On 27/02/2020 11:18, Dave Plowman (News) wrote:
In article
,
Tim+ wrote:
wrote:
On Wednesday, 26 February 2020 11:12:20 UTC, Dave Plowman (News) wrote:
In article
,
Tim+ wrote:
Cars haven# had fan belts for years. Fans are all electric these days.

********.

AFAIK those aren't normally electric.


So what kind of pixies drive your cooling fans? If you car is younger
than about 20 years old, they€˜ll be electric pixies.

Not so. Many much later than that used a temperature controlled viscous
coupling to drive an ordinary fan. Which just idles round when not needed.

To provide the same degree of cooling, you'd need an extremely powerful
electric one.

When a car is moving, the airflow through the rad means a decent viscous
coupling is going to waste a tiny amount of power, unless needed to cool
things. And when needed (like say when stopped or moving slowly, is an
electric one going to be any more efficient? After all the same belt
drives the alternator which feeds the electric motor.

Viscous fans disappeared from most cars in the '90s.

Engine driven fans are not really needed at all when at speed as natural
airflow is good enough, but electric ones are far, far better when the
engine is idling in a queue on a hot day.

I actually removed the viscous fan from one of my cars and replaced it
with an electric one. Keeping the temperature under control under all
conditions was no longer a problem. A decent electric fan can flow an
enormous quantity of air - far more than a mechanical one can at low
engine speeds.

Many of these setups will also have a supplementary electric fan, for the
AC, at high demand times.

Yes, because they use smaller fans that cool the a/c radiator, without
having to cool the engine coolant radiator when it does not need it.

SteveW