EP1770275A1 - Hole-type nozzle with a storage volume for a fuel injection apparatus - Google Patents

Abstract

An orifice nozzle (24) has a nozzle body (30) which has a nozzle needle cavity (34) for supply fuel into the nozzle body (30), a storage cavity (94) is provided which is joined hydraulically by at least one nozzle element to the nozzle needle cavity (34). An independent claim is included for a fuel injection device.

Description

State of the art

The invention relates to a hole nozzle for a fuel injection device of a fuel injection system, in particular for use in a common rail system, with a nozzle body having a nozzle needle chamber.

Such a perforated nozzle is known for example from the book "Diesel Engine Management" Robert Bosch GmbH. In order to inject fuel finely atomized into an associated combustion chamber of an internal combustion engine, the stored in a fuel storage, such as a "rail" fuel is brought to very high pressures. Earlier common-rail systems have been designed for a maximum pressure of approx. 1350 bar. Current common-rail systems operate at a maximum pressure of 1600 bar. For future applications, much higher pressures are desired.

The nozzle needle arranged in the hole nozzle acts as a valve during opening and closing, ie when lifted from an associated nozzle needle seat and when closing it. Due to the high pressures mentioned, starting from the valve needle acting as a valve body Pressure waves are generated, which may exceed the above maximum pressures. As a result, the fuel-carrying components of the common rail system are exposed to high load peaks.

It has therefore been proposed to compensate for the pressure waves caused by the opening and closing of the nozzle needle by pressure being applied in the memory of the fuel injection system, for example the "rail" fuel, so that pressure wave compensation can be achieved.

On this basis, it is an object of the invention to provide a fuel injection system which is as insensitive to pressure waves.

This object is achieved by a perforated nozzle with the features of claim 1. Advantageous embodiments are specified in the subclaims.

Advantages of the invention

Due to the additional, formed in the nozzle body storage space which is hydraulically connected via at least one throttle element with the nozzle needle chamber, pressure waves in the fuel can be damped. Since the pressure waves generated by the opening and closing of the nozzle needle and thus propagate from the nozzle needle chamber, it is particularly advantageous that the attenuation of the pressure waves can take place spatially close to this area.

By the hydraulic connection of the storage space with the nozzle needle chamber by means of at least one throttle element is ensured that in the nozzle needle chamber and the Storage space adjacent pressures can be different from each other. Thus, the nozzle needle space and the storage space form independent hydraulic elements.

The perforated nozzle according to the invention is based on the idea that it is possible in a region of a fuel injection system to be able to use a material section oversized even when a maximum pressure is applied in order to relieve other regions of the fuel injection system that are spatially remote from this material section. Thus, a total fuel injection system can be created, which is particularly robust against high maximum loads, which are particularly caused by pressure waves.

The developments of the invention according to claim 2 and 3 have the advantage that the storage space limiting material can be uniformly loaded, at the same time a comparatively large storage space is created.

In the dependent claims 4 to 7 embodiments of the invention are proposed with which a particularly simple production of a perforated nozzle according to the invention with storage space is made possible.

The invention further relates to a fuel injection device of a fuel injection system with a hole nozzle.

drawings

Figur 1

eine schematische Darstellung eines Kraftstoff-Einspritzsystems einer Brennkraftmaschine mit einer Kraftstoff-Einspritzvorrichtung, die eine Lochdüse aufweist;

Figur 2

eine Seitenansicht der Kraftstoff-Einspritzvorrichtung und der Lochdüse gemäß Figur 1;

Figur 3

eine geschnittene Seitenansicht eines Ausschnitts III gemäß Figur 2 mit einer aus dem Stand der Technik bekannten Lochdüse;

Figur 4a

eine perspektivische Ansicht eines Düsenkörpers einer erfindungsgemäßen Lochdüse;

Figur 4b

eine perspektivische Ansicht eines in den Düsenkörper gemäß Figur 4a einsetzbaren Hülsenelements;

Figur 5a

eine der Figur 4a entsprechende, geschnittene Ansicht;

Figur 5b

eine der Figur 4b entsprechende, geschnittene Ansicht;

Figur 6a

den Düsenkörper gemäß Figur 4a bzw. Figur 5a und das Hülsenelement gemäß Figur 4b bzw. Figur 5b in einem montierten Zustand;

Figur 6b

eine perspektivische Ansicht eines Ausschnitts aus Figur 6a;

Figur 7

eine der Figur 6b entsprechende Ansicht gemäß einer zweiten Ausführungsform der Erfindung; und

Figur 8

eine einem Ausschnitt der Figur 6a entsprechende Ansicht einer dritten Ausführungsform der Erfindung.

