GAS INJECTOR INCLUDING LIFT DETHROTTLING

Abstract

A gas injector for injecting a gaseous fuel, in particular directly into a combustion chamber of an internal combustion engine, including: a valve closing element for opening or closing a pass-through opening, a valve body, and a sealing seat between the valve body and the valve closing element, in the case of a maximum lift of the valve closing element a flow cross section between the valve body and the valve closing element being smaller in the flow direction upstream from the sealing seat than a flow cross section between the valve closing element and the sealing seat and being smaller than a flow cross section in the flow direction downstream from the sealing seat.

Claims

1-15. (canceled)

16. A gas injector for injecting a gaseous fuel directly into a combustion chamber of an internal combustion engine, comprising: a valve closing element for opening or closing a pass-through opening; a valve body; and a sealing seat between the valve body and the valve closing element; wherein in the case of a maximum lift of the valve closing element, a flow cross section between the valve body and the valve closing element is smaller in a flow direction upstream from the sealing seat than a flow cross section between the valve closing element and the sealing seat and is smaller than a flow cross section in the flow direction downstream from the sealing seat.

17. The gas injector as recited in claim 16, wherein the valve closing element includes an outside cylinder area defining the flow cross section which delimits the through-flow.

18. The gas injector as recited in claim 16, wherein the valve body includes an inside cylinder area defining the flow cross section which delimits the through-flow.

19. The gas injector as recited in claim 16, wherein one of: i) a flow cross section which delimits the through-flow is defined by several bores and recesses in the flow direction upstream from the sealing seat, ii) a flow cross section which delimits the through-flow is defined by a polygonal geometry, or ii) a flow cross section which delimits the through-flow is defined by at least one of an elliptical outer contour and an elliptical inner contour.

20. The gas injector as recited in claim 16, wherein a flow cross section between the valve body and the valve closing element in the flow direction upstream from the sealing seat is asymmetric to a center axis of the gas injector.

21. The gas injector as recited in claim 16, wherein the gas injector is a gas injector which opens outwardly.

22. The gas injector as recited in claim 16, wherein the flow cross section at the flow cross section in the flow direction upstream from the sealing seat is selected in such a way that at least the speed of sound is reached in this area in the case of an open gas injector.

23. The gas injector as recited in claim 16, wherein the valve body includes a thermal protection device at an end of the valve body on the combustion chamber side.

24. The gas injector as recited in claim 23, wherein the thermal protection device includes a heat dissipation cap having a first heat conduction coefficient which is greater than a heat conduction coefficient of the valve body.

25. The gas injector as recited in claim 24, wherein the thermal protection device includes a first thermal protective layer having a second heat conduction coefficient which is at least one of: i) smaller than the heat conduction coefficient of the valve body, and ii) smaller than the first heat conduction coefficient of the heat dissipation cap.

26. The gas injector as recited in claim 25, wherein the first thermal protective layer is situated on the heat dissipation cap.

27. The gas injector as recited in claim 24, wherein the heat dissipation cap includes a plate-shaped area or a plate-shaped base area, and a wall area situated at the plate-shaped base area.

28. An injector system, comprising: a gas injector for injecting a gaseous fuel into a combustion chamber; and a cylinder head having a cylinder head opening in which the gas injector is situated, an end of the gas injector facing the combustion chamber being situated in the axial direction at a predetermined distance from an end of the cylinder head opening on the combustion chamber side.

29. The injector system as recited in claim 28, wherein the gas injector including a gas injector injects a gaseous fuel directly into the combustion chamber, the gas injector including a valve closing element for opening or closing a pass-through opening, a valve body, and a sealing seat between the valve body and the valve closing element, wherein in the case of a maximum lift of the valve closing element, a flow cross section between the valve body and the valve closing element is smaller in a flow direction upstream from the sealing seat than a flow cross section between the valve closing element and the sealing seat and is smaller than a flow cross section in the flow direction downstream from the sealing seat.

