saviour stivala wrote: ↑09 Oct 2021, 10:35
The valve clearance is adjustable as explained on page 192. The formula one valve gear which includes valve and valve seat being part of the engine is designed to last the mandated mileage of engine life at the designated temperature the engine is designed to operate at. Because of the very high compression used which necessitates the use of as compact a combustion chamber as possible but with the need of very high valve lifts The formula one engine camshaft lobe configuration uses what is called ‘the Bezier curve (created by Pierre Bezier in 1960). Using the ‘Bezier’ cam-lobe curve, the valve is made to follow the piston at very close tolerances.
The Bezier Curve just allows the lobe designer more control when designing the lobe. Honda outlined that in this:
http://www.f1-forecast.com/pdf/F1-Files ... P2_09e.pdf
With Honda, they knew their acceleration constraint, so they were able to design to that point and have a more refined control of the lift profile. I'd be really curious to see the Jerk curve with their "new" acceleration curve, but might be as much of an issue with pneumatic valve "springs".
Old school cam lobe designers typically used polynomials. You can play with one here:
http://www.mjpsoft.dk/cam_instructions.html
A lot of lobe designers use Blair's software.
http://www.profblairandassociates.com/G ... esign.html
It also allows them to design the acceleration or velocity curves and calculate things backwards. Helps when you know what your constraints are. It might have have as fine resolution as the software Honda designed.
A cam designer shared one time that he thought old Cosworth cams were a radius nose and base circle connected by two flanks.
He was not being complimentary.... Here is what another one said. Harold Brookshire passed some years ago, but was Comp Cam's original cam lobe designer in the 1970s before doing his own thing. At the end of his life, he was doing some consultant work for the Dodge NASCAR teams. His camshafts had a lot of wins in the US in the 1970s-1990s
Jon,
Revisit Harvey Crane's web-site. He recommends AGAINST using his "No-Pulse" ramp on the closing side, and he uses the acceleration-reversal closing ramp.
Constant-velocity opening or closing ramps are so "Old-School" that I have NEVER used them since I started designing in 1972. When Harvey saw my ramps in 1974, he asked me if I had been Cosworth's designer, as they used similarly-shaped opening and closing ramps, which involved constant-acceleration/constant-jerk curves.
My main curve, from the opening point to the closing point, was of the PolyDyne method, which I stopped using by 1977, when I discovered I could do everything I wanted with regular polynomial equations.
In the Spring of 1980, when I started UltraDyne, I 'invented' Multi-Segmented Polynomial' (MSP) equations, which I still use today, and they are what you call 'Spline-Fits', or 'Knots'.
All graphs shown by me are of MSP equations, or Spline-Fits........