| Title of Invention | FUEL INJECTION VALVE FOR INTERNAL COMBUSTION ENGINES |
|---|---|
| Abstract | The invention relates to a fuel injection valve for internal combustion engines having a valve body (1) in which a blind hole (10) is formed, with at least one injection opening (7) proceeding from said blind hole (10). A longitudinally displaceable needle (5) is arranged in the valve body (1), with a valve sealing face (11) being formed at that end of said valve needle (5) which faces towards the blind hole (10), said valve sealing face (11) being formed from one or more conical faces, and the valve needle (5) interacting, by means of a body seat (9), with said valve sealing face (11) to control a fuel flow to the at least one injection opening (7). A needle tip (30) adjoins the valve sealing face (11), said needle tip (30) dipping into the blind hole (10) when the valve needle (5) bears against the body seat (9), the needle tip (30) being curved in a concave fashion directly adjacent to the valve sealing face (11). (DE) Kraftstoffeinspritzventil für Brennkraftmaschinen mit einem Ventilkörper (1), in dem ein Sackloch (10) ausgebildet ist, von dem wenigstens eine Einspritzöffnung (7) ausgeht. Im Ventilkörper (1) ist eine längsverschiebbare Ventilnadel (5) angeordnet, an deren dem Sackloch (10) zugewandten Ende eine Ventildichtfläche (11) ausgebildet ist, die aus einer oder mehreren Konusflächen gebildet wird und mit der die Ventilnadel (5) mit einem Körpersitz (9) zur Steuerung eines Kraftstoffflusses zu der wenigstens einen Einspritzöffnung (7) zusammenwirkt. An die Ventildichtfläche (11) schließt sich eine Nadelspitze (30) an, die in das Sackloch (10) eintaucht, wenn die Ventilnadel (5) am Körpersitz (9) anliegt, wobei die Nadelspitze (30) unmittelbar anschließend an die Ventildichtfläche (11) konkav gewölbt ist. |
| Full Text | FUEL INJECTION VALVE FOR INTERNAL COMBUSTION ENGINES PRIOR ART While several injection ports are generally provided in the case of fuel injection valves that are used for direct fuel injection into the combustion chamber of an internal combustion engine, a minimum of at least one injection port, is provided, however. Here fuel injection valves control the injection of fuel, which is compressed and is under pressure as a result, through the longitudinal movement of a valve needle which has a valve sealing surface and works together with a body seat. Two basic types are generally differentiated between In this connection: one Is a so-called seat orifice-type injector in which the injection ports emanate directly from a conical body seat and the other is a so-called blind hole nozzle in the case of which injection ports emanate from a blind hole. The advantage in the case of the blind hole nozzle when compared to the seat orifice-type injector thereby is that the distribution of fuel to the individual injection ports takes place evenly as a result of which a uniform spray pattern is achieved, in general, when compared to the seat orifice-type injectors. The problem in the case of such blind hole nozzles, however, is that fuel that passes between the valve sealing surface and the body seat is agitated in the blind hole during transfer so that the effective injection pressure upon the injection ports gets reduced. A fuel injection valve is established in DE 36 05 082 A1 that functions according to the principle of the blind hole nozzle. A needle tip is designed in such a manner here at the valve needle that the same projects into the blind hole even in the open position of the valve needle i.e. when the valve needle has been lifted from the body seat. The needle tip has a conical sealing surface with which the valve needle sits upon the body seat. A convex region i.e., a region that is curved outwards, is connected to this sealing surface, this region in turn crossing over into a concave region i.e. a region that is curved inwards. The end of the valve needle then forms a dome that also curves outwards and connects tangentially to the concave region. This shape of the valve sealing surface should result in the fuel flow being turned in to the blind hole without displacement from the needle tip in order to avoid agitations. The disadvantage, however, in this connection is that the shape of the needle tip cannot be matched to the same extent to all injection bores since these, as a rule, form varying angles to the longitudinal axis of the valve needle. Optimised intake thus results only at some of the bores while other injection ports have a rather unfavourable flow of fuel due to the adjacent stream. ADVANTAGES OF THE INVENTION The fuel injection valve, in accordance with the invention, with characterising features of Patent Claim 1, on the other hand, has the advantage that fuel intake at the blind hole and, therewith, effective injection pressure is optimised at the injection ports. The valve needle has a conical valve sealing surface for this purpose and a valve needle tip that connects to the same, whereby the valve needle tip has a concave curve directly at that point at which it connects to the conical valve sealing surface. As a result of this, fuel stream gets displaced from the valve needle when flowing into the blind hole but is, however, deflected by that part of the needle tip that lies further downstream so that fuel flows