WO2017080757A1

WO2017080757A1 - Nozzle assembly for a fuel injection valve for injecting a gaseous and/or liquid fuel, and fuel injection valve

Info

Publication number: WO2017080757A1
Application number: PCT/EP2016/074846
Authority: WO
Inventors: Jochen Wessner; Martin Katz
Original assignee: Robert Bosch Gmbh
Priority date: 2015-11-11
Filing date: 2016-10-17
Publication date: 2017-05-18
Also published as: DE102015222162A1

Abstract

The invention relates to a nozzle assembly for a fuel injection valve for injecting a gaseous and/or liquid fuel into a combustion chamber of an internal combustion engine, comprising a nozzle body (1) and an injection valve member (2) which is received such that it can be moved with a reciprocating movement at least in sections in the nozzle body (1) for opening and closing at least one injection opening with the formation of an annular space (3). According to the invention, a closure element (4) which is arranged in a stationary manner and is prestressed radially with respect to the injection valve member (2) is received in the annular space (3), with the result that a non-positive and/or positively locking connection can be realised between the closure element (4) and the injection valve member (2). Furthermore, an axially displaceable disconnecting element (5) is received in the annular space (3) for cancelling the non-positive and/or positively locking connection, which disconnecting element (5) can be loaded with a fluid pressure in the direction of the closure element (4). Moreover, the invention relates to a fuel injection valve having a nozzle assembly of this type.

Description

NOZZLE ASSEMBLY FOR A FUEL INJECTION VALVE FOR INJECTING A

GASEOUS AND / OR LIQUID FUELS, AND FUEL INJECTION VALVE

Description title

A nozzle assembly for a fuel injector for injecting a gaseous and / or liquid fuel, fuel injector

The invention also relates to a fuel injector for injecting a gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine having such a nozzle assembly. The fuel injection valve may be designed as a mono-fuel injector or as a dual-fuel injector.

State of the art

Fuel injection valves or injectors known from the prior art generally have inwardly opening injection valve members, which are acted upon in the closing direction by the spring force of a spring. The spring force must be dimensioned sufficiently large to prevent unintentional opening of the injection valve member by the present in the combustion chamber compression pressure in the unpressurized state, especially in the starting case of the internal combustion engine. The spring therefore regularly occupies a large space within the injector.

The risk of accidental opening increases when the pressure-loaded surfaces on the injection valve member are particularly large. This is particularly the case with dual-fuel injectors for gas engines with integrated diesel ignition, the case having two nested injection valve members, of which an inner first injection valve member of the injection of a liquid fuel and an external second injection valve member of the injection of a gaseous fuel. Since the comparatively large diameter of the outer injection valve member is a ne correspondingly large spring requires to ensure the Zuhaltefunktion when starting the internal combustion engine, a compact design arrangement is usually impossible to achieve.

The present invention has for its object to provide a nozzle assembly for a fuel injection valve for injecting a gaseous and / or a liquid fuel, which is particularly compact.

To solve the problem, the nozzle assembly is proposed with the features of claim 1. Advantageous developments of the invention can be found in the dependent claims. Further, a fuel injection valve is provided with such a nozzle assembly.

Disclosure of the invention

The nozzle assembly proposed for a fuel injector for injecting a gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine comprises a nozzle body and an injection valve member. The injection valve member is at least partially received in a liftable manner for releasing and closing at least one injection opening in the nozzle body, wherein an annular space is formed between the nozzle body and the injection valve member. According to the invention, a stationary arranged and with respect to the injection valve member radially biased tumbler is received in the annular space, so that between the tumbler and the injection valve member a force and / or form fit can be realized. To cancel the force and / or positive connection, an axially displaceable separating element is further accommodated in the annular space, which can be acted upon in the direction of the tumbler element with a fluid pressure.

