Assembly line covering the complete pneumatic shifting and clutch actuation system.
Groups the CO2 tank and mount, regulator, solenoids, actuators, air lines, driver's clutch lever and the shift position sensor. Design Philosophies and Processes: Inherited from the Shifting subsystem design process: 1. Route every line and fitting in SolidWorks. Lines cannot be within 1 in of the engine casing or 3 in of the exhaust; bend radius is 4 in. 2. Size the cylinder bore and line inner diameter with full calculations rather than by picking a catalogue part. 3. Fit the linear potentiometer and set the position bounds that define a completed shift. 4. Tune the preload duration and the torque reduction window on track. 5. Measure the result. CR26I averaged 65 ms cut time across endurance closed loop against 85 ms open loop; across 180 upshifts that is 9 seconds under power cut instead of 15.3 seconds.
From the Sphinx wiki shifting page. Its pneumatic section describes CR22 as the current design. 1. Choose the architecture. CO2 pneumatics have been the choice since Crimson Racing first automated shifting. If an electric system is proposed instead, the page requires a comparison sheet against pneumatic showing why it was chosen. 2. Set the solenoid and actuator layout. CR22 runs three solenoids (upshift dual acting, downshift dual acting, clutch single acting) and two actuators (a combined up/down shift actuator and a clutch actuator). 3. Size the actuators. Full calculations must be shown for air cylinder bore sizing and for line inner diameter. 4. Route every line and fitting in SolidWorks before anything is made. 5. Control through the MoTeC M150 GPRP feature set rather than an external controller. 6. Build a test bench before anything new goes on a car. The page states this as a requirement for the electric option and recommends it generally.
From the Sphinx wiki shifting page: - Line routing clearances. No line within 1 in of the engine casing or 3 in of the exhaust, and the bend radius of the shifting lines is 4 in. - CO2 supply. The tank has to be mounted in the only orientation allowed for CO2 bottles. Doing that is what stopped lines bursting. - Reliability. The system must achieve 99.9% shift to execution. - Shift delay must not get worse than CR21's, which the page puts at approximately 40 ms. - Gear position is calculated from transmission output shaft speed and engine speed, so gear is unavailable to the driver whenever the car is not moving. - A custom shift drum is constrained by tolerance above everything else. The page warns that anything out of tolerance will cause a catastrophic gearbox failure, and cites Auburn's 7075 aluminium shift drum failure at Lincoln 2019 as the reason not to make one from aluminium.
What the Sphinx wiki shifting page requires, rather than what it reports. No completed analysis appears on it. - Full calculations justifying air cylinder bore sizing and line inner diameter. - Shift delay verified in MoTeC i2 Pro against the CR21 baseline of approximately 40 ms. - A mathematical model of the pneumatic system, with Excel, MATLAB or Simulink suggested, paired with a test bench. The page names cylinder sizing as one of the last areas with significant gain available, and the model plus bench as the route to it.
None recorded. This part has no entry in Knowledge_Transfer/Issue Logging/Fault Vault.xlsx, in either Issue Log.xlsx, in CR22/Issue Tracking/Shakedown 7-15-23.xlsx, or in any design review issue list found in CrimsonStorage or Box.
From the Sphinx wiki shifting page: - Pneumatic cylinder sizing is called out as one of the last areas with significant improvement available. A test bench plus a mathematical model is the stated route to it. - Gear sensing when stationary. The page proposes putting different resistors on the shift drum and using the neutral switch as a rotary potentiometer, so the driver and the team can read gear with the car stopped. - A custom shift drum could move neutral to the bottom (N-1-2-3-4-5-6) and remove the pass through neutral on the 1-2 shift. The same page recommends against making one unless the gain is clearly large, and against aluminium if one is made. A 3D scan of the current drum, on the FARO arm the team has access to, would be the starting point. - Electric shifting is answered point by point on the page and rejected for now. CO2 can be filled in house, lines stopped bursting once the tank orientation was fixed, shift reliability is good, and a linear pot on the shift lever already confirms a completed shift. More control over actuation force is the one advantage the annotation accepts, and it accepts it for the clutch rather than for shifting.
From the Sphinx wiki shifting page, describing the CR22 pneumatic system: - Working fluid CO2, regulated to approximately 100 psi. - Three solenoids: upshift (dual acting), downshift (dual acting), clutch (single acting). - Two actuators: a combined up/down shift actuator and a clutch actuator. - Control through the MoTeC M150 GPRP feature set. - Shift delay on CR21 was approximately 40 ms, measured in i2 Pro. - Shift pattern 1-N-2-3-4-5-6. The same page's later annotation records shift time falling from 300 ms to 55 ms. That is a different quantity from the 40 ms shift delay above, and from CR26I's 65 ms average closed-loop cut time recorded elsewhere on this wiki. The three numbers come from different tests and should not be compared directly.
Nothing in CrimsonStorage covers these yet.