JPH0765554B2 - Fuel injection nozzle for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention has a nozzle body and a nozzle needle guided in the nozzle body, and the nozzle body ends with a cap-shaped nozzle head. The head forms a conical valve seat on the inside, the corresponding conical end of the nozzle needle is pressed against the conical valve seat by a spring, a plurality of jets are provided in the range of this conical valve seat, The needle is the first
In the stroke stage, the pressure of the fuel to be supplied causes it to move away from the valve seat against the force of the first spring and hit the stopper, and in the second stroke stage of the nozzle needle, the stopper moves to the second stroke. The present invention relates to a fuel injection nozzle for an internal combustion engine, which is movable within a limited range against the force of a spring.

[Conventional technology]

A nozzle body ending in a nozzle head having a jet, and a nozzle needle guided in the nozzle body and resiliently pressed against a conical valve seat formed inside the nozzle head; The needle, under the pressure of the fuel supplied, resists the force of the spring in the first stroke stage and leaves the valve seat to contact the stopper, which in turn exerts another spring force in the second stroke stage. A fuel injection nozzle for internal combustion engines, which is movable in a restricted manner, is known from DE 2711350 A1, in which two groups of jets are provided at different points of the nozzle body, namely the nozzle head. Is provided on a conical valve seat and a cylindrical inner surface that are formed inside. In the first stroke stage of the nozzle needle, its conical end leaves the conical valve seat and only the jet at this valve seat is opened, and only in the second stroke stage, like the spool. The working nozzle needle also opens the jet on the inner cylindrical surface. Both springs acting sequentially open the outlets of both groups in a pressure-dependent manner.

The disadvantage of this known structure is that the characteristic curve of the fuel discharge rate is unfavorable when the nozzle needle moves from the first stroke stage to the second stroke stage to open the jet on the inner cylindrical surface of the nozzle body. These discontinuities occur, causing non-uniform combustion processes and producing noise. Furthermore, the ejection port on the cylindrical inner surface of the nozzle body is opened while changing the cross section from a fan shape to a circular shape by the cylindrical portion of the nozzle needle that moves in the axial direction and acts like a spool,
The fuel jet fluctuates, which also disturbs the combustion process. Such a non-uniform combustion process also adversely affects the efficiency of the engine and the emission of harmful substances in the exhaust gas.

In a known fuel injection nozzle having only one spring for loading the nozzle needle (German Patent Publication No. 3239462), the nozzle head of the nozzle body forms a conical valve seat inside. The conical valve seat is followed by a cylindrical inner surface, which further transitions via a frustoconical shoulder into a large cylindrical inner surface for the fuel space. An outlet is provided in the conical valve seat. The nozzle needle also has a conical part and a truncated cone part, starting from the conical end corresponding to the conical valve seat. An annular gap is formed between the cylindrical inner surface of the nozzle body that follows the conical valve seat and the cylindrical portion that follows the conical end of the nozzle needle. It is specified to be smaller than the cross-sectional area of. The annular gap as the throttled portion is formed at a position apart from the ejection port.

Therefore, during the opening and closing movement of the nozzle needle, while the cylindrical portion moves along the cylindrical inner surface of the nozzle body, that is, in the stroke range in which the annular gap is maintained, it is squeezed by the annular gap serving as the throttling point. When a large amount of fuel is discharged from the ejection port and the cylindrical portion of the nozzle needle leaves the cylindrical inner surface of the nozzle body, the throttling portion disappears, so the amount of fuel discharged from the ejection port increases rapidly. Therefore, the fuel discharge amount changes discontinuously and the combustion process becomes non-uniform. Moreover, pressure loss occurs due to the fuel being throttled at the annular gap as the throttled portion. Due to this pressure loss, the pressure of the fuel is already low before the fuel flow is strongly diverted at the jet, thus the jet exiting the jet becomes a laminar flow containing relatively large droplets. , It does not become a three-dimensional turbulent vortex that spreads conically from the jet. because,
This is because in order to form a three-dimensional turbulent vortex that spreads in a conical shape, the pressure of the fuel must be very high before turning, and therefore the pressure loss before turning must be as small as possible. A laminar flow that contains large droplets without being atomized has a large reach, and therefore the fuel jet that forms a laminar flow from the jet outlet hits the wall of the combustion chamber and part of the fuel adheres to the wall. Therefore, especially at low rotation speed and low load, complete combustion is hindered, hydrocarbon emission amount in exhaust gas is increased, and ignition noise is increased.

