[kspacewalk2]

>This isn't like a hybrid car. It's a parallel hybrid, where the gas engine is just big enough for efficient cruise at altitude, and the electric motor/generator provides extra power for takeoff and ascent (or go-around power), and then charges slowly during cruise if needed.

Isn't that exactly what hybrid cars (e.g. Prius) are? Extremely efficient gas engine for highway cruising, but insufficient for acceleration, which is aided by electric motors?

[Tade0]

The Prius uses a planetary gear set to blend power of the engine with that of the two motor-generators.

Both the engine and motors are used at all speeds. Particularly during highway acceleration the entire assembly rotates in the same direction.

[dgfl]

This is a great related watch if you have some time to kill: https://youtu.be/KnUFH5GX_fI

[delecti]

That's such a fantastic video. I never totally grasped why hybrids were so much more efficient, because my naive assumptions about how they worked were so simplistic. The real-time graphs he showed were excellent for making his points.

[cogman10]

TC is filled with these sorts of videos. If you have time to burn then they are basically all this quality. His interests are also just wildly all over the place. From Christmas lights to dishwashers to coffee machines you just don't know what the next video will be.

[chabska]

One thing I really don't like about this video, is that he was specifically describing the advantages of that specific van and drivetrain, that being Toyota Sienna, and he's not wrong at that, but then he made grandiose general statement like "Hybrids are simple" and "minivans are great".

No, quite a few other hybrids are just an electrical motor tacked on to an existing ICE drivetrain, and they are actually more complicated than a regular ICE car, with horrible reliability and repair cost. And other non-hybrid minivans are either seriously underpowered, or require a seriously big engine that eats fuel.

The complaints that people have against hybrids and minivans are valid, if they're not talking about Toyota hybrids or this specific Toyota minivan.

[to11mtm]

IDK if anyone really answered -this- question properly, so I will.

> Isn't that exactly what hybrid cars (e.g. Prius) are? Extremely efficient gas engine for highway cruising, but insufficient for acceleration, which is aided by electric motors?

Well, it kinda depends. Where Hybrids get the biggest MPG boost is in city driving. The stop and go traffic lets you use Regen braking and go quite some time without the engine kicking back on while still moving forward.

I still don't understand Honda's system enough to speak well on it, but I can speak to THS because it seems to be the cheapest to do and is most proven on the road.

The general parameters for a THS type system on a Toyota Prius or Rav4, or a Ford Maverick/Fusion/Escape is a 2.0L or 2.5L (at least in modern US examples) engine paired to a simple planetary gearset containing a power split device. It is a single speed (At least in the cheap configurations, however that simplicity is possibly close enough to be viable for air usage vs a reduction gear.) That's part of why they tend to have fairly large engines, the valve timing magic gives them at least a bit more HP to not be too bad on the highway.

> but insufficient for acceleration

Going back to the modern cases, the engine is typically sized large enough to give some acceleration even on the highway. Not always great but usually enough.

At least as far as the non-plug-in hybrids, the 0-35MPH can be surprisingly peppy.

The bigger magic (again, at least as far as THS) is it makes it easy to just run the engine at the 'most optimal RPM' for certain tasks, excess energy gets piped to the battery or back out through the system, this does also help reliability tho, because you can then design the reliability of the engine around certain RPM ranges...

[coderenegade]

This is mostly correct. The Prius is actually a series-parallel hybrid, as it maintains a direct mechanical link between the engine and the wheels (and the engine is capable of adding power to the wheels) but it also uses two electric motors to isolate the two degrees of freedom (engine rpm and wheel speed). This second part is the series bit: the wheels and the engine are, in principle, fully independent, because the motors can absorb or add power to the crankshaft and the driveshaft to hit a target rpm without changing the rpm of the other shaft. In practice, the Prius doesn't run at a constant rpm due to sizing constraints of the motors, as the mechanical linkage means that one motor has to be able to absorb the engine power and torque of the other motor, which is impossible across all conditions.

Most hybrids are actually parallel or series-parallel. Series hybrids are comparatively rare because the traction motor has to be sized for the full operational range of the vehicle. Their primary advantages are mechanical simplicity and packaging; even though the power electronics and motors are bigger, the lack of mechanical coupling means you can put them wherever is convenient.

[arijun]

The Prius is in series, or something like it.

[idontwantthis]

No it’s not. The majority of power comes from the engine. It drives the electric motor mechanically, using it as a transmission. It is not just charging the battery.

[arijun]

Sorry, I meant in the low speed, high acceleration regime (maybe easily confounded with takeoff?). There the engine will turn one motor to generate electricity, which will then power the second motor, like a series hybrid.

[cwillu]

No, that's just wrong: at no point is (say) a Toyota Hybrid burning gas to generate electricity to immediately turn another motor that actually moves the wheels.

[arijun]

What do you imagine happens if the battery is low and the car wants to start from a stop? The engine can't shift down to first so it would just stall out if you tried to use it to drive the driveshaft directly, and there's no other source of electricity to put into the motor driving the wheels.

[cwillu]

It's a planetary geartrain, with electric motors on the outer and inner, and the gas on the middle. If the electric is _completely_ dead, the gas will just spin without driving the wheels at all. There is no first gear, the mechanical advantage and “clutching” all comes from the inner electrical motor driving the sun gear, while the electric boost/drive comes from the electric motor on the drift shaft (which is on the outermost gear of the planetary set).

There's a video linked elsewhere in this thread that explains how the toyota system works, it's worth watching as it clears up several common misconceptions about the system.