Patent Application
20240240577
This application claims priority to German Patent Application No. DE 10 2023 200 287.6 filed on Jan. 16, 2023, the contents of which are hereby incorporated by reference in its entirety.
The present invention relates to a valve for an internal combustion engine which comprises a hollow space with sodium for cooling received therein. Further, the invention relates to a method for producing such a valve.
Usually, a valve in an internal combustion engine serves for the optional opening and blocking of flows, for example of air, fuel, an air-fuel mixture and exhaust gas. Thus, such a valve is exposed during the operation to elevated temperatures and an aggressive environment. In order to fulfil requirements in terms of the thermal and/or thermo-chemical stability of such a valve, valves are usually produced from metals and/or alloys.
It is known to introduce sodium into a hollow space of such a valve in order to cool the valve during the operation.
The present invention deals with the object of stating for a valve of the type mentioned above, for a method for producing such a valve, improved or at least other embodiments. In particular, the present invention deals with the object of stating for the valve and for the method improved or at least alternative embodiments which are characterised by increased component strength.
According to the invention, this object is achieved through the subjects of the independent claim(s). Advantageous embodiments are subject of the dependent claims.
The present invention is based on the general idea of additionally introducing a non-evaporable getter in a hollow space of a valve, in which sodium for cooling is received. The getter binds, in particular by means of sorption, foreign constituents present in the hollow space which differ from sodium, which includes hydrocarbons such as oils, greases and the like. Especially, the getter results in binding short-chain hydrocarbons. The knowledge that the said foreign constituents result in an increase of the pressure in the hollow space and a reduction of the cooling achieved by means of the sodium is utilised here. By using the getter in the hollow space and the binding of the foreign constituents thus taking place, both the pressure in the hollow space, i.e. the internal pressure, is reduced and the cycle for cooling the valve performed by the sodium, improved. Besides the directly improved cooling achieved thereby, the reduced internal pressure also results in an improved heat transfer within the hollow space and a further improved cooling. Thus, the valve during the operation has a reduced temperature and a reduced internal pressure, so that the strength of the valve and thus the component strength are increased.
According to the inventive idea, the valve comprises a valve bottom and a valve stem projecting from the valve bottom. In the interior of the valve, the valve delimits a hollow space in which sodium for cooling the valve during the operation is received. In addition, a non-evaporable getter is arranged in the hollow space.
The getter is also familiar to the person skilled in the art as “absorbing material”. The non-evaporable getter is also familiar by the English designation “non-evaporable getter” and the abbreviation “NEG”.
Preferentially, the getter binds the foreign constituents which are present in particular as gases by means of chemical sorption. As a consequence, the foreign constituents are bonded to the getter with a higher bonding energy. Thus, it is prevented that the foreign constituents during the operation of the valve are again passed on into the hollow space from the getter. Thus, a reliable cooling and a lasting increase of the component strength takes place in this manner.
Advantageously, the valve is employed in an internal combustion engine in order to open and block flows in the internal combustion engine, in particular into an associated cylinder and/or from an associated cylinder.
Practically, the valve bottom interacts with an associated valve seat in order to block and open a corresponding opening.
The adjustment of the valve practically takes place via the valve stem.
To produce the valve, sodium and the non-evaporable getter are introduced into the hollow space of the valve and the hollow space closed.
The order in which sodium and the getter are introduced into the hollow space can be any.
It is conceivable to initially introduce the getter into the hollow space so that the getter is preferentially present in the region of the hollow space facing the valve bottom.
In preferred embodiments, the getter is activated only after the introduction into the hollow space, preferentially additionally after the closing of the hollow space. Thus, the getter is preferentially activated only in particular when it has already been introduced into the hollow space, preferentially in addition, when the hollow space has already been closed. The activation of the getter results in the said bonding of the foreign constituents in the hollow space. Thus, when the getter following the introduction into the hollow space, preferentially in addition after the closing of the hollow space, is activated, the getter exclusively binds foreign constituents present in the hollow space. This means that the saturation limit of the getter is not reached through the bonding of constituents present outside the hollow space. Consequently, a reliable bonding of all foreign constituents or at least an increase of the portion of the bonded foreign constituents is achieved in this manner. This effect is improved/increased by closing the hollow space prior to the activation. Thus, less getter is ultimately required in this way, wherein at the same time the said improved cooling and increased component strength are attained.
In preferred embodiments, the getter comprises a metal base. This means in particular that the main constituent of the getter is a metal. Thus, the non-evaporable characteristic of the getter can be more easily achieved.
Preferentially, the getter comprises a zirconium base. Besides the said non-evaporable characteristic, the zirconium base results in an increased temperature resistance of the getter so that a reliable bonding of the foreign constituents is achieved even during the operation of the valve. Thus, the improved cooling and increased component strength are provided even at elevated operating temperatures of the valve, so that the valve can be employed altogether in a greater operating temperature range. In addition, the use of zirconium as base results in a cost reduction, in particular compared with getters having a titanium base.