away from the injection ports with higher speed and, therewith, with a higher effective injection pressure. Advantageous designs of the object of the invention are feasible through the dependent claims. An edge is designed at the transition of the conical body seat to the needle tip in a first advantageous design which ensures that intake of fuel into the blind hole is optimised. The design is especially beneficial if the blind hole has a conical wall from which the injection ports emanate. In another advantageous design, the needle tip stretches to such an extent into the blind hole that the concave needle tip extends right up to the injection ports even when the valve needle is in its open position. Deflection can be further optimised by this if the same is indicated by corresponding dimension and pressure ratios. A curved dome connects to the concave needle tip in another advantageous design, this dome forming the conclusion of the valve needle. Turbulence in the blind hole can be reduced depending upon the extent to which the valve needle projects into the blind hole. Further advantages and beneficial designs of the object of the invention can be derived from the description and the drawings. DRAWING An exemplary embodiment of the fuel injection valve, in accordance with the invention, is illustrated in the drawings. Figure 1 illustrates a longitudinal section of a fuel injection valve with its essential components and Figure 2 is an enlargement of section II of Figure 1 in the region of the body seat. DESCRIPTION OF THE EXEMPLARY EMBODIMENT A longitudinal section of the fuel injection valve, in accordance with the invention, is presented in Figure 1, whereby only the essential components are illustrated. The fuel injection valve has a valve body 1 in which a bore 3 is designed with a longitudinal axis 8, whereby the bore 3 is bordered at its end that faces the combustion chamber by a body seat 9. A blind hole 10 connects to the body seat 9 from which at least one injection port 7 emanates, whereby several injection openings 7 are usually provided that are located distributed along the periphery of the blind hole 10. Here it can also be provided that the individual injection ports 7 have varying angles of inclination with regard to bore 3. A piston-shaped valve needle 5, which can be moved in the longitudinal direction and which is guided in a sealing manner in a guiding section 15 in the bore 3, is located in bore 3. Starting from the guiding section 15, the valve needle 5 tapers towards the body seat 9 due to the formation of a pressure shoulder 13 and finally crosses over to a valve sealing surface 11 at its end that faces the body seat. The end of the valve needle 5 ultimately forms a needle tip 30, which then projects into the blind hole 10 when the valve needle 5 lies upon the body seat 9. A pressure chamber 19 that is expanded in a radial fashion at level to the pressure shoulder 13, is formed between the wall of bore 3 and the valve needle 5. A supply conduit 25 running in the valve body 1 ends in the radial expansion of the pressure chamber 19, which can be filled with fuel under high pressure through this supply conduit. The valve needle 5 is loaded by a clarnping force at its end that faces the body seat, this force manifesting in the direction of the body seat 9 and being produced by a spring element, for example, or by hydraulic means. The valve needle 5 moves in the longitudinal direction within bore 3, depending upon the ratio of this clamping force to the hydraulic opening force that essentially occurs due to the pressurisation of the pressure shoulder 13. If the valve needle 5 lies on the body seat 9 then the blind hole 10 opposite the pressure chamber 19 is closed. Should fuel injection take place, on the other hand, the valve needle 5 will be moved away from the body seat 9 either by an increase in pressure in the pressure chamber or by a reduction of the clamping force. Fuel, thereby, flows between the valve sealing surface 11 and the body seat 9 and into the blind hole 10 from where the fuel is injected through the injection ports 7. Figure 2 is an enlargement of section II of Figure 1 in the region of the body seat 9. The valve sealing surface 11 is designed to be conical whereby two or more conical surfaces with slightly different angles can also be provided instead of one conical surface, whereby all cone angles of these conical surfaces, just as the cone angles of the valve sealing surface 11, are essentially equal to the cone angle of the similarly conical body seat 9. A needle tip 30, which also projects into the blind hole 10 in the opening position of the valve needle 5 that is illustrated in Figure 2, is attached to the conical valve sealing surface 11. The needle tip 30 is concave at that point where it connects to the valve sealing surface 11, i.e., curving inwards, so that an edge 34 is formed between the valve sealing surface 11 and the needle tip 30. As illustrated in Figure 2, a level front surface 32 or a dome 36 can connect to the needle tip 30, this being indicated in Figure 2 by a line of dashes. This depends upon the extent to which the needle tip 30 projects into the blind hole so that a certain slowing down of the stream in the blind hole 10 can be achieved due to the dome 36. If fuel flows out, in the case of