I'm not going to run an idle test, because I don't have the equipment, but suffice it to say that a diesel "smokes" a gasoline engine in low consumption at idle. LOL
But in bwilson4web's application of using the car as a generator it is much more efficient to use an engine to charge batteries, shut down, and run from the batteries for awhile than leaving the engine on all the time.
I think the idea of a constant-on diesel hybrid is worthy of production. Using the same philosophy of a smaller ICE boosted by the electric motor, an idling diesel could stay idling and charging until it is needed for powering higher speed travel. Diesels waste most of their fuel getting up to speed. If instead they could be used to charge the battery and for cruise power, the same bump in efficiency we see with gasoline based designs would probably hold up.
This is actually a good alternative to idle-stop, and I personally wish that my own gasoline hybrid woudl do this when it is in "warm-up" mode and doesn't like to shut down the engine (cold start wear and tear). It could rev up to some faster RPM level, and do intense charging, if there is battery capacity to take advantage of it (as there often is in my case) This would then both relieve some charging that would need to be done later, such as when I'm climbing hills and could use the engine power, and it would warm up the engine a lot faster, to allow for subsequent auto-stops to kick in a lot sooner.
Fast-idle charging, combined with regenerative braking, and a somewhat different assist algorithm could make for a fairly effective diesel hybrid. Another option might be to elecrtonically detune the turbocharger for normal accelerations so that it would not produce as much boost until it settled into a stead speed or got into the ~2000 RPM range. That extra torque could be "filled in" by the electric motor, and it would save the fuel consumption. If the computer detected WOT acceleration, it could go ahead and spool up the turbo at lower RPMs for extra power, though. The turbocharger would also still providesufficient boost to help keep the engine at optimal RPMs for highway cruising.
I'm not going to run an idle test, because I don't have the equipment, but suffice it to say that a diesel "smokes" a gasoline engine in low consumption at idle. LOL
It doesn't take much equipment:
1) Fill-up in the evening
2) Drive to where it can be left running all night
3) Leave it running for 12 hrs.
4) Fill-up in the morning
Divide the fuel to refill by the hours. It works best if the filling station is near-by. However, if concerned, do a round-trip to measure fuel burn to adjust the idle burn value.
Like I said, I'm just curious as to what numbers were looking at. We know it is greater than 0.0 L./hr.
The fills on the smart's tiny 22 L tank are so varied in their top-up levels that the margin of error would massively exceed the amount of fuel actually consumed. My fills are plus or minus 1.5 L, even at the same diesel pump, in the same position. Depends upon what mood the car's tank is in I suppose.
I assumed you were using one of those on-board computers to generate your figures. Now I'm not so sure how accurate they are.
The smart cdi leans out to the point that a gasoline engine would stall, when idling.....if you want the A/F ratio at idle, let me know and I'll look it up.
If you have an instantaneous display that is accurate, you may be able to test idle consumption using that. I calculated the idle rate on the Civic Hybrid of mine at around .1 gallons an hour, when warmed up, by doing a coast-down test in neutral, and noticing at exactly what speed the meter dropped from being pegged at 120mpg, which in my case was 12mph. At 120mpg that would require 10 hours to consume one gallon, or .1 gallons/hour. Of course, the display could be wildly inaccurate at near-idle levels, but the results are interesting if nothing else.
The fills on the smart's tiny 22 L tank are so varied in their top-up levels that the margin of error would massively exceed the amount of fuel actually consumed. My fills are plus or minus 1.5 L, even at the same diesel pump, in the same position. Depends upon what mood the car's tank is in I suppose.
I assumed you were using one of those on-board computers to generate your figures. Now I'm not so sure how accurate they are.
The smart cdi leans out to the point that a gasoline engine would stall, when idling.....if you want the A/F ratio at idle, let me know and I'll look it up.
I've used both methods but prefer to pump (I pay the pump.) Fortuantely, my fill-up is a discount station one mile from the house, new, and I can use the same pump each time.
I have used the Multi-Function Display. To use it effectively, you need to 'burn' enough fuel to approximately equal the expected amount that will be burned. Then park the car and start the test. The MPG will automaticly decrement and what you want is the MPG at the end of the test to be half of the begining test MPG. Then you use algerbra to calculate the fuel burn.
Diesels run so lean at idle that stopping is unnecessary, and also, starting and stopping reduces catalyst efficiency, as the honeycomb cools and then needs to re-heat (I refer to gas engines here).
Re: Hybrid Diesels
Re: Hybrid Diesels
