The problem with series hybrids

[RobertSmalls]

Originally Posted by Old Mechanic

I read somewhere that the peak BSFC on the lean burn insight motor was close to 49%.

regards
Mech

49%? That's an enormous number.

But a hybrid does not need to be a series hybrid to keep the engine at a constant load. I am building MIMA expressly because it will allow me to stay in lean burn most of the time.


Consider the Prius:



The Prius' Atkinson cycle engine, with a CVT and throttle-by-wire, delivers within 8% of peak BSFC, as long as load is >= 25% of maximum load. The Prius ought have an ICE just large enough to allow high-speed crusing on the ICE alone, and an electric motor large enough to give the car quick acceleration. If the load falls to less than 25% of maximum, the ICE should either be used to recharge the batteries, or it should shut off and allow the electric motor to propel the car.

A series hybrid drivetrain would need to be more than 92% efficient to outperform this arrangement, and that is the problem with series hybrids.

[Tweety]

Originally Posted by NeilBlanchard

Hi Dave,

Serial hybrids have batteries (and/or supercapacitors), and this is the basis for their strong advantage over ICE only vehicles. You can't compare serial hybrids to ICE only and ignore the electric mode -- this is why they are used, and it is why they are so much more efficient.

The corollary argument would be to insist that the ICE-only car has to use just one gear for the whole test. Hey, it wouldn't be fair to let it use it's transmission, because the serial hybrid only has one gear!

I'll take a serial hybrid with a discharged battery and you take an ICE and drive it in one gear and we'll see who gets better FE, okay?

Yes and no... If you take into account that the car is needed to go beyond the range of the smaller EV's an hybrid is a lot more efficient than a standard ICE car... I'm quite certain nobody here made any counter claims, so why drag that into the comparasion?

An EV is more efficient on small range than an ICE by far... And I doubt the hybrid does that much better than the EV if even the same...

As for limiting comparasions, then disengage any and all regen braking, as that is by your defentition an unfair advantage... We where supposed to compare overall performance and efficiency right? Not the efficiency of the windscreen wiper... So compare the car as a whole, like you yourself said...

A electric/ICE hybrid (series or paralell) makes a half effiecient EV and a better than half efficient ICE (or a good one with a boot full of unused stuff)... Compare the EV part to a good no compromise EV (EV1 or RAV-EV) and the ICE part to a good no compromise highway specific ICE car (can't think of a good example, sorry) and they come up short...

They are a compromise, and they will always suffer from converting losses, that's a given... How much can be argued and compared, the fact that there are losses cannot... However, right now the best compromise on the road is a Prius...

[user removed]

Charles Gray one of the heads of the EPA HH program stated he could hold a 500 HP hydraulic motor in my hand.

Easily light enough for an in wheel drive.

A Virginia Tech Engineering school group that studied my design for one year, concluded that an in wheel drive would generate 35 HP per wheel (at the wheel itself) and 380 pounds feet of torque from 0 wheel speed, per wheel.

Thats energy density and high torque from 0 wheel speed with no large battery (read expensive) for storage.

Ths INNAS configuration (previously linked) used engine on operation less than 12% of the test cycle.

Same 0-60 in 8 seconds performance.

Half the fuel consumption

better than 50% reduction in emissions.

Now if you addressed engine design and optimized it for efficiency in the narrow range of BSFC, you could reduce the weight of the pistons and connecting rods, eliminate any throttle control or fuel delivery control, add a heat racovery system to the exhaust to operate the accessories and increase the efficiency. In fact you could use a smaller engine to further increase efficiency.

Reduce the fuel tank capacity to reduce weight.

While electrics could apply that same torque to each wheel, either system could reach the limits of the traction of the tires themselves, so performance becomes a function of actual traction.

Next time you feel like wasting some fuel, do a single panic stop from 60 MPH and measure the distance your car travels.

