WO2017102246A1

WO2017102246A1 - Injector assembly comprising a gas injector

Info

Publication number: WO2017102246A1
Application number: PCT/EP2016/078112
Authority: WO
Inventors: Michael Knorpp; Olaf SCHOENROCK; Sven Krissler; Friedrich Moser
Original assignee: Robert Bosch Gmbh
Priority date: 2015-12-15
Filing date: 2016-11-18
Publication date: 2017-06-22
Also published as: DE102015225216A1

Abstract

The invention relates to an injector assembly comprising a gas injector (2) for injecting a gaseous fuel, the gas injector comprising: a valve seat (3), a valve member (4) which opens and closes a passage on the valve seat (3), and a jet forming element (6) which is located downstream of the valve seat (3) in the direction of flow through the passage; the jet forming element (6) is geometrically designed in such a way that a flow rate of the gaseous fuel is increased on the jet forming element (6).

Description

description

title

Injector arrangement with gas injector prior art

The present invention relates to an injector arrangement with a gas injector with significantly reduced heat problems. In particular, due to cost advantages are also increasingly gaseous fuels for internal combustion engines, especially at

Vehicles, used. Here, in particular, the so-called. Direct injection is preferred in the gaseous fuel directly into a combustion chamber of the

Internal combustion engine is blown. However, this results in a large heat load of the gas injectors. Due to the high pressures to be sealed in the case of gaseous fuels, the use of elastomer sealants would be expedient in this case. However, the elastomer sealants are less suitable at high temperatures or are very expensive elastomer special materials necessary, which significantly increase the cost of gas injectors. Since wall wetting does not lead to deposits and soot formation in gas injectors, a wide variety of valve seat geometries can theoretically be provided. Depending on the geometry design, however, it is also possible for additional heat to be absorbed from the combustion chamber at the gas injector. It would therefore be desirable to have a simple and inexpensive cooling concept for

To have gas injectors.

Disclosure of the invention

In contrast, the injector arrangement according to the invention with the features of claim 1 has the advantage that a temperature at a gas injector during operation can be significantly reduced. this will

According to the invention achieved in that the gas injector a valve seat and a Valve member comprises, which opens and closes a passage at the valve seat. The valve member is for example a valve needle. Furthermore, a beam-shaping element is provided, which is arranged in the flow direction of the passage at the valve seat to the valve seat. In this case, the beam-shaping element is geometrically designed such that a

Flow rate of the gaseous fuel is increased. By increasing the flow velocity, the pressure of the gaseous fuel decreases after the released passage, and in particular, the temperature of the gaseous fuel also decreases. This will be an excellent

Cooling effect achieved during operation of the gas injector. Thus, according to the invention, the gas injector can be cooled effectively and close to the combustion chamber. Thus, according to the invention by the beam-shaping element in addition to the function of a beam shaping of the gaseous fuel and a

Cooling effect achieved. In this case, the temperature in the region of the projecting toward the combustion chamber tip of the gas injector can be cooled down so far that the use of elastomeric sealants is possible. Thus, a particularly effective and secure sealing of the gas injector can be made possible. The dependent claims show preferred developments of the invention.

Preferably, the beam shaping area is in

Direction of flow tapered area, in particular conical area on. Through this geometric design can specifically

Temperature history at the components of the gas injector, where the gas flows past, are influenced.

More preferably, the beam-shaping element has a widening region, which in particular widens conically. The widening area is downstream of the tapered area in the flow direction. Particularly preferred is an embodiment of the

Beam shaping element in the form of a Laval nozzle. Here is the

guided gas preferably accelerated to supersonic speed and achieved a particularly good cooling of the gas. Furthermore, this results in advantages in the blowing process and the generation of a Einblasstrahls in a combustion chamber or the like. More preferably, the beam-shaping element to a deflection with a Wnkel of 90 ° or more. By this deflection, an acceleration of the gas is also achieved and thus a pressure reduction and a temperature reduction of the gas, so that cooling of adjacent components of the gas injector is possible. In this case, the beam-shaping element can consist exclusively of the deflection region or, in addition, have a deflection region in addition to the tapering and widening region.

For a defined beam shaping is the deflection of the

Beam shaping element preferably followed by a ring area.

More preferably, the beam-shaping element comprises a heat-conducting ring. The heat-conducting ring serves to dissipate heat from the beam-shaping element. The heat-conducting ring is preferably a Teflon ring and particularly preferably arranged on an outer circumference of the beam-shaping element.

Particularly preferably, the beam-shaping element is geometrically designed such that a flow velocity in the beam-shaping element is greater than or equal to a speed of sound.

According to a further preferred alternative embodiment of the invention, the beam-shaping element comprises a plurality of nozzles, in particular with a small diameter. The small nozzles are preferably in one

Bottom area of the beam-shaping element arranged. Particularly preferably, the plurality of small nozzles are each on circular rings in the ground

arranged.