In the nozzle assembly according to the invention, the locking function is realized by the locking element, so that a spring loading the injection valve member in the closing direction is dispensable. This also eliminates the space for receiving the spring, so that the nozzle assembly according to the invention can be made very compact design. To implement the locking function, the locking element is radially biased relative to the injection valve member. This means that the tumbler element bears radially on the outside of the injection valve member in order to keep it in its closed position. However, this is only the case when the system is depressurized, ie no fluid pressure acts on the separating element in the direction of the locking element. If, in contrast, the separating element is acted upon in the direction of the locking element by a fluid pressure, this causes the force and / or positive locking of the locking element is canceled with the injection valve member, since the pressurized separating element exerts an axial compressive force on the locking element, which counteracts the radial biasing force ,

Preferably, the separating element is always pressurized during operation of the internal combustion engine, so that the opening of the injection valve member is ensured and the influence of the tumbler element is kept as low as possible to the stroke of the injection valve member. The Zuhaltefunktion should therefore only prevent accidental opening of the injection valve member when starting the engine. If, after starting the internal combustion engine, a fluid pressure builds up in the annular space, this can be used for the axial displacement of the separating element in the direction of the locking element, so that the force and / or positive connection between the locking element and the injection valve member is canceled.

According to a first preferred embodiment of the invention, the locking element is designed as an elastically deformable spring arm, which is radially biased relative to the injection valve member. The radial bias ensures the positive and / or positive locking of the locking element with the injection valve member in the pressureless state. In contrast, the elastic deformability of the spring arm ensures that the force and / or positive connection can be canceled by the separating element.

So that the injection valve member is uniformly loaded by the radially biased tumbler over the circumference, preferably more than elastically deformable spring arms formed Zuhalteelemente are provided in the annular space of the nozzle assembly, which are further preferably arranged at the same angular distance from each other. Instead of a plurality of individual tumbler elements, it is also possible to provide a single tumbler element which comprises at least one elastically deformable spring arm which is radially prestressed with respect to the injection valve member. Preferably, the locking element comprises a plurality of such spring arms, which are further preferably arranged at the same angular distance from one another in order to load the injection valve member evenly over the circumference.

According to an alternative embodiment of the invention, the locking element is designed as a spring-loaded arm or comprises at least one spring-loaded arm, which is radially biased relative to the injection valve member. The radial bias is effected in this case via a spring whose spring force acts on the arm in the direction of the injection valve member. In contrast to the spring arm of the spring-loaded arm is further preferably not formed elastically deformable, but hinged to a fixed part of the tumbler pivot. The joint can be formed for example by a film hinge.

In a development of the invention, it is proposed that the injection valve member have at least one shoulder and / or at least one recess on the outer circumference side. The paragraph and / or the recess allows or allow in a simple way the production of a positive connection between the tumbler element and the injection valve member. In order to ensure in the closed position of the injection valve member, a rear engagement of the paragraph by the tumbler element or engagement of the tumbler in the recess, the axial position of the shoulder or the recess is adapted to the axial position of the tumbler. The recess may be formed as a groove, in particular as an annular groove. The annular groove has the advantage that the desired positive locking is independent of the angular position of the injection valve member relative to the locking element produced. The same applies to the paragraph, which is therefore preferably designed as a ring-shaped paragraph.

Advantageously, the locking element is axially supported on the nozzle body. The axial support can be done for example on an annular shoulder of the nozzle body. For this purpose, at least one support tab or an annular support section can be formed on the tumbler element. The axial support is intended to prevent an axial displacement of the locking element by the separating element. Advantageously, the separating element is arranged on the side facing away from the combustion chamber of the locking element. The pressurization of the separating element then takes place automatically after the starting of the internal combustion engine by the fluid pressure building up in the annular space. This has the consequence that the separating element is axially displaced in the direction of the tumbler element and exerts an axial compressive force on the tumbler element, which counteracts the radial prestressing force, so that the force and / or positive locking of the tumbler element with the injection valve member is canceled.

The separating element is preferably designed as an axially displaceable sleeve. This ensures that the locking element - regardless of the angular position of the separating element - is evenly loaded and the force and / or positive connection with the injection valve member is safely repealed.

Advantageously, the sleeve is executed on the outside circumference stepped. As a result, the surface acted upon by fluid pressure increases, so that greater pressure forces can be achieved. As an alternative to a stepped outer contour, the sleeve may also have a collar portion. The pressurizable with fluid pressure larger area, in particular end face, is preferably arranged at the end of the separating element, which faces away from the locking element.

