BMW is looking at a new way to extend your oil change intervals. No, it’s not by claiming your motor oil is a lifetime fluid; there’s a real method to this madness. The CarBuzz research team has just uncovered a patent for an air-oil separator that would help extend the life of your engine’s oil.
Even better, it could also help stop carbon buildup on the valves, maybe saving some poor, innocent walnut shells from a trip through your intake tract.
You’ve Got To Keep It Separated
BMW Centrifuge PatentBMW
The new invention is a centrifugal separator that is meant to separate engine oil from gas. It’s essentially a PCV valve on steroids, without the headaches that positive crankcase ventilation can cause your engine. Not only when there’s a problem, but also when it’s working almost perfectly.
BMW wants to separate engine oil, which should be in your engine’s oil passages and sump, and other combustion gases, which should be either recirculated to the intake or sent into the exhaust. This invention would do that by spinning a rotor inside a housing. It starts by taking the high-pressure air from the engine’s crankcase and sending it into the new device. The separator has a rotor that spins and a housing that will let gas through but not liquid oil.
When the air-oil mix hits the rotor, the oil sticks to it. The rotor then spins it at high speeds, flinging it off against the housing. That high-force flinging squeezes the air out, while the oil sinks down to the bottom of the separator and is returned to the oil sump. In theory, this keeps the oil cleaner and more effective for a longer period of time. That means fewer oil changes, which also means fewer visits to the dealership for maintenance. Dealerships probably don’t want that.
Much of the patent covers lubricating the bearing that lets the rotor spin. It turns out that the gases inside the separator love to get in there and ruin it. BMW has a fix, but the problem and the solution aren’t really part of the main innovation.
How Did These Gases Get In The Engine?
Why are there gases in the engine, and why does BMW want to get them out? Because combustion engines aren’t perfectly sealed. With every engine cycle, a tiny amount of fuel-air mixture, either semi-burned or unburned, sneaks past the piston rings and into the engine crankcase. It’s worse with cold or worn engines, but it will always happen. Water likes to find its way inside as well.
In the past, automakers just let it burn off or ignored it. A breather let some of the air out, but the fuel and water stayed in the oil. Getting the engine up to temperature solved the water problem, but the fuel and other gases remained until the next oil change.
PCV, or positive crankcase ventilation valves, were one of the first steps in fixing this. The valves let the crankcase air, with its combustion gases and water vapor, get back into the intake to be re-burned. It worked, but it didn’t get everything out, and the system could let oil vapor into your intake, which then contributes to carbon buildup on your intake valves. That’s a big part of why direct-injected engines need their valves cleaned from time to time.
This system would get all the oil vapor out of the combustion gases, and vice versa. The cleaner oil would hold less contamination, so it could work better, for longer. The air going back into the intake wouldn’t have any oil in it (or at least less oil), meaning it wouldn’t cause problems in the intake.
CarBuzz Insight – Why This Matters:
BMW S65 V8 Engine Found In Fouth-Generation M3BMW
Doing a better job of separating oil and combustion gases is good for your engine’s top and bottom end. The oil can do its job, gases are re-burned to reduce emissions, and the intake valves don’t get covered in carbon buildup. The best part is that this is a simple device, so it shouldn’t need much attention, maintenance, or replacement. It sounds like a win for reliability and emissions alike, and that’s a rare thing these days.
Patent filings do not guarantee the use of such technology in future vehicles and are often used exclusively as a means of protecting intellectual property. Such a filing cannot be construed as confirmation of production intent.
Source: DPMA