[Problems to be Solved by the Invention]

The object of the present invention is to maximize atomization of fuel, improve the uniformity of fuel distribution, achieve complete combustion, reduce the emission of harmful substances in exhaust gas, and reduce noise. , A fuel injection nozzle.

[Means for Solving the Problems]

According to the invention to solve this problem, according to the invention, during the first stroke stage, each jet is extended and the inner edge of the jet and the nozzle needle leaving the valve seat at the end of the first stroke stage. The moving distance of the nozzle needle until it hits the stopper is set so that the area of the peripheral surface of the virtual cylinder generated between the conical end and the conical end is smaller than the area of the cross section of the jet outlet. Fuel flow is throttled in the upstream region.

〔The invention's effect〕

Thus, according to the invention, during the first stroke stage, the area of the peripheral surface of the virtual cylinder, which is formed between the inner edge of the jet and the conical end of the nozzle needle, is smaller than the area of the cross section of the jet. As described above, since the moving distance of the nozzle needle until it hits the stopper is set, the fuel flow throttled immediately upstream of the ejection port is strongly diverted twice immediately after flowing into the ejection port, and A circumferential velocity component is given during the first turn, and the flow cross section is rapidly increased during the second turn, forming a violent three-dimensional spray that spreads in a conical shape. The fuel is atomized well, the fuel distribution in the first stroke stage is uniform,
Since the ignition delay time is shortened, more complete combustion of fuel is performed, the emission amount of harmful components is reduced, and combustion noise is reduced. Further, the rapid increase in the flow cross section reduces the distance that the fuel jet travels during the ignition delay time, so that the fuel does not reach the combustion chamber wall and wets it, and therefore the release of hydrocarbons is significantly reduced. .

〔Example〕

 An embodiment of the invention is shown in the drawing.

The nozzle body 1, which is connected to the other device parts by means of a bag nut 2, ends in a nozzle head 3, which has a nozzle opening 4. A nozzle needle 5 is guided in the nozzle body, which nozzle needle is elastically pressed against the conical valve seat 6. The weakened spring 8 first acts on the reduced-diameter extension 6 ′ of the nozzle needle 5 via the spring bearing 7, which spring is surrounded by a much stronger spring 9. It is supported on the end surface 12 of the nozzle body 1 via a washer 10 and a diametrical protrusion 11. Fuel flows from a fuel pump (not shown) to the passage 13 of the sleeve 14 and the passage 15 of the nozzle body 1.
The fuel reaches the gathering space 16 via the nozzle, and the fuel flows from there to the valve seat 6 along the nozzle needle 5.

Both compression coil springs 8, 9 are arranged eccentrically with respect to each other and a sleeve 14 is provided between these compression coil springs, through which the fuel supply passage 13 extends in its maximum wall thickness range. It is growing. The projection 11 has a longitudinal slit 17 which penetrates the sleeve 14 and has a central hole 18 for penetration of the extension 6 ′ of which the diameter of the nozzle needle 5 is reduced.