Hereinafter, particularly preferred embodiments of the present invention below With reference to the accompanying drawings explained in more detail. In the drawing show:

FIG. 1

a schematic representation of a fuel injection system of an internal combustion engine having a fuel injection device having a hole nozzle;

FIG. 2

a side view of the fuel injection device and the hole nozzle according to Figure 1;

FIG. 3

a sectional side view of a section III of Figure 2 with a known from the prior art hole nozzle;

FIG. 4a

a perspective view of a nozzle body of a perforated nozzle according to the invention;

FIG. 4b

a perspective view of an insertable into the nozzle body according to Figure 4a sleeve member;

FIG. 5a

a sectional view corresponding to Figure 4a;

FIG. 5b

a sectional view corresponding to Figure 4b;

FIG. 6a

the nozzle body according to FIG. 4a or FIG. 5a and the sleeve element according to FIG. 4b or FIG. 5b in an assembled state;

FIG. 6b

a perspective view of a section of Figure 6a;

FIG. 7

a view corresponding to Figure 6b according to a second embodiment of the invention; and

FIG. 8

a view corresponding to a detail of Figure 6a of a third embodiment of the invention.

Description of the embodiments

In FIG. 1, a fuel injection system of an internal combustion engine as a whole carries the reference numeral 10. It comprises a fuel tank 12, from which a delivery system 14 delivers the fuel to a fuel rail 16 ("rail"). The conveyor system 14 may include a prefeed pump and a high pressure pump.

To the fuel manifold 16 a plurality of fuel injection devices 18 are connected, of which only one is shown in FIG. For this purpose, the fuel injection device 18 has a high-pressure port 20. the fuel injection device 18 is assigned to a combustion chamber 22 of an internal combustion engine, not shown, into which it directly injects the fuel using a hole nozzle 24 described in more detail below. From the fuel injection device 18, a return line 26 leads back to the fuel tank 12. The return line 26 is connected to the fuel injection device 18 via a low pressure port 28.

The fuel injector 18 and the orifice nozzle 24 mounted thereon are shown in more detail in FIG. The marked in Figure 2 section III is shown in Figure 3 enlarged. The hole nozzle 24 has a elongated nozzle body 30, which has at its fuel injector 18 end facing a radially outwardly extended portion 32. In the nozzle body, a centrally arranged nozzle needle chamber 34 is provided, in which a nozzle needle 36 is arranged. The nozzle needle 36 opens and closes a nozzle needle seat 38 provided at the end of the nozzle needle space 34.

The radially widened region 32 has, on its side facing away from the fuel injection device 18, an annular nozzle body shoulder 40, which cooperates with a corresponding annular shoulder 42 of a nozzle retaining nut 44. The nozzle retaining nut 44 is secured to the fuel injector 18 via a thread, not further shown in FIG. With the help of paragraph 42, the nozzle body shoulder 40 and thus the radially expanded portion 32 is pressed against a in Fig. 3 above the hole nozzle 24 shown intermediate member 46.

The intermediate element 46 (throttle plate) is adjoined by a valve plate 48, which has a valve designated overall by 50. The valve 50 can be moved by means of a known and therefore not further shown actuator in 52 directions of actuation directions to open the valve 50 or close.

The valve 50 is hydraulically connected via a flow restrictor (not shown in FIG. 3) to a control chamber 54. The control chamber 54 is essentially limited by the upper end of the nozzle needle 36 and the intermediate element 46 in FIG. 3. An inlet throttle 56, which is supplied with fuel by means of a fuel inlet 58, opens into the control chamber 54. The fuel inlet 58 is also hydraulically with the Düsennadelraum 34 connected. Between the valve 50 and the nozzle needle chamber 34, a further line 60 is provided.

In order to lift the nozzle needle 36 out of its nozzle needle seat 38, so that injection into the combustion chamber 22 shown in FIG. 1 can take place, the valve 50 is opened, so that fuel can flow out of the control chamber 54 via the outlet throttle (not shown). At the same time, fuel flows through the inlet throttle 56 into the control chamber 54. If the throttling effect of the outlet throttle (not shown) is smaller than the throttle effect of the inlet throttle 56, the pressure in the control chamber 54 can be reduced. From a certain pressure drop, the nozzle needle 36 can be lifted out of the nozzle needle seat 38 against the action of a spring element 62 with the aid of the higher pressure applied in the nozzle needle chamber 34, so that injection takes place into the combustion chamber 22.

