Zynerji wrote: ↑17 Sep 2021, 14:09
Wasn't there a thing called the Hydristor that did something with the transmission fluid as the energy store?
https://en.wikipedia.org/wiki/Hydristor
Regenerative braking and hybrid vehicles
The Hydristor torque converter can also accomplish total hydraulic braking and energy storage. Once a cruising speed has been achieved with front and rear Hydristors at some appropriate relative displacements, hydraulic braking is achieved by first simultaneously reducing both front and rear to zero displacement, then leaving the front Hydristor at zero (thus hydro mechanically disconnecting the engine from the torque converter hydraulic circuit and finally beginning to increase rear displacement as a braking function with the braking pressure and flow being directed to a hydraulic accumulator pressure tank. The decaying vehicle speed (kinetic energy), the rising tank pressure and the desired rate of deceleration determined by the driver all are variables which are easily managed by the Hydristor system. The stored braking energy can then be re-used for subsequent re-acceleration. With hydraulic storage capability, the acceleration at highway speeds can result in wheel spin.
The installation of a Hydristor torque converter into a typical car or truck [7] already on the highways will create a hybrid vehicle which will out-perform the current crop of hybrids[citation needed], thus adding other alternatives to that technology. One benefit of this approach is that the existing fleet can be re-configured thereby incurring monetary and natural resource savings[citation needed].
What I can understand from it, the basics is a two-way pump and an pressure vessel (with air). So, energy is still stored as compressed air (or at least something that is compressed, could also be a spring, etc). If I read the wiki page, it’s a bit like a mad professor and his invention.