Patent Application
20170321636
The present invention relates to a direct-injecting gas injector for directly injecting a gaseous fuel into a combustion chamber of an internal combustion engine including an outwardly opening valve closure element and improved characteristics for injection into a combustion chamber.
Recently, in addition to liquid fuels, recently gaseous fuels, for example, natural gas or hydrogen are also increasingly being used in internal combustion engines. In the case of injectors for liquid fuels, outwardly-opening valve closure elements are used, which, for example, use sealing seat geometries, such as a ball, against a spherical section or the like. In this case, a seat angle on the cone defines the angle of the jet occurring in the combustion chamber and thus the mixture formation. If a customer desires another injection jet, this is usually made possible by a modification of the seat angle. However, in the case of liquid fuels, care must be taken to prevent the fuel from wetting a wall, since this entails the risk of droplet formation, which may result in impermissible particulate emissions and exhaust gas problems.
An example direct-injection gas injector according to the present invention for the direct injection of gaseous fuel into a combustion chamber of an internal combustion engine may have the advantage that customer-specific approaches are possible without great effort. According to the present invention, an independent design of a valve seat and a fuel flow in the combustion chamber is possible for the first time in an outwardly opening injector in gas injectors. Outwardly opening valve closure elements have the property that the direction of movement for opening is directed in the direction of the combustion chamber of the internal combustion engine. Consequently, a desired shape of a gas jet in the combustion chamber may be designed individually for customers, independently of a valve seat or other geometrical conditions. Since the present invention is limited to gas injectors which use gaseous fuels, there is also no risk of wetting walls including the associated exhaust gas problems which is present in the case of liquid fuels. According to the present invention, a cost-effective modular concept may thus be made possible to make customer-specific jet designs possible. Another great advantage of the present invention is that the gas injector may also be situated individually at any position on the combustion chamber, for example for a central installation in the cylinder head or also a lateral or inclined installation in the axial direction of the cylinder of the internal combustion engine. As a result, further design freedoms may be gained, which is very important due to the effort to reduce the size of internal combustion engines. Individual space-optimized approaches and installation positions of the injector may also be made possible. According to the present invention, this is achieved by the fact that the gas injector has a valve closure element for releasing and closing a passage opening. The valve closure element is in this case an outwardly opening valve closure element, for example, a valve needle, which opens in a flow direction of the gas injector. Furthermore, the gas injector includes a sealing seat between the valve closure element and a valve body, as well as a flow-guiding element. The flow-guiding element is configured to form a gas jet to be injected into the combustion chamber. Consequently, the geometric design of the flow-guiding element may be used to respond individually to customer-specific wishes with regard to a gas jet to be injected.
Preferred refinements of the present invention are described herein.
Preferably, the flow-guiding element is situated on the valve body. It is particularly preferred that the flow-guiding element is designed integrally with the valve body. As a result, a very simple and cost-effective manufacturing may be achieved. For different shapes of a gas jet, it is only necessary to simply exchange the valve body in each case.
It is also preferred that the flow-guiding element is situated on the valve closure element. Preferably, the flow-guiding element is provided integrally connected to the valve-closure element. Also, this measure makes it possible to achieve a shaping of a gas jet to be injected into a combustion chamber.
It is particularly preferred that the flow-guiding element includes both a device for flow guidance on the valve closure element and a device for flow guidance on the valve body.
Preferably, the flow-guiding element includes a partial sphere surface as a flow guide. By changing a radius of the partial sphere surface, it is possible to obtain a different gas jet to be injected.
According to another preferred embodiment of the present invention, the flow-guiding element includes a conical surface.
It is also possible to combine different geometric shapes with one another, for example, in the flow direction of the gas injector, a partial sphere surface adjoining a conical surface or conversely. Other geometric surfaces, for example, cylindrical surfaces or the like, are also possible.
According to another preferred embodiment of the present invention, a center axis of a gas jet to be injected intersects an axial axis of the gas injector at an angle γ. Angle γ is preferably in a range between 0° and 180°. As a result, the gas jet to be injected may be configured individually for customers. Angle γ is in a range from 0 to 60°, particularly preferably in a range from 10 to 60°.
According to another preferred embodiment of the present invention, the sealing seat between the valve closure element and valve body is a flat seat. According to the present invention, a gas injector for injecting a gaseous fuel is thus proposed for the first time, which has a flat seat as a sealing seat and which is provided as an outwardly opening injector. The great advantage of a flat seat in the case of gaseous fuels is in particular that there is a relatively wide sealing surface between the valve closure element and valve body and thus a secure seal may be provided in a relatively simple and cost-effective manner.
