DD154871A3 - INJECTION DEVICE FOR DIESEL ENGINES - Google Patents

Abstract

The invention relates to a Einspritzduese with at least two spray holes and a Duesenkoerper with sufficient to a blind hole Duesennadel, which is held by means of spring force on their seat. To be achieved is a different injection quantity distribution characteristic between the spray holes as a function of engine speed and injection quantity. The object is to design an injection nozzle of the type mentioned in such a way that the mentioned distribution characteristic is achieved without double guides on the nozzle needle and in the nozzle body between seat contours and possibly controlling shape contours. This is solved by arranging at least one spray hole in the region of the seat of the nozzle needle in a manner known per se, and this spray hole has a larger diameter than a further injection bore in the blind hole.

Description

Title:.

Injector for diesel engines

Field of application of the invention

The invention relates to an injection nozzle, preferably for directly injecting diesel engines with a piston arranged in the rotary body combustion chamber, in particular with the combustion chamber longitudinal axis rotating air movement and with a fuel accumulation on the wall or near the wall, the injector has at least two spray holes and from a nozzle body with a sufficient to a blind hole nozzle needle, which is held by means of spring force on their seat,

Characteristic of the Prior Art:

There is a whole series of constructive variants of the above urarissenen multi-hole nozzle type previously known, with which different ratios between the spray rates of Spritzbohrüngen speed and injection quantity are realized depending. It is already known from US Pat. No. 3 559 892 to carry out the nozzle needle with a conical seat and a control pin sealingly guided in a blind hole, wherein a sprayed bore of small cross-section from the conical seat of the

Düsenkörpers is arranged starting and another larger injection bore emanating from the blind hole. In this construction, the proportions of the subsets of the two aforementioned spray holes speed and quantity dependent - influenced, the needle stroke is controlling this. ,

Furthermore, it is previously known from DE-OS 2 434 339 and PR-PS 1 256 474 for influencing the distribution of the fuel, in particular at idle and low speeds. Equip nozzles with several controlling seat or, Passungsquerschnitten, each of which one or more Spritζöffnungen are assigned. Thus, in the nozzle type DE-OS 24 34 399 and the DDR PS 133 179 arranged a series of spray holes in a seat cone of the nozzle needle downstream annular space opening. Another series of spray holes is from the blind hole, which are influenced in their spray behavior of a nozzle body fitted to the control pin on the nozzle needle. In this case, the nozzle needle can be dependent on the stroke of a variable spring force and spring stiffness.

According to FR-PS 1 256 474 a double seat is effected by means of a conical nozzle needle tip with an annular reset in the region of the center of the conical surface, in which rests at the lower and upper end of the nozzle needle, the conical contour on a seat in the nozzle body. A spray hole with a small cross-section is arranged starting from the region of the annular reset in the conical surface of the nozzle needle, while further spray holes open below the second seat at the apex in the blind hole.

A disadvantage of all constructions described above, that in each case two matched seat contours or seat and fit contours on the nozzle needle vnd must be made in a blind hole in the nozzle body. Furthermore, it is known from DE-OS 2,147,719 and DD-PS 102 198, two series of spray holes at

For this purpose, the nozzle needle is in two parts, each part is individually loaded by spring force, executed so that two sealing cross sections open at different pressures successively, ao that the spray holes are different in their characteristics at different speeds and injection quantities effective In particular, this two-part construction is complicated and complicated to produce because several parts must be performed to each other and have to ensure fitting-related sealing functions, Torbekannt it is also by GB-PS 1 418 574 "a number of circumferentially distributed spray openings from the conical seat starting to act * With this design, a different jet condition is created, which occurs with different nozzle needle lift «,

Object of the invention

In an injector of the type mentioned, a different quantity distribution characteristic between the spray holes is to be achieved depending on engine speed and injection quantity, wherein in the lower speed and load range of the engine, the fuel preferably via a secondary spray hole and with further speed and load increase on the Main injection hole emerges. Also, a simple construction of the nozzle should be ensured with good manufacturing and durability.

Explanation of the essence of the invention:

The invention has for its object to provide a suitable arrangement and dimensioning of the spray holes for an at least two-jet nozzle, which ensures the above-mentioned quantity distribution characteristic and in particular avoids double guides on the nozzle needle and the nozzle body between seat contours and optionally controlling shape contours. Especially in the

Nozzle body is to ensure a simple production of the sealing and control contours.

According to the invention the object is achieved in a multi-hole injection nozzle of the type described above, that in known per se at least one spray hole in the region of the seat of conical or flattened cone-shaped nozzle needle is arranged opening and this spray hole a larger diameter has another in the blind hole opening arranged injection hole. Due to the geometric conditions of the spray holes and their arrangement and the resulting inflow conditions to the spray holes at different valve needle, it is possible that a control pin on the nozzle needle for the control of the injection quantity ratios between the two spray holes deleted. Due to the flow conditions at the valve needle seat at relatively low flow velocities, e.g. at start and idle, the leakage of fuel aua the larger spray hole is largely prevented. Only at higher engine speed arises over the blind hole such an overpressure on the valve needle seat, that even the larger injection bore brings a proportionately higher injection quantity. Thus, in the upper load and speed range, the injection quantity is increased mainly in the larger spray hole. Preferably, the diameter ratio between the larger injection opening in the seat and the smaller injection opening in the blind hole is 1.5 to 2.3. With the vorangegebenen characteristics, the desired distribution of the injection quantity is achieved in dependence on the rotational speed and the injection quantity to the at least two spray holes. This ensures an advantageous adaptation of the injection to the engine conditions of the initially determined type of diesel engine for achieving low exhaust emission.

