CN103502624B - Fuel distributor - Google Patents

Abstract

A fuel distributor (1), in particular for a fuel injection system of a hybrid compression external ignition internal combustion engine, comprising at least one housing part (2) surrounding a fuel chamber (3), at least one screw element (6) and at least one sealing ring (14). Here, a recess (4) is provided on the housing part (2), into which recess the screw element (6) is screwed in a self-tapping manner. Here, the sealing ring (14) forms a seal between the screw element (6) and the housing part (2). Thus, chips formed during the threading process remain reliably separated from the fuel chamber (3). The screw element (6) has an external thread (7), wherein an annular groove (15) for receiving the sealing ring (14) is formed on the screw element (6), and wherein the sealing ring (14) ) before the external thread (7) of the screw element (6).

Description

fuel dispenser

technical field

The invention relates to a fuel distributor, in particular for a fuel injection system of a hybrid compression external ignition internal combustion engine. In particular, the invention applies to fuel injection systems designed as medium-pressure systems.

Background technique

In the case of fuel distributor rails suitable for direct injection fuel injection systems, which operate at high pressure and are used in motor vehicles, steel or aluminum can be used as construction material. In contrast, in the case of fuel distributor rails for fuel injection systems with intake manifold injection structures, thin-walled steel tubes, plastic tubes or possibly also aluminum tubes are used. Whereas fuel injection systems suitable for high-pressure applications work especially at around 20 MPa (200 bar), low-cost fuel injection systems suitable for low-pressure applications generally operate at only 0.3 MPa to 0.5 MPa, or 3 bar to 5 bar.

In the case of fuel distributor rails made of steel, it is conceivable to fasten the high-pressure connection to the manifold made of steel by means of a brazing process. Technically, this is not possible in the case of plastic pipes. In the case of plastic pipes, of course, the connection is made by a suitable welding process.

Contents of the invention

The fuel distributor according to the invention has the advantage of providing a connection suitable for medium pressures, in particular suitable for fittings or plugs, which has comparatively low production costs.

Advantageous developments of the fuel distributor presented in the preferred embodiment can be obtained by means of the measures listed in the alternative embodiment.

Advantageously, the screw element is designed as a joint element with a connection piece and a through-opening from the connection piece into the fuel chamber. Thereby, a joint suitable for medium pressure is achieved. A fuel conduit may be fitted on such a fitting in order to direct fuel under pressure into the fuel chamber of the fuel distributor. The connection can advantageously be realized here by screwing in, in particular self-tapping screws.

It is of course also advantageous if at least one screw element is designed as a plug. For example, the fuel distributor is designed as an elongated fuel distributor, wherein the connection element is arranged at one end and the plug is arranged at the other end. As a result, the fuel distributor can optionally also be adapted to different installation situations.

Advantageously, said screw element has an external thread and an annular groove is formed on said screw element to receive a sealing ring. It is also advantageous here if the inner diameter of the annular groove is smaller than the inner thread diameter of the outer thread of the screw element. As a result, the sealing ring cannot be stressed during screwing in and is therefore not damaged. It is additionally advantageous for the sealing ring to be associated with a smaller diameter, since the hydraulically effective diameter is thus smaller and thus also the forces that occur are smaller.

Also advantageously, the external thread of the screw element has a conical thread shape with a steeper angle than the cylindrical or conical shape of the receptacle of the housing part. Due to the conical thread form, the first thread lead advances less than the last thread lead in the plastic part, wherein the conical thread form has a steeper angle than, for example, the demolding slope of a plastic die-cast part . Thus, a smaller gap is produced on the first thread lead of the screw, and absolutely still a recognizable transmissible load occurs on the last thread lead, wherein at the first thread lead of the screw The smaller gap has the advantage of a high strength of the housing part, especially the tubular housing part, since a possible breaking point of the preferably tubular housing part occurs on the upper surface. As a result, the screw element can be designed to be preferably short, so that the material consumption is reduced and the required installation space is reduced.

Also advantageously, an annular groove is arranged on the screw element between the outer thread of the screw element and one end of the screw element facing the fuel chamber. It is advantageous here if the sealing ring is upstream of the outer thread of the screw element. Thus, a configuration can be achieved in which the sealing ring arranged in the annular groove is ahead of the outer thread when screwing in the screw element. The special advantages of self-tapping screw-ins are obtained here. The sealing ring seals the outer thread of the screw element with respect to the fuel chamber. Chips and other impurities in the region of the external thread can thus no longer move inward, ie reach the fuel chamber. Furthermore, these shavings and perhaps other impurities do not move outwards. Thus, existing impurities remain enclosed in the region of the outer thread. Impairment of the functional effectiveness of the fuel injection system during operation is thus immediately avoided.