30. An internal combustion engine, comprising: a combustion chamber; and a gas injector injects a gaseous fuel directly into the combustion chamber, the gas injector including a valve closing element for opening or closing a pass-through opening, a valve body, and a sealing seat between the valve body and the valve closing element, wherein in the case of a maximum lift of the valve closing element, a flow cross section between the valve body and the valve closing element is smaller in a flow direction upstream from the sealing seat than a flow cross section between the valve closing element and the sealing seat and is smaller than a flow cross section in the flow direction downstream from the sealing seat.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Exemplary embodiments of the present invention are described in detail below with reference to the figures, identical or functionally identical parts being denoted by the same reference numerals.

[0028] FIG. 1 shows a schematic, highly simplified sectional view of an injector system including a gas injector in a closed state according to a first exemplary embodiment of the present invention.

[0029] FIG. 2 shows a schematic, highly simplified sectional view of the injector system according to the present invention from FIG. 1, the gas injector according to the present invention being in an open state.

[0030] FIG. 3 shows a schematic, highly simplified sectional view of an injector system including a gas injector in a closed state according to a second exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0031] An injector system 8 according to a first exemplary embodiment of the present invention is described in detail below with reference to FIGS. 1 and 2.

[0032] Injector system 8 includes a gas injector 1 for injecting a gaseous fuel into a combustion chamber 9 and a cylinder head 5 having a cylinder head opening 50 of an internal combustion engine (not shown). Gas injector 1 is situated in cylinder head opening 50, an end 10 of gas injector 1 facing combustion chamber 9 being situated at a first predetermined distance 100 from an end 51 of cylinder head opening 50 on the combustion chamber side.

[0033] Gas injector 1 furthermore includes a valve closing element 2, a valve body 3 having a pass-through opening 37, which opens or closes valve closing element 2, and a sealing seat 4 which is situated between valve body 3 and valve closing element 2. In FIG. 1, gas injector 1 is in a closed state, pass-through opening 37 being closed by valve closing element 2. FIG. 2 shows gas injector 1 in a fully open state, i.e., at a maximum lift of valve closing element 2.

[0034] Valve body 3 furthermore includes a thermal protection device 31 at an end 30 of valve body 3 on the combustion chamber side.

[0035] In particular, thermal protection device 31 includes a heat dissipation cap 32 having a first heat conduction coefficient. In addition, thermal protection device 31 includes a first thermal protective layer 33 having a second heat conduction coefficient. Furthermore, heat dissipation cap 32 includes a plate-shaped area 34 which is fastened to valve body 3 with the aid of a welded connection 38.

[0036] Moreover, valve closing element 2 is provided with a second thermal protective layer 20 which has a third heat conduction coefficient.

[0037] The first heat conduction coefficient of heat dissipation cap 32 is greater than a heat conduction coefficient of valve body 3. Furthermore, the second heat conduction coefficient of first thermal protective layer 33 is smaller than the heat conduction coefficient of valve body 3 and smaller than the first heat conduction coefficient of heat dissipation cap 32. The third heat conduction coefficient of second thermal protective layer 20 of valve closing element 2 is advantageously equal to the second heat conduction coefficient.

[0038] As a first measure, a transfer of the heat occurring in the combustion chamber to valve body 3 is thus prevented as a result of the poor heat-conducting properties of first thermal protective layer 33 and second thermal protective layer 20 as compared to valve body 3. If despite these protective measures some of the heat is conducted through first thermal protective layer 33 and second thermal protective layer 20, this heat is dissipated as a second measure via heat dissipation cap 32 to cylinder head 5. It may thus be ensured that valve body 3 and sealing seat 4 are not subjected to thermal stress.

[0039] On a contact surface 36, heat dissipation cap 32 includes a surface structuring (not shown), contact surface 36 being configured to establish contact between heat dissipation cap 32 and a cylinder head 5 and being situated on heat dissipation cap 32. The surface structuring is in particular designed as a knurling. The recesses of the knurling, which are not shown, are provided with a heat conduction paste, thus increasing the heat transfer between heat dissipation cap 32 and cylinder head 5.

[0040] Furthermore, sealing seat 4 is situated on valve body 3 at a second predetermined distance 200 from a stop area 11 of valve body 3 in axial direction X-X of gas injector 1. This results in a constructive separation between sealing seat 4 and stop area 11 of valve body 3.

