DE102016204437A1 - Nozzle assembly for a fuel injector, fuel injector - Google Patents

Abstract

The invention relates to a nozzle assembly for a fuel injection valve for injecting gaseous and / or liquid fuels into a combustion chamber (1) of an internal combustion engine, comprising a nozzle body (2) and a valve member (3) for releasing and closing at least one injection opening (4), which is formed in the nozzle body (2) or in a seat attached to the nozzle body (2) seat plate (5), in the nozzle body (2) is received in a lift or rotationally movable. According to the invention, the valve member (3) interacts with a plurality of closing elements (6), each associated with a sealing seat (7) communicating with the at least one injection opening (4), so that the closing elements (6) during a lifting or rotary movement of the valve member ( 3) the at least one injection port (4) release or close. Moreover, the invention relates to a fuel injection valve with such a nozzle assembly.

Description

The invention relates to a nozzle assembly having the features of the preamble of claim 1. Furthermore, the invention relates to a fuel injection valve with such a nozzle assembly. Gaseous and / or liquid fuels can be injected into a combustion chamber of an internal combustion engine via the nozzle assembly or via the fuel injection valve.

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 of the abovementioned type generally have at least one needle-shaped valve closure member cooperating with a sealing seat, which is guided in a liftable manner in a nozzle body for releasing and closing at least one injection opening. If it is a dual-fuel injector two such needle-shaped valve closure members or nozzle needles are provided, one of which is designed as a hollow needle to allow a coaxial arrangement. The outer needle designed as a hollow needle controls the injection of a gaseous fuel, such as natural gas, while via the inner nozzle needle, the injection of a liquid fuel, such as diesel fuel, is controllable.

The injection of gaseous fuels, regardless of whether the fuel injection valve is designed as a mono-fuel injector or as a dual-fuel injector, requires comparatively large seat diameters in order to obtain the same energy content of the injection quantity compared to the diesel injection. This leads to a large sealing circumference at the nozzle needle, which consequently experiences the alternating pressure in front of the at least one injection opening with a large area. This in turn has a negative effect on the pressure balance of the nozzle needle, so that the risk of unintentional opening exists. In order to reliably prevent unintentional opening of the nozzle needle, the nozzle needle can be axially biased in the direction of the sealing seat by means of a strong spring. However, this also increases the switching forces required to open the nozzle needle, which has a negative effect on the energy requirement of the injector.

When closing the sealing seat is exposed by the impacting nozzle needle a high load. In the injection of gaseous fuels is aggravating added that the sealing seat undergoes no lubrication. The sealing seat is thus exposed to increased wear. In this context, the temperature load from the combustion chamber also has a negative effect. The wear in the sealing seat can cause the nozzle needle does not close safely, so that the life of the fuel injection valve is significantly reduced.

The present invention has for its object to provide a nozzle assembly for a fuel injection valve, which is less subject to wear in order to increase the life of the fuel injection valve. Furthermore, the energy requirement of the fuel injection valve should be reduced by the nozzle assembly.

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 gaseous and / or liquid fuels into a combustion chamber of an internal combustion engine comprises a nozzle body and a valve member adapted to release and close at least one injection port formed in the nozzle body or in a seat plate attached to the nozzle body - or is recorded rotatably. According to the invention, the valve member cooperates with a plurality of closing elements, to each of which a sealing seat communicating with the at least one injection opening is assigned, so that the closing elements release or close the at least one injection opening during a lifting or rotary movement of the valve member.

In the nozzle assembly according to the invention, therefore, the sealing of the fuel-carrying area relative to the combustion chamber is not effected by a single nozzle needle cooperating with a sealing seat, but by a plurality of "small" closing elements, which have a much lower momentum when closing due to their reduced mass. This reduces the load in the area of the sealing seats and reduces wear. The load can be further reduced when the closure members are rolled out of their sealing seats upon movement of the valve member. The rolling of the closing elements can - depending on the arrangement of the sealing seats - be effected via a lifting or rotating movement of the valve member. The rolling movement of the closing elements further reduces wear in the area of the sealing seats.

Furthermore, the effective pressure surface is reduced to the combustion chamber via the plurality of closing elements. Because with a constant seat cross-section, which results in the sum of all seat cross-sections in the case of the several closing elements, the pressure surface which experiences the alternating pressure in front of the injection openings is reduced compared to the individual nozzle needle. Accordingly, the biasing force of the closing elements can be reduced in the direction of their sealing seats. Furthermore, the switching forces required for opening are reduced.

Accordingly, not only the service life of a fuel injection valve can be increased by using a nozzle assembly according to the invention, but also the fuel injection valve can be operated in an energy-efficient manner. Due to the reduced switching forces simplified control concepts can be realized beyond. For example, the fuel injection valve may be designed as a direct switch.