Advantageously, the housing part is formed from plastic, in particular configured as an injection molding part. This enables cost-effective production. It is also advantageous if longitudinal ribs or transverse ribs are formed on the housing part in the longitudinal and/or transverse direction relative to the axis of the screw element. This improves the stability of the housing part made of plastic. In particular, in the case of plastic die castings, the wall strength is limited. Advantageously, at least in the region of the screw element, the length of the longitudinal ribs or the mutual spacing of the transverse ribs is greater than the thread lead of the outer thread of the screw element which is screwed into the housing part. As a result, the force is transmitted outwards via the recess of the first thread lead to the higher-strength region of the housing part which is free of recesses.

Description of drawings

Preferred embodiments of the invention are explained in detail in the following description with reference to the accompanying drawings, in which like elements are provided with like reference numerals. Shown in the accompanying drawings:

Figure 1 shows a schematic cross-sectional view of a fuel dispenser corresponding to a first embodiment of the present invention; and

FIG. 2 shows a schematic cross-sectional view of a fuel distributor corresponding to a second embodiment of the invention.

detailed description

FIG. 1 shows an exemplary embodiment of a fuel distributor 1 according to the invention in a schematic cross-sectional view. The fuel distributor 1 can in particular be designed in the form of a fuel distributor pressure plate 1 . The fuel distributor 1 is especially suitable for hybrid compression externally ignited internal combustion engines. In particular, the fuel distributor 1 is here adapted for use in medium-pressure systems. The medium pressure for such a medium-pressure system can here lie in the range of 3 MPa to 10 MPa, or 30 bar to 100 bar. In particular, the medium pressure may be in the range of 5 MPa to 7 MPa, or 50 bar to 70 bar. The fuel distributor 1 according to the invention is of course also suitable for other applications.

The fuel distributor 1 has a housing part 2 which surrounds a fuel chamber 3 . The housing part 2 can form the housing 2 of the fuel distributor 1 . The housing can of course also be formed by a plurality of housing parts 2 . The housing part 2 has a recess 4 on which an internal thread 5 is arranged.

A screw element 6 is also provided, which has an external thread 7 . The screw element 6 is screwed with an external thread 7 into the recess 4 with the internal thread 5 .

In the exemplary embodiment here, the screw element 6 has a connection piece 8 and a through-hole 9 guided by the connection piece 8 into the fuel chamber 3 . An external thread 10 and a cone 11 can be arranged on the connecting piece 8 . The connecting piece 8 here accordingly forms a high-pressure connection in order to enable the connection of fuel lines. Fuel is led by the pump to the fuel chamber 3 of the fuel distributor 1 through a fuel conduit.

Furthermore, a screw seat 12 is arranged on the screw element 6 , which bears against the end face 13 of the housing part 2 in the screwed-in state and limits the screwing of the screw element 6 into the recess 4 of the housing part 2 .

In this embodiment, the screw element 6 is designed as a joint element 6 . The screw element 6 can of course also be designed as a plug. The via 9 is omitted here. Furthermore, the connecting piece 8 can also be omitted.

The fuel distributor 1 has a sealing ring 14 . The sealing ring 14 forms a seal between the screw element 6 and the housing part 2 . The fuel chamber 3 is thus sealed against the environment in the region of the screw element 6 . In the initial state, the sealing ring 14 is preferably designed as an O-ring 14 with an approximately circular contour. The sealing ring 14 is preferably designed to be fuel-resistant, especially diesel-resistant. The sealing ring 14 is also designed to be low temperature resistant, preferably down to -30° C. or at low temperatures.

The screw element 6 has an annular groove 15 which receives a sealing ring 14 . The inner diameter 16 of the annular groove 15 is here set smaller than the thread inner diameter 17 of the outer thread 7 of the screw element 6 . As a result, the sealing ring 14 is not stressed during screwing in and is therefore not damaged. In addition, a smaller hydraulically effective diameter and smaller resulting forces result.

The annular groove 15 is arranged between the outer thread 7 of the screw element 6 and the end 18 of the screw element 6 facing the fuel chamber 3 . Thus, when screw element 6 is screwed into recess 4 , sealing ring 14 first moves along the wall of recess 4 . The cutting of the internal thread 5 of the recess 4 is preferably achieved by self-tapping and self-cutting of the screw element 6 . The sealing ring 14 thus moves along the flat wall so that the sealing ring 14 is not damaged. Next, the external thread 10 is cut into the wall of the recess 4 so that the internal thread 5 of the recess 4 is shaped. A sealing ring 14 precedes the external thread 7 of the screw element 6 .

Between the sealing ring 14 and the screw seat 12 , the region of the external thread 7 of the screw element 6 is thus guaranteed to be sealed from the fuel chamber 3 on the one hand and the environment on the other hand. Chips or other foreign matter produced during the screw-in self-tapping and self-cutting processes are thus retained inside and cannot reach the fuel chamber 3 . In particular, self-cutting screw-in by the cutting edge of the screw element 6 is advantageous in the case of glass fiber reinforced fuels.

In order to ease the leak check by the seal formed by the sealing ring 14 , a transverse bore 20 can be provided, for example on the housing part 2 between the sealing ring 14 and the external thread 7 of the screwed-in screw element 6 .