The control chamber 54 is sealed relative to the nozzle needle chamber 34 radially outward by means of a sleeve member 64 (control chamber sleeve), which bears sealingly against the intermediate element 46. At this sleeve member 64 is formed in Figure 3 as a helical spring spring member 62 from. Alternatively, the spring element 62 could also be formed as a cylindrical sleeve, as shown in the DE 102 13 382 A1 is described. This possibility also exists for the hole nozzle according to the invention described below.

FIGS. 4a and 5a show the nozzle body 30 of a hole nozzle 24 according to the invention. This nozzle body 30 has a comparatively slender nozzle body shaft 66, to which a radially outwardly stepped portion 68 connects, to which in turn the radially outwardly extended region 32 connects. The wall of the radially outwardly widened region 32 delimits a substantially cylindrical space 70. This space 70 is limited to the nozzle body shaft 66 by an annular bottom 72.

The radially widened region 32 has two part-cylindrical depressions 74 extending essentially in the longitudinal direction of the nozzle body 30. The depressions 74 are offset from one another by a distance deviating from 180 ° in order to receive correspondingly arranged pins which are arranged in the intermediate element 46 according to FIG. In this way, the hole nozzle 24 can be mounted in a certain rotational position on the fuel injection device 18.

At the upper edge of the radially expanded region 32 in FIGS. 4a and 5a, an annular, outer contact surface 76 is formed. This seals the space 70 against the intermediate element 46.

FIGS. 4b and 5b show a sleeve element 78 which essentially has a hollow-cylindrical section 80, against which a collar 82 which widens radially outward is fired. The collar forms an annular, inner contact surface 84, which can seal the sleeve member 78 against the intermediate member 46.

In the collar 82 recesses 86 are provided, which are complementary to the recesses 74 forming material portions of the radially enlarged portion 32 of the nozzle body 30 are formed.

FIG. 6 a shows a partially mounted hole nozzle 24, wherein the sleeve element 78 according to FIGS. 4 b and 5 b is mounted in the nozzle body 30 according to FIGS. 4 b and 5 b. The radially outwardly widened region 32 of the nozzle body 30 has a radially inwardly facing cylindrical wall 88. Correspondingly, the cylindrical portion 80 of the sleeve member 78 has a radially outwardly facing wall 90. Furthermore, the collar 82 of the sleeve member 78 has a wall 92 facing the annular bottom 72 of the nozzle body 30. The walls 88, 90, 92 and the annular bottom 72 define a generally annular formed storage space 94 which is arranged concentrically to the nozzle needle space 34. The nozzle needle space 34 is bounded along its course by the nozzle body 66 and the stepped portion 68 of the nozzle body 30 and by the cylindrical portion 80 of the sleeve member 78.

According to FIG. 6b, a first, essentially cylindrical sealing region 96 is formed between the collar 22 and the radially widened region 32. Further, between the cylindrical portion 80 and the nozzle body 30, another, designated 98 sealing region is formed. The sealing region 98 is formed by abutment of an annular rim 100 (see FIG. 5b) of the sleeve element 78 with an inner section 102 of the annular bottom 72 (see FIG. 5a).

Via the sealing region 96, the storage space 94 is sealed in the direction of the intermediate element 46 according to FIG.

In the sealing region 98 throttle elements 104 are formed by 78 provided in the cylindrical portion 80 of the sleeve member small material recesses are. By means of the combination of at least one throttle element 104 with the sealing region 98, a defined throttle effect can be achieved when fuel flows between the nozzle needle chamber 34 and the reservoir 94.

The storage space 94 has the following function: If the nozzle needle 36 is moved out of its nozzle needle seat 38 in the nozzle needle chamber 34 of a perforated nozzle 24 according to the invention, high-pressure fuel can be injected from the nozzle needle chamber 34 into the combustion chamber 22 (see FIG. 1). When the nozzle needle 36 now moves back into the closed position, so that the nozzle needle seat 38 is closed, creates a pressure wave, which is transmitted through the applied fuel in the nozzle needle chamber 34. This pressure wave can be damped to a considerable extent by the fact that fuel flows from the nozzle needle chamber 34 via the throttle elements 104 into the storage space 94. In this case, 104 pressure can be reduced due to the throttling effect of the throttle elements, so that the maximum pressures of the pressure waves can be reduced and areas of the fuel injection system 10, which are acted upon by the fuel with the high pressure, are less heavily loaded.

