Patent Application
20210332724
This U.S. Utility Patent application claims priority to Germany Patent Application No. 10 2020 111 090.1, filed Apr. 23, 2020, the entire contents of which are incorporated herein by reference.
The present invention relates to a cover body for a valve rotating device for internal combustion engines, a corresponding valve rotating device, and a method for producing the cover body.
To prevent uneven load on the valves of an internal combustion engine in the circumferential direction, a constant rotation of the valves is necessary during operation. Due to the rotation, one-sided wear and deposits on the valve seat are avoided. In addition, an even temperature distribution in the circumferential direction is achieved. If the “natural rotation” of the valves is too slight, forced rotation devices, so-called valve rotating devices, are used.
Valve rotating devices generate valve rotation in that balls that are arranged in pockets in a base body and rest against a disk spring are forced to roll on inclined raceways formed in the pockets and thus rotate the base body and the disk spring relative to one another about the valve axis. A cover which at the same time supports the valve spring is connected to the disk spring by frictional locking. The rotation can take place either during the valve opening stroke or during the valve closing stroke. Top-mounted designs, i.e., the valve rotating device is located on the side of the valve spring facing away from the combustion chamber, as well as bottom-mounted designs, i.e., the valve rotating device is located on the side of the valve spring facing the combustion chamber, are possible. In the top-mounted design, the base body has a conical opening into which conical sections are inserted which hold the valve on the stem end. In the bottom-mounted design, the base body rests on the cylinder head, and the rotation is transmitted to the valve via the valve spring.
Due to the point contact of the balls with the disk spring, high rolling pressures occur which result in a high load on the disk spring. The high rolling load results in wear on the disk spring, in particular pitting (i.e., pitting corrosion or point corrosion).
From DE 10 2017 126 541 B3, a valve rotating device with a cover body is already known, which has a housing intended to accommodate an axial spring element. The disadvantage of this is that the housing-shaped cover is complicated and is to be produced in multiple steps with the material input being high and causing correspondingly high costs.
It is an object of the present invention to provide an improved valve rotating device with a cover body which can be produced in a simple and material-saving manner.
According to a first aspect, the invention relates to a cover body for a valve rotating device comprising a ring-shaped upper part and a ring-shaped lower part, wherein the upper part and the lower part are axially spaced apart and are adapted to accommodate an axial spring element therebetween, wherein the upper part and the lower part are connected to each other by at least one connecting piece, wherein the at least one connecting piece is arranged at the location opposite an insertion position of the axial spring element.
The advantage of the cover body according to the invention is that it can be produced in few work steps in a material-saving manner, thereby reducing the production costs.
It is preferred that the at least one connecting piece is arranged radially outside the inserted axial spring element. The advantage of the arrangement is that the inserted axial spring element is not hindered in its function.
It is preferred that the at least one connecting piece is arranged laterally outside the edge on the lower part. The arrangement laterally outside the edge on the lower part saves material.
It is preferred that the at least one connecting piece is arranged laterally outside the edge on the upper part. The arrangement laterally outside the edge on the upper part saves material.
It is preferred that the at least one connecting piece is arranged within a space spanned by the cross-sections of the upper part and the lower part. An advantage of the arrangement of the at least one connecting piece within this spanned space is a more compact design.
It is preferred that the at least one connecting piece detachably connects the upper part and the lower part. A detachable connection of the upper part and the lower part ensures easy replacement of the axial spring element by disassembling the cover body.
It is preferred that the at least one connecting piece has at least 2 connecting pieces spaced apart from each other. This has the advantage that the load is distributed more evenly.
It is preferred that the at least one connecting piece has at least 3 connecting pieces spaced apart from each other. This has the advantage that the load is even more evenly distributed.
It is preferred that the upper part and the lower part are formed integrally or in one piece with the at least one connecting piece. The advantage of an integral or one-piece design is that few work steps are necessary during production. For example, the cover body can be produced from a metal sheet by punching and bending.
