They aren't going away (hydraulic hybrids)

[serialk11r]

Originally Posted by jamesqf

Suggest you come out here and try driving down some of our hills, without using brakes or engine braking :-) Of course you don't need to store 100% of the energy needed to raise the weight of the vehicle that distance (though it would be nice). What you need is the capacity to store all the EXCESS energy that would otherwise be wasted in braking.



Your beliefs are not at issue. If you want a vehicle that doesn't have such capabilities, there are many on the market to choose from. I do want one, and am speculating on how best to design it.

I don't know where you live but I think most people don't need to deal with big hills on a regular basis.

Some of the hills in San Francisco are so steep that if I engine brake down in 1st gear (I have 4.3 rear diff C56, 1.8L, 2170 ish pounds so the braking is *very* strong) I keep accelerating until the engine reaches over 4000 rpm :O Does that mean all cars should have hybrid racecar like regenerative braking capability?

The more energy capacity you put in, the more cost, mass, and volume is used. What I'm saying is that not many people will have much of a use for the extra capacity. Maybe something more reasonable like enough energy to climb 500ft, which would be like storing the excess energy from descending 1000ft at a faster speed. In a city environment that would already be massive overkill.

[user removed]

The best car for long grades is the lightest car that has gearing to climb the grades efficienctly, while it's lower sectional density means it will not accelerate downhill as rapidly as a heavier car or one with better aerodynamics. Everything is balance and you can always find a scenario where that balance is lacking. The question is how large of a percentage of scenarios can you cover COST EFFECTIVELY.
With hydraulic hybrids if you want greater hydraulic storage then you increase the size of the high and low pressure accumulators, which could be offered as an inexpensive option with a new vehicle purchase. The weight penalty must be considered as well as the cost.
My goal with my individual pursuit is to see all vehicles become more efficient as Ian so eloquently posted in his thread.
Building a vehicle with no cost penalty means the payback from fuel cost savings begins immediately. No other design currently available has that capability, and it is not likely that will change in the near future. Even those whose priorities are completely different from mine should be able to agree that this objective is valid. I want every vehicle on the planet to be much more efficient, not just the few who come to this forum. We are a minuscule percentage of the worlds vehicle population and drivers, and even a number of our wives don't hypermile their cars.
Bottom line is make the cars hypermile themselves, which will negate inefficient driving to the greateest degree possible and it will be planetary in it's effects, with a huge reduction in global fuel demand with consequences far beyond any individual effect.

regards
Mech

[user removed]

Ian, since the in wheel drives place the power precisely at the point of application, I think you can understand the effectiveness.
The drives will be subject to considerable pressures in the cylinders and pistons, with the hub enlarged to allow the offset journal location, the bearings will be around 3-4 inches in inside diameter. In this case they have a capacity of about 12,000 pounds load per wheel, while the whole assembly would weight about the same as the disc brakes assemblies they would replace.
If that proves to be more practical than just mounting them inboard, like the brakes on the Jag XKEs then that would eliminate the need for any drive shafts to connect the drives to the wheels. If not them move them inboard and cut total suspended wieght by over 50%.
The drives would be "flooded" eliminating the necessity for any sealing of the individual piston-cylinder assemblies. Thsi would also provide cooling for the hydraulic fluid. If temps rose above normal you could also add a radiator in the return (low pressure) circuit, but then again you increase complexity and inefficiency.

regards
Mech

[jamesqf]

Originally Posted by serialk11r

I don't know where you live but I think most people don't need to deal with big hills on a regular basis.

East side of the Sierra. I don't know about most people - some folks stay in Kansas all their lives - but there are a lot of people who do.

Some of the hills in San Francisco are so steep that if I engine brake down in 1st gear (I have 4.3 rear diff C56, 1.8L, 2170 ish pounds so the braking is *very* strong) I keep accelerating until the engine reaches over 4000 rpm :O Does that mean all cars should have hybrid racecar like regenerative braking capability?

