[rentien]

Does anyone know where I can find diagrams (I have done searches but didn't find what I wanted) for how the Alternator Engages and Disengages?

Is it mechanical? Or is it electrical? (Electrical being something like not putting current to the coils, so the alternator spins with no field inside it, so does not generate electricity, and putting charge to the coils when you want more drag but also generation of electricity)?

Just curious. Thanks.

[Orion4]

I don't believe the Alternator engages/disengages. Most cars require an constant output from the alternator to function due to the electricaly load in a modern car- the battery would drain pretty rapidly. It is engaged whenever the engine in running. It is not like the A/C compressor which does cycle "on" and "off"

[CLittle]

There's a clutch in the pulley for the alternator that disengages while accelerating to reduce engine load. So the accessory belt spins the pulley but the alternator isn't spinning because the clutch isn't transferring the spinning motion to the alternator. Since the alternator isn't spinning, no power is generated.

I don't know how the clutch works though, I'd imagine a magnetic field would work but I really have no clue.

[Orion4]

Learn something new every day!

[TheCamboRambo]

Originally Posted by rentien

Does anyone know where I can find diagrams (I have done searches but didn't find what I wanted) for how the Alternator Engages and Disengages?

Is it mechanical? Or is it electrical? (Electrical being something like not putting current to the coils, so the alternator spins with no field inside it, so does not generate electricity, and putting charge to the coils when you want more drag but also generation of electricity)?

Just curious. Thanks.

I'm not sure about a diagram, but I would say it's a bit of both, I know there is a clutch that reduced drag on the engine whenever it's full or close to full, but also that there's regenerative breaking to charge the alternator as well. That probably doesn't help you much though.

[drob23]

Originally Posted by TheCamboRambo

I'm not sure about a diagram, but I would say it's a bit of both, I know there is a clutch that reduced drag on the engine whenever it's full or close to full, but also that there's regenerative breaking (SIC) to charge the alternator as well. That probably doesn't help you much though.

The clutching alternator is there to allow "regenerative braking" (I put quotes since real regen braking requires an electric motor somewhere in the drivetrain). So when you lightly coast to a stop, the alternator is dragging itself to emulate braking. But then it disengages when you're driving unless the battery level gets sufficiently low.

[rentien]

You would think they could just change the field which is electrically driven, to avoid mechanical parts, to change how much resistance (and charging) you get from the alternator. A clutch wears out eventually.

Oh well, just something i was curious about.

I assumed (but am not sure) that this is how the Prius changes the amount of regenerative braking that is being applied on the car.

[rentien]

Thanks for the responses!

[drob23]

Originally Posted by rentien

You would think they could just change the field which is electrically driven, to avoid mechanical parts, to change how much resistance (and charging) you get from the alternator. A clutch wears out eventually.

Oh well, just something i was curious about.

I assumed (but am not sure) that this is how the Prius changes the amount of regenerative braking that is being applied on the car.

I think it's a lot more expensive to start engineering fancy alternators with electronically controlled impedance. IMO the current setup is a slightly gimmicky way to get regen braking. But what do I know, maybe it does save some emmpeegee's! I do know I've read a lot of posts where people complain about drivability, possibly because they don't understand what's going on.

The Prius has a motor in the drivetrain (Toyota have pretty advanced parallel hybrid drivetrains), therefore they just use the drive motor in reverse as a generator. Not sure if they can control the magnitude of energy flow into the battery, which would allow them to vary the regen brake torque.

I believe they usually just have the regen happen and apply mechanical brakes additively once the driver requests more than the regen capability.