Three unrelated questions

[orenf]

Hi,

Here are three unrelated questions - answers/comments are welcome.

1. The gas engine is variable/continuous - the harder you push the pedal, the more power you generate. Does the electric engine work the same way, or is it a simple on/off discrete mode, and it does not matter how hard/fast I push the pedal (within the applicable speed limit for the electric engine)?

2. I've read several times that when gliding at high speeds the MFD does not show any energy flow, but the gas engine is "spinning" - what exactly does it mean? Is fuel being consumed or not? the MPG is always at 99 when gliding.
Is this the equivalent of taking your foot off your non-hybrid's gas pedal (have no idea what actually happens then)?

3. I was recently stuck in a traffic jam off hwy 1 near Vancouver. Other than being stuck in traffic, it was not that bad - music was playing ,car was not consuming any gas for several miles, the perfect hybrid experience.

Next to me was a Civic hybrid - can anyone tell me what happens in a Civic hybrid - I understand there is no EV, does that mean that in a traffic jam the only benefit is the engine cut-off when stopped, but otherwise, while plodding along at 5-10 MPH, it consumes gasoline just like any other car?

That's all for now...

--- Oren

[Tideland Prius]

1. It's more like how much power is fed into the electric motors to feed power to the front wheels. (engine + battery). The more power from these two sources, the greater the power fed to the wheels. I can't remember my physics class but it should be the greater the amps, the greater the mechanical force (given the fact that the length of the wire is standard and so so the density of the motor i.e. how tightly wound it is)

2. The engine spins to keep MG2 from overspinning. There is no fuel consumed but there is friction as the pistons move up and down which is where the energy is "wasted" (rather converted into heat)

3. It shuts off only at a complete stop. It may let the engine idle if the computer "detects" a stop-and-go traffic situation (dunno how many times you have to lift off and depress the brake pedal before it'll let the engine idle). I can assure you it's not a pleasant ride. I test drove the HCH-II and making a left turn was not smooth. I'm so used to moving in EV that inching out to make a left turn had the engine cycling on and off.

[donee]

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.

[orenf]

donee: the scary thing is, I actually understand what you're talking about... - thanks!

TP: re spinning - are you saying the engine is "spinning" due to inertia, or is "something" powering that spin? If so, what? I'm gliding - no energy flow whatsoever to/from batter/electric/gas engine.

If it is inertia, does that mean the speed in which it is spinning slows down, while I glide?

--- Oren

<div class='quotetop'>QUOTE(donee @ Oct 5 2007, 05:01 PM) [snapback]521960[/snapback]</div>

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.
[/b]

[Tideland Prius]

<div class='quotetop'>QUOTE(orenf @ Oct 5 2007, 03:04 PM) [snapback]521965[/snapback]</div>

donee: the scary thing is, I actually understand what you're talking about... - thanks!

TP: re spinning - are you saying the engine is "spinning" due to inertia, or is "something" powering that spin? If so, what? I'm gliding - no energy flow whatsoever to/from batter/electric/gas engine.

If it is inertia, does that mean the speed in which it is spinning slows down, while I glide?

--- Oren
[/b]

Spinning as in like B mode but not that high of an rpm.

I guess.. "pumping" might be a better word?

IOW, the PSD makes the sun gear rotate which is connected to the engine so the crankshaft moves and the pistons move.

Now I'm not entirely sure what tells the sun gear to move at x rpm .

[Bob64]

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)

[Per]

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

3. I was recently stuck in a traffic jam off hwy 1 near Vancouver. Other than being stuck in traffic, it was not that bad - music was playing ,car was not consuming any gas for several miles, the perfect hybrid experience.

Next to me was a Civic hybrid - can anyone tell me what happens in a Civic hybrid - I understand there is no EV, does that mean that in a traffic jam the only benefit is the engine cut-off when stopped, but otherwise, while plodding along at 5-10 MPH, it consumes gasoline just like any other car?

That's all for now...

--- Oren
[/b]

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.

[ACORNBLUES]

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

Hi,

Here are three unrelated questions - answers/comments are welcome.

1. The gas engine is variable/continuous - the harder you push the pedal, the more power you generate. Does the electric engine work the same way, or is it a simple on/off discrete mode, and it does not matter how hard/fast I push the pedal (within the applicable speed limit for the electric engine)?
[/b]

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>

2. I've read several times that when gliding at high speeds the MFD does not show any energy flow, but the gas engine is "spinning" - what exactly does it mean? Is fuel being consumed or not? the MPG is always at 99 when gliding.
Is this the equivalent of taking your foot off your non-hybrid's gas pedal (have no idea what actually happens then)?
[/b]

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>

3. I was recently stuck in a traffic jam off hwy 1 near Vancouver. Other than being stuck in traffic, it was not that bad - music was playing ,car was not consuming any gas for several miles, the perfect hybrid experience.

Next to me was a Civic hybrid - can anyone tell me what happens in a Civic hybrid - I understand there is no EV, does that mean that in a traffic jam the only benefit is the engine cut-off when stopped, but otherwise, while plodding along at 5-10 MPH, it consumes gasoline just like any other car?
[/b]

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.

[Tideland Prius]

<div class='quotetop'>QUOTE(ACORNBLUES @ Oct 5 2007, 04:57 PM) [snapback]522004[/snapback]</div>

The fact that they mated a V6 on <strike>some</strike> none of their hybrids <strike>doesn't</strike> helps <strike>much</strike> .
[/b]

haha.. don't mind me modifying your response. They only have ONE V6 Hybrid and it's gone now.

[9G-man]

1. The gas engine is variable/continuous - the harder you push the pedal, the more power you generate. Does the electric engine work the same way, or is it a simple on/off discrete mode, and it does not matter how hard/fast I push the pedal (within the applicable speed limit for the electric engine)?

[/b]

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.