HHL said:
The car does have a "clutch", it is the torque limiter that is between the engine and the drive unit. It looks just like a clutch with a friction and pressure plate, except it does not have a release mechanism, so it is designed to slip when the engine develops more torque than the generator/drive unit can handle. I don't know how often that would actually happen, but if it did slip a lot, it could certainly produce that type of odour.
IMHO, the info we believed to be true so far was this:
- There is a permanent fixed gear ratio connection between engine and generator.
- There is a permanent fixed gear ratio connection between front E-motor and front axle.
- There is a clutch between engine/generator side of the drivetrain and e-motor/axle side of the drivetrain, which is closed in parallel mode and opened in series mode.
That friction plates in that clutch have very little work to do, because right before closure of the clutch the generator is used to match the speed of the engine to the speed of the wheels. This is also why parallel mode is engaged so smoothly.
So, the only clutch we knew of does have a release mechanism, there has been no talk about a clutch between engine and generator and none about a torque limiter either. Do you have a source for your information?
BTW: assuming the old info was correct, I think the clutch could only be a source for the smell if it was mal functioning (and if it was not 'wet'). Or after very many transitions between serial and parallel hybrid mode in a very short time frame. And even then, it would be not very likely to produce a smell, taking into account the role of the generator.
Some of the reports about the smell are related to long high speed motorway hauls. My personal experiences with the smell are related to low speed (< parallel mode speed) towing, where the clutch does not come in play at all. Personally, I think we can safely rule out the clutch as a source for the smell.