WO2002063161A1

WO2002063161A1 - Fuel injection nozzle for an internal combustion engine

Info

Publication number: WO2002063161A1
Application number: PCT/DE2002/000418
Authority: WO
Inventors: Günter KAMLAGE; Eberhard Kull; Hakan Yalcin
Original assignee: Siemens Aktiengesellschaft
Priority date: 2001-02-08
Filing date: 2002-02-05
Publication date: 2002-08-15
Also published as: DE10105674A1

Abstract

The invention relates to a fuel injection nozzle for an internal combustion engine comprising a nozzle body (2) and a nozzle needle (6) which is guided therein comprising an injection hole channel (16) in a cone shaped area (8) of the nozzle body (2), which is at least fitted in sections.

Description

description

Fuel injection nozzle for an internal combustion engine

The invention relates to a fuel injection nozzle for an internal combustion engine according to the preamble of claim 1.

Fuel injection nozzles of this type are generally used in particular in direct-injection internal combustion engines. In an injection system of an internal combustion engine with fuel injection, the fuel injection nozzle has the task of supplying the combustion chamber of the internal combustion engine with fuel in a targeted and metered manner. The type of fuel preparation by the fuel injector and the course of the injection process have a significant impact on combustion in the combustion chamber.

From DE 195 02 171 a fuel injection nozzle for an internal combustion engine is known, in which a piston-shaped nozzle needle is guided axially displaceably in a shaft bore of a nozzle body. The shaft bore is essentially cylindrical and has a conical tapered region at its combustion chamber end, which is closed off by a blind hole. The lower end of the nozzle needle has a sealing cone, one

In the idle state, the nozzle spring presses on the tapered area of the shaft bore. Depending on the type of injection nozzle, at least one spray hole channel leads from the blind hole or the tapered region of the shaft bore in the nozzle body downstream of the sealing seat through the nozzle body into an adjacent combustion chamber of the internal combustion engine.

Since the diameter of the shaft bore is larger than the diameter of the nozzle needle, a pressure chamber is formed in the front area of the fuel injection nozzle on the combustion chamber side, which is connected via a pressure channel in the nozzle body to a fuel supply, e.g. B. an injection pump or ω OJ MK, P »P ¹

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cut narrowed in the area of a waist of the injection hole channel and then widened again or remained essentially constant. In the spray hole channel shape according to the invention, the flow rate increases more and more from an inlet of the spray hole channel to the narrowest cross section. In addition, in the presence of an enlarged end section on the spray hole channel, the flow velocity of the fuel can increase further after the narrowest cross section in the enlarged end section of the spray hole channel, since the fuel flow spreads in the enlarged part of the spray hole channel, so that a very high outflow speed of the Fuel for an optimization of the combustion process is achieved.

By means of the waisted spray hole channel shape, the flow velocity of the fuel flow is effectively increased, so that an injection jet is generated with a strong jet pulse, which enables deep penetration into the combustion chamber of the internal combustion engine. In this way, even combustion chamber areas that are structurally far away from the injection point can be reliably supplied with fuel. This improves the fuel preparation in the combustion chamber and significantly improves the quality of the combustion process, which leads to a reduction in the emission values, the combustion noise and the fuel consumption.

Preferred embodiments of the invention are described in the further claims.

It is preferred that a waist of the spray hole channel is arranged in the region of an inlet, a middle or an outlet of the spray hole channel. By varying the location of the waist along the longitudinal extent of the spray hole channel in the nozzle body, a jet cone angle of the emerging fuel injection jet and, in connection therewith, the penetration depth of the fuel injection jet into the Combustion chamber influenced and controlled specifically. For example, a short, wide injection jet can be generated when the waist is arranged in the area of the inlet or a long, narrow injection jet when the waist is formed in the area of the outlet of the spray hole channel.