That same distance (and time) is exactly the same distance you would need to accelerate in a HH to 60 MPH, and only 20% of the energy would be from fuel consumption. The rest would be from the energy you accumulated in the previous stop.

regards
Mech

[Tweety]

Originally Posted by Old Mechanic

Charles Gray one of the heads of the EPA HH program stated he could hold a 500 HP hydraulic motor in my hand.

Easily light enough for an in wheel drive.

A Virginia Tech Engineering school group that studied my design for one year, concluded that an in wheel drive would generate 35 HP per wheel (at the wheel itself) and 380 pounds feet of torque from 0 wheel speed, per wheel.

Thats energy density and high torque from 0 wheel speed with no large battery (read expensive) for storage.

Ths INNAS configuration (previously linked) used engine on operation less than 12% of the test cycle.

Same 0-60 in 8 seconds performance.

Half the fuel consumption

better than 50% reduction in emissions.

Now if you addressed engine design and optimized it for efficiency in the narrow range of BSFC, you could reduce the weight of the pistons and connecting rods, eliminate any throttle control or fuel delivery control, add a heat racovery system to the exhaust to operate the accessories and increase the efficiency. In fact you could use a smaller engine to further increase efficiency.

Reduce the fuel tank capacity to reduce weight.

While electrics could apply that same torque to each wheel, either system could reach the limits of the traction of the tires themselves, so performance becomes a function of actual traction.

Next time you feel like wasting some fuel, do a single panic stop from 60 MPH and measure the distance your car travels.

That same distance (and time) is exactly the same distance you would need to accelerate in a HH to 60 MPH, and only 20% of the energy would be from fuel consumption. The rest would be from the energy you accumulated in the previous stop.

regards
Mech

And since hydraulic fluid has no mass it doesn't effect efficiency like the weight of the battery?

And no, I'm not talking about the weight you save or nullify by removing components made redundant by the hydraulic transmission system... I'm talking about the accumulator tank... It's probably atleast similar in weight to a superconductor? and since that does the exact same thing in this instance, regen brake feeding it to use it for take off and acceleration... I'm not going to quote figures but in a pure EV I think the numbers are fairly close as to the 20% from the traction pack vs superconductor...

Why would the electric car apply the same torque to both (all) wheels if it where using wheel motors with a decent controller?

An traditional ICE would... And a EV converted from an ICE would... But there is no reason a pure EV would...

You keep comparing to a traditional ICE car... The HH or B-EV will both beat that, that's mostly a given... I'm trying to ask you why you couldn't use an electric motor to create the pressure needed for the HH ?

If the INNAS is efficent enough to only use the ICE on 12% of the test cycle, and a very small one is sufficient, why not replace it with an electric motor? Stick an decent sized battery in there and it should be getting the same range as the ICE version? since now the battery is only used 12% of the time...

[user removed]

Originally Posted by Tweety

And since hydraulic fluid has no mass it doesn't effect efficiency like the weight of the battery?

And no, I'm not talking about the weight you save or nullify by removing components made redundant by the hydraulic transmission system... I'm talking about the accumulator tank... It's probably atleast similar in weight to a superconductor? and since that does the exact same thing in this instance, regen brake feeding it to use it for take off and acceleration... I'm not going to quote figures but in a pure EV I think the numbers are fairly close as to the 20% from the traction pack vs superconductor...

Why would the electric car apply the same torque to both (all) wheels if it where using wheel motors with a decent controller?

An traditional ICE would... And a EV converted from an ICE would... But there is no reason a pure EV would...

You keep comparing to a traditional ICE car... The HH or B-EV will both beat that, that's mostly a given... I'm trying to ask you why you couldn't use an electric motor to create the pressure needed for the HH ?

If the INNAS is efficent enough to only use the ICE on 12% of the test cycle, and a very small one is sufficient, why not replace it with an electric motor? Stick an decent sized battery in there and it should be getting the same range as the ICE version? since now the battery is only used 12% of the time...

What you decide to talk about is your choice. You don't write the rules for my choice. Components replaced by a HH powertrain are a critical consideration in any cost analysis basis for comparison. Less complicated powertrain systems are the opposite of hybrids available today, and inexpensive solutions to hybrid applications are a real factor whether you choose to accept that fact or ignore it.

