I don't have the math to back it up, but I really doubt those figures. I can only base this on the human energy it takes to do both tasks. I have pushed a car from a stop to 3 mph. I have hand-turned the crankshaft of a REGULAR 4 cylinder engine (no tools, just hands around the harmonic balancer). In my opinion, pushing the car consumed more energy.

The above doesn't take into account the disconnection of the valves (no valve spring pressure to overcome) and all low-friction components and use of 0W 20 oil in our HCHII engines.

To be fair, I certainly wasn't turning the engine at 1,000 RPM... but I was turning it! Like the inertia on the moving vehicle, I assume that keeping the engine turning takes less power than getting it up to speed.

Regardless of the math, slow-speed EV mode still appears to be a decent option for at least those short slow traffic situations!

 

If you believe it works, go ahead to do your own modification or wait for someone to do that.
Anyway, there are a lot of discussions about the Insight modification.
Their conclusion is placing the 5th wheel.
http://www.insightcentral.net/forum/...pic.php?t=4391

Ken@Japan

 

Oh... I don't think I'll be trying that!!! Adding a separate wheel, motor and controller system is out of the question! All that extra weight and complexity.

As infrequently as this would be used (maybe a couple of times a day to creep up at a light... and a 30 minute period once or twice a month during one of our "Sigalert" traffic jams), just wouldn't make sense. I just want to use the equipment I already have. I know it works well at 11 - 16 MPH. I was able to stay in "EV" mode for almost two full miles once!

I just want to get EV mode from 0 MPH. I bet if I fed faulty information into the VSS (vehicle speed sensor) it would "trick" the system into letting me do EV from a stop. Although, on second thought, if I tricked the computer into thinking the car was going 11 MPH at a stop, then it would never autostop. Guess I can't win!

I really need to investigate the fuel cut option... but I'm just dreaming here because I'm not going to touch my car until the warranty expires (in ten years!).

 

Jeff;

We have calculated the approximated maximum torque figures (which is directly related to the nominal capacity of the 3 phase coil stator and the maximum current can be provided by the existing battery module) and we concluded that EV-Assist from 0 is only "conceptually" possible in the best of scenarios. One of these scenarios would be when the vehicle in on a forward encline of 2 or more degrees.

Anyway, in the HCH-2, we are faced with a "packaged" design that simply prohibits simple conversion solutions. It was explicitly (and efficiently) designed to operate in its current performance envelope as a secondary assist facility. We figured that many things would have to be altered in order to allow the vehicle to start from 0 to x safely. For example:

-We would have to explicitly monitor (and understand) the inputs for the BCM as well as the outputs for the MCM to ensure safe operation when our "final logic" kicks in. This would require a purposely designed smart add-on module with a bit of software to run it.
-We would have to re-engineer the contactors and possibly the high current wiring for heavier duty operation.
-We would have to upgrade the MCM - This is a definite !
-We also suspect that the outter shell of the motor would have to be strengtened and dampened in order to contain the vibrations from the initial torque application. In fact, I suspect that servicing the Motor Stator assembly and bearing replacement would become a regularly performed task on an HCH-2 as well.
-Heat management in the IPU would have to be made more agressive. Right now, it is modestly suited to accommodate its intended regimen.

... and the list goes on, and on. Like I said, it is a VERY good academic analysis effort. Sadly, I fear it is also an exercise in economic and technical futility to make it happen.

As Ken said, this has been looked at by many folks already and their conclusions are consistent.

Cheers;

MSantos

 

Again, I'm not using math to do my calculations... just comparisons. I think it's possible that you might be under-estimating the capabilities of that little 20 hp motor!

As you may know, I work for another auto (mostly truck) manufacturer, Isuzu. In our long-ago past, we sold a car called the I-Mark. The diesel was very popular (Isuzu is the second largest producer of diesels in the world). That car (sold from 1981 - 1985) had a 51 HP engine, which produced 72 ft. lbs. torque (at 2,000 rpm). The curb weight of the car was 2,346 lbs.

Compare this to the HCHII's electric motor. 20 HP, 76 ft. lbs., 2,875 curb weight.

That's 39% of the HP, 106% of the torque and 23% more weight. Not great power, and certainly nothing you'd want to drive with, but enough to get it moving!

Also, for comparison purposes, the GVWR on the I-mark was 3,157, so in theory, a loaded I-mark could be compared to an empty HCHII (with a driver & passenger totaling of 280 pounds) to give nearly identical weight. I admit the I-Mark wasn't exactly a rocket ship, but it was adequate (and got 45 MPG!).

Also, there are the folks who have run out of gas and still report that they can drive their cars from a dead stop. It is certainly possible.

Of course, none of this takes into account the stress and abnormally high loads this puts on the motor, battery and wiring. It might not be able to take it on a regular basis... but the question is: what IS "a regular basis"??? If I use the proposed feature to creep up in traffic on level ground a couple of times a day, that's not likely to break anything.

Oh how I wish I had a spare HCHII to experiment with!

 

MSantos, I'm curious... have any of you guys taken a gander at making the 0mph start system completely independent of the existing IMA/ICE/NiMH system, controlled through a position lever similar to that of a boat or airplane throttle?

 

Yep. We studied that option. We almost dissected an HCH-2 at our faculty several times. We used it primarily as a "working study vehicle" for our students. The car actually belongs to a long-time friend of mine who happens to be a professor at the faculty of engineering. He purchased the car for his son earlier this year and has since been used as a multi-role vehicle <grin>.

As a result of our evaluation of the technology (also aided by Honda's excellent technical documentation and assistance) we have gathered a fair amount of insight and information into the principles and attributes of the technology - so much so - that soon afterwards, I ended up buying an HCH-2 for myself too .

Right now, we're trying to finish an "assist-inhibit" feature to actually prevent EV-assist as a result of driver input via a small switch on the dead pedal. We hope to have a product that is user installable soon (at least as soon as we stop damaging the IPU sub-systems).

Cheers;

MSantos

 

Ok, call me naieve, but isn't the whole point of a hybrid to maximize electric assist? Given that you must have found a good reason for it, any idea why it make the IPU so unhappy when you do it? I could see such an inhibitor being little more than an SCR in series with the DC motor, toggled by the foot switch you mention. Open circuit, no current flow, nothing to go *pop*. Unless there's an IGBT driving the DC windings, in which case all bets are off... We call those things "It Go Boom Today" chips where I work

Anyways... Why, pray tell, do you Canucks get to have all the fun, and why didn't I get to play with any of this stuff in my BSEE classes (which I finished not five years ago)?

 

Unfortunately, as you may suspect, it is a little more complicated than that. The principle of a high current SCR is applicable (if you ignore the un-wanted downstream voltage and current drop) but you still have the cooperative logic that must enable normal operation when the switch is not being activated by the driver.

The reason for the inhibit switch is to maximize SoC for strategic use instead of allowing the IMA to drain it in regular city-only duty. We figure that there are circumstances where the regen opportunities are few and managing the SoC may be more important. The common consensus is that forced regens can be very expensive in terms of effective fuel economy. Of course, all of this is still debateable and the final judgement is subject to the data we collect as we test.

Well, this fun is actually costing us a little. But we'll see how we can make up for it in the end.


Cheers;


MSantos

 

Just FYI...
In the Prius world, the "Pulse and Glide" technique is the most famous one.
http://hybridcars.about.com/od/owner...seandglide.htm
To pulse, "avoid using energy from the large hybrid battery while accelerating".
To glide (coasting), "without any energy being drawn away to regenerate the battery".

Ken@Japan