inner wall (4) of the tubular main body (3) delimiting an elongate fuel chamber (5), the tubular main body (3) being formed from a plastic, and at least one through opening (7-15) being provided on the tubular main body (3), which through opening (7-15) opens on the inner wall (4) of the tubular main body (3) into the fuel chamber (5) eccentrically with respect to a longitudinal axis (2) which runs centrally through the elongate fuel chamber (5), characterized in that a convex surface (24) is configured on the inner wall (4) of the tubular main body (3) in the region of the through opening (8), in which convex surface (24) the through opening (8) lies at least partially, an extent (50) of the convex surface (24) in a longitudinal direction (25) along the longitudinal axis (2) of the elongate fuel chamber (5) protruding beyond an opening width (32) of the through opening (8) in the longitudinal direction (25) on both sides.
2. Fuel distributor according to Claim 1, characterized in that the tubular main body (3) is configured at least substantially as an injection moulded part (3), a spraying direction (6) being at least approximately parallel to the longitudinal axis (2).
3. Fuel distributor according to Claim 2, characterized in that an edge (42, 43) of the through opening (11, 12) in the region of a weld line (36, 37) is of non-concave configuration towards the weld line (36, 37).
4. Fuel distributor according to Claim 2 or 3, characterized in that an edge (43) of the through opening (12) in the region of the weld line (36) has an at least approximately straight section (44).
5. Fuel distributor according to Claim 4, characterized in that the through opening (12) is configured as a slot-shaped through opening (12), and in that the slot-shaped through opening (12) is oriented in a circumferential direction (22) with regard to the longitudinal axis (2).
6. Fuel distributor according to Claim 3, characterized in that an edge (43) of the through opening (13) in the region of the weld line (37) is of convex configuration towards the weld line (37).
7. Fuel distributor according to one of Claims 1 to 6, characterized in that an opening width (40) of the through opening (11) in a circumferential direction (22) with regard to the longitudinal axis (2) is greater than an opening width (41) of the through opening (11) in a longitudinal direction (25) along the longitudinal axis (2).
8. Fuel distributor according to Claim 1, characterized in that an extent (26, 29) of the convex surface (24) in a circumferential direction (22) with regard to the longitudinal axis (2) of the elongate fuel chamber (5) lies within an opening width (27, 30) of the through opening (8) in the circumferential direction (22) on both sides.

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