Exhaust system

The invention relates to an exhaust system for a W-12 reciprocating piston internal combustion engine with three rows of cylinders of four cylinders each, with outlet channels connected to the exhaust lines, in which there are two separate exhaust runs to which two cylinders per row of cylinders are connected in order to achieve a functional, structurally favorable system.

The invention relates to an exhaust system for a W-12 reciprocating piston 
internal combustion engine with three rows of cylinders of four cylinders 
each. 
Internal combustion engines of the generic type are characterized by a 
compact construction with high power density, however require high 
construction and control engineering cost for the exhaust system and 
engine control in order to achieve the legally stipulated low exhaust 
emission values. 
The problem of the invention is to propose an exhaust system for generic 
W-12 internal combustion engines which is advantageous in terms of 
function and control engineering at reasonable construction cost. 
This problem is solved according to the invention. 
According to the invention there are two exhaust runs to which two 
cylinders of the internal combustion engine per row of cylinders are 
connected. This yields a double six cylinder distribution, in which the 
entire engine control with the connected lambda control can be accordingly 
made double. This results in a functionally easily manageable motor 
control which also allows consumption-optimized operation of the internal 
combustion engine only as a six cylinder engine with only low power 
requirements. Moreover, an exhaust system split in this way is 
advantageously simplified both with respect to mounting on the internal 
combustion engine and also placement of the piping system on the motor 
vehicle. 
The cylinders per row of cylinders can be connected especially feasibly to 
the yoke-shaped manifold sections which are located on the front of the 
internal combustion engine and which are connected to the continuing 
exhaust system with a three-way catalytic converter. Preferably in 
addition the yoke-shaped exhaust sections can be structurally combined 
into a double-flow exhaust manifold. 
In the stipulated ignition sequence the indicated cylinders can be 
connected to one manifold section and the other cylinders can be connected 
to the other manifold section. This enables good tuning with respect to 
the power of the internal combustion engine with pressure pulsations or 
exhaust emissions which are uniformly distributed over time. 
One structurally favorable placement of the exhaust lines from the outlet 
channels of the cylinder heads of the internal combustion engine to the 
exhaust manifold is also engendered by the features disclosed. It is 
proposed at the same time that these exhaust lines be made heat-insulated 
in a conventional manner in order to prevent unwanted heatup in the engine 
vicinity and to ensure prompt response of exhaust neutralization.

The W-12 four-cycle reciprocating piston internal combustion engine 20 
shown in FIGS. 1 through 3 has three rows of cylinders 22, 24, 26 in a 
W-configuration with four cylinders each (numbering from 1 to 12). As FIG. 
2 shows, the middle row of cylinders 24 in the embodiment is arranged 
vertically, while the outside rows of cylinders 22, 26 are aligned 
peripherally offset by 60.degree. to the middle row of cylinders 24. 
The exhaust system is divided into two exhaust runs (compare FIG. 1) 28, 
30, the one exhaust run 28 being connected to cylinders 1 and 4 of row of 
cylinders 22, to cylinders 6 and 7 of the middle row of cylinders 24, and 
to cylinders 9 and 12 of the third row of cylinders 26. The exhaust run 30 
is accordingly connected to the still remaining cylinders 2 and 3, 5 and 
8, and 10 and 11 of cylinder rows 22, 24, 26. 
Exhaust run 28 is composed of exhaust lines 32, 34, 36, 38, 40, 42 which 
connect to the outlet channels in the cylinder heads of the internal 
combustion engines (of convention design if not described) and which 
discharge into a manifold section 44 of a common exhaust manifold 46. From 
manifold section 44 on the outlet side a preliminary tailpipe branches, 
into which conventionally a lambda probe which is not shown is inserted 
and which is connected to a three-way catalytic converter 50. Via the 
three way catalytic converter the exhaust flows to the remaining exhaust 
system of the internal combustion engine which can be of conventional 
design and which therefore is not shown. 
The exhaust run 30 has in the same way two exhaust lines 52, 54 on the 
first row of cylinders 22, two exhaust lines 56, 58 on the middle row of 
cylinders 24 and two exhaust lines 60, 62 on the third row of cylinders 26 
which discharge into the second manifold section 64 of the exhaust 
manifold 46. A second preliminary tailpipe 66 which is connected to a 
second catalytic converter 68 emerges from this manifold section 64. 
In an ignition sequence of the W-12 internal combustion engine of 
1-8-9-3-6-11-4-5-12-2-7-10 the exhaust lines of the one exhaust run 28 are 
connected to cylinders 1 and 4 of one row of cylinders 22, to cylinders 6 
and 7 of the middle row of cylinders 24 and to cylinders 9 and 12 of the 
third row of cylinders 26, while the other cylinders are connected to the 
second exhaust run 30 as described above. 
As FIG. 2 shows, exhaust lines 36, 38 and 56, 58 are located in a free 
space which is formed between the two rows of cylinders 22, 24 and which 
is overlapped by one line section 72 of the intake system of the internal 
combustion engine which is not detailed. 
Exhaust lines 32, 24 and 52, 54 of the left outside row of cylinders 22 and 
exhaust lines 40, 42 and 60, 62 of the right outside row of cylinders 26 
are each roughly vertical under the it cylinder heads, by which an 
arrangement of the exhaust lines which is favorable with respect to the 
installation space is engendered. 
These exhaust lines discharge, as FIG. 3 shows, as described above, in the 
yoke-shaped exhaust manifold 46 which is made double-flow divided by a 
bulkhead and which is placed on the power-delivering front 76 of the 
internal combustion engine. Preliminary tailpipes 48, 66 of the separate 
exhaust runs 28, 30 are connected to the double-flow exhaust manifold 46. 
As can be seen especially from FIG. 2, exhaust lines 32, 34, 36, 38, 40, 42 
as well as 52, 54, 56, 58, 60, 62 are provided with heat insulation 
(double-walled with inserted insulating pads). In the same way the exhaust 
manifold 46 and preliminary tailpipes 48, 66 are insulated up to catalytic 
converters 50, 68. 
There is one lambda probe per preliminary tailpipe which is connected 
conventionally in terms of control engineering to the double engine 
control provided for each six cylinders.