Particularly preferably, the beam-shaping element is a separate component which is fixed to the gas injector. This allows an individual production of beam shaping elements for different manufacturers of

Internal combustion engines are provided. In this case, in particular, a standardized gas injector can be used and in each case only the separate beam-shaping element can be exchanged.

Alternatively, the beam-shaping element is integral with a component of the

Gas injector, such as a housing of the gas injector formed. As a result, a number of parts of the gas injector can be reduced. Due to the temperature reduction in the region of the tip of the gas injector, a valve seat with at least one elastomer component can particularly preferably be disposed of for sealing purposes. As a result, a simple and cost-effective sealing of the high pressures of the gaseous fuel is possible.

Further preferably, the injector assembly further comprises a liquid injector which injects a liquid fuel, in particular gasoline or ethanol.

The gas injector is more preferably an outwardly opening injector. Alternatively, the gas injector is an inwardly opening injector.

Furthermore, the present invention relates to an internal combustion engine with an injector arrangement according to the invention. The injector arrangement is preferably arranged directly on a combustion chamber of the internal combustion engine. Thus, the injector assembly is a direct-injection injector assembly.

drawing

Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. In the drawing is:

FIG. 1 shows a schematic representation of an internal combustion engine with an injector arrangement according to the invention,

Figure 2 is a schematic sectional view of a gas injector of

Injector assembly of Figure 1 in the closed state,

Figure 3 is a schematic sectional view of a gas injector a

Injector assembly according to a second embodiment of the invention in the closed state,

Figure 4 is a schematic partial sectional view of the gas injector of

Figure 3 in the open state, and Figure 5 is a perspective, schematic view of a

Injector assembly according to a third embodiment of the invention.

Preferred embodiments of the invention

Hereinafter, with reference to Figures 1 and 2 a

Internal combustion engine 101 with an injector assembly 1 according to the invention described in detail.

As can be seen from FIG. 1, the internal combustion engine 101 comprises a gas injector 2 and a liquid injector 1 1 for liquid fuel. The gas injector 2 and the fuel! Njektor 1 1 are arranged in a cylinder head 13 of the internal combustion engine. The reference numeral 12 denotes a combustion chamber. The gas injector 2 and the fuel! Injector 11 are arranged directly on the combustion chamber 12 and inject or blow the fuel directly into the combustion chamber 12 a.

FIG. 2 shows the gas injector 2 in detail. The gas injector 2 comprises a valve seat 3 on a valve body 14 and a valve member 4 in the form of a valve needle. The valve member 4 is an outwardly opening valve member. FIG. 2 shows the closed state of the gas injector.

The valve member 4 is actuated by means of an actuator, not shown, to release a passage 5 between the valve member 4 and the valve seat 3. As a result, gaseous fuel can be blown into the combustion chamber 12.

The gas injector 2 further comprises a beam-shaping element 6, which in this embodiment is a separate component. The

Beam-shaping element 6 is substantially sleeve-shaped and has a tapered region 60 and a widening region 61. In this case, the widening region 61 is arranged downstream of the tapered region 60 in the direction of flow A. The beam-shaping element 6 of the first embodiment thus has the shape of a Laval nozzle. For better heat transfer from the beam-shaping element 6 to the cylinder head 13, a heat-conducting ring 7 is furthermore arranged on the outer circumference of the beam-shaping element 6. In operation, when opening the gas injector 2, the gas flowing through the passage 5 is accelerated at the tapered portion 60. This reduces the pressure and in particular the temperature of the gas also decreases. By forming the beam shaping element 6 in the form of a Laval nozzle, in which a cross-sectional area at each point in the axial direction XX is circular, the gaseous fuel is accelerated to supersonic speed. Thus, a temperature of the beam-shaping element 6, which is directly exposed to the hot gases in the combustion chamber 12, can be reduced. The temperature of the gaseous fuel during the injection process can be significantly reduced. Since the beam-shaping element 6 is also in contact with the valve body 14, the valve body 14 is cooled as well as the other components of the gas injector 2, and in particular on the valve seat third

According to the invention is thus in the operation of the gas injector 2 an effective and close to the combustion chamber cooling of components of the gas injector 2, which the

Fuel gases from the combustion chamber 12 are exposed directly or in the next

Proximity to the combustion chamber are possible.

Natural gas or hydrogen can be used as fuel of the internal combustion engine 101. The valve seat 3 of this embodiment is a metallic valve seat. However, the improved heat dissipation or cooling by the accelerating gaseous fuel, it would also be possible that an elastomeric seal is used.

