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Hybrid vehicles

My John Deere compact utility tractor (and many others, including Kubotas, uses a Yanmar 23 hp 3 cylinder diesel engine. The engine has a fairly high operating rpm (for a diesel) of 3500. At that speed, it develops its peak torque with a fuel consumption of 0.9 gallons per hour. For those unfamiliar with diesels, the 23 hp figure is deceptive because (due to the higher specific energy of diesel fuel and the 20+ to 1 compression ratio, the torque produced is vastly greater than that of a 23 hp gasoline engine.



I wonder why no car maker has developed a hybrid vehicle utilizing such an engine to run an alternator for recharging the batteries.



Any thoughts?

The Chevrolet Volt will do essentially that, but with a 3 cylinder turbo gasoline engine. I understand that GM considered a diesel instead, but chose the small gasoline engine. No manufacturer has done it yet because the energy density of the drive batteries made it impractical.

Not sure why the energy density problem would be different for diesels vis-a-vis gasoline engines. Of course, emissions from diesel engines would present some difficulties, though not overly so.

I have several Kubotas. They make their own engines and don’t have Yanmar boat aux motors shipped to India as Deere does to assemble their tractors. Sorry for the dig among tractor owners. jk The engine operating RPM is well below 3000 rpm which I agree is ideal for power generation. But cheaper still is the gasoline carb Coleman generator I had for years. When limited RPM for series hybrids, not parallel like Prius is used, any limited RPM , but efficient ICE will due. Right now, I don’t see any out their and the wide power band motors for today’s hybrids is still required I feel.
Personally, I like your observation overall if and when series becomes the norm and battery tech is still lagging or hidden, what ever your politics.

BTW, diesels in power generation are great long term investments, but for cars where high turnover is “valued”…cheap and cheaper gas engines is the way to go. Good diesels have too long inherent reliability for car use overall. I’m a fan of the old carb., push rod for the use except for the weight factor.

Excellent question! A Diesel-Electric hybrid would be fantastic. I know many years ago Honda was working on one. They had the car (all hush-hush) at a small development shop in Denver testing its performance at high altitude…I helped in a small way by setting up some emissions monitoring equipment…

It seems, in the States, there is a limit on the number of Diesel-powered passenger vehicles the “Powers-That-Be” want on the road…The market for #2 distillate is tight (globally) and currant users do not want a whole new class of consumers forcing prices up should that market go into shortage. We got a taste of that 15 months ago, lest you forget, when Diesel fuel prices surged to more that a dollar above gasoline prices…Someone has to burn the gasoline and that someone are North Americans…

Amtrak has been using diesel electric hybrids for decades.
Sorry, Saturday humor.

I agree that it sounds like a good platform, but I think here in the U.S. the term diesel has taken on an image of noisy, smoke-belching semi-truck operation. And not without some truth to the image. Would you want to listen to your John Deer engine while cruising down the highway with your family sedan to the beach?

Modern automobile diesels reduce the noise levels primarily by running lowering combustion ratios, but that compromises the energy available in each stroke.

And then there was the GM “let’s just convert our gas engines to diesels” fiasco some years back.

Remember too that we just recently began with ultra low sulpher diesel fuel here in the states.

The bottom line is that diesels have had a rocky history here and just do not seem to sell well in automobiles in the U.S., and I think this has carried over to hybrid designs.

Modern locomotives are all diesel-electric hybrids.

As for cars, I guess they figure a straight diesel engine is efficient enough to compete with anything that exists right now, so why bother with the electric system. They’re also more expensive than gasoline engines already, and are you going to pay ANOTHER couple of thousand dollars over what you’re already paying above the base price for the diesel engine?

Well, diesels cost extra over gas, and hybrids cost extra over gas. That makes the economics of diesel+hybrid pretty poor over diesel or hybrid. Say diesels are $1500 more and hybrids are $1500 more than the gas version. Lets say the gas gets 25 mpg, the diesel or hybrid gets 50 mpg, and the diesel/hybrid gets 75 mpg. Over 100k miles the gas uses 4,000 gallons, the diesel or hybrid uses 2,000 gallons (saving $4000 in fuel at $2/gallon). The 75 mpg diesel/hybrid uses 1,333 gallons, worth $2,666, saving $1,333 over the diesel or hybrid, less than the cost.

