BACKGROUND OF THE INVENTION Turbo units are often used for extracting energy from engine exhaust gases, wherein the turbo unit comprises an exhaust driven turbine which drives a compressor for compressing the intake air supplied to the engine, so called supercharging. A turbo compound unit is sometimes arranged after the turbo unit for extracting some of the remaining energy from the exhaust gases.

One example of such a turbo compound unit is a second exhaust driven turbine which e. g. mechanically transfers energy to the drive shaft of the engine or the like.

The turbo compound unit normally comprises a shaft in a bearing with a rigidly mounted turbine wheel that can be driven at high speed by the exhausts, e. g. up to about 80.000 rpm. This speed is reduced by means a gear train and possibly other methods down to a considerably lower speed and is transferred to the engine shaft via a fluid coupling which prevents torsional vibration occurring in the engine shaft to be transmitted to the turbine shaft. Normally, a very efficient lubrication

of the turbine shaft bearing is needed in order to endure the high rotation speeds occurring. For this object, lubrication oil may be fed with an overpressure of about 1-5 bar to said turbine bearing.

It appears that the oil leaving the turbine bearing which is supposed to drain down into the crankcase, may hit the fluid coupling which is rotating with high speed as well as other rotating parts. This results in a formation of a turbulent spray of drops that move in the radial direction outwards until they hit the surrounding surfaces. It now appears that the oil flow impedes the rotation of the fluid coupling, which negatively influences the efficiency.

SUMMARY OF THE INVENTION One object of the invention is therefore to provide an enclosure of the rotating fluid lubricated element that avoids the problem described above.

For this object, the enclosure according to the invention is characterized by a partition wall that is mounted between the drainage point and the second element, in such a manner that lubrication fluid is substantially prevented from migrating from the drainage point to the second element.

Advantageous embodiments of the invention are shown in the subsequent depending claims.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be further described in the following, in a non-limiting way with reference to the accompanying drawing which is a vertical section

through a turbo compound unit designed according to the invention.

DETAILED DESCRIPTION OF THE INVENTION The turbo compound unit shown in the figure is meant for use in a combustion engine, preferably included in the drive train of a heavy truck or a bus.

The turbo compound unit comprises a power turbine 11 located in an exhaust channel 10 which turbine is mounted on a turbine shaft 12. The shaft is mounted by means of a front radial bearing 13, a rear radial bearing 14 and an thrust bearing 15. Lubrication oil is fed to these bearings via not shown channels with an overpressure in the range of about 1-5 bar. The oil is drained from these bearings in a manner known in the field via not shown draining points.

A gearwheel 16 is rigidly connected to the shaft 12 and is in mesh with a larger gearwheel 17 that belongs to the primary side of a fluid coupling 18, that is carried in a combined radial and axial bearing 20 at a front end wall 19 of the turbo compound housing. Thus, rotation energy is transferred from the turbine shaft via the fluid coupling to its secondary side.

The lubricating oil having passed through the bearings 13-15 and being present in front of the gearwheel 17 is intended to flow down along the inside of the front end wall 19 turbo compound housing. A partition wall 21 is mounted in the space between the end wall 19 and the gear wheel 17 by means of for example a screw 22, so that there is a gap 23 between the partition wall and the inside of the end wall 19. The partition wall 21 is

formed by a piece of sheet metal, which is provided with an opening 21a for the fluid coupling bearing 20 and which otherwise essentially follows the sides of the turbo compound housing with its edges.

Due to the arrangement of the partition wall 21 in the space between gearwheel 17 and the end wall 19, the oil may drain into the gap space 23, without being affected by the turbulence being generated by the rotation of the gear wheel 17. The comparatively small amount of oil that may hit the gear wheel 17 and be thrown in the direction radially outwards by said wheel, will among other things hit the side of the partition wall that is turned towards the gear wheel and can flow down along this surface.

In order to avoid having oil from the rear radial bearing 14 and the axial bearing 15 hitting the gear wheel 17 or the coupling 18, or other moving parts, a peripheral shield 24 has been arranged around the fluid coupling 18, so that the oil may not be forced into the fluid coupling, and instead has to move along the e outside of the shield 24 down into the draining space.

This shield may at the same time function as blast protection for rotating parts, e. g. the coupling.

The invention is not limited to the above-described embodiments,, but several modifications are possible within the scope of the following claims.