Sure. First, some of the hills in San Francisco may be steep, but they are not particularly high - a quick look at the map shows nothing over 1000 ft in San Francisco itself. Even further south, going over 17 to Santa Cruz doesn't even get to 2000 ft. OTOH, when I used to travel to San Jose via 88, I could darn near coast from the summit west of Silver Lake into Jackson. Now a really efficient hybrid would have enough energy capacity that if I had charged it at home, it would have been nearly empty at Carson Pass, and fully charged again at the valley floor.

The more energy capacity you put in, the more cost, mass, and volume is used. What I'm saying is that not many people will have much of a use for the extra capacity.

Of course, but this also applies to engine horsepower.

In a city environment that would already be massive overkill.

So who cares about city environments? In a city, if you're so unfortunate as to have to live in one, you should either bike or take public transport.

[niky]

Conversely, if you live up in the mountains, where elevation changes and long commutes waste a lot of your fuel, you should consider moving closer to where you have to drive.

People drive, for whatever reason. There is no problem with designing a hybrid that meets the needs of a certain cross-section of those drivers.

And I don't see the problem either, with not designing it to capture energy all the way down a mountain. There's a limit to how cost-effectively you can package energy storage on a car. Even on Prii, there comes a point where the motors simply bleed off electricity in order to keep from overcharging the battery.

And, as said, non-hybrids don't even store braking energy, anyway.

[IamIan]

Originally Posted by Old Mechanic

Ian, since the in wheel drives place the power precisely at the point of application, I think you can understand the effectiveness.

Potentially more effective ... not necessarily ... nor automatically.

__ Torque at the tire road interface from a motor in the wheel ... or the same ___ Torque at the tire road interface from a centrally located motor will both see exactly the same vehicle performance... the tire road interface doesn't care where the source of the torque came from.

If the combination of the in wheel system is better than the combination of centrally located system and its connected transmission ( etc ) to get to the wheel ... then yes it's better... but if not ... then it's not... no magic happens just because it happens to be in the wheel ... if anything putting it in the wheel imposes additional design complications , and issues , that a centrally located hydraulic unit does not have to deal with as much.

I would like to clarify ... I am not suggesting it won't work ... or that a in wheel motor can not be built to withstand the stresses ... it can ... But that doesn't change that the wheel is pretty much one of if not the most abusive locations on a vehicle ... and it is because of that , that I am / would be concerned about putting it in the wheel ... not just your design with a hydraulic ... for the same reasons I would be concerned about putting an electric motor in the wheel ( even though companies sell them )... or any other type of drive motor.

[user removed]

Ian, there are strong rational points of debate about in wheel and central locations for drives. The first vehicle I plan on building will be a tadpole trike with the rear wheel being powered. The drive could be connected to a separate wheel with a chain, like a motorcycle or be in the wheel itself. At this point I think I will build it separate since the losses through a chain are minimal and the fluid connections could be solid tubing with the drive fixed to the frame. It woud also allow the brake to be retained as a backup.

regards
Mech

[jamesqf]

Originally Posted by niky

Conversely, if you live up in the mountains, where elevation changes and long commutes waste a lot of your fuel, you should consider moving closer to where you have to drive.

Ah, but the mountains ARE where I have to drive in order to do most of the things that matter in life, so by living in/close to mountains, I minimize my driving. Occasions when I have to drive in/to a city are rare. If I were so unfortunate as to have to live in one, I'd be driving even more, in order to escape the city.

[Cobb]

If they arent going away, then where are they? This should be something almost anyone can rig to a petal bike or a soap box racer, right?

As is I think we truely only have one successful hybrid vehicle on the road, th Prius. We may have a few with an EV, however it looks like the Leaf has battery issues just like the Volt.

I doubt neither Honda or Chevy has sold enough to be profitable. Thats why I didnt say Insight, HCH, etc as to be successful for the company they need to sell enough to be profitable.

As I recall UPS had a delivery truck with this equipped for testing purposes? Cant say I ever seen a truck come to my house that was equipped with the system.

[user removed]

I guess your bike is flower powered .

Using the same logic there would never be any advancement in any transportation device, going back to the invention of the wheel, which did not exist before someone made one.

Do you still roll to work on logs?

regards
Mech