BTW, without having done the research and only depending upon older info; parallel hybrid technology is more efficient than series, which makes the diesel electric generation use less viable. Gas engines still have wider power band for parallel use.

If your tractor has a hyrostatic trans, you essentially have a series diesel to hydraulic pump drive. This reinforces the diesel as the proper choice in a limited series application, but still not the best solution for over the road performance for today’s parallel hybrids. A stronger belt CVT (which the hydro stat is but lots of slippage) to handle a high torque diesel, could push 60mpg to 75 mpg in a compact; but ain’t gonna happen IMO.

a guy I knew waaaay back in time (80’s ish), turned an Opel electric. and he used a briggs and stratton. when the batterys died, get out, pull the cord, and drive along. puttering all the way.

also, as people have pointed out,“diesel” trains, arent powered by diesel. they have massive 16 cyl. diesel engines, but they power a generator. there are electric motors in the trucks that make it go.

The energy density of the batteries so far has been too low to make the system you or I describe feasible.

In Locomotives, the diesel-electric system offers this: No clutch. No transmission. 100% drive power available at zero speed. Tremendous engine braking available if needed.

When the final drive of a hybrid is all electric motors, such as the Chevy Volt, then a diesel running at a constant speed seems to make sense. There maybe issues with more pollution problems or restarting the diesel frequently which need to be overcome prior to a refined production model going on the general market. The fuel efficiency of the diesel is clear so there must be some other hurdles either technological, or economic (costs of diesel fuel vs reg. gas) that still need to be cleared.

The Honda diesel hybrid I mentioned earlier was indeed a constant speed, constant load engine…When the battery was charged, it shut off until needed again…

The hybrid will work just fine when the batteries are fully charged. Once they are depleted, the electric motor only get 29 hp worth of power, minus the efficiency in the electrical system. 25 hp would be realistic. That’s how much power a large SUV needs to cruise on the highway. It won’t be close enough to climb hills.

As an example, my compact car makes about 100 hp at 6k rpm. Once I was taking it up a 10,000’ mountain, at 50mph, with about 2800lbs, at wide open throttle with the engine spinning at 4k rpm. Taking the thinner air into consideration, I’d guess that the engine was making about 60 hp on that run. If my car was running on 25 hp, it probably would have been doing 20 mph. If it was as heavy as a Chevy Volt, 25 hp would take it up that hill at about 20 mph, which is unacceptable where speed limit is 50.

I know that diesel engine used in construction have low power but plenty of torque. But torque only tells you whether or not you can do the job. Horsepower tells you how quickly you can finish the job.

“The hybrid will work just fine when the batteries are fully charged. Once they are depleted, the electric motor only get 29 hp worth of power, minus the efficiency in the electrical system. 25 hp would be realistic.”

I suspect that battery charge level would be constantly monitored, and the engine would run to charge the battery until it has enough charge to run without the engine. Remember, the engine only charges the battery in this version; it never propels the car.

I was surprised that GM’s Volt does not recharge the batteries when the IC engine kicks in. I wonder why not?

I think you are on the right track. With low sulfur diesel there is no reason why such a strong engine could not power a hard load like an electric generator on a car. But what happens to the refinery market in the us if 3 million cars using diesel are added to the road in a year or two. This would compete with trucks and home heating fuel.

“I was surprised that GM’s Volt does not recharge the batteries when the IC engine kicks in. I wonder why not?”

Actually the IC engine does recharge the battery (so does regenerative braking); it just can’t do it fully. I guess there might be two reasons. It already costs $40,000 without being able to fully recharge the battery on the road. Adding this feature would increase the price, which is already high, even with the $7500 Govt. tax credit. Another reason might be weight. The battery only stores enough charge for 40 miles. GM could have doubled the range, but at an unacceptable weight penalty.