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Pneumatic Shifting and Clutching and integration

UCONN FSAE. Pneumatic Shifting and Clutching and integration. Overview of Pneumatics specific to our application. The use of pneumatics in this application is tried and trued Provides the fastest means of shifting the car when paired up with the ECU

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Pneumatic Shifting and Clutching and integration

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  1. UCONN FSAE Pneumatic Shifting and Clutching and integration

  2. Overview of Pneumatics specific to our application • The use of pneumatics in this application is tried and trued • Provides the fastest means of shifting the car when paired up with the ECU • Solves the issue of having to get the input from the driver back to the engine • Overall cost can be anywhere from $200 to over $400

  3. Integration with related systems • Shifting goes hand in hand with many systems • ECU • Driver • Frame • Engine • Lets go into detail...

  4. Pros and cons over other methods • VS Mechanical: Pros: • Faster shifts • Easier to operate for inexperienced drivers • Easier to fit (more mounting options) • Cons: • More complex • Heavier • More expensive

  5. Pros, cons, continued • VS All electric: Pros: • Lower current draw (10 watts) • Common in our application • Less expensive? • Cons • More parts

  6. RAPTO-R

  7. Supply: CO2 v. HPA • CO2 • Small, Light tanks • Cheap ($15 for 20oz tank) • Risk of freezing, liquid CO2 getting into lines, and pressure flux • Risk of venting (if left in the sun) • HPA • No risk of risk of freezing, liquids or pressure flux • Fill level is easy to know (explain) • Slightly larger (radius), slightly heavier • More expensive (20 to 120 more (explain))

  8. On HPA • A 48ci, 3000psi HPA tank is good for over 3000 shifts • assuming ideal gas, and no heat transfer and using P1*V1=P2*V2 • Given an operating pressure of 100psi and a 3/4in bore cylinder with 1in stroke • A 3000psi, 48ci, steel tank weighs 2.8 pounds and measures 9 7/8 inches high with reg ($40) • A 4500psi, 48ci Guerrilla Air fiber tank weighs 1.8 pounds empty and measures 3.7w X 8h ($164)

  9. Regulator and piping • Palmer Pursuit custom paintball produces low pressure regulators for $50-110 depending on the reg. The only paintball company I know of that does so. • Most of their regulators output in 1/8in, solenoid valves are common in that size, so are pneumatic cylinders

  10. Controller (RAPTO-R) • Primary goal: create something with enough intelligence to open the valve and hold it until a new gear has been successfully engaged • receive a signal to indicate successful completion of a shift • Secondary goals: • Over-rev protection • Auto up-shifting • Automated clutching

  11. About clutching • The clutch only needs to be used on downshifts • Automating the clutch means you only need two pedals • However it creates the issue of not having revs matched on down shifts • Possible solution: “Preselect gearbox.” Set the controller so that it will only down shift after it has received a signal from both the clutch and the shift button • This requires either a third pedal, a hand clutch or separate clutch button

  12. Valves • 3 port, 2 position valves • Valve must have sufficient flow to energize and vent the cylinder quickly • Most solenoid valve have +1million cycle life • Less than 10w power draw is typical

  13. Cylinder • Bore size and stroke length need to be considered • Both affect the cylinder's footprint • Bore size directly affects the cylinder's power • Stroke length is determined by how long the lever is coming off the shift rod • Which is better, short stroke high force, long stroke low force, somewhere in between?

  14. Cylinder, another consideration • To long of a stroke (for a given shift arm) can mean the cylinder uses the shift linkage to bottom out, possible resulting in breakage • The cylinder has to be long enough to move the shift lever as if it were still on the bike • Rubber bushings on the mounting points for the cylinder reduce this risk while allowing a long enough cylinder to be used

  15. Redundancy • Micro Switches: A common point of failure • Solution: Include a pair of push buttons mounted on the dash that completely bypass the controller and energize the valves directly • Lines and Connections: No redundancy • thorough testing and high quality parts should be adequate

  16. Time line • Within 3 weeks: Complete all required calculations and measurements • Before Winter break: Finalize part choices, look for discounts/sponsors. Possibly order parts. • Back from break: Order parts • Mid February or earlier: Begin testing, bench or otherwise.

  17. Final thoughts (finally) • How important do I consider shifting? • It's all a matter of gearing • Mechanical, pneumatic, both? • Well, it depends • Is it worth it? • My opinion: Yes, letting the driver keep there hands on the wheel at all times make up for the 2 or 3 pounds of extra weight • Lets take a step back and look at what we are actually doing.

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