Cylinder head for a uniflow-scavenged two-stroke internal-combustion engine

A cylinder head for a uniflow-scavenged two-stroke internal-combustion engine, particularly in motor vehicles, is provided with outlet valves which can be controlled by a camshaft. Outlet ducts connected with the outlet valves extend out of the cylinder head. A total of four outlet valves are provided for each cylinder, with the associated outlet ducts being guided to one side of the cylinder head. The camshaft is arranged laterally of the cylinder head opposite the outlet side of the outlet ducts. The outlet valves which are situated on the side facing away from the camshaft can be operated from the direction of the camshaft by way of operating members transversely penetrating the cylinder head.

BACKGROUND AND SUMMARY OF THE INVENTION 
The present invention relates to a cylinder head for a uniflow-scavenged 
two-stroke internal-combustion engine, and more particularly, to a 
cylinder head having outlet ducts controlled by camshaft outlet valves. 
A conventional cylinder head is described, for example, in DE-GM 82 23 945. 
An outlet valve is provided in the cylinder space which is controlled by a 
cam which has a lift shoulder and a drop shoulder and is arranged on the 
camshaft. A disadvantage in the case of uniflow-scavenged two-stroke 
internal-combustion engines is the relatively large height of the cylinder 
head. 
It is, therefore, an object of the present invention to provide a cylinder 
head which has a relatively low height and nevertheless has a high 
efficiency while the constructional expenditures are kept to a minimum. 
According to the present invention, this object has been achieved by 
providing four outlet valves respectively for each cylinder, respective 
outlet ducts of the outlet valves being guided to a side of the cylinder 
head, wherein the camshaft is arranged laterally of the cylinder head 
situated opposite the outlet side of the outlet ducts, and certain of the 
outlet valves situated on the side facing away from the camshaft being 
operable by the camshaft via operating members transversely penetrating 
the cylinder head. 
By providing four outlet valves for each cylinder in a navel arrangement, a 
space-saving construction is achieved for the four outlet valves, 
particularly a clear reduction of the height of the cylinder head in 
comparison to known cylinder head constructions. Specifically, because of 
the fact that the outlet ducts assigned to the four outlet valves are 
guided to one side of the cylinder head, a corresponding space becomes 
vacant on the other side of the cylinder head which according to the 
present invention can now be utilized for the positioning of the camshaft. 
Instead of the generally customary arrangement of the camshaft in the 
longitudinal axis of the cylinder head between and above the valves, the 
camshaft of the present invention is now situated axially parallel to the 
longitudinal axis of the laterally adjacent cylinder head. In this manner, 
the cylinder head need only be constructed as high as required for 
operating the outlet valves. 
The outlet valves situated on the side facing away from the camshaft must 
be operated from the direction of the camshaft by operating members 
transversely penetrating the cylinder head. For this purpose, various 
possibilities are within the contemplation of the present invention. In a 
simple manner, for example, a push rod can be guided along the cylinder 
head ceiling diagonally through the control space of the cylinder head. 
For the outlet valves arranged directly laterally next to the camshaft, 
known rocker arm constructions can be used in a simple manner. 
By way of the arrangement of the valves and the pertaining outlet ducts 
according to the invention, relatively large outlet cross-sections for 
reducing the scavenging pressure can also be provided according to the 
present invention. In addition, in this manner, only one hot engine side 
can be implemented. The cylinder head according to the present invention 
is nevertheless of a relatively simple construction so as to achieve a 
substantial cost reduction. 
With the cylinder head according to the present invention, an application 
of a phase adjuster to the camshaft can also be implemented. That is, 
several relative positions of the camshaft can be adjusted with respect to 
the crankshaft, whereby changes of the outlet times of the outlet valves 
become possible.

DETAILED DESCRIPTION OF THE DRAWINGS 
A cylinder head 1 covers cylinders (not shown) by a cylinder head bottom 1a 
(FIGS. 2 and 3). For each cylinder, the cylinder head 1 has a centrally 
arranged shaft 2 for an injection nozzle. For reasons of clarity in FIG. 
1, only the parts of the cylinder head 1 for one cylinder are provided 
with reference numbers. 
The cylinder head 1 also comprises four outlet valves 3, 4, 5 and 6 for 
each cylinder which are arranged in a V-shape with respect to one another 
and symmetrically with respect to a longitudinal axis 7. The outlet valves 
3, 5 are therefore situated on one side of the longitudinal axis 7 of the 
cylinder block, and the outlet valves 4, 6 are situated correspondingly on 
the other side of the longitudinal axis 7. 
On the side of the longitudinal axis 7 with the outlet valves 4, 6, the 
cylinder head 1 has a slightly wider construction to permit the 
installation of a camshaft 8 axially parallel to the longitudinal axis 7 
of the cylinder head. With respect to the height, the center axis of the 
camshaft 8 is situated approximately at the half point of the length of 
the outlet valve shafts. The outlet valves 4, 6 which are situated on the 
same side of the cylinder head as the camshaft 8 are operated by cams of 
the camshaft 8 by way of a rocker lever construction 9 with play 
compensating elements. 
The outlet valves 3, 5 situated on the other side are operated by rocker 
levers 10 having play compensating elements. For the operation of the 
rocker levers 10, push rods 11 are used which extend through the cylinder 
head 1 transversely and sloped downward in the direction of the camshaft 8 
along the cylinder head ceiling as seen in see FIG. 3. The push rods 11 
are operated in the same manner as the rocker levers 9 by cams of the 
camshaft 8. 
The outlet valves 3, 4, 5 and 6 each control one respective outlet duct 12, 
13, 14 and 15. The outlet duct 13 for the outlet valve 4, which is 
situated on the side of the cylinder head 1 in which the camshaft 8 is 
also disposed, is guided in the direction of the outlet valve 3 situated 
on the other side, where it is combined with the outlet duct 12 to form a 
common collecting duct 16. On the side (i.e., outlet side) facing away 
from the camshaft 8, the collecting duct 16 is guided laterally out of the 
cylinder head in the direction of arrow A as seen in FIGS. 1 and 3. 
Likewise, the outlet duct 14 of the outlet valve 6 is guided to the side of 
the cylinder head facing away from the camshaft 8 and is combined there 
with the outlet duct 15 of the outlet valve 5 to form a common collecting 
duct 17 which corresponding to arrow B in FIG. 1 leads out of the cylinder 
head on the same side as the collecting duct 16. For reasons of clarity, 
the individual ducts are illustrated in FIG. 1 only by broken lines. In 
conjunction with FIGS. 2 and 3, however, their respective position and 
course are clearly recognizable. 
The guiding together of the outlet ducts 13, 14 in pairs to form the two 
collecting ducts 16, 17 represents another constructive simplification and 
saving of space. In addition, an intensive water cooling can be achieved, 
particularly between the outlet ducts. In comparison to known cylinder 
head constructions, a height reduction of approximately 40% can be 
achieved. As illustrated, the cylinder head can be closed off in a known 
manner directly above the rocker levers 9, 10 by a cylinder head cover 18. 
Although the invention has been described and illustrated in detail, it is 
to be clearly understood that the same is by way of illustration and 
example, and is not to be taken by way of limitation. The spirit and scope 
of the present invention are to be limited only by the terms of the 
appended claims.