The external thread 7 of the screw element 6 preferably has a conical thread shape, which extends conically into the fuel chamber 3 in the annular groove 21 . The recess 4 of the housing part 2 can likewise have a conical shape. In both cases, the conical thread shape of the external thread 7 of the screw element 6 is implemented with a steeper angle than the cylindrical or conical shape of the recess 4 of the housing part 2 . A smaller gap is thus obtained on the first thread lead of the screw element 6 , with the advantage of a high strength of the screw element 6 and of the housing part 2 . Furthermore, a recognizable load is absolutely still transmitted at the final thread advance. As a result, the screw can be optimally short. Otherwise, the first thread lead bears most of the load, while the opposite thread lead hardly contributes at all. The screw element 6 then also does not need to be very long.

The advantage of a steep taper of the screw element 6 with respect to the housing part 2 is thus an improved strength of the screw element 6 with an optimally short outer thread 7 .

Due to the screw seat 12 serving as a stop, the sealing ring 14 has a defined position after assembly, in particular with respect to the transverse bore 20 . Furthermore, the screw seat 12 has the effect that chips generated during screwing-in are also prevented from being discharged at this end.

FIG. 2 shows a schematic sectional view of a fuel distributor 1 corresponding to a second exemplary embodiment of the invention. The housing part 2 is designed here as a plastic injection-molded part. In the case of such plastic die-cast parts (plastic die-cast parts) 2 , the wall strength is limited. To improve the strength, longitudinal ribs 22 , 23 , 24 and transverse ribs 25 , 26 are provided on the housing part 2 . The strength can thus be improved by the cage-like configuration of the ribs 22 to 26 . The longitudinal ribs 22 to 24 can be used here as axial tension ribs 22 to 24 . In order to simplify the illustration, only the ribs 22 to 26 are marked in FIG. 2 .

The length 27 of the longitudinal ribs 22 to 24 or the mutual spacing of the transverse ribs 25 , 26 is greater than the thread length 28 of the screw element 6 screwed into the housing part 2 ( FIG. 1 ). As a result, the force is transmitted outwards via the recess of the first thread lead to the higher-strength region of the housing part which is free of recesses. Thus, based on the existing geometry of the threaded edge of the self-tapping screw element 6, a stronger and thicker joint or plug for the pressure-resistant fuel distributor 1, the housing part 2 of which can be provided Manufactured from plastic. The screw element 6 is screwed in here by means of a suitable driver 29 , wherein the driver 29 is arranged on the screw element 6 . The longitudinal ribs 22 to 24 are arranged in the longitudinal direction 21 with respect to the axis 31 of the screw element 6 . The longitudinal ribs 25 , 26 are arranged in the transverse direction 30 with respect to the axis 31 of the screw element 6 .

The invention is not limited to the described embodiments.

Claims (8)

1. A fuel distributor (1) having a fuel chamber (3) surrounded by at least one housing part (2), at least one screw element (6) and at least one sealing ring (14), wherein A recess (4) is provided on the housing part (2), into which the screw element (6) is screwed, wherein the sealing ring (14) A seal is formed between (6) and the housing part (2), wherein the screw element (6) has an external thread (7), wherein an annular groove (15) is arranged on the screw element (6), the An annular groove for receiving said sealing ring (14) and wherein said sealing ring (14) is in front of the external thread (7) of said screw element (6) so that said annular groove (15) is in said The screw element (6) is arranged on the screw element (6) between the external thread (7) of the screw element (6) and the end (18) of the screw element (6) facing the fuel chamber (3), characterized in that the shell The body part (2) is constructed of plastic, the external thread (7) of the screw element (6) has a steeper angle than the cylindrical or conical shape of the recess (4) of the housing part (2) conical thread shape. 2. The fuel distributor according to claim 1, characterized in that the screw element (6) is designed with a connection piece (8) and is guided by the connection piece (8) into the fuel chamber (3 ) of the joint element (6) in the through hole (9). 3. The fuel distributor according to claim 1, characterized in that the at least one screw element (6) is designed as a plug (6). 4. The fuel distributor according to claim 1 or 2, characterized in that the inner diameter (16) of the annular groove (15) is smaller than the thread inner diameter of the outer thread (7) of the screw element (6) (17). 5. The fuel distributor according to claim 1, characterized in that on the housing part (2) in the longitudinal direction (21) with respect to the axis (31) of the screw element (6) and/or Or molding longitudinal ribs (22-24) or transverse ribs (25, 26) in the transverse direction (30). 6. The fuel distributor according to claim 5, characterized in that, at least in the region of the screw element (6), the length (27) of the longitudinal rib (22-24) or the length (27) of the transverse rib ( 25, 26) are at a distance greater than the thread length (28) of the screw element (6) screwed into the housing part (2). 7. The fuel distributor of claim 1, wherein the fuel distributor is used in a fuel injection system of a hybrid compression external ignition internal combustion engine. 8. The fuel distributor according to claim 1, characterized in that the housing part (2) is designed as a plastic injection molding.