Patent Application
20180328238
The invention concerns a pushrod for a valve gear of an internal combustion engine.
The invention furthermore concerns a valve gear of an internal combustion engine comprising such a pushrod, in particular a valve gear for an internal combustion engine with side- or bottom-mounted camshaft. The invention furthermore concerns such an internal combustion engine, e.g. an engine in particular for a vehicle, e.g. a motor vehicle, a truck, a water vessel, a rail vehicle, or an internal combustion engine for power generation, comprising such a pushrod.
The invention furthermore concerns a vehicle, in particular a motor vehicle, e.g. a truck, a water vessel, a rail vehicle, with a pushrod or a valve gear as described in this document.
A pushrod for a valve gear forms the transmission element in the drive mechanism from the camshaft to the valves. Colloquially, the term tappet pushrod is often used for the pushrod. The pushrod in an internal combustion engine is part of the valve gear in engines, in particular engines with side- or bottom-mounted camshaft. Known pushrods consists of a cylindrical shank with ball heads or ball sockets on its ends.
To increase the bending stiffness, it is known from the prior art not to configure the shank of the pushrod so as to be tubular or cylindrical, but to make a portion of the shank more resistant to bending with a double conical form in a middle region of the pushrod, as described for example from AT 005 130 U1, U.S. Pat. No. 4,850,315 A or U.S. Pat. No. 5,027,763 A. Thus AT 005 130 U1 discloses a pushrod with a region of maximum cross-section arranged preferably centrally between the ends of the pushrod, wherein the pushrod consists of a first and a second substantially hollow rod part; these rod parts each have a maximum cross-section in the region of an open end face, wherein the rod parts are connected together inseparably at their open end faces (2b, 3b).
It is an object of the invention to refine the known prior art in order to provide a pushrod with a high bending stiffness which can be used flexibly in valve gear with restricted installation space.
This object is achieved by a pushrod with the features of the independent claim. Advantageous embodiments and applications of the invention are the subject of the dependent claims, and are explained in more detail in the description below with partial reference to the figures.
According to general aspects of the invention, a pushrod is provided, in particular for a valve gear of an internal combustion engine, the shank of which has a rib structure.
The ribs, i.e. the provision of a rib structure to increase the bending strength of a defined region of the pushrod, increases the bending resistance of the pushrod in comparison with a cylindrical design of the pushrod shank. In addition, a weight reduction can be achieved, which also improves the valve drive dynamics. A further advantage of this pushrod design is the use of the pushrod even in regions in which installation space is critical, thanks to the tapering of the pushrod in regions which are less susceptible to bending. In particular, in comparison with the double conical or “swollen” design of the shank known from the prior art, the rib structure offers, with equally good bending strength, greater flexibility in adapting the dimensions of the pushrod to the prevailing space requirement in regions in which installation space is critical. Depending on the installation space available, for example the length of the rib structure, the number and/or size of the ribs of the rib structure, may be adapted. The spacing of the start and end of the ribs may thus suitably be selected depending on the installation space in the engine.
According to a particularly preferred embodiment, the rib structure has several radially protruding ribs extending in the longitunal direction of the shank. In other words, several ribs running at least approximately axially parallel to the shank centre axis may be provided. The ribs may protrude to the same extent or to different extents in the radial direction. An advantageous variant provides that the ribs protrude to the same extent in the radial direction.
The number of ribs of the rib structure may lie in the range from three to twelve, further preferably in the range from four to eight.
The rib structure is arranged in a region of the shank between the ends of the pushrod. A preferred embodiment provides that the rib structure is arranged in a middle region of the shank. Here, the rib structure may be arranged only in the middle region, so that no rib structure is arranged on the two opposing ends of the pushrod. A possible embodiment here provides that the rib structure is arranged only in a middle region of the shank which corresponds at most to ⅔, further preferably at most to half of a length of the shank.
In this way, the pushrod can be configured tapering at the ends of the pushrod in a region which is less susceptible to bending. This is furthermore advantageous for arrangement in a region, in which installation space is critical, between the pushrod and the cylinder head of the internal combustion engine.