[0041] In FIG. 2, gas injector 1 is shown in an open state, pass-through opening 37 being fully opened by valve closing element 2. This state corresponds to a maximum lift of valve closing element 2. According to the present invention, a flow cross section 6 between valve body 3 and valve closing element 2 is in this case smaller than a flow cross section 7 between valve closing element 2 and sealing seat 4. An injected fuel quantity is therefore determined by flow cross section 6 and not by flow cross section 7. As a result of this measure, a cross section which determines the through-flow is moved to the inside of gas injector 1.

[0042] As is apparent from FIGS. 1 and 2, flow cross section 6 which is situated inside the gas injector is defined by a cylindrical outer contour of valve closing element 2 and a cylindrical inner contour of valve body 3. The contours of valve closing element 2 and valve body 3 may be generated having minor tolerances with the aid of simple manufacturing processes, in particular metal-cutting manufacturing processes. In this way, the dependence on strong temperature changes, wear and tolerance chains occurring in the related art may be minimized for the injected fuel quantity. Flow cross section 6 inside the gas injector is not subjected to any type of wear, as is the sealing seat in the related art which usually determines the through-flow.

[0043] Another advantage is that the flow in flow cross section 6 inside the gas injector may reach the speed of sound and therefore determines the stationary through-flow even in the case of a further increased lift of the valve closing element. Thus, the minimal flow cross section which generates the gas flow, to be injected, at the speed of sound is defined very precisely.

[0044] When designing the gas injector, a maximum lift is selected to be big enough for a flow cross section 6 situated inside the gas injector, i.e., in the flow direction through the gas injector, upstream from sealing seat 4 to be smaller than a flow cross section 7 situated downstream from sealing seat 4 in the case of a maximally open gas injector. In addition to the tolerance chain, a potentially occurring oscillation of valve closing element 2 may also be taken into consideration in the design process. Temperature-related length changes due to different materials may also be taken into consideration. Wear does not play a role either for the static through-flow defined by flow cross section 6. The gas injector according to the present invention may thus ensure a high, constant through-flow quantity over its entire service life.

[0045] Gas injector 1 according to the present invention provides a plurality of advantages. In particular, thermal protection device 31 of valve body 3 as well as second thermal protective layer 20 of valve closing element 2 make it possible to reduce a temperature, in particular in the area of gas injector 1 on the combustion chamber side. Thermal stress of valve body 3 and of sealing seat 4 may thus be prevented. Repositioning gas injector 1 into cylinder head opening 50 also contributes to reducing thermal stress on valve body 3 and sealing seat 4. This and repositioning sealing seat 4 results in the fact that sealing seat 4 may be formed from a soft material. This is particularly advantageous since a soft material has very good sealing properties and damping properties. In the case of gas injector 1 according to the present invention and the injector system according to the present invention, a consistent separation of functions is furthermore made possible. For example, the sealing, the determination of the static through-flow quantity, the absorption of mechanical stresses, the spray or mixture formation as well as the absorption and dissipation of thermal stresses are provided by different components of gas injector 1. This results in a more cost-effective configuration and a fail-proof operating mode of gas injector 1.

[0046] Gas injector 1 of the second exemplary embodiment in FIG. 3 in general differs from gas injector 1 of the first exemplary embodiment in that heat dissipation cap 32 includes a plate-shaped base area 34 and a wall area 35 situated on plate-shaped base area 34. This allows for contact surface 36 to have a larger design between heat dissipation cap 32 and cylinder head 5, thereby increasing a heat transfer to the cylinder head. Heat dissipation cap 32 is furthermore fastened to valve body 3 with the aid of a calked connection 39. Furthermore, the inner flow cross section between valve closing element 2 and valve body 3 is smaller in the case of a fully open valve than a flow cross section 7 situated in the flow direction downstream from the sealing seat in the case of a fully open gas injector.

[0047] It should be noted that the above-named specific embodiments are provided for illustration purposes only and not for limitation purposes of the present invention. Within the scope of the present invention, different changes and modifications are possible without departing from the scope of the present invention or its equivalents.