The stepped outer contour or the collar portion of the separating element also facilitates a subdivision of the annular space into different pressure chambers, since the thickness of the separating element in the radial direction can be selected such that a gap seal between the separating element and the nozzle body and between the separating element and the injection valve member is trained. This ensures that - at least during operation of the internal combustion engine - prevail on both sides of the separating element always different pressure conditions. In this case, the pressure should be greater on the side facing away from the tumbler element than on the side facing the tumbler element, in order to reliably prevent force and / or positive locking of the tumbler element with the injection valve member. The pressure difference can be, for example, 3 to 10 bar. Alternatively or additionally, the separation of the annular space into different pressure chambers can also be effected by at least one sealing element which is connected to the separating element for this purpose.

According to a further preferred embodiment of the invention, the injection valve member is formed at least in sections as a hollow needle and in the hollow needle, a further injection valve member is received liftable. That is, the nozzle assembly includes two injection valve members, one inside the other, for controlling the injection of two different fuels. The nozzle assembly is therefore particularly suitable for a dual-fuel injector. Due to the comparatively large areas on the outer injection valve member, the advantages of the invention are particularly effective here. The holding of the internal injection valve member can, on the other hand, continue to be effected by means of a spring, since here the surfaces or forces are significantly smaller.

To solve the above-mentioned object, a fuel injection valve for injecting a gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine with a nozzle assembly according to the invention is also proposed. The fuel injection valve may be designed as a mono-fuel injector or as a dual-fuel injector.

Preferred embodiments of the invention are explained below with reference to the accompanying drawings. These show:

1 shows a schematic longitudinal section through a nozzle assembly according to the invention according to a first preferred embodiment,

2 shows a schematic longitudinal section through a nozzle assembly according to the invention according to a second preferred embodiment,

3 shows a schematic longitudinal section through a nozzle assembly according to the invention according to a third preferred embodiment, 4 shows a schematic longitudinal section through a nozzle assembly according to the invention according to a fourth preferred embodiment,

5 is a perspective view of the separating element of the nozzle assembly of Fig. 4,

6 is a perspective view of a locking element for a nozzle assembly according to the invention, and FIGS. 7 a) -c) are each a sectional view of a locking element for a nozzle assembly according to the invention.

DETAILED DESCRIPTION OF THE DRAWINGS FIG. 1 shows a nozzle assembly with a nozzle body 1 and an injection valve 2 received in a liftable manner. Between the nozzle body 1 and the injection valve member 2, an annular space 3 is formed, in which a locking element 4 and a separating element 5 are accommodated. The locking element 4 is arranged stationarily in the annular space 3. In the axial direction, it is supported by a Stützla- see 15 on an annular shoulder 10 of the nozzle body 1 from. It also has an elastically deformable spring arm 6, which is radially biased relative to the injection valve member 2 and engages in a recess 9 formed as an annular groove of the injection valve member 2. In this way, a positive connection between the locking element 4 and the injection valve member 2 is achieved. However, this only applies as long as the separator 5, which is also received in the annular space 3, is pressure-relieved. Because a fluid pressure builds up in the annular space 3, the separating element 5 is acted upon in the direction of the locking element 4 by a compressive force F (see arrow 17), which causes an axial displacement of the separating element 5 in the direction of the locking element 4. In this way, the positive connection between the locking element 4 and the injection valve member 2 is canceled by the separating element 5.

In order to ensure that the fluid pressure building up in the annular space 3 effects an axial displacement of the separating element 5 in the direction of the locking element 4, the separating element 5 in the present case has two sealing elements 12 which seal the seal Pressure chamber above the separator 5 with respect to the pressure chamber below the separator 5 effect. The pressure difference also ensures that the separating function of the separating element 5 is maintained during normal operation.

The nozzle assembly shown in Fig. 1 is that of a dual-fuel injector. For the injection valve member 2 is formed as a hollow needle and has on the inside a further injection valve member 13. In a modified nozzle assembly for a mono-fuel injector eliminates the injection valve member 13 and the injection valve member 2 is preferably designed as a simple needle.