Advantageously, the smaller bore coincides approximately with the Düeenachse, the angle between the two spray holes is 20 to 40 ° ,, This design ensures the low installation of the nozzle in the cylinder head, taking into account the necessary beam position.

Embodiment t

With reference to drawings, an embodiment of the invention and the results obtained will be described below, It shows;

1 shows a partial section through the cylinder head of a diesel engine with direct injection, from which the arrangement of the injection nozzle and the position of the injection jets in the combustion chamber can be seen,

Figure 2 _e shows a longitudinal section through an inventive multi-hole nozzle,

Pig "3 is a diagram of the quantity distribution at the same and different sized spray openings at different operating conditions of the engine,

Pig. 4 a Diagr'amm on the flow rates of the injection holes at different stroke of the nozzle needle.

Pig * 1 shows the arrangement of a multi-hole nozzle according to the invention in a diesel engine with direct injection. The fuel jets ST 14 ST 15 from the spray holes 14; 15 are directed in different directions in the rotationally symmetrical combustion chamber 2 in the piston 3des engine. It can be seen that the jet ST 15 of the smaller spray bore 15 passes through the center of the combustion chamber, which leads predominantly to air-distributed fuel. On the other hand, the jet ST 14 of the spray hole 14 extends in the vicinity of the wall of the combustion chamber 2, wherein it is preferably directed perpendicular to the block twist flow 4 or slightly obliquely against this «The fuel is in the vicinity of the

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Wall processed and then burned evenly with the participation of the swirl.

In Pig. 2, the essential section of a multi-hole nozzle according to the invention is visible. In the nozzle body 12, a conventional nozzle needle 10 is guided guided. This nozzle needle 10 has a nozzle needle seat 11, which is associated with a seat 13 in the nozzle body 12.

A large injection bore 14, which provides the main jet under normal operating conditions, opens in the seat 13 in the nozzle body 12 and is covered by the nozzle needle seat 11 at the lowest position of the nozzle needle. A smaller spray hole 15, which emits fuel preferably at start conditions at idle and in the low part load range, opens in the blind hole 16 of the nozzle body 12. It should be emphasized that the blind hole 16 is performed minimized in volume, which partly by shallow depth or by a tapered approach at the end of the nozzle needle 10 to the area of the nozzle needle seat 11 is effected «

Fig. 3a; b conveys characteristic Abspritzmengenkennlinien with the spray hole arrangement according to the invention. The left diagram - Fig. 3a - applies for a pump speed of 300 rpm and the right - Fig. 3b - for 1400 rpm. In both diagrams are on the ordinate, the subsets of the spray holes 14; For the solid curves, the diameter ratio of the spray holes is 1.5 and for the dashed curves is 1.0, i. the spray holes are the same size here.

At 300 pump revolutions per minute and idling amount of fuel occurs as desired almost exclusively through the spray hole 15. With larger total amount, the subsets for the injection bore ratio d14 to d15 = 1.5 then approximately equal, while the same size spray holes 14; 15 constantly leaking substantially more fuel from the opening into the blind hole 16 spray hole.

At 1400 rpm, for the di4 to d15 = 1.5, there is approximately equal quantity of both spray holes 14 even with a smaller total quantity. 15 »and for equally large spray holes, the QSt15 spray quantity clearly outweighs this. The effects of the different inflow conditions to the two spray holes 14; 15 on the effective Durchflußquerachnitt same illustrate stationary Durchflußraessungen on a nozzle with the same size spray holes 14; 15 after Pig «> 4 again clearly. Up to a Kadelhub of about · 0.06 mm occurs from the opening into the seat 13 injection bore H virtually no fuel, and at full Hadelhub outweighs the effective flow area of the opening into the blind hole 16 bore 15 again clearly * The spray quantity distribution at 1400 U / min corresponds to Pig, 3b corresponds approximately to the ratio of the effective flow cross sections in Pig «4«

Claims (2)

- »- 220547 Invention claim: "U injector, preferably for direct-injection diesel engines with a arranged in the piston rotary body-shaped combustion chamber, in particular with the combustion space longitudinal axis rotating air movement and with a fuel attachment on the wall or near the wall, wherein the injection nozzle has at least two spray holes and from a nozzle body with a a blind hole sufficient nozzle needle is made, which is held by means of spring force on their seat, characterized by that in known per se at least one spray hole (14) in the region of the seat (13) of the cone-shaped or flattened cone-shaped nozzle needle (10) is arranged opening and this spray hole (14) has a larger diameter than another in the blind hole (16) arranged spraying opening (15) disposed *. Injection nozzle according to item 1, characterized in that the diameter ratio between the larger injection bore (14) opening into the seat (13) and the smaller injection bore (15) opening in the blind hole (16) is 1.5 to 2.3. 3. Injection nozzle according to item 1, characterized in that the smaller bore (15) coincides approximately with the nozzle axis. 4. Injection nozzle according to item 1, characterized in that the angle between the two injection bores (14; 15) is 20 to 40 °. For this .. "v3 pages drawings