It is preferred that the upper part has at least 2 axial projections for guiding at least one valve spring. This provides a simple adjustment for variation possibilities of the valve spring guide.
It is preferred that the upper part has at least 1 recess for guiding at least one valve spring. The advantage of a recess for guiding at least one valve spring is further material savings.
It is preferred that the upper part and the lower part are flat disk-shaped bodies made of metal. The advantage of flat disk-shaped bodies is that they can be punched without any problems.
According to another aspect of the invention, a valve rotating device is provided which is equipped with the cover body according to the invention. The valve rotating device comprises a ring-shaped base body which has a plurality of pockets oriented in a circumferential direction, in each of which a ball and a tangential spring are arranged, wherein the pockets have a variable depth in the circumferential direction such that inclined raceways are formed for the balls arranged therein, wherein the tangential springs push the balls towards an end of the respective pocket, a cover body according to any one of the preceding claims, wherein the axial spring element is ring-shaped and a first end of the axial spring element is supported on a ring-shaped stop surface of the base body and a second end of the axial spring element is supported on a surface of the upper part, wherein a surface of the lower part facing away from the axial spring element rests against the balls, and wherein the balls and the axial spring element are arranged overlapping in the radial direction.
The advantage of the valve rotating device according to the invention is that it can be produced in a simple and material-saving manner, thereby reducing production costs.
According to another aspect of the invention, a method of producing a cover body for a valve rotating device is provided, comprising punching a metal sheet which, after punching, has two ring-shaped parts connected to each other by at least one connecting piece, wherein the punched metal sheet is transformed into a cover body by bending.
The method according to the invention has the advantage that few work steps have to be carried out for producing a cover body.
It is preferred that the punched metal sheet has at least 2 connecting pieces that are spaced apart from each other. At least 2 connecting pieces that are spaced apart from each other have the advantage that the load is distributed more evenly.
It is preferred that the punched metal sheet has at least 3 connecting pieces that are spaced apart from each other. At least 3 connecting pieces that are spaced apart from each other have the advantage that the load is distributed even more evenly.
It is preferred that the punched metal sheet has at least 2 projections for guiding at least one valve spring which, by bending, are brought into a position aligned at substantially 90° relative to the upper part. This provides a simple adjustment for variation possibilities of the valve spring guide.
It is preferred that the punched metal sheet has at least 1 recess for guiding at least one valve spring. The advantage of a recess for guiding at least one valve spring is further material savings.
In the following, exemplary embodiments of the invention are described in more detail with reference to the figures, wherein:
The upper part 4 and the lower part 6 are axially spaced apart and connected to each other by the bead-like connecting piece 8. The connecting piece 8′ and a further connecting piece 8′ (not visible) have an L-shaped configuration, are arranged laterally on the lower part 6 and are aligned in the direction of the upper part 4 by bending and connected thereto.
The connecting pieces 8 and 8′ are arranged such that an axial spring element can be passed between them, the connecting pieces 8 and 8′ being welded, screwed or riveted to the mating part if or as required.
Projections 10 are shown on the upper part 4, which are punched out, cut or sawed. They are aligned axially outward at 90° by bending and guide the valve spring. Alternatively, a recess (not shown) on the upper part 4 can be the guide of the valve spring.
Projections 10′ are shown on the upper part 4′ which are punched out, cut or sawed. They are axially aligned by bending and guide the valve spring. Alternatively, a recess (not shown) on the upper part 4′ can be the guide of the valve spring.
Projections 10″ are shown on the upper part 4″ which are punched out, cut or sawed. They are axially aligned by bending and guide the valve spring. Alternatively, a recess (not shown) on the upper part 4′ can be the guide of the valve spring.
