5 ms·
So, as I understand it, it combines the compression ignition of diesels with opposing pistons. The opposing pistons go toward one another and compress the air/g
by elbigbad 11y ago
So, as I understand it, it combines the compression ignition of diesels with opposing pistons. The opposing pistons go toward one another and compress the air/gas mixture and ignite it. The exhaust escapes when the pistons move back through ports machined in the sides (kind of like a wankel/rotary engine removes exhaust gasses).
Sounds like they're trading the spark system (a pretty easy to maintain system) for a second piston/crankshaft/etc. Essentially pulling out a cheap and perfected system for one that adds a bunch of high stress, expensive parts. Just from that sounds like a bad idea.
They say the extra efficiency comes from heat loss from the cylinder head, but I have a hard time believing they're capturing that much extra (double-digits) efficiency from heat loss alone, especially given the reduced efficiency of having more moving parts.
- mjb 11y ago> Sounds like they're trading the spark system (a pretty easy to maintain system) for a second piston/crankshaft/etc. Opposing pistons and compression ignition are (mostly) orthogonal optimizations. From years of working on engines, I'd also be more willing to call the mechanical parts "perfected" and the ignition system "not perfected", at least for common consumer engines.
- digi_owl 11y agoSide ports are also used in 2-stroke piston engines. Most often found on mopeds and chainsaws.
- Gracana 11y agoAnd big diesel engines.
- taneq 11y agoThis engine design is, in fact, 2-stroke according to the article.
- digi_owl 11y agoIt seems to lack a defining characteristic of your typical 2-stroke though, that the fuel is initially drawn in below the head to lubricate the crankshaft (this require mixing oil in the gasoline, done automatically on modern mopeds). https://en.wikipedia.org/wiki/Two-stroke_engine https://en.wikipedia.org/wiki/Two-stroke_engine
- mzs 11y agoYou lose all the valve train.
- marssaxman 11y agoSure, it's easy to maintain the ignition system, but it's also a system that needs maintenance: spark plugs, batteries, distributor caps, and alternators are all parts which wear out and need replacement during the normal course of vehicle operation. This is not true of pistons, crankshafts, and the like; it doesn't really matter that replacing them would be a difficult and expensive job, because they almost never break, and when they do you are generally better off just replacing the car and scrapping the old one. So, I think that an engine which had fewer of the former sort of components and more of the latter sort would, on balance, be a more reliable machine.
- deleted 11y ago[deleted]