an injection, from the pressure chamber 19 between the valve sealing surface 11 and the body seat 9 into the blind hole 10, the stream will accelerate during its flow into the blind hole 10 since the velocity of flow that is available reduces continuously. Fuel thus flows past the edge 34, whereby the stream breaks away from the valve needle 5 due to the concave shape of the needle tip . This is indicated by small arrows in Figure 2. Fuel then impacts again upon the needle tip 30 within the blind hole 10 and is effectively deflected by the same in the direction of the injection openings 7. Energy lost during the deflection is minimised in this manner, resulting in a higher effective injection pressure that is ultimately available within the injection port 7. The stream within the blind hole 10 is slowed down over and above this, which produces a further increase in the effective injection pressure. The described effect produced by the needle tip 30 can be optimised further by designing an intake edge 38 between the body seat 9 and the blind hole 10, at which displacement of the fuel stream from the wall of the valve body 1 takes place similarly within a certain periphery. An inlet edge 38 is designed in those cases where the wall of the blind hole 10 is shaped conically, as is illustrated in Figure 2. Displacement of the stream does not mean that the other regions in the blind hole 10 and at the valve sealing surface 11 form dead water areas in which no flow takes place. The above description of the stream displacement instead signifies that the mainstream takes place with the highest stream velocity of the process described, whereby the injection pressure is essentially determined by these highest stream velocities of the injection pressure. The needle tip 30 can also be designed to be so long that the same stretches to the level of the injection ports 7. This can contribute to improved turning of fuel into the injection openings 7, depending upon the dimensions of the blind hole 10 and of the injection pressure used. CLAIMS 1. Fuel injection valve for internal combustion engines with a valve body (1) in which a blind hole (10) is designed from which at least one injection port (7) emanates and with a valve needle (5) in the valve body (1) that can be moved longitudinally, a valve sealing surface (11) being designed at that end of the valve needle (5) that faces the blind hole (10), the valve needle (5) with a body seat (9) working together with the valve sealing surface (11) to control fuel flow to the at least one injection port (7) and with a needle tip (30) that connects to the valve sealing surface (11) and that plunges into the blind hole (10) when the valve needle (5) is adjacent to the body seat (9), characterised in that, the needle tip (30) is concave at the point at which it connects to the valve sealing surface (11). 2. Fuel injection valve in accordance with Claim 1, characterised in that, the concave curvature of the needle tip (30) is shaped in such a manner that the fuel stream that flows between the valve sealing surface (11) and the body seat (9) is displaced from the valve needle (5) at the transition from the valve sealing surface (11) to the needle tip (30). 3. Fuel injection valve in accordance with Claim 1, characterised in that, an edge (38) is designed at the transition from the body seat (9) to the blind hole (10) which lies at the level of the needle tip (30) when the valve needle (5) is lifted from the body seat (9). 4. Fuel injection valve in accordance with Claim 1, characterised in that, several injection ports (7) are designed to emanate from the blind hole (10). 5. Fuel injection valve in accordance with Claim 4, characterised in that, the opening stroke of valve needle (5) is measured in such a manner that the injection ports (7) are located at the level of the concave section of the needle tip (30) when the valve needle (5) is lifted from the body seat (9). 6. Fuel injection valve in accordance with Claim 3, 4 or 5, characterised in that, the blind hole (10) has a conical wall that connects directly to the body seat (9). 7. Fuel injection valve in accordance with Claim 1, characterised in that, a dome (36) that curves outwards is connected to the concave needle tip (3). 8. Fuel injection valve in accordance with Claim 1, characterised in that, a level front surface (32) connects to the concave needle tip (30). 9. Fuel injection valve in accordance with Claim 1, characterised in that, the valve sealing surface (11) is formed by one conical surface or several conical surfaces. Dated this 30 day of November 2007 |
|---|
| Patent Number | 268583 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Indian Patent Application Number | 5509/CHENP/2007 | ||||||||||||
| PG Journal Number | 37/2015 | ||||||||||||
| Publication Date | 11-Sep-2015 | ||||||||||||
| Grant Date | 04-Sep-2015 | ||||||||||||
| Date of Filing | 30-Nov-2007 | ||||||||||||
| Name of Patentee | ROBERT BOSCH GmbH | ||||||||||||
| Applicant Address | POSTFACH 30 02 20, D-70442 STUTTGART | ||||||||||||
Inventors:
|
|||||||||||||
| PCT International Classification Number | F02M 61/18 | ||||||||||||
| PCT International Application Number | PCT/EP2006/061400 | ||||||||||||
| PCT International Filing date | 2006-04-06 | ||||||||||||
PCT Conventions:
|
|||||||||||||