When I was thinking about a variable drive for the new Kawasaki H2s centrifugal supercharger, I thought of the constant-speed drives formerly used on jet engines to drive aircraft 400-cycle alternators. They were densely packaged hydrostatic drives like the transmission of Honda Foreman side-by-sides and the DN-01 automatic-transmission bike. In such drives, a variable-stroke, multi-piston hydraulic pump sends fluid to a fixed-stroke-driven hydraulic motor. As the output of the pump is varied by increasing or decreasing its stroke, the rpm of the driven motor can be varied. If you recall the asking price for DN-01, you will see that such variable drive systems are not cheap, which is surely why Kawasaki instead showed patent drawings of a two-speed gear drive. Yet with only two ratios, getting a wide enough spread of boost will be a problem. What alternatives? One might be a Salsbury variable-pulley drive, used as a transmission on millions of snowmobiles. Such a drive is fairly bulky. There are also the so-called traction drives, which employ the steep increase in the viscosity of certain fluids at very high pressures to allow transmission of power through contact between metal rotors. Finally, car makers are playing with using fairly powerful electric motors to assist the spin up of turbocharger rotors. This would require a larger-than-normal alternator to supply the current.
Posted on: Wed, 10 Sep 2014 21:29:24 +0000
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