Team # 47 Chief Delphi Choosing the Correct Motor Michael Ciavaglia January 6, 2001

Team # 47 Chief Delphi Choosing the Correct Motor Agenda Michael Ciavaglia... Who am I? Work Examples Power Examples Motor Curves Motor Power Effective Gear Ratio and Power Power Needed vs. Effective Power

Team # 47 Chief Delphi Choosing the Correct Motor Michael Ciavaglia B.S.Mechanical Engineering –‘93 University of Michigan M.S.Mechanical Engineering –‘99 Purdue University Advanced Development Group –Electro-Mechanical Systems 5 Issued Patents (~ 5 more in process)

Team # 47 Chief Delphi Choosing the Correct Motor Work Work = Force * Distance Example 1: A box weighs 130 lbs and must be moved 10 ft. The coefficient of friction between the floor and the box is.5. How much work must be done??

Team # 47 Chief Delphi Choosing the Correct Motor Work f = mu*N =.5*130 f = 65 lbs so… Work = f * dist Work = 65 * 10 = 650 ft lbs

Team # 47 Chief Delphi Choosing the Correct Motor Example 2: The arm weighs 10 lbs and moves 3 ft vertically. The mechanism that contains the balls weighs 5 lbs. The balls weigh 3 lbs. The mechanism and balls move 6 ft vert. Work = Force 1*Dist 1 + Force 2*Dist 2 = 10 lbs * 3 ft + 8 lbs * 6 ft = = 78 ft lbs

Team # 47 Chief Delphi Choosing the Correct Motor Power Power = Work / Time = Force * Distance / Time Note: There is only a certain amount of power available.

Team # 47 Chief Delphi Choosing the Correct Motor Power Example 2A: Desire this motion to be completed in 10 seconds. Power = 78 ft lbs / 10 seconds * (60sec/1min) * = 10.6 Watts

Team # 47 Chief Delphi Choosing the Correct Motor Power Example 2B: Desire this motion to be completed in 3 seconds. Power = 78 ft lbs / 3 seconds * (60sec/1min) * = 35.3 Watts

Team # 47 Chief Delphi Choosing the Correct Motor Speed-Torque Curve

Team # 47 Chief Delphi Choosing the Correct Motor Current-Torque Curve

Team # 47 Chief Delphi Choosing the Correct Motor Power-Torque Curve

Team # 47 Chief Delphi Choosing the Correct Motor Combined Motor Curves

Team # 47 Chief Delphi Choosing the Correct Motor Motor Power Motor Power = Power Available = Free Speed / 2 * Stall Torq. / 2 * C.F. where: Free Speed is in rad / min Stall Torque is in ft lbs Conversion Factor =

Team # 47 Chief Delphi Choosing the Correct Motor Speed Free Speed (rev/min) * 2 Pi (rad/rev) Torque Stall Torq. (in oz)*(1 ft/12 in)*(1 lb/16 oz)

Team # 47 Chief Delphi Choosing the Correct Motor Drill Motor Free Speed = 20000(rev/min) *2PI(rad/rev) = rad/min Stall Torque = 650 (Nmm)*(1 lb/4.45 N)* (1 in/ 25.4mm)*(1 ft/12 in) =.48 ft lbs

Team # 47 Chief Delphi Choosing the Correct Motor Drill Motor Power = Free Speed / 2 * Stall Torque / 2 *Conv. Factor = / 2 *.48 / 2 * = 340 W

Team # 47 Chief Delphi Choosing the Correct Motor Available Power from FIRST Motors Bosch Motor Only340 W Bosch Motor w/ Gear box in HIGH 260 W Bosch Motor w/ Gear box in LOW 230 W Fisher Price Motor Only140 W Fisher Price Motor w/Gearbox91 W Delphi Sliding Door Motor (MFG: Taigene)69 W Globe Motor Only63 W Globe Motor w/ Gearbox50 W Delphi Seat Motor (MFG: Keyang)31 W Delphi Window Motor (MFG: Valeo) 22 W

Team # 47 Chief Delphi Choosing the Correct Motor Required Max Torque Torque = Force * Moment Arm = 10 lbs * 1.5 ft + 8 lbs *4.5 ft = 15 ft lbs + 36 ft lbs = 51 ft lbs

Team # 47 Chief Delphi Choosing the Correct Motor Pick Which Motor: Delphi Window Motor ?? Delphi Seat Motor?? Globe Motor?? Delphi Sliding Door Motor??

Team # 47 Chief Delphi Choosing the Correct Motor Try Globe Motor w/ Gearbox Working Torque = Stall Torque / 2 = (15 ft 12 V) / 2 = 7.5 ft lbs

Team # 47 Chief Delphi Choosing the Correct Motor Determine Gear Ratio Gear Ratio = Torque Needed / Torque Avail = 51 ft lbs / 7.5 ft lbs = 6.8 :1 Use Spur Gears with 90% efficiency

Team # 47 Chief Delphi Choosing the Correct Motor Effective Gear Ratio Try: 6.8 = 2.5 * 2.7 Eff. Gear Ratio = Ratio*Eff.*Ratio*Eff. = 2.5 *.9 * 2.7 *.9 = 5.5

Team # 47 Chief Delphi Choosing the Correct Motor Effective Gear Ratio Try Two Stages of 3:1 Eff. Gear Ratio = Ratio*Eff.*Ratio*Eff. = 3 *.9 * 3 *.9 = 7.3

Team # 47 Chief Delphi Choosing the Correct Motor Effective Power With Two Stages of Efficiency & Globe Motor w/Gearbox 50 W Effective Power = 50 *.9 *.9 = 40.5 W

Team # 47 Chief Delphi Choosing the Correct Motor Power Needed vs. Effective Power Power Needed = 35.3 W (from Ex. 2B) Effective Power = 40.5 W Note: The effective power is true only if system is operating at or near Peak Power.

Team # 47 Chief Delphi Choosing the Correct Motor Q: Could you lift a 200 lb man through 90 degrees of rotation at with a one foot moment arm??

Team # 47 Chief Delphi Choosing the Correct Motor Q: (In your mind should be…) IN HOW MUCH TIME !!