For the design of the spray hole channel geometry, it is preferred if a longitudinal profile of the spray hole channel essentially corresponds to a profile of an intensity distribution of a laser beam in focus. The tailored shape of the spray hole channel is introduced into the nozzle body in a simple manner by means of a drilling operation, preferably laser drilling, with a rounding of the inlet area of the spray hole channel optionally by reworking, eg. B. can be done by means of hydroerosive grinding.

For the generation of a long and narrow fuel injection jet, it has proven to be advantageous if the spray hole channel is essentially bottle-shaped.

To achieve a high flow velocity and a low flow coefficient in the spray hole channel, it is advantageous if the narrowest flow cross section of the spray hole channel is arranged in the region of the waist. In this way, a compact fuel injection jet with an optimized flow profile can be generated.

Some embodiments of the invention illustrated by way of example in the drawings are explained in more detail below. Show it:

1 shows a detail of a first embodiment of the fuel injection nozzle according to the invention;

2 shows a detail of a second embodiment of the fuel injection nozzle according to the invention; 3 shows a detail of a third embodiment of the fuel injection nozzle according to the invention; and

Fig. 4 shows a detail of a fourth embodiment of the fuel injector according to the invention.

1 shows the part of a fuel injection nozzle for an internal combustion engine which is essential to the invention and which has a nozzle body 2 with a shaft bore 4 in which a nozzle needle 6 is arranged. The nozzle body 2 has, at its end area arranged in a combustion chamber of the internal combustion engine, a conically tapering tip area 8 which is rounded at the tip. The essentially cylindrical shaft bore 4 is likewise designed to taper in the conical dome region 8 of the nozzle body 2 and ends in a blind hole 10.

The nozzle needle 6 running in the shaft bore 4 has a shaft region 12 which carries at its lower end a sealing cone which preferably consists of two sections 14, 15. The flattened lower section 15 has essentially the same opening angle as the tapered region of the shaft bore 4, whereas the conical intermediate section 14 connecting the shaft region 12 and the lower section 15 has a smaller opening angle. When the nozzle needle 6 is pressed in the idle state by a nozzle spring and / or a hydraulically or pneumatically actuated control piston onto the conical area of the shaft bore 4, the different opening angles of the two sections 14, 15 result in a line contact with the conically tapering area of the shaft bore 4 with high press and therefore good sealing effect. Alternatively, the sealing cone can also consist of a continuous individual section which essentially has the same opening angle as the conically tapering fende area of the shaft bore 4 and directly adjoins the shaft area 12.

Since the diameter of the cylindrical region of the shaft bore 4 is larger than the diameter of the shaft 12 of the nozzle needle 6, a pressure space is formed between the nozzle body 2 and the nozzle needle 6, which is connected to a via a pressure channel (not shown) in the nozzle body 2 Fuel supply is connected. The pressure chamber formed between the nozzle body 2 and the nozzle needle 6 is delimited on its side facing away from the combustion chamber by a pressure shoulder formed on the nozzle needle shaft 12, on which the fuel pressure generated by the fuel supply acts. If the pressure on the pressure shoulder becomes greater than the holding force on the nozzle needle 6, the nozzle needle lifts off from the sealing seat in the shaft bore 4, as shown in FIG. 1, and fuel can be injected into the combustion chamber.

To inject the fuel, a spray hole channel 16 is formed in the nozzle body 2 in the conically tapering region of the tip region 8 of the nozzle body 2 downstream of the line contact with the sealing cone of the nozzle needle 6. Here, the spray hole channel 16 is formed waisted. When the nozzle needle 6 is open, the fuel fed by an injection pump into the pressure chamber between the nozzle needle 6 and the nozzle body 2 is injected into the combustion chamber of the internal combustion engine via the tailored injection hole channel 16. In general, several spray hole channels 16 are provided distributed in the dome area 8 of the nozzle body 2 in order to achieve fuel injection with a defined spray hole cone angle, depending on the shape of the combustion chamber. In the case of a central, vertical installation of the fuel injection nozzle, the spray hole channels 16 are preferably arranged symmetrically at an equal height angle around the tip area 8 of the nozzle body 2. In contrast, in the case of an inclined fuel injection nozzle, the spray hole channels 16 are used to achieve a desired spray hole cone angle. kels introduced at different heights, but preferably with the same side angles in the tip region 8 of the nozzle body 2.

