Thanks to all for your suggestions. Now I'll blather on about my revised technical presentation.
First, I should have said that I expect two possible audiences at the National Electric Drive Week event. First, there will be the owners of the other plug-in cars being exhibited at the event. The board presenting the chart and diagrams illustrating the operation of the Clarity Plug-In Hybrid’s i-MMD system are mostly for them, but some technically oriented visitors may also be interested in this information.
The less-technical board will have two audiences: the owners of the other plug-in cars and the new-to-plug-in-cars visitors to the event. This board will list the features of the largely unknown Clarity Plug-In Hybrid and describe how easily people can take advantage of its EV drive capabilities to both save gas and drive a more enjoyable car. Another part of the second board will compare the Clarity Plug-In Hybrid to the Volt, Prius Prime, and, of course, the always-in-the-news Tesla Model 3 (even though it’s not a hybrid car). I'm hoping to get a rise out of the non-Clarity plug-in owners by denigrating their cars to the Clarity's advantage.
Second, I must say I was surprised no one commented on my last diagram, Zero-Regen Engine Braking. This topic has been of special interest to me because of the people on this forum reporting their cars starting the engine upon deceleration when the battery is fully charged. I couldn’t think of a good way to graphically illustrate my theory about the starter motor/generator reversed to use up excess electricity by trying to slow down the engine. So I decided to put the word “FIGHT!” in the arrow connecting the starter motor/generator and the engine. If nothing else, it will spark some conversation between me and a Volt owner while we’re standing around waiting for any non-owner visitors to show up.
@Sandroad pointed out that the Mode Transitions chart at the top shows charging occurring in Engine Drive mode, but my diagram of Engine Drive mode shows power coming from the battery to the traction motor. I found
this article that directly addresses the misconceptions of Engine Drive mode. It points out that the SAE paper by the 3 Honda engineers indicates that both battery charging and assisting can take place in Engine Drive mode:
> Although “Engine Drive” mode is mainly utilized during high speed cruise,….
>
engine load adjustment by charging or discharging the high voltage
>
battery is also performed in this mode to fix engine operating points in
> highly efficient area…
So I changed the Mode Transitions chart to include a segment where battery assist is taking place in Engine Drive mode. Then I changed the Engine Drive diagram by making the arrow between the traction motor and the battery bidirectional.
@V8Power commented that the chart titled “Clarity PHEV Driving Mode Transition of Typical Driving Cycle” wasn’t an accurate representation because the Clarity PHEV stays in EV Drive mode much more of the time than the 2014 Accord Hybrid for which this chart was originally prepared. Rather than expanding the width of the EV segments (which would make the chart too wide), I simply changed the title to “Clarity Plug-In Hybrid Driving Cycle Mode Transitions.” The important thing about the chart is to illustrate the ways the battery, engine, motor, and generator interact to maximize efficiency.
@V8Power’s suggestion to explain the Clarity Plug-In Hybrid as essentially an electric car with a gas engine as back-up generator to eliminate range anxiety is a good one and I will work it into the less-technical board I plan to bring to the National Electric Drive Week event.
@Pushmi-Pullyu made a good suggestion to abandon the hard-to-read green text in the diagram for Engine Drive Mode and also to indicate in the label of each diagram whether the Engine Drive clutch was engaged or disengaged. I incorporated those suggestions in all the mode diagrams. I also indicated when the engine is running and when it is off.
The always helpful
@KentuckyKen noted that the Mode Transition chart does not graphically illustrate how in HV mode all the power flows cycle on and off. Like the authors of the original chart, I couldn’t figure out a graphical way to make this clear. However, the boxes at the top of the chart indicate that the car cycles intermittently through different modes while cruising.
Then came @ab13’s suggestion that I adjust the diagrams to match Honda’s diagrams from one of their videos that explains the i-MMD system. It was a good suggestion to base the diagrams on info directly from Honda instead of Car & Driver’s interpretation. All the diagrams have been changed to use Honda’s gearing and component arrangement.
No one complained about my theory that the starter motor/generator is fighting the engine to provide pseudo engine-braking when the battery is fully charged, so I kept that--and even added two more exclamation marks!!!
I extend my grateful thanks to all of you who helped me improve my presentation! I’ll submit my other board when I finish it, but after spending so much time on the mode diagrams, I’ll be lucky to get that board finished before the Sunday event.
If there's anything really wrong with the revised chart and diagrams, please tell me, but I'm running out of time to make the less-technical board listing the virtues of the Clarity vs. the other plug-in cars, so I won't be able to make any major changes like the one to mimic Honda's diagram.