I understand that most hybrids use their gas engine for high output and switch to electric for low outpu,t saving gas by killing the gas engine.
I seem to remember Mitsubishi planning on making a hybrid where the engine would be a smaller underpowered engine to be used for low output and then have the electric engine kick in in parallel as a boost when high output was needed.
Are there any hybrids out there using this alternative model?
Are there any serious objections to it that would prevent it from being used? Are there any major and obvious technical impediments to implement a combination of both (electric for very low output, gas for medium, gas+electric for high)?
I don’t remember if it was a production car or a prototype/concept car, but I’ve seen a hybrid that had several different modes of operation. It could run electric only, gasoline only (while charging the battery), and it could run electric and gasoline together for “full power”. It had a computer that would automatically switch modes if necessary, like it would switch to gas/electric when you were running electric only and the battery became too far drained.
GMC/Chevy SUVs have a mode where one of the following happens:
the electric motor provides power alone
the engine provides power alone
the electric motor and gas engine work in combination
But more direct to the OP is a gas engine that is scaled down, and electric motor just provides extra kick: What you want to search on is ''Power assist hybrids ‘’ (Honda Insight, Saturn Vue, and others). These have gas engines running all the time, and it’s a frugal/smaller engine. It uses electric boost to get the performance of larger engine.
Mazda has E-4wd techology that uses a motor only on one axle when 4wd is needed.
I think a better way to think about it is that the electric engine runs the car all the time, and the gasoline engine kicks on when it needs to recharge the battery, either because you’re accelerating a lot and draining the battery quickly, or just have been driving a long time slowly without recharging the battery.
That scheme saves a lot of gas compared to a straight gas engine for two reasons: first, gas engines have a certain speed that’s most efficient, and lose a lot of efficiency at slower or faster speeds. So by having the gas engine charging a battery at a constant speed, you get the best use of your gas.
The second big efficiency gain from a hybrid is that you can capture energy from the brakes and send it back to the battery. All this means you can have a much smaller engine that you would otherwise need, and even shut it off a lot of the time.
So, with those in mind, it’s clear that running gas-only at low speeds would make for a very inefficient hybrid. You’d need a much bigger, gas-guzzling engine, and you wouldn’t get to use any stored braking energy. If fact, I doubt it would even be worthwhile putting the electric in at all, if the gas engine was running all the time.
This is how my Honda Civic Hybrid works.
The gas engine does shut down when you are at a stop. And you get some electrical power recovery from slowing down and breaking to help charge the batteries.
Toyota (Camry) does same - the engine is usually on when you are running; it can power the wheels with a variable transmission, or charge the batteries; the batteries also help the engine when real power is needed, as well as being an electric-only at low speeds and low power demands. Braking easy will recapture energy.
As a result, you essentially get highway gas mileage in stop and go traffic; and the fairly large Camry has only an 1800cc engine, not much bigger than my old Civic hatchback with 1600cc. Most cars this size have 2.5L or 3L.; but it is no sluggard on the road.
Sorry I abandoned my own thread. Thanks for the responses.
Armed with “power assist hybrids” I have been able to google what I was looking for. The whole thing is a lot more complicated and interesting than I knew.