When the pump pressure rises, the nozzle needle 5 resists the force of the spring 8 and first comes out from the valve seat 6 so that the nozzle needle 5 protrudes.
It is separated until it contacts the surface on the underside of 11 which acts as stopper 19. In this first stroke stage, the peripheral surface M of the virtual cylinder, which is shown in FIG. 4 and which extends between the inner edge R of this extension and the surface of the nozzle needle 5, shown in FIG. It must be smaller than the cross section of the outlet 4. As the fuel pressure rises further, the projection 11 also rises against the force of the spring 9 until it comes into contact with the inner shoulder 20 of the sleeve 14, so that in total two stroke stages occur for the nozzle needle 5. The path taken by the nozzle needle 5 until it hits the stopper 19 and until the nose piece 11 hits the inner shoulder 20 is shown in a highly exaggerated manner in the drawing, which also applies to the size of the diameter of the spout 4.

The nozzle needle 5 has two guide portions 21, 22 of the nozzle body 1.
In the upper half of the nozzle needle 5, these guides are spaced apart from one another. The upper guide 21 is much shorter than the single guide of a conventional nozzle needle. This is because the guide part 21 is supported or complemented by the lower guide part 22 on the support part of the nozzle needle. In order to ensure a high pressure seal of the pressure space of the nozzle needle with respect to the space above the needle, the guide 21
The diameter must be several microns and must be accurately machined. Since the lower guide portion 22 exists in the pressure space of the nozzle needle, the accuracy of the surface of the lower guide portion depends on the upper guide portion.
No request is made as in the case of 21. It is therefore advantageous if only a small length of the nozzle body 1 has to be machined particularly accurately. The guide 22 is arranged as close as possible to the valve seat 6 in order to ensure a high centering performance of the nozzle needle 5 and to prevent bending of the needle. Two flat portions 24 and 25, which are diametrically opposed to each other, are provided on the outer peripheral surface of the nozzle needle 5 in order to allow the fuel to flow from the collecting space 16 to the passage 23.
This opposing configuration of the flats 24 and 25 on the nozzle needle 5 ensures a correct centering of the needle due to the hydraulic pressure of the fuel. The cross-sectional areas of all passages through which the fuel flows are chosen to be of the same size, which makes it possible to avoid pressure peaks and guarantee a constant fuel pressure and approximately the same flow rate in the entire nozzle range. Thereby, less material stress on the individual parts and a longer life of the nozzle are realized. Since the improved support of the nozzle needles and the advantageous pressure distribution allow the simultaneous opening of all the jets 4, a uniform distribution of the fuel in the fuel space and thus also good discharge values are obtained.

On the lower side of the protrusion 11, an annular shoulder portion 26 is centered and mounted on the nozzle body 1. As a result, the restraint of the nozzle needle 5 can be avoided during the stroke movement of the nozzle needle 5 on the projection 11. The centering surface 27 of the shoulder portion 26 of the protrusion 11 must be larger than the stroke of the protrusion 11 in the axial direction of the nozzle needle 5. Due to the centering of the protrusion 11 with respect to the nozzle body 1, the maximum contact surface of the nozzle needle 5 on the protrusion 11
19 are guaranteed and the tolerances between the individual parts are minimized.

Align pin with blind hole 28 or 29 in sleeve 14 or lug 11.
30 or 31 are inserted and these dowel pins are attached to the pump lid
34 or the holes 32 or 33 of the nozzle body 1 so that the parts can be fixed in place relative to each other.

2 of the fuel flow in the first stroke stage of the nozzle needle 5
The conversion of times will be explained. First, as shown in FIG.
The fuel supplied from the upstream side (one side) to the jet port 4 along the conical valve seat 6 of the nozzle head is uniformly distributed over the entire circumference of the jet port 4 as shown by the arrow. 4 flows into the conical surface of the valve seat, particularly in the arc range on the downstream side of the inner edge of the jet port 4, as can be seen from the arrow,
A strong turn is performed, and a circumferential velocity component is given to the fuel.

Further, as can be seen from FIG. 6, the fuel flow that is strongly throttled between the conical end portion of the nozzle needle 5 and the conical valve seat 6 of the nozzle head portion 3 suddenly crosses the flow cross section when entering the ejection port 4. While undergoing an increase in the number of turns, it undergoes a second 90-degree turn.

