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how about a drivetrain that looks like this:
2x 500cc motorcycle engines +turbo @80hp each
1x 50hp electric engine
The transmission would be a nightmare, the best i can think of is 3x CVT (constantly variable, think skidoo tranny) to add the torques of all 3 engines together,
Instead of batteries
use a series of capacitors (ala Honda Dualnote)
Use electric engine to generate power while braking as in every hybrid electric.
This uses the standard hybrid principle but uses 2 small gas engines instead of 1 large one to keep the hp scaleable. The 2 engines are to provide variable displacement.
This is the spec for a performance hybrid, for economy just replace the 500cc engines with 250cc ones.
Car with two engines
http://www.bbc.co.u...rog10/germans.shtml
Car with two engines, though not many pics [suctionpad, Oct 04 2004, last modified Oct 21 2004]
[link]
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// uses 2 small gas engines instead of 1 large one to keep the hp scaleable // |
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Can you explain this bit? |
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Aren't there already systems which can drive a variable number of pistons in an engine, which would be mechanically simpler? |
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3x the things to go wrong but any 1 thing won't make the vehicle unuseable.
scaleable power; i can use 1 gas engine = 80hp OR 1 gas + 1 electric = 130hp OR 2 gas = 160hp OR all engines = 210 hp Essentially i don't have waste gas to make 210 hp all the time if i don't need 210hp. |
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Engines by their nature already produce "scaleable" power. It's called "throttle". |
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I'm not sure I'm really getting the advantages of this one. |
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Also, [WhiteWiz], you've got some bad science going on with |
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// i don't have waste gas to make 210 hp all the time//. |
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That's not how engines work anyway. You might want to read up on horsepower in general. |
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CF; If you take your foot off the gas you go slower. Zig; So in your world it takes the same amt of gas to go 40mph in a Lamborghini or a Firefly? In reality smaller engines take less gas, that's why Volvo is working on variable displacement engines. My model has variable displacement in the form of 2 engines built with current technology. Admitedly CVT's go a long way to alieviating the displacement to mileage link. |
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//40mph in a Lamborghini or a Firefly//...If the engines were designed to do 40mph at peak efficiency, then pretty much yes you would use the same amount of petrol (gas is the stuff that comes through the air filter and combines with petroleum product to give a deflagration). The Lamborghini is less efficient at 40mph because it has been designed for acceleration/top speed, NOT specifically because it has a larger displacement. If you have a dig around you will find that the smallest car engines available for a particular model are not necessarily the most efficient. |
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Thanks, [suctionpad], well said. |
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you can only run an engine so lean after which the combustion temperature rises and it starts making high ammounts of Nitrogen Oxide (http://www.interro.com/techgas.html) you can only turn down the rpm so low after which the size of the flywheel you need to keep the engine running outweigh's the car. GM isn't researching cylinder deactivation because it's fun, they are doing it because it saves gas, up to 2mpg in fact. (http://www.autobeatdaily.com/pdfs/05-09-03.pdf) |
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a variable displacement engine (like lincoln ls) coupled with a hybrid system and a cvt would accomplish the performance and fuel savings you want but with better emissions and FAR FAR FAR more reliability. |
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The only variable displacement engine to come to market that i know of is GM's displacement-on-demand engine which is a 5.3liter v8 with a 50/50 split. Ya much more economical than the 1.0liter I proposed. The big 3 are intentionally using DOD on large engines first because they are the biggest gas hogs. This means we will have to wait for a few years for the technology to trickle down to smaller engines. I disagree that this engine will be more reliable as it is a new design full of new idea's and no doubt full of new bugs. The design i stated uses all current proven-reliable technology. |
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The Big 3 are using DoD because it allows them to grab sales with huge engines and power, while making some concessions to economy, methinks... |
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I second the idea of driving the wheels independently. I think, theoretical considerations aside, that two small engines could be an advantage only if the losses in the geartrain were low. |
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I'm not sure driving each wheel through its own gas/electric combo IS the simplest solution, but it sounds like a good place to start. |
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I remember reading an idea for a fully integrated hybrid engine on halfbakery. Maybe this idea would benefit from another look in that direction. Link when I can find it -- it wasn't very popular though, as I recall. |
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A better idea I read than just idling cylinders on inline 4's or V8's would be to add new a new valve to each cylinder which would connect to a common manifold (which would in turn connect to nothing else). |
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When lots of power was needed, the new valves would simply stay closed and the engine would operate as normal. When little power was needed, the outer cylinder's intakes would operate as normal but the 'extra' valves would open instead of the exhaust valves. The inner cylinder's 'extra' valves would open on both downstrokes and their exhaust valves would open on both upstrokes (the intakes would stay closed and the fuel injectors would not operate). |
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The effect would be that when operating in lower-power mode, the engine would have a much-increased expansion ratio because each cylinder worth of gas input would be expanded to two cylinders' worth of gas out. |
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The author of the paper indicated that he'd modified an engine to operate full-time in this new mode (by changing cams and reshaping manifolds) and efficiency was improved at the expense of power. If an engine could switch modes, one would have the best of both worlds. |
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