_* As shown in Fig. 1 can be seen, the perforated spray channel 16 to a waist 18, which forms the narrowest flow cross section of the injection port channel 16. In the present case, the flow cross-section at the inlet 20 essentially corresponds to the flow cross-section at the outlet 22 of the spray hole channel 16. The flow cross-section from the inlet 20 to the outlet 22 initially decreases to the narrowest cross-section in the region of the waist 18 and then then evenly again to the outlet 22. The tailored shape of the spray hole channel 16 is chosen such that an inlet 20 of the spray hole channel is designed essentially in the tip area 8 in accordance with the direction of flow of the fuel, in particular diesel fuel, so that the fuel flow is gently deflected through the nozzle body 2 into the spray hole channel 16 , The inlet 20 of the spray hole channel 16 is rounded at the transition into the nozzle tip 8 in order to enable a funnel-shaped fuel flow. Due to the gentle deflection of the fuel flow from the nozzle body 2 into the spray hole channel 16, which is reinforced by the funnel-shaped design of the inlet 20, there is an increase in the flow coefficient of the fuel flow. The flow rate of the fuel thus increases up to the narrowest cross section of the spray hole channel 16 in the region of the waist 18, then the flow rate of the fuel stream in the widened part of the spray hole channel 16 increases further from the waist 18 to an outlet 22 of the spray hole channel 16. The waisted hole geometry in the longitudinal direction of the spray hole channel effectively increases the injection speed of the fuel and at the same time achieves a uniform injection with improved fuel preparation in the combustion chamber. The resultant uniform injection with high flow speed and improved co CO l \ J IV) P ¹ cn o Cπ o Cπ O cn φ P- i— ■ a P- ¹

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that can penetrate far into the combustion chamber of the internal combustion engine to be supplied.

FIG. 4 shows a fourth embodiment of the fuel injection nozzle according to the invention, in which the spray hole channel 16 has a bottle-shaped contour. As can be seen in FIG. 4, the spray hole channel 16 is essentially conical in the area of the inlet 20. The flow cross section then narrows in the region of the waist 18. From the waist 18 to the outlet 22 of the spray hole channel 16, the flow cross section remains essentially constant along the longitudinal extent of the spray hole channel 16. The inlet 20 has a substantially larger flow cross section than the outlet 22 of the spray hole channel 16. A long and narrow injection jet can in particular be achieved with the bottle-shaped spray hole channel geometry shown in FIG. 4.

The concepts of a tailored geometry of the spray hole channel shown in FIGS. 1 to 4 can be used not only in the illustrated fuel injection nozzle shape, in which the sealing cone of the nozzle needle covers the inlet area of the spray hole channel in the rest position, but also in the other known nozzle shapes, in which the Spray hole channel is arranged in the blind hole. Furthermore, depending on the type of construction, this blind hole can be cylindrical, cylindrical with a conical top, conical or round.

Claims

claims

1. Fuel injection nozzle for an internal combustion engine with a nozzle body (2), which has at least one spray hole channel (16) for injecting fuel into the internal combustion engine, characterized in that the spray hole channel (16) is at least partially fitted.

2. Fuel injection nozzle according to claim 1, characterized in that a waist (18) of the spray hole channel (16) in

Area of an inlet (20), a center or an outlet (22) of the spray hole channel (16) is arranged.

3. Fuel injection nozzle according to claim 1 or 2, characterized in that a longitudinal profile of the spray hole channel

(16) corresponds essentially to a profile of a laser beam.

4. Fuel injection nozzle according to claim 1 or 2, characterized in that the spray hole channel (16) is substantially bottle-shaped.

5. Fuel injection nozzle according to at least one of the preceding claims, characterized in that the narrowest flow cross section of the spray hole channel (16) is arranged in the region of the waist (18).