In this way, the fuel flow undergoes two immediately following turns, and in the first turn it is given a circumferential velocity component, and in the second turn the flow cross-section rapidly increases. Since it produces a strong three-dimensional atomization of the fuel to maximize atomization of the fuel, and even distribution of the fuel, the fuel is more complete and the emission of harmful components is reduced.
Noise is reduced and combustion efficiency is improved.

Regarding a vehicle equipped with a diesel engine equipped with a fuel injection nozzle according to the present invention,
The amount of emissions in the exhaust gas measured according to the guidelines of the Protection Agency) USFTP 75 under various operating conditions of the vehicle is shown in FIG. Here, the amounts of emission of hydrocarbons HC and nitrogen oxides NO _x are shown on the horizontal axes extending from the origin to the right and left, respectively, and carbon monoxide is shown on the vertical axes extending upward and downward from the origin. CO and particulate PA
The amount of RTICLES released is shown respectively. Emissions are expressed here in grams / mile (1609m). 1987
The allowable emission limit set by the US Government for the year is shown by the thick dashed diamonds. Also, the thick solid line shows the actual emission measured in a vehicle equipped with a diesel engine equipped with a fuel injection nozzle according to the invention. As can be seen, the emission amount of the diesel engine using the fuel injection nozzle according to the present invention is within the allowable limit.

[Brief description of drawings]

1 is a sectional view taken along the axis of the main part of the present invention of the fuel injection nozzle, FIG. 2 is a sectional view taken along the line II-II of FIG. 1, and FIG. 3 is taken along the line III-III of FIG. Fig. 4 is the first section
FIG. 5 is a partial cross-sectional view of the range of the ejection port of the ejection nozzle according to the figure
FIG. 6 is a development view of a conical valve seat showing a fuel flow, FIG. 6 is an enlarged sectional view of an injection nozzle tip region showing a fuel flow, and FIG.
The figure is a diagram showing the test results of the fuel injection nozzle. 1 ... Nozzle body, 3 ... Nozzle head, 4 ... Jet outlet,
5 ... Nozzle needle, 6 ... Conical valve seat, 7,8 ... Spring, M ... Circumferential surface, R ... Inner edge.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Haralart Schyumitt Wien Helv Arcsiutrasse, Austria 15/2 (72) Inventor Emerich Schiurainel Schutil Gaplerschutrasse, Austria 53 (56) References 131572 (JP, U) West German patent application publication 2711350 (DE, A)

Claims (4)

[Claims] 1. A nozzle body having a nozzle needle guided into the nozzle body, the nozzle body ending with a cap-shaped nozzle head, the nozzle head forming an inner conical valve seat, The corresponding conical end of the nozzle needle is pressed by a spring against the conical valve seat, a plurality of jets are provided in the region of this conical valve seat, and the nozzle needle is supplied in the first stroke stage. First due to fuel pressure
Against the force of the spring of, and away from the valve seat, hit the stopper,
During the second stroke stage of the nozzle needle, in the case where this stopper is movable within a limited range against the force of the second spring, during the first stroke stage each jet (4) Of the imaginary cylinder that extends between the inner edge (R) of this jet (4) and the conical end of the nozzle needle (5) which leaves the valve seat (6) at the end of the first stroke stage. The moving distance of the nozzle needle (5) before hitting the stopper (19) is set so that the area of the peripheral surface (M) is smaller than the area of the cross section of the jet outlet (4), and the inside of the jet outlet (4) is set. Fuel injection nozzle for an internal combustion engine, characterized in that the fuel flow is throttled in a region immediately upstream of the edge (R). 2. The nozzle needle (5) is guided by guide portions (21, 22) provided separately from each other in the nozzle body (1) so as to be movable in the longitudinal direction. The fuel injection nozzle according to claim 1. 3. The fuel injection nozzle according to claim 2, characterized in that the upper guide part (21) is configured as a high-pressure sealing part. 4. A fuel injection nozzle according to claim 1, characterized in that all the injection ports (4) can be opened simultaneously.