A plurality of pockets 16 (or recesses) are formed in the base body 22 in the circumferential direction, which pockets are oriented in the circumferential direction and extend in each case over a certain angular range in the circumferential direction (perpendicular to the drawing plane). A depth of the pockets 16 (thus, the extent of the pockets in the axial direction) is variable in the circumferential direction such that an inclined raceway 26 is formed in each of the pockets 16, cf.
Furthermore, the base body 22 has a stop surface 18 on which a first end of the axial spring element 24 is supported, wherein the stop surface 18 is preferably located radially (thus, in a direction perpendicular to the axis) further inward than the pockets 16. A bearing 20 is arranged on the stop surface 18, which allows low-friction rotation of the base body 22 and the axial spring element 24 relative to each other about the axis.
In the axial direction, the axial spring element 24 is arranged between the upper part 4 and the lower part 6, wherein a second end of the axial spring element 24 is supported on a surface of the upper part 4. In the radial direction, the axial spring element 24 is arranged further inward than the connecting piece 8. The axial spring element 24 causes a spring force in the axial direction, which pushes the base body 22 and the cover body 2 apart, if necessary, since the first end of the axial spring element 24 is supported on the stop surface 18 of the base body 22. The axial spring element 24 and the balls 14 are arranged to overlap in the radial direction. In the axial direction, the axial spring element 24 and the balls 14 are arranged side by side, with the lower part 6 being located between the axial spring element 24 and the balls 14. Overall, the preferred sequence in the axial direction is: upper part 4, axial spring element 24, lower part 6, balls 14, or, in other words, these four parts overlap in the radial direction. A disk spring is preferably used as the axial spring element 24.
A surface of the lower part 6 facing away from the axial spring element 24 rests against the balls 14 which are arranged in the pockets 16 of the base body 22. If the base body 22 and the cover body 2 are pressed together against the force of the axial spring element 24, e.g. during the opening stroke of the valve, an axial force is exerted on the balls 14 which then roll on the inclined raceway 26 in the pockets 16 on the one hand and on the surface of the lower part 6 facing away from the axial spring element on the other. As a result, the base body 22 and cover body 2 are rotated relative to each other about the axis. When the valve rotating device is unloaded, e.g. during the closing stroke of the valve, the axial spring element 24 pushes the base body 22 and the cover body 2 apart again, whereby the force acting on the balls 14 becomes smaller and thus no rolling of the balls takes place when they are reset by the tangential springs 32.
In contrast to known valve rotating devices, the rolling of the balls 14 does not take place on the disk spring 24, but on the lower part 6. As a result, high rolling pressure on the disk spring 24 and the accompanying wear is avoided. The lower part 6, in turn, can be designed in a simpler manner according to the rolling loads that occur, since it does not have to assume a spring function at the same time. Likewise, the selection of the axial spring element 24, in particular a disk spring 24, is not restricted by the rolling loads, thus, a freer design of the axial spring element 24 is made possible. This also enables a compact, space-saving design of the valve rotating device. Since the disk spring 24 is fully inserted into the cover body 2, the complete stroke movement of the disk spring 24 is converted into a rotary movement via the inclination of the pockets 16. Compared to previous designs, the rotary movement per stroke can be increased by a factor of approximately 1.5 to 2. With the rotation remaining unchanged, a stiffer disk spring 24 with increased service life can be used as an alternative.
The upper surface of the lower part 6 facing away from the axial spring element 24 can have a ball raceway, thereby reducing the rolling pressure on the lower part 6, for example.
The upper surface of the upper part 4 facing away from the axial spring element 24 is preferably configured to serve as a support surface for a valve spring.
Furthermore, the upper part 4 has projections 10 which are directed inwardly and bent in the axial direction for guiding a valve spring and, moreover, the lower part 6 has connecting pieces 8′ which are directed outwardly and are provided bent in the axial direction for connection to the upper part 4.
Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that the invention may be practiced otherwise than as specifically described while still being within the scope of the invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 111 090.1 | Apr 2020 | DE | national |