Figures 3 and 4 show an injector 1 according to a second embodiment of the invention. As can be seen from the closed state shown in FIG. 3, in the second exemplary embodiment, an elastomer component 10 is arranged on the valve member 4 as a sealing element. The

Elastomer component 10 of this embodiment is a sealing ring with in

Essentially square cross section, which is fixed to the valve body 14.

The beam-shaping element 6 of the second embodiment is a sleeve which is fixed on the outer circumference of the valve body 14. The valve member 4 is in Section substantially T-shaped, wherein the valve member 4 in

Essentially has a flat valve disc 40. Here are the

As can be seen from the open position of the gas injector 2 shown in Figure 4, the gas flows through the released passage 5 against the inner wall of the sleeve-shaped beam shaping element 6 and is deflected there by 90 °. Starting from this deflection region, the gas then flows through an annular region 63 between the side region of the valve disk 40 and the sleeve-shaped beam-shaping element 6 into the combustion chamber 12. A supersonic region 15 results in the annular region 63, so that the temperature is in particular in the region of the valve disk 40 of the valve member 4 and on

Beam shaping element 6 can be significantly reduced. These

Lowering the temperature by accelerating the gaseous fuel also allows the elastomeric member 10 to be used for sealing.

FIG. 5 shows a gas injector 2 according to a third exemplary embodiment of the invention. The gas injector 2 of the third embodiment has a substantially cup-shaped beam-shaping element 6. In a ground area

64 of the beam-shaping element 6, a plurality of spray holes 65 are arranged. As can be seen from FIG. 5, the injection holes 65 in this exemplary embodiment are arranged on three spray-hole circles, which are provided concentrically to the central axis X-X. Through this multitude of small ones

Spray holes 65 can be obtained a significantly larger passage surface than in the previous embodiments. As a result, improved cooling of the beam-shaping element 6 and with the

Beam shaping element 6 connected components of the gas injector 2,

can be achieved in particular in the area directed toward the combustion chamber 12 of the gas injector 2. Another advantage of the cup-shaped beam-shaping element 6 is that no hot combustion chamber gases can pass directly to the valve seat and the valve member. Thus, these components of the gas injector are thermally better protected from the hot combustion chamber gases. The spray holes

65 are also preferably provided with a tapered portion and a widening portion corresponding to a Laval nozzle.

In this case, the bottom portion 64 has a relatively large thickness, so that long injection holes 65 are present, in which sufficient cooling is possible. Further preferably, a thermal protective layer is provided on the bottom region 64 on the side directed toward the combustion chamber, whereby a heat input into the gas injector 2 can be further minimized.

Claims

An injector assembly comprising a gas injector (2) for injecting a gaseous fuel, the gas injector comprising:

a valve seat (3),

a valve member (4) which opens and closes a passage at the valve seat (3), and

a beam-shaping element (6) which is arranged in the flow direction of the passage to the valve seat (3),

wherein the beam-shaping element (6) is formed geometrically such that a flow velocity of the gaseous fuel at the beam-shaping element (6) is increased.

Injector arrangement according to claim 1, characterized in that the beam-shaping element (6) has a region (60) which tapers in the flow-through direction.

Injector assembly according to claim 2, characterized in that the beam-shaping element (6) has a widening region, which is arranged in the flow direction after the tapered region.

Injector arrangement according to claim 3, characterized in that the beam-shaping element (6) is designed as a Laval nozzle.

Injector arrangement according to one of the preceding claims, characterized in that the beam-shaping element (6) has a deflection region (62) at an angle of 90 ° or greater.

Injector assembly according to claim 5, characterized in that at the deflection region (62) in the flow direction of the passage, an annular region (63) is connected downstream.

7. Injector arrangement according to one of the preceding claims, characterized in that the beam-shaping element (6) comprises a heat-conducting ring (7).

8. Injector arrangement according to one of the preceding claims, characterized in that the beam-shaping element (6) is designed such that the flow velocity in the region of

Beam shaping element (6) is greater than a speed of sound.

9. injector arrangement according to one of the preceding claims, characterized in that the beam-shaping element (6) has a plurality of nozzles.

10. Injector arrangement according to one of the preceding claims, characterized in that the beam-shaping element (6) is a separate component which is fixed to the gas injector, or that the

Beam shaping element (6) is integrally formed with a component of the gas injector (2).

1 1. Injector assembly according to one of the preceding claims, further comprising a Flüssigkeitsinjektor.

12. Injector arrangement according to one of the preceding claims, characterized in that the valve seat (3) at least one elastomeric component (10) is arranged for sealing in the closed state of the gas injector.

13. Internal combustion engine, comprising an injector according to one of the preceding claims.

14. Internal combustion engine according to claim 13, characterized in that the injector assembly (1) is arranged directly on a combustion chamber (12) and in particular a liquid injector adjacent to the gas injector (2) is arranged.