Three unrelated questions

Hi Orenf,

The engine output is split by a constant torque ratio between the drive line (ring gear) to the wheels, and MG1. MG2 is also directly attached to the ring gear. The potential developed out of MG1 can either be left open circuited or guided to the battery, or guided to MG2, or split and some sent to MG2 and some to battery. Under hard accelleration all the MG1 energy (potential times current) is sent to MG2, and battery energy is also sent to MG2 as well. That is why MG2 has to be so big, it has to take the 30 hp from the max reving engine (while 46 goes directly to the drive line), and the 25 hp from the battery simultaneously.

So, its not a discrete system. Its all a variation depending on demand and battery state of charge (SOC). The lower the SOC, the faster and more often the engine will run. The more driver power demand, the higher the engine RPM will be, and more current will be pulled from MG1 and sent to MG2. And since the engine has nearly constant torque the higher the shaft hp out of the engine. The computer knows it needs to load MG1 to balance the speed of the engine against the road speed as experessed at the ring gear.

 

I think sending power into mg2 will control it's rpm. If its spinning too fast, you can slow it down by sending it power so it tries to spin in "reverse".

Electric motors can spin both ways, so if its spinning one way, all you need to do when sending power to the 3(i think) electro-magnets is to hold one of them with 100% of the power, therefore locking/slowing it down, at that one section of the motor. All of a sudden, instead of a magnetic force ahead of it pulling, it is met with something pulling it back (and energy can be sent ahead to reverse the polarity, so it repels the section of the motor, thus pushing it back into the pulling one)

 

<div class='quotetop'>QUOTE(orenf @ Oct 5 2007, 03:31 PM) [snapback]521947[/snapback]</div>

Every time you lift off the brake from a stop, the engine will restart in a HCH. Honda states under certain load conditions, fuel injection will cease, and both intake and exhaust valves will close, making for close to no engine drag. When that happens, the HCH is in essence an EV, since it will only be on electric power, even though the engine is still turning. Unfortunately, the HCH owner's amnual did not give any more detail of this mode of operation. From driving both the HCH and the Prius, the start-up in an HCH is a little more noticeable than in a Prius, although even in the Prius, in a three-day rental, the engine start-up became second nature.

 

<div class='quotetop'>QUOTE(orenf @ Oct 5 2007, 04:31 PM) [snapback]521947[/snapback]</div>

its a combined system that Toyota has dubbed eCVT. By controlling how fast the ICE, MG1 and MG2 one can vary the effective gear ratio.
http://priuschat.com/Introduction-to-Prius...low-t30286.html

<div class='quotetop'>QUOTE(orenf @ Oct 5 2007, 04:31 PM) [snapback]521947[/snapback]</div>

under those circumstances, the intake valves are open to reduce the "air pump" effect.

<div class='quotetop'>QUOTE(orenf @ Oct 5 2007, 04:31 PM) [snapback]521947[/snapback]</div>

Honda has been working to improve their hybrid system - it is less efficient than the HSD because they try to get around paying royalty for some stuff that toyota has patented. From what I've read, the newer Honda hybrids can operate in EV mode, but only if you accererate really slowly. The fact that they mated a V6 on some of their hybrids doesn't help much.

 

I don't think question #1 has been answered. The preceeding responses all pertained to variable rotational speed. That was not the question.

Yes, The power output of the electric motor(s) is variable with accelerator pedal pressure, just as ICE power output is variable. The electric portion is not just on/off when you step on the accelerator in electric mode.

.
There really isn't an 'electric engine'. More like an electro-mechanical transmission. (very simplistic description): A standard gas engine is connected to a unique transmission that contains the electric motors. The inner working of the Prius transmission can allow the gas engine and/or the electric motors to drive the wheels individually, or seperately. The inner working of the Honda transmission do not allow the possibility of independent mechanical operation of gas engine and electric motors, one will always spin the other. But there are brief moments the honda ICE can be spun with no fuel flow to it, thus moments it's not using gas.

 

<div class='quotetop'>QUOTE(orenf @ Oct 5 2007, 02:31 PM) [snapback]521947[/snapback]</div>

questions 1 and 2 can be answered by http://www.cleanmpg.com/forums/showthread.php?t=1224 and questions 3 http://www.cleanmpg.com/forums/showthread.php?t=1306

 

<div class='quotetop'>QUOTE(9G-man @ Oct 6 2007, 03:26 PM) [snapback]522255[/snapback]</div>

Ah, you beat me to it. When you start off from a stop gently, you can clearly see that the "EV mode" has variable power output from the accelerator pedal. You can "drive" with battery only. If it were a toggle switch, it would be pretty uncomfortable to drive! Would be like lighting JATO units, on a little, tiny scale.

 

<div class='quotetop'>QUOTE(darelldd @ Oct 6 2007, 07:03 PM) [snapback]522270[/snapback]</div>

And if you get an EV switch you can really see that electric power is highly variable with accelerator pedal input

 

1. The electric motors work the same as the gas one. The harder you press on the accelerator, the more electricity you use. They are electronically controlled three phase motor/generators. If you press hard enough, whether you are in "EV mode" or not, the engine will start. The reason is the system has to protect the battery. The electric motors can generate more power than the Prius uses, but the battery cannot deliver that much current safely (for battery life). So the engine is started to deliver some of the current being demanded and to provide direct propulsion as well.

2. The engine must spin when you go faster than 43 MPH/66 kmPH to avoid over-spinning MG1. It is spun up by MG2 to about 950 RPM, with no fuel being injected. Below the above speed it is allowed to stop.
If you take your foot off the accelerator the system goes to "engine braking simulation regeneration". That is, it regenerates enough to cause as much braking as the Toyota engineers thought an engine would under similar circumstances in a "normal" car.
To see this, use the flash program available in the sticky thread under Prius Technical:-
http://priuschat.com/Introduction-to-Prius...low-t30286.html
With this you can vary the engine speed, vehicle speed, etc. and see the effect on the various components.

3. I have no experience with the Civic Hybrid, but from reading the forums, the latest version should work very much like the Prius.