It is also preferred that the flow-guiding element is designed asymmetrically. This measure makes it possible to obtain very individual jet shapes for injecting into the combustion chamber. In particular, it is possible in this way, for example, to achieve flows which cause the gas jet to be applied to a cylinder head roof (coanda effect) or the gas jet to be collapsed into a concentrated central jet. As a result, the gas jet may be modulated in such a way that optimum mixture formation is achievable in the combustion chamber.
According to an alternative embodiment of the present invention, the flow-guiding element is designed symmetrically. As a result, symmetrical shapes of the gas jet in the combustion chamber may be achieved.
In order to make a particularly simple design possible, the valve closure element preferably has a conical sealing surface. This makes it possible to provide a sealing seat, which is simple to manufacture, between the valve closure element and the valve body.
The present invention also relates to an internal combustion engine including a combustion chamber and a gas injector according to the present invention, the gas injector being situated directly on the combustion chamber in order to inject gaseous fuel directly into the combustion chamber.
The internal combustion engine further preferably includes a cylinder head, the gas injector according to the present invention being situated at a predetermined distance from an end of the cylinder head directed toward the combustion chamber. According to an alternative embodiment, the gas injector protrudes by a predetermined distance from an end of the cylinder head directed toward the combustion chamber. In other words, the gas injector partially protrudes into the combustion chamber. Both measures may be used for obtaining different jet shapes of the gas jet.
It is also preferred that the gas injector is situated in the internal combustion engine at a predetermined angle to a center axis of the combustion chamber. This also makes a lateral mounting of the gas injector on the combustion chamber possible, so that a high design freedom with regard to positioning of the gas injector on the combustion chamber is obtained. This is particularly advantageous, since there are ongoing efforts to reduce the overall sizes of internal combustion engines or reduce their number of cylinders, so that an increasingly smaller installation space is present on the internal combustion engines.
Preferred exemplary embodiments of the present invention are explained in greater detail below with reference to the figures. Identical or functionally identical parts are denoted using the same reference symbols.
A gas injector 1 according to a first preferred exemplary embodiment of the present invention is described in detail below with reference to
As shown in
Valve closure element 2 opens and closes a passage opening 8, which is formed in a valve body 3. Valve body 3 also forms the housing of gas injector 1.
Valve closure element 2 is opened with the aid of a solenoid actuator 7. Solenoid actuator 7 includes an armature 70, which is directly connected to the valve closure element 2. Furthermore, a coil 71 and an internal pole 72 are provided. When coil 71 is energized, the armature is moved in the direction of combustion chamber 10 against a spring force of a restoring element 9, as a result of which valve closure element 2 lifts off from sealing seat 4. As a result, passage opening 8 is released, so that gaseous fuel is injected into combustion chamber 10.
An angle between axial axis X-X and flow-guiding element 5 is denoted by α/2 and is approximately 250. This angle α may be arbitrarily set between 0° and 180° according to the requirements of the combustion method.
According to the present invention, flow-guiding element 5 is thus situated downstream of sealing seat 4 in flow direction B of gas injector 1. Consequently, according to the present invention, a shaping of gas jet 6 is carried out separately from sealing seat 4 or from an annular gap between valve closure element 2 and valve body 3 in the completely open state of the gas injector, which defines the maximum volume flow. As a result, a customer-specific design of flow-guiding element 5 may be made possible. According to the present invention, sealing seat 4 may also be optimized independently of additional, in particular, shaping influences for gas jet 6 in order to optimally absorb occurring flow forces and closing forces. This is achieved according to the present invention in combination with an outwardly opening gas injector 1. Consequently, a very variable design of gas injector 1 is obtained, which is possible both for a central installation as shown in
In the fifth exemplary embodiment, a conical gas jet 6 results, since combustion chamber-side end 50 of flow-guiding element 5 is shortened compared to
In the ninth exemplary embodiment of gas injector 1 shown in
In the tenth exemplary embodiment of gas injector 1 shown in
The eleventh exemplary embodiment of gas injector 1 shown in
Gas injectors 1 described in the preceding exemplary embodiments in
The fourteenth exemplary embodiment of gas injector 1 shown in
According to the present invention, in the case of an outwardly opening gas injector, a separation of the geometry of the sealing seat from the geometry of the jet formation, which is predefined with the aid of flow-guiding element 5 on valve body 3 and/or flow-guiding area 20 on valve closure element 2, is achieved for the first time. As a result, individual approaches for gas jets 6, which are injected directly into a combustion chamber 10, are possible. Therefore, the fact is particularly utilized that due to the gaseous fuel there is no wall wetting and droplet formation of the fuel during the injection process. Consequently, sealing seat 4 may also be designed independently of the jet application process of gas jet 6.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2014 224 344.0 | Nov 2014 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2015/072301 | 9/29/2015 | WO | 00 |
