Hydrualic prime mover - the accumulator

[jettlea]

I am working on a hydraulic system for a vehicle of nominal weight. Of course, the hp required to keep it at reasonable highway speeds is reasonably in the 30-40 hp range.

My issue is energy storage for acceleration (s). This of course is substantial (like 150hp, over 8-10 seconds).

My first instinct is to consider a robust accumulator. But when I jump into the most basic of napkin approaches, I end up with a tank in the order of 80 gallons, 4-5kpsi, with the resulting storage capacity of only a few MJ of energy storage. Enough only to accelerate ~ 2 x. (I will address later (as others have) regeneration energy storage during deacceleration)

Am I heading down the wrong path here in considering a hydraulic accumulator (s), in a mid-sized car, to provide ~ 10 MJoules of energy storage?

Thanks in advance. Mike

 

[Pkruse]

It has been done before, and yes you will end up with a large and heavy accumulator system. The one I saw had three cylinders a little larger than a K-bottle on a 3000 psi system. This is more often used on large and specially design moble heavy equipment. Accumulators are never small and light weight.

 

[Danger]

I have no expertise in this matter, but did have the brilliant () idea about 30 years ago of using hydraulic motors on a homemade sports car. I figured that it would provide ridiculous torque and eliminate the need for differentials. I wanted it to exceed the performance of my Roadrunner, which was 12-second quarter-mile times and a top speed of 160 mph, with 4-wheel drive. It was based upon the best equipment available from the Rucker catalogue at the time.
Jeez, but did that not work out! I can't even remember what sort of accumulator arrangement I had, if any. The pump was to be driven by a 1,500 hp diesel engine. The main killer, though, was that it would have required something on the order of a 1,000 gallon reservoir in order to allow for decent cooling of the fluid. That would have been bigger than the rest of the car.