My understanding is ...
This is wrong.


This is correct.


power = torque X revolution

When the car is not moving, (ICE torque) X 72% X 0 rpm => zero power.
Therefore, all power from ICE goes to MG1(generator).

When the car is moving...
Drive power = motor power + (ICE torque) X 72% x some rpm
MG1 power = (ICE torque) X 28% x some rpm

Ken@Japan

 

Based on my much more layman's view of my car since I've had it, I've gotten accustomed to what it "feels" and sounds like when it's accelerating with the electric motor, or with the ICE.

When I turn on the car in the morning and the ICE kicks over to warm up the emissions et al., when I roll out of my driveway and begin to accelerate forward, the sound and feeling the ICE makes never changes. It's as if it's idling the whole time, just sitting there warming up things, and my acceleration "feels" just like it does when I'm in EV mode. If I press down the accelerator harder, *then* I feel the CVT kick in, the revs go up, and I feel the pull of the ICE. Whether this addresses the "engine charge the battery while the electric motor pulls the car" question, I don't know, but it seems it's at least anecdotal evidence to suggest that in at least one circumstance the ICE might run but not pull the car. Of course I could be way off.

 

Ken I see the math but I'm not sure how it relates to:

Pushing is a force, the power path is not the issue. The motors may contribute to the overall force but the ICE is always trying to push the car when it is running. Do you agree?

 

Let's look at this way...
Drive torque = MG1 torque X 2.6

When the MG1 is free (no generating), the drive torque is zero, which means no pushing force.
That's my understanding.

Ken@Japan

 

I have to point this out. The Prius has no reverse gear. The vehicle turns MG2 in reverse to go backward. Nearly every morning and evening when leaving for work or leave the parking lot at the office my ICE is running (to warm up the cats, etc.) yet I put the car in reverse and move backward, and there is no reverse gear. This indicates that the ICE can be running without contributing to vehicle movement even when the vehilce is moving.

So, if the ICE is spinning and the vehicle is moving in reverse, where are the forward revolutions of the ICE going? They are going to MG1. Whether or not the computer is actually directing the electrical system to collect electrical power from MG1 or not while in reverse remains on my mind for further clarification.

I think the qualitative answer to this discussion is that the operating theory between the Honda IMA system and the Toyota HSD system is significantly different. I can't speak to IMA, but I do understand that HSD is about operating the ICE at its most efficient points, based upon RPM, and then using the motor/generators, regenerative braking and the battery as a buffer to span the gap between efficient ICE RPM points in terms of acceleration and ground speed maintenance.

 

JeromeP

From:

http://www.ecrostech.com/prius/original/PriusFrames.htm



If the ICE is running it is trying to push the car forward, period. Reverse is no exception. The ICE is directly connected to the planet carrier with no clutch. The wheels are connected to the ring gear also without a clutch. These connections mean that the ICE is always trying to push the car forward when it is on. You should be able to back up faster with the ICE off than with it on.


I'm becomming more and more sure of myself and of my understand of how the HSD works. I'm not confused. I might have been wrong in an old thread about how HSD works because I was confused between power and torque but this is no longer the case.

 

So, you believe Prius does not have "Neutral" position.

Ken@Japan

 

I'm surprises me that in this long discussion noone has referenced the HSD simulator. You can get a copy at my web site (I didn't create it):

http://doctord.dyndns.org:8000/cours...sSimulator.jar

It actually simulates a 2001-2003 Prius, but it can be used to understand the workings of the HSD. You do need to have the Java JRE installed to run it:

http://javashoplm.sun.com/ECom/docs/...actionId=noreg
(free from Sun)

Download the simulator. Play with it. Learn. Show it to friends. Enjoy!

JeffD

 

I'll start by saying that I've read this thread numerous times. I'm also not nearly as mathematically inclined as others on the board, so I tend to view these discussions graphically and in terms of various PSD simulators out there. A lot of PSD information I have reviewed a long time ago and as such some ideas are foggy. If I make mistakes I do my best to accept the criticism with appropriate support for contrary ideas. The mistakes I make are not intentional.

I think the question or questions that started this thread have been lost, or at least as the thread has aged the focus has been lost. As such I'm in a fog as to what the original issue was. If that could be clarified that would be great.

Here's the thing; If ICE is running and the vehicle is in park it is not necessarily actually being allowed to direct power (or force) to the wheels. In park MG2 is locked. That leaves MG1 and ICE free to spin. With MG2 (ring) locked there are two other gear movement possibilities. MG1 (sun) can remain stationary with ICE (planet gears) running. All that will happen is the planet carrier will spin forward and the planet gears themselves will spin backward between the sun and ring gears. This is essentially neutral. The other possibility is that the vehicle can generate power in this situation. So, with the ring locked, the sun gear can be moved forward by allowing it to spin with the planets and carrier. The planet gears themselves will spin much more slowly as the sun gear moves in the same direction with the planet carrier. You can tell both of these situations, not by looking at the MFD, but by listening to the vehicle. When the vehicle is parked or stopped and is running ICE and not generating power the ICE is very smooth and quiet and the ICE sounds as if it is not under load, which is true. On the other hand during that self test charge routine the car does at startup, you can tell the ICE is loaded and running MG2 as a generator because the ICE sounds loaded. As soon as the self-test is completed the ICE returns to an unloaded state.

I think this discussion started with regard to the ability for the vehicle to propel itself via electric only (MG2) with the ICE running. Conceptually, in theory, visually, and however you want to put it, it sure seems possible that the car can do this; if the computer system deemed it necessary or advantageous it would be possible to have a net 0 input from a running ICE. With MG2 spinning forward (vehicle moving forward) and ICE spinning forward it would be possible to nullify the ICE contribution by having MG1 spinning backward at a rate where the forward contribution of the ICE and the reverse action of MG1 essentially nullify each other and there is no net contribution in revolutions to MG2. Does this make sense? I hope so because I'm not sure how else to explain this situation. Nor can I come up with a good idea about when this situation would occur. However we have to keep in mind that the vehicle's computer system is tuned to use primarily electric propulsion in high torque operations as the ICE has very little torque and will supplement with direct ICE power contribution when necessary or advantageous.

 

Ken you are the "Grand Master" so if you say it does I believe you. My understanding is that the Prius has no clutch and that the ICE is always spinning the planet carrier when it is running. Since the wheel are hooked up to the ring gear the ICE is trying to push the car forward all the time when it is running like a car with an automatic tranny in gear at a stop light. Something may prevent the car from moving but the ICE is still attempting to push the car.

BTW I'm getting this from:

tp://www.ecrostech.com/prius/original/Understanding/Animations/WarmUp.gif