A further preferred embodiment of a nozzle assembly according to the invention is shown in FIG. It differs from that of FIG. 1 by minor modifications in the region of the tumbler element 4 and the separating element 5. For example, the tumbler element 4 has a somewhat differently shaped spring arm 6. The separating element 5 has a collar portion 11, which is adapted to the cross section of the annular space 3 in such a way that the sealing elements 12 can be omitted. The subdivision of the annular space 3 into different pressure chambers is effected here solely by the separating element 5.

A further preferred embodiment of a nozzle assembly according to the invention is shown in FIG. 3. For the sake of simplicity, the separating element 5 is not shown, since the essential difference from the preceding embodiments is realized by the locking element 4. This has no elastically deformable spring arm 6, but a spring-loaded arm 7. The arm 7 is pressed by the spring force of a spring 14 against the injection valve member 2. In order to achieve the desired fit, a circumferential shoulder 8 is formed on the injection valve member 2, which is engaged behind by the arm 7.

In contrast, FIG. 4 is limited to the illustration of a separating element 5. The collar section 11 is particularly large in order to achieve a particularly high pressure force P acting in the axial direction over the fluid pressure building up in the annular space 3. 5, the separating element 5 of FIG. 4 is shown in a perspective view.

6 shows a perspective view of a locking element 4, which has a plurality of spring arms 6 and a plurality of support tabs 15 for support on the nozzle body 1. Spring arms 6 and support tabs 15 are connected via an annular portion 18.

Further possible embodiments of a locking element 4 are shown in FIGS. 7a) -c), each of which shows the cross-section of a locking element 4.

The locking element 4 of FIG. 7a) largely corresponds to that of FIG. 2, so that will not be discussed in detail. The support on the nozzle body 1 is effected via a plurality of support tabs 15.

The retaining elements 4 shown in FIGS. 7b) and 7c) comprise, for support on the nozzle body 1, in each case an annular support section 16 which renders the formation of individual support tabs 15 superfluous.

Claims

claims

1. nozzle assembly for a fuel injection valve for injecting a gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine, comprising a nozzle body (1) and an injection valve member (2) for releasing and closing at least one injection port to form an annular space (3) at least partially received in the nozzle body (1) liftable,

characterized in that in the annular space (3) a stationarily arranged and with respect to the injection valve member (2) radially biased tumbler (4) is taken so that between the tumbler (4) and the injection valve member (2) a force and / or Form closure is feasible, wherein for the repeal of the force and / or positive connection further an axially displaceable separating element (5) in the annular space (3) is received, which in the direction of the locking element (4) can be acted upon by a fluid pressure.

2. Nozzle assembly according to claim 1,

characterized in that the locking element (4) is designed as elastically deformable spring arm (6) or at least one elastically deformable spring arm (6) which is radially biased relative to the injection valve member (2).

3. Nozzle assembly according to claim 1,

characterized in that the locking element (4) as a spring-loaded arm (7) is formed or at least one spring-loaded arm (7) which is radially biased relative to the injection valve member (2).

4. Nozzle assembly according to one of the preceding claims,

characterized in that the injection valve member (2) has on the outer circumference at least one shoulder (8) and / or at least one recess (9), for example in the form of a groove or annular groove.

5. Nozzle assembly according to one of the preceding claims, characterized in that the locking element (4) on the nozzle body (1), preferably on an annular shoulder (10) of the nozzle body (1), is axially supported.

6. Nozzle assembly according to one of the preceding claims,

characterized in that the separating element (5) is arranged on the side facing away from the combustion chamber of the tumbler element (4).

7. Nozzle assembly according to one of the preceding claims,

characterized in that the separating element (5) is designed as a sleeve, which is preferably executed stepped outside circumference and or has a collar portion (11).

8. Nozzle assembly according to one of the preceding claims,

characterized in that the annular space (3) forms different pressure chambers which are separated by the separating element (5) and / or by at least one sealing element (12) connected to the separating element (5).

9. nozzle assembly according to any one of the preceding claims,

characterized in that the injection valve member (2) is at least partially formed as a hollow needle and in the hollow needle, a further injection valve member (13) is received liftable.

10. Fuel injection valve for injecting a gaseous and / or liquid fuel into a combustion chamber of an internal combustion engine with a nozzle assembly according to one of the preceding claims.