According to a preferred embodiment of the invention, the closing elements are spherical. The spherical shape simplifies the production, so that difficult-to-process materials, especially high-performance materials, such as ceramics, can be used. Since such materials are usually particularly resistant to wear, the wear can be further reduced in this way. This increases the quality and service life of the seal seat.

The sealing seats associated with the closing elements are preferably formed in the nozzle body or in the seat plate. Further preferably, the sealing seats are designed as a flat seat or conical seat. In both cases, sealing in conjunction with a spherical closure element is effected via an annular sealing contact which has a high sealing force.

Preferably, the closing elements are guided over the valve member. The guidance of the closing elements via the valve member ensures that they are lifted during a lifting or rotary movement of the valve member, from their sealing seats. The valve member may form a cage end for guiding the closing elements, in which the closing elements are accommodated at least in sections. The guide via a cage has the advantage that the closing elements are decoupled so far that they are able to align themselves independently with respect to the respective associated sealing seat.

The leadership of the closing elements may be such that not all closing elements at the same time, but temporally staggered open or close. In this way, the required opening force can be further reduced. Furthermore, different spray patterns and / or injection rates can be displayed as a function of the stroke or of the rotation of the valve member. In particular, small quantities can be easily achieved.

Further preferably, the closing elements are axially biased by at least one spring element in the direction of the sealing seats. The bias counteracts unintentional opening, wherein the biasing force can be selected comparatively small, since the closing elements have a reduced pressure area acted upon by the alternating pressure in the combustion chamber. Preferably, the spring element is supported on the side facing away from the closing elements on the valve member, so that it is carried by the valve member.

Furthermore, it is proposed that the valve member is axially biased by a spring in the direction of the sealing seats. The spring causes or supports the return of the valve member after a lifting or rotating movement. If the valve member carries out a lifting movement, the nozzle body or the seat plate attached to the nozzle body can serve as an end stop for the valve member. The valve member strikes outside the sealing seats of the closing elements on the nozzle body or on the seat plate, so that an additional load on the sealing seats is not to be feared.

Advantageously, the valve member is secured against rotation. This means that there are means which counteract a relative movement of the valve member relative to the nozzle body or the seat plate. These means may include, for example, a dowel pin or the like. Furthermore, an anti-rotation of the valve member via at least one rotation stop for the valve member or the closing elements can be effected. The rotation of the valve member ensures correct alignment of the closing elements with respect to their respective associated sealing seats in the operation of the fuel injection valve.

Preferably, the valve member has at least one geometry on the end, which engages behind at least one closing element. If the end of the valve member is formed as a cage, the cage forms such a geometry. This may for example be a foot edge, which partially engages under the closing element. This can be particularly easily realized when the closing element is spherical. During a lifting or rotary movement of the valve member, the closing element is then lifted or rolled out of the sealing seat via the foot edge.

In a further development of the invention it is proposed that the valve member is at least partially designed as a hollow body and surrounds a further nozzle body, in the release and Closing further injection openings, via which a liquid fuel can be injected, a needle-shaped valve member is received liftable. Such a nozzle assembly is used in a dual-fuel injector. The added in the valve member further nozzle body causes a secure media separation. In addition, the further nozzle body can be used to guide at least one valve member.

In contrast to a dual-fuel injector with two coaxial, nested nozzle needles, in the nozzle assembly according to the invention can be dispensed with a close to the combustion chamber guide the outer valve member. Because the several preferably spherical locking elements are guided over the cage. The injection openings for the gaseous fuel can thus be arranged further down, that is to say in the direction of the combustion chamber. By the same amount, the fuel injector having the nozzle assembly may be reset from the combustion chamber, thereby reducing the thermal load on the nozzle assembly.

Preferably, the further nozzle body forms the further injection openings for injecting the liquid fuel and a sealing seat for the needle-shaped valve member. In this way, the formation of the nozzle assembly can be kept simple.

It is also proposed that the further nozzle body passes through the outer nozzle body or the seat plate. This ensures that the injection openings formed in the further nozzle body open directly into the combustion chamber for the purpose of injecting the liquid fuel.

The additional nozzle body is preferably acted on radially outward by gas pressure and radially inward by the pressure of the liquid fuel. Due to the two-sided pressurization, the total load is reduced and the other nozzle body can be formed comparatively thin-walled.

To solve the object mentioned above, a fuel injection valve for injecting gaseous and / or liquid fuels is further proposed in a combustion chamber of an internal combustion engine comprising a nozzle assembly according to the invention. By using a nozzle assembly according to the invention, the life of the fuel injector can be increased because the sealing seats are less subject to wear. In addition, such a fuel injection valve can be operated energy-efficiently.

The fuel injection valve may be designed as a mono-fuel injector or as a dual-fuel injector.