According to a further aspect, the rib structure may be formed integrally with the shank, which is advantageous for stability reasons and with respect to production of the pushrod.
According to a further aspect, a thickness of at least one rib of the rib structure diminishes in the radial direction away from the shank at least in portions.
According to a further aspect, a rib of the rib structure may in cross-section have the form of a wedge or rectangle. Furthermore, a rib of the rib structure may have radially rounded corners at the radially outer edge of the rib.
According to a further aspect, an outside of the ribs of the rib structure may in cross-section have the form of a circle portion with the radius of the shank in the region of the rib structure. The radius of the shank in this region constitutes the height of the ribs in this region. Furthermore, the two edges which extend inward from an outside of the ribs may be bevelled, widening towards the inside.
The ends of the shank of the pushrod may be provided with a ball head or a ball socket. The pushrod may be made of conventional structural steel or tool steel. The pushrod and/or the pushrod shank may be produced as a drawn tube with ribs, wherein the shank is freely turned at its two opposing ends. The pushrod and/or the pushrod shank may be produced as a drawn round bar with ribs and freely turned at the ends of the shank. The pushrod and/or the shank may furthermore be forged or formed as round material.
The rib structure may run out straight or be “swollen” on the shank. The rib structure may be configured with or without chamfer.
The invention furthermore concerns a valve gear of an internal combustion engine comprising a pushrod as described in this document, in particular a valve gear for an internal combustion engine with side- or bottom-mounted camshaft. The invention furthermore concerns such an internal combustion engine, e.g. an engine in particular for a vehicle, e.g. a motor vehicle, a truck, a water vessel, a rail vehicle, or for power generation, comprising a pushrod as described in this document.
The invention furthermore comprises a vehicle, in particular a motor vehicle e.g. a truck, a water vessel or a rail vehicle, with a pushrod or a valve gear as described in this document.
The preferred embodiments and features of the invention described above may be combined with each other arbitrarily. Further details and advantages of the invention are described below with reference to the enclosed drawings. The drawings show:
The same elements or those with equivalent function are designated with the same reference signs in all figures.
The pushrod 1 may be used in a valve gear for an internal combustion engine, and here form the transmission element in the drive mechanism from the side- or bottom-mounted camshaft to the gas exchange valves. Colloquially, the term tappet pushrod is often used for the pushrod.
The pushrod 1 comprises a shank 2, at the ends of which a ball head 6 or a ball socket 5 are provided.
In the embodiment variant shown in
The longitudinal direction here corresponds to the longitudinal axis L of the shank 2. A radial direction is perpendicular to the longitudinal axis L. The two opposing end regions 2a of the shank 2, which are configured cylindrically, adjoin the middle region 2b of the shank 2.
The rib structure 3 is also shown in
In the present case, the rib structure has four ribs 4 which run in the longitudinal direction parallel to the longitudinal axis L of the shank and protrude to the same extent in the radial direction. Merely as an example, a thickness of the ribs 4 of the rib structure 3 diminishes in the radial direction R away from the shank at least in portions. The ribs 4 have in cross-section the form of a wedge or rectangle with rounded corners on the radially outer edge 4a. The two edges which extend inward from an outside 4a of a rib 4 are bevelled, widening towards the inside.
Although the invention has been described with reference to specific exemplary embodiments, it is evident to a person skilled in the art that various changes may be made and equivalents used as substitutes without leaving the scope of the invention. Consequently, the invention is not restricted to the exemplary embodiments disclosed but comprises all exemplary embodiments which fall within the scope of the enclosed claims. In particular, the invention also claims protection for the subject and features of the subclaims independently of the claims to which they refer.
1 Pushrod
2 Shank
2
a Outer portion of shank
2
b Middle portion of shank
3 Rib structure
4 Rib
5 End region formed as ball cup
6 End region formed as ball
L Longitudinal axis
| Number | Date | Country | Kind |
|---|---|---|---|
| 102017004210.1 | Apr 2017 | DE | national |