I have a Nissan shop manual for a 1981 model. Would you like to see the pages that consititute 1/3 of the whole content of the manual that are non existant on a HH, or would you like to add serveral hundred additional parts in your hybrid electric vehicle?


Try reading my prior posts. I clearly stated that it did not matter what consumable energy source you utilized.

All it has to do is recharge the accumulator. That can be done with a battery and electric motor, a steam engine with a pan of coal heating the boiler, an IC gas or diesel engine, a microturbine, a natural gas engine, or any other source you desire that consumes a replenishable fuel.

Already said that earlier, but I guess it requires repeating. I won't use the I word again as long as you keep the responses civilized.

The HH wins in regeneration and reapplication, by a margin of over 100% increase in efficiency.

Without any storage whatsoever the IVT (Infinitely Variable Transmission) feature allows you to optimise engine efficiency. The accumulator storage allows you to maintain engine operation at only best BSFC levels, regardless of the engine-motor-fuel-battery choice.

The accumulator which (as previously stated) could also serve the purpose of a structural component of the vehicle.

Can your battery or superconductor be the frame of your vehicle (whether it is uni body or separate frame construction)?

NO

Can your battery or superconductor regenerate enough energy to recover 80% of a single stop-start cycle, down to 0 wheel speed.

NO

Unless you have a monster of an electric motor.

Do the batteries and or superconductors exist, and are they available for purchase in a vehicle that could be commercially produced for $15,000.

Probably not for at least another 20 years.

Why all wheel drive?

Because that is the source of regenerative energy. Any wheel or number of wheels can be instantly disconnected by going to 0 stroke on that individual wheel drive.

Traction control and ABS are easily incorporated by dumping some of the pressure necessary to maintain any stroke position, unlike conventional ABS and traction control systems that use friction brakes to maintain traction, which is a total waste of energy.

In your BEV you still need friction brakes, not necessary with a HH.

What BEV is available today for $15k without a battery or superconductor.

What happens to your 400 pound battery or your superconductor in a very serious collision?

regards
Mech

[Tweety]

Originally Posted by Old Mechanic

What you decide to talk about is your choice. You don't write the rules for my choice.

And you do "write the rules" for me? Since you try to dictate to me what to discuss?! Obviously different rules apply...

I was as I said asking you, that means you can choose not to respond... If you do I don't care either way, I'm done with this discussion as your tone is decidedly hostile...

I have read your previous posts... I'm fairly certain you missed a few of mine or decided to disregard them entirely...

[user removed]

Industrial property

Direct IC to hydraulic storage with 50+% overall efficiency. Eliminates the need for a separate pump driven by an engine.

40% fewer parts than a diesel engine.

17KW rating.

Might be enough heat energy lost to operate a heater in wintertime.

No warm up enrichment and lower emissions.

regards
Mech

[roflwaffle]

Originally Posted by Old Mechanic

A horse is proven to be effective, same logic was used against the first cars.
I guess the grass to hoof comparison has been long forgotten, along with the statement that if man was meant to fly he would have wings.

In the UPS comparison you draw a conclusion without data, just assumptions based on the number of vehicles purchased.

The HH versions supposedly saved 800 gallons of fuel per year on average, while never needing a battery replacement, which would destroy the comparison, and is an inevitable cost.

There's plenty of data. A HH conversion for a pickup costs $13,000 plus labor, so probably around $15,000 and up. A factory 2-mode hybrid system carries a ~$4000 premium over a similarly equipped model out the door. Certainly an OEM w/ a HH option would charge less than $15000 since they can purchase in volume, but I haven't seen anything to indicate that it's cost competitive w/ battery electric hybrids.

[NeilBlanchard]

How is the pressure stored in a hydraulic system? In the accumulator? What provides the "spring"? Isn't this the actual place the energy is stored? (Since the hydraulic fluid cannot be compressed...)

[roflwaffle]

OM can correct me if I'm wrong, but in most auto apps I think the accumulators tend to use N2.