When the storage space 94, as shown in FIGS. 6a and 6b, is formed in the radially expanded area 32 of the nozzle body 30, the wall thickness of the extended area 32 is reduced. Thus, the wall thickness of the expanded portion 32 and the wall thickness of the nozzle body 66 are approximately equal. Thus, the space taken up by the nozzle body 30 as a whole, can be used so that the hole nozzle 24 can withstand high pressures, but the maximum Pressure loads generated by pressure waves are degraded, so that other components, such as the fuel injector 18 are exposed to lower peak loads. The volume of the storage space 94 may be several hundred cubic millimeters in an arrangement according to FIGS. 6a and 6b.

FIG. 7 shows a hole nozzle 24 similar to the hole nozzle 24 according to FIGS. 6 a and 6 b, which differs from the embodiment illustrated in FIG. 6 b due to the formation of the sealing region 96. The collar 22 of the sleeve element 78 according to FIG. 7 has an outer annular shoulder 106 pointing in the direction of the bottom 72 of the nozzle body 30. This annular shoulder 106 engages around an inner annular shoulder 108 formed on the widened area 32 of the nozzle body 30. When the fuel contained in the storage space 94 is subjected to high pressure, the annular shoulder 108 is pressed outwardly against the annular shoulder 106, so that the sealing effect of the sealing area 96 increases with increasing pressures in the storage space 94.

In the embodiments described so far, the sleeve member 78 and the nozzle body 30 have been connected to each other via a press fit formed in the respective seal portion 96. However, it is also possible to connect the sleeve member 78 latching with the nozzle body 30, as shown in Figure 8. In this embodiment, the radially expanded portion 32 at its fuel injection device 18 end facing a radially inwardly facing annular collar 110. On the cylindrical portion 80 of the sleeve member 78 is an outwardly facing, at least partially annular locking element 112 is arranged.

When the sleeve member 78 is inserted into the nozzle body 30 in the mounting direction denoted 114, guide bevels 116 of the detents 112 engage the collar 110 of the radially expanded portion 32. This allows the sleeve member to be compressed radially inwardly until the detents 112 engage the collar 110 behind. In this position, a sealing region 96 is formed between an end portion 118 of the cylindrical portion 80 of the sleeve member 78 and the collar 110 of the radially expanded portion 32. The sealing of the cylindrical portion 80 with respect to the bottom 72 of the nozzle body 30 is carried out in the manner described with reference to Figures 5a to 6b. Instead of or in addition to the throttle elements 104 already described, hole throttles 120 can also be provided for the hydraulic connection between the nozzle needle chamber 34 and the storage space 94, which are preferably arranged in the cylindrical section 80 of the sleeve element 78. Of course, such an alternative throttle arrangement can also be used in the embodiments according to FIGS. 4a to 7.

The use of hole throttles 120 has the advantage that the throttling effect can be set particularly well.

Claims (10)

A hole nozzle (24) for a fuel injection device (18) of a fuel injection system (10), in particular for use in a common rail system, comprising a nozzle body (30) having a nozzle needle space (34), characterized in that for storing fuel in the nozzle body (30) a storage space (94) is provided, which is hydraulically connected via at least one throttle element (104, 120) with the nozzle needle chamber (34). Punch nozzle (24) according to claim 1, characterized in that the storage space (94) in a region (32) of the nozzle body (30) is arranged, which is widened to form a nozzle body shoulder (40) radially outward. Punch nozzle (24) according to claim 1 or 2, characterized in that the storage space (94) is annular and in particular is arranged concentrically to the nozzle needle chamber (34). Punch nozzle (24) according to at least one of the preceding claims, characterized in that the storage space (94) in the radial direction through a wall (88) of the nozzle body (30) and through a wall (90) of a sleeve member connected to the nozzle body (30) (78) is limited. Punch nozzle (24) according to claim 4, characterized in that the wall (68) of the nozzle body (30) is arranged radially on the outside and the wall (90) of the sleeve element (78) radially inwards. Punch nozzle (24) according to claim 4 or 5, characterized in that the sleeve member (78) and the nozzle body (30) are interconnected via a press fit. Punch nozzle (24) according to at least one of claims 4 to 6, characterized in that the sleeve member (78) and the nozzle body (30) are interconnected via a latching connection. Punch nozzle (24) according to at least one of claims 4 to 7, characterized in that between the sleeve member (78) and the nozzle body (30) formed sealing region (96) are formed such that its sealing effect at an increase in the pressure of in increases the storage space (94) existing fuel. Punch nozzle (24) according to at least one of the preceding claims, characterized in that the throttle element (104) by two in a throttling acting region spaced apart, different components, in particular by the nozzle body (30) and sleeve member (78) is formed. Fuel injection device (18) of a fuel injection system (10) with a hole nozzle (24) according to at least one of the preceding claims.

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