The low switching forces for switching a fuel injection valve with nozzle assembly according to the invention enable the implementation of simple control concepts. For example, the fuel injection valve may be designed as a direct switch. As a result, the efficiency in the operation of the fuel injection valve can be further increased.

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

1 FIG. 2 shows a schematic longitudinal section through a fuel injection valve with a nozzle assembly according to the invention according to a first preferred embodiment, FIG.

2 an enlarged section of the 1 in the area of the nozzle body,

3 a schematic longitudinal section through a fuel injection valve with a nozzle assembly according to the invention according to a second preferred embodiment,

4 a sectional view of the nozzle assembly of 3 in an enlarged view,

5 a longitudinal section through a nozzle assembly according to the invention according to another preferred embodiment and

6 a comparison of a conventional nozzle assembly (left side) and a nozzle assembly (right side) according to the invention for a dual-fuel injector.

Detailed description of the drawings

That in the 1 shown fuel injection valve is used for the injection of gaseous fuel into a combustion chamber 1 an internal combustion engine. It is designed as a direct switch, since the opening requires comparatively low switching forces. Because the injection takes place via injection openings 4 in a seat plate 5 are formed, the per injection port 4 a conical sealing seat 7 for a spherical closing element 6 formed. The several spherical locking elements 6 Dense with a relatively small area, so that even a relatively small area of the changing pressure in the combustion chamber 1 is charged. Correspondingly small is the biasing force of a spring element 9 chosen, whose spring force the closing elements 6 against the sealing seats 7 axially biased (see also 2 ).

The switching force required to open the fuel injection valve is effected by a solenoid actuator having an annular solenoid 17 for acting on a lifting anchor 18 includes. The anchor 18 is with a valve member 3 coupled, the at its combustion chamber end of a cage 8th for guiding the spherical locking elements 6 formed. Through the cage 8th are the closing elements 6 from the valve member 3 decoupled, leaving them self-reliant in relation to their respective sealing seat 7 able to align. The magnetic actuator is via a clamping nut 19 with an injector body 20 and a nozzle body 2 axially braced.

How the particular 2 it can be seen, is the valve member 3 is with a spring plate 16 connected, on the one hand, the spring element 9 , on the other hand, a spring 10 is supported, the spring force of the valve member 3 in the direction of the seat plate 5 axially biased. The seat plate 5 thus serves as a stroke stop for the valve member 3 , However, only the cage gets 8th in contact with the seat plate 5 outside the sealing seats 7 , so that they are not burdened by this. On the sealing seats 7 only the momentum of the spherical locking elements acts 6 when the fuel injector closes. This can cause wear in the area of the sealing seats 7 be significantly reduced.

When opening the fuel injection valve, the cage passes through 8th a Tothub until he sees the spherical locking elements 6 from their sealing seats 7 lifts. At the cage 8th this is a geometry 11 formed in the form of a foot edge, which the spherical closure elements 6 engages behind (see 5 ). By decoupling the spherical locking elements 6 in relation to the cage 8th becomes the free orientation of the closing elements 6 ensures that they can align themselves when closing. The cage 8th is flowed around by the gaseous fuel, so that it is largely pressure balanced. To open so only small forces must be overcome, which from the relatively small seats of the sealing seats 7 for the spherical locking elements 6 arise. The bias of the closing elements 6 over the spring element 9 ensures that when starting the engine when the pressure in the combustion chamber 1 greater than the gas pressure is in their sealing seats 7 be pressed.

In the 3 another fuel injection valve is shown with a nozzle assembly according to the invention. This is designed as a dual-fuel injector and allows the injection of a gaseous fuel and / or a liquid fuel. The valve member 3 For this purpose, it is hollow and surrounds a nozzle body 12 in which a needle-shaped valve member 14 is received in a liftable manner, so that over the lifting movement of the needle-shaped valve member 14 Injection ports 13 are releasable or closable for the liquid fuel. The needle-shaped valve member 14 acts with one in the nozzle body 12 trained seal seat 15 together (see also 4 ).

The nozzle body 12 passes through the seat plate 5 , so that all injection ports 4 . 13 directly into the combustion chamber 1 lead. The injection openings 4 are closer to the combustion chamber 1 oriented than with a conventional dual-fuel injector (see 6 ). Accordingly, the fuel injection valve can be reset by the difference h in the combustion chamber 1 to be ordered. This reduces the temperature load on the nozzle assembly.

As with the fuel injector the 1 and 2 become the spherical locking elements 6 in the 3 and 4 illustrated fuel injection valve via a lifting movement of the cage 8th or the cage 8th forming valve member 3 from their sealing seats 7 lifted. The cage 8th forms end geometries 11 in the form of foot edges, which are the closing elements 6 engage behind. When closing the cage lowers 8th including the closing elements 6 However, the seat closure and the centering of the spherical closure elements 6 be effected over the prevailing flow forces and the subsequent pressure gradient. In addition, the biasing force of the spring element supports 9 the closing process. The main task of the spring element 9 however, it consists of the spherical locking elements 6 in the starting case of the internal combustion engine when the pressure in the combustion chamber 1 greater than the gas pressure is in their sealing seats 7 to press until the gas pressure has reached a predetermined operating pressure.

