karn:有文章说cvt效率92-96,与速比有关,我觉得未必是成熟稳定和普遍状况,所以我没提这事。
省油不靠效率实现,但是效率是省油的必要条件,这是无可争议的事实,要是cvt效率低的超乎想象,比如70%,那就不用玩了,先想想怎么散热再说。而且工况再好,也未必能弥补效率的损失。
==== ..
(2014-12-31 23:00)
效率高低是比出来,单方面给数据根本没有意义。钢带锥轮传动怎么也比不上齿轮。CVT液压系统的巨大功耗更是不可忽略。你给的数据再高,相比起来它还是效率低。而且即便是现在被CVT鄙视的传统AT,也在积极引入更智能更有效的液力变矩器锁死技术,CVT今后说不定连AT的传动效率都比不上了。
你说的“Cvt能省油,首先是因为它传动效率高。。。”CVT的传动效率非但不是“首先”,它其实连次要优点都不算,而是实实在在的缺点。再粉CVT的人,吹CVT的时候都是避开传动效率这个缺点的。
即便是为了推广CVT,日产为代表的日系厂商都能做出标称油耗CVT比MT还低的这么没节操的事情。但看看日产在它的宣传文章里是怎么说的:
The results on the powertrain due to improved
transfer efficiency and
engine efficiency greatly affect vehicle mileage, and thus any transmission works to improve efficiency. However, their main approaches are different. In particular, let’s look at how DCT and CVT contrast.
DCT’s approach is to
raise transmission transfer efficiency in order to improve fuel efficiency. It has the same kind of mechanisms as manual transmission and, with its high transmission efficiency, in particular it can extend mileage when cruising at high speeds.
On the other hand, CVT raises fuel efficiency by
using the most efficient parts of the engine. As we saw before, CVT can set the transmission gear ratio freely, and is characterized by gear changing and driving that is seamless.
虽然传动效率输,CVT依然有非常好的油耗表现(但决不能夸张到比MT还好),完全可以证明CVT在被你忽视的方面优势有多大。下面这幅图应该只有学汽车的人才能完全看懂,解释起来也挺复杂,所以就不详细解释了,但一眼就能看出来CVT和齿轮变速有多大的不同,这才是CVT真正牛逼的地方。
[ 此帖被coolsear在2015-01-01 06:00重新编辑 ]