Advantageously, besides the metal base, in particular the zirconium base, the getter also comprises further components of metal. In preferred embodiments, the getter comprises vanadium and/or titanium.
Particularly preferably, the getter comprises a zirconium base as well as vanadium and titanium. In particular, the getter consists of the zirconium base as well as vanadium and titanium. Besides the described increase of the possible operating temperatures of the valve, this leads to an improved binding of the foreign constituents and an increase of the saturation limit of the getter. Altogether, more foreign constituents at simultaneously increased possible operating temperatures are bonded in this manner. Consequently, the cooling is further improved and the component strength further increased.
Preferred are embodiments, in which the getter is present in the form at least of a contiguous body, i.e. as at least a getter piece. Thus, the getter preferably consists of at least one getter piece. This results in a simplified handling and thus simplified production of the valve. In addition to this, a more reliable bonding of the foreign constituents takes place in this manner, so that the cooling is further improved and the component strengths further increased.
In particular, the getter is present as a single getter piece; the getter thus consists of a single getter piece.
Preferably, a body forming the valve later on is provided for producing the valve, which in the following is also referred to as starting body. The starting body comprises the valve bottom of the valve. In addition, the starting body comprises a portion projecting from the valve body, which at least partially forms the valve stem of the valve. In the following, the portion is also referred to as stem portion. The starting body delimits in its interior a hollow space which extends into the stem portion. On the side facing away from the valve bottom, the hollow space is open via the stem portion, i.e. comprises an opening that is open towards the outside, which in the following is also referred to as stem opening. For producing the valve, sodium and the getter are introduced into the hollow space via the stem opening and the stem opening subsequently closed with a closure.
It is likewise conceivable to introduce sodium and/or the getter into the hollow space via the valve bottom. For this purpose, the starting body can comprise in or on the bottom an opening also referred to as bottom opening in the following. Sodium and/or the getter are/is introduced into the hollow space via the bottom opening and the bottom opening then closed. The closing of the bottom opening can take place by means of press-fit stemming of a closure body and subsequent welding.
Preferably, the activation of the getter takes place after the closure of the hollow space.
Preferably, the getter is initially introduced into the hollow space and subsequently sodium.
In preferred embodiments, the closing of the stem opening by means of the closure takes place through a welded connection. The closure and the stem portion are thus welded together. Thus, a reliable and fluid-tight sealing of the hollow space with increased temperature resistance at the same time takes place.
Advantageously, the valve, after the closure of the stem opening, is heat-treated for balancing the microstructure that was changed by the welding. This means that the changes in the microstructure of the valve that occurred because of the increased temperature that occur during the welding are in particular balanced with the heat treatment, in particular at least partially reversed. In this way, the mechanical stability of the valve and thus the component strength are further increased.
Preferentially, the activation of the getter takes place during the said heat treatment for balancing the changed microstructure. This means that both the balancing of the changed microstructure and also the activation of the getter take place during the same process for producing the valve. This results in a substantial simplification of the valve production.
The activation of the getter during the heat treatment for balancing the changed microstructure is achieved in particular in that the getter has a zirconium base.
Preferably, the getter is passivated before being introduced into the hollow space. The passivation of the getter prevents that the surface of the getter is covered and/or occupied, or such an occupation is at least reduced. Only through the subsequent activation is the passivation cancelled, so that the getter binds the said foreign constituents in the hollow space.
The passivation of the getter advantageously takes place by means of the forming of oxides and/or carbides and/or nitrites on the surface of the getter by means of physisorption. This physisorption is broken/dissolved upon the activation of the getter so that the getter binds the said foreign constituents in the hollow space.
Further important features and advantages of the invention are obtained from the subclaims, from the drawings and from the associated figure description by way of the drawings.
It is to be understood that the features mentioned above and still to be explained in the following cannot only be used in the respective combination stated but also in other combinations or by themselves without leaving the scope of the present invention.
Preferred exemplary embodiments of the invention are shown in the drawings and are explained in more detail in the following description, wherein same reference numbers relate to same or similar or functionally same components.
It shows, in each case schematically
A valve 1, as is exemplarily shown in
In the shown exemplary embodiment, sodium 5 and the previously passivated getter 6 are introduced into the hollow space 4 in a first measure 100. In the shown exemplary embodiment, initially the getter 6 and subsequently sodium 5 are introduced into the hollow space 4. Thus, the getter piece 7 is arranged in the representation of
As is evident in particular from
With the valve 1 according to the invention and the associated production method, foreign constituents present in the hollow space 4, in particular hydrocarbons and air-gases, for example nitrogen, oxygen, etc. are bonded on the getter 6, preferentially by means of chemical sorption. This results in a reduced internal pressure in the valve 1 and thus, besides an improved cooling, in an increased strength of the valve 1.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2023 200 287.6 | Jan 2023 | DE | national |