The valve member 3 the Indian 4 illustrated nozzle assembly could instead of a lifting movement and a rotational movement to open the sealing seats 7 To run. The on the valve member 3 or on the cage 8th of the valve member 3 trained geometries 11 which the spherical locking elements 6 engage behind, then to roll out the closing elements 6 from the sealing seats 7 to lead. To a rotational movement of the valve member 3 Instead of allowing a stroke movement, only the actuator would have to be adjusted.

A rolling out of the spherical closing elements 6 from their sealing seats 7 is also at a stroke movement of the valve member 3 possible. This embodiment is exemplary in the 5 showing a nozzle assembly according to the invention for a dual-fuel injector. The sealing seats 7 are arranged obliquely, so that the spherical locking elements 6 at a stroke of the valve member 3 or when opening via the sealing seats 7 roll. These are therefore exposed to any impact stress. This can cause wear in the area of the sealing seats 7 be reduced to a minimum. In addition, those on the cage 8th acting switching forces further lowered.

The opening and closing by means of a rolling movement of the spherical closure elements 6 can be used analogously in a mono-fuel injector according to the 1 and 2 be implemented, regardless of whether the valve member 3 performs a lifting or rotating movement.

Claims (13)

Nozzle assembly for a fuel injection valve for injecting gaseous and / or liquid fuels into a combustion chamber ( 1 ) of an internal combustion engine, comprising a nozzle body ( 2 ) and a valve member ( 3 ) for releasing and closing at least one injection opening ( 4 ) in the nozzle body ( 2 ) or in a to the nozzle body ( 2 ) seat plate ( 5 ) is formed in the nozzle body ( 2 ) is received in a liftable or rotatable manner, characterized in that the valve member ( 3 ) with several closing elements ( 6 ), which in each case one with the at least one injection opening ( 4 ) communicating sealing seat ( 7 ), so that the closing elements ( 6 ) during a lifting or rotary movement of the valve member ( 3 ) the at least one injection opening ( 4 ) release or close. Nozzle assembly according to claim 1, characterized in that the closing elements ( 6 ) are spherical. Nozzle assembly according to claim 1 or 2, characterized in that the closing elements ( 6 ) associated sealing seats ( 7 ) in the nozzle body ( 2 ) or in the seat plate ( 5 ), preferably as a flat seat or as a conical seat are formed. Nozzle assembly according to one of the preceding claims, characterized in that the closing elements ( 6 ) via the valve member ( 3 ) are guided, wherein preferably the valve member ( 3 ) end a cage ( 8th ), in which the closing elements ( 6 ) are included at least in sections. Nozzle assembly according to one of the preceding claims, characterized in that the closing elements ( 6 ) via at least one spring element ( 9 ) in the direction of the sealing seats ( 7 ) are axially biased, wherein preferably the spring element ( 9 ) on the valve member ( 3 ) is supported. Nozzle assembly according to one of the preceding claims, characterized in that the valve member ( 3 ) via a spring ( 10 ) in the direction of the sealing seats ( 7 ) is axially biased, wherein preferably the nozzle body ( 2 ) or the seat plate ( 5 ) as an end stop for the valve member ( 3 ) serves. Nozzle assembly according to one of the preceding claims, characterized in that the valve member ( 3 ) is secured against twisting. Nozzle assembly according to one of the preceding claims, characterized in that the valve member ( 3 ) at least one geometry ( 11 ), which has at least one closing element ( 6 ) engages behind. Nozzle assembly according to one of the preceding claims, characterized in that the valve member ( 3 ) is executed at least in sections as a hollow body and another nozzle body ( 12 ), in which for releasing and closing further injection openings ( 13 ), via which a liquid fuel can be injected, a needle-shaped valve member ( 14 ) is received in a liftable manner. Nozzle assembly according to claim 9, characterized in that the further nozzle body ( 12 ) the further injection openings ( 13 ) and a sealing seat ( 15 ) for the needle-shaped valve member ( 14 ) educated. Nozzle assembly according to claim 9 or 10, characterized in that the further nozzle body ( 12 ) the outer nozzle body ( 2 ) or the seat plate ( 5 ) interspersed. Fuel injection valve for injecting gaseous and / or liquid fuels into a combustion chamber of an internal combustion engine having a nozzle assembly according to one of the preceding claims. Fuel injection valve according to claim 12, characterized in that the fuel injection valve is designed as a direct switch.

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