PRELIMINARY
DESIGN REVIEW
Outline
2
 Background Information
o
 Primary Analysis
 Project Focus
o
o
o
o
Mission Statement
Design/Performance Criterion
Goals
Inspiration
 Design Overview - Primary
o
Overall Concept and Generation
o
Mechanism Design
Kinematics
Cam Profiles
Gear Ratio
Torque
Packaging
BOM
o
o
o
o
o
o
Team and Motivation
 Controls
Hardware and Packaging
Software
o
o
 Design Overview - Secondary

o
Overall Concept and Generation
o
Mechanism Design
Logistics
o
o
Speaker: Nick Schwartzers
Cost
Schedule
3
BACKGROUND INFORMATION
Team and Motivation
Speaker: Nick Schwartzers
Team Composition
4
Speaker: Nick Schwartzers
Objective
5
To design and create an automatic Continuously
Variable Transmission (CVT) for a bicycle,
eliminating discrete steps in gear ratio in order to
maintain the ideal human cadence, with no user
input.
Speaker: Nick Schwartzers
Motivation
6





For years bicycles have relied on the same basic
transmission design.
While this is an efficient and light weight design, there
could be massive improvements for the average
recreational rider
The inexperienced casual rider is often bewildered by
derailleur shifting
Increase human efficiency by continuously maintaining
the ideal cadence
Make bicycling more user friendly in order to elevate
bicycling as viable transportation and reduce emissions
Speaker: Nick Schwartzers
Human Efficiency vs. Cadence
7



Cadence: The
pedaling speed in
RPM’s
The optimum cadence
for human efficiency
is shown to be near
100 rpm
This will lead to lower
fatigue and a more
enjoyable experience
Speaker: Nick Schwartzers
Taken from : Cycling Science
Comparison to Current Designs
8
Shift Points of Various Systems
SHIFT CVT Has seamless gear free
Road Double
Road Compact
Mounatian Triple
Nexus 8
Dots Represent
Shift Points
0
20
40
60
80
Gear Ratio (Gear Inches)
100
120
Shift CVT
Linear (Shift CVT)
140
Gear Inches: the diameter of the drive wheel times the gear ratio
Speaker: Nick Schwartzers
You’ll have an infinite number of ratios within its range to
seamlessly transition to exactly the right ratio for you and your
personal riding style.
9
Project Focus
Mission Statement, Goal, and Design Criteria
Speaker: Nick Schwartzers
Mission Statement
10
“
TO PROMOTE THE ACTIVITY OF BICYCLING BY
ENHANCING THE EXPERIENCE FOR THE CASUAL
RIDER, BY DESIGNING, DEVELOPING, AND
PROTOTYPING A DEVICE THAT WILL OPTIMIZE THE
PEDALING SPEED OF THE USER THROUGH A
CONTINUOUSLY VARIABLE TRANSMISSION WHILE
REMAINING AESTHETICALLY PLEASING. BICYCLING
WILL BECOME A MORE ENJOYABLE MEANS OF
EXERCISE OR MODE OF TRANSPORTATION. WE
AIM TO PROMOTE CLEANER TRANSPORTATION
AND A HEALTHIER POPULATION.
Speaker: Nick Schwartzers
”
Goals
11







Requires minimal user input and easy to use.
Contains a gear range suitable for average rider.
Automated and maintains user-selected, constant cadence.
Automatically adjusts gears for riders preference, position,
and conditions. Compact, unobtrusive and light-weight.
Uses a standard interface to easily mount to any bike frame.
System is safe and low maintenance.
Quiet and efficient
Speaker: Nick Schwartzers
Design Criteria
12








Maximum of 10 net pounds of additional weight
Q-factor < 12 inches
Efficiency of 85%
Gear ratio range of at least 1:1 to 3 ½: 1
Controls cadence to within 5 rpm while bike is in
gear range
Retail Price Below $300
Maintenance of 1 year or 2,000 miles
No more than 20% increase in noise (decibels)
Speaker: Nick Schwartzers
13
Concept Generation
Inspiration and Ideas
Speaker: Nick Schwartzers
House of Quality
14
Results:
Emphasis on
Packaging,
contact stress,
torque
capability
Speaker: Nick Schwartzers
Previous CVT Work
15
Four Different Types of CVTs have
been developed:
 Variable diameter pulley systems

Toroidal or roller-based CVT

Hydrostatic CVTs

Ratcheting CVTs
Speaker: Nick Schwartzers
Decision Matrix
16
Ratcheting
Roller Based
Hydrostatic
Variable Pulley
Efficiency
Rotational
Speeds
Contact Stress
Weight
Controls
= Optimal
= Acceptable
= Unacceptable
Ratcheting CVT
17



Uses static friction ratchets as
opposed to dynamic friction
Uses variable kinematics to
change ratios.
Capacity to handle larger
torques without slipping
Speaker: Nick Schwartzers
Ratcheting CVT Example
18
Speaker: Nick Schwartzers
19
DESIGN OVERVIEW
Primary Design: Non Variable Cam
Assembly Models
20
Speaker: Nick Schwartzers
Assembly Models
21
Speaker: Nick Schwartzers
Assembly Models
22
Speaker: Nick Schwartzers
Sub Systems
23




Cam and input shaft
Follower assembly
Moving output shaft
Motion Control
Speaker: Nick Schwartzers
Assembly Models
24
Speaker: Nick Schwartzers
Assembly Models
25
Speaker: Nick Schwartzers
26
Design Analysis
Primary Design: Non Variable Cam
Desired Characteristics
27

Constant output torque
 Constant
follower velocity vs cam angle
 At least 1 follower in this segment at all positions


Continuous displacement and velocity
Requirements for cam:
 Constant
Velocity segment
 Smooth return
 Low pressure angle
 No undercutting
Speaker: Tom Gentry
Lift Curve
28
Cam Lift (in)
Lift
Cam Angle (Degrees)
Follower 1 Lift
Cycloidal
Half Rise
Speaker: Tom Gentry
Constant Velocity Rise
Cycloidal Cycloidal
Half Rise
Fall
Lift Curve
29
Lift
1.2
1
Cam Lift (in)
0.8
0.6
0.4
0.2
0
0
-0.2
50
100
150
200
Cam Angle (Degrees)
Follower 1 Lift
Speaker: Tom Gentry
250
Follower 2 Lift
300
350
400
Kinematic Analysis of the
Cam/Follower System
30
Speaker: Tom Gentry
Kinematic Analysis of the
Cam/Follower System
31
Speaker: Tom Gentry
Design Inputs
32
Variable
Value
Unit
Smooth Lift (in)
0.11
inches
Chain ring (tooth)
106
tooth
Input Gear (tooth)
11
tooth
Cam Rises
2
integer
Followers
2
integer
Base circle diameter (in)
3.5
inches
Planet Shaft to Cam Clearance (in)
0.1
inches
Output Gear (tooth)
30
tooth
Back wheel Gear (tooth)
11
tooth
Quick Return
3.7
ratio
Eccentricity (in)
0
inches
Roller Diameter (in)
0.5
inches
Output Shaft Travel (in)
6
inches
Preload (lbf)
8
lbf
Follower Type
Roller
N/A
Rise
Constant V
N/A
Fall
1
Cycloidal/SHM
alpha (rad/s^2)
0
rad/s^2
Single/Variable Profile
Single
N/A
Input Shaft Torque (ft-lb)
114.8293963
ft-lb
Follower Mass
0.2
lbm
Cadence (rpm)
110
rpm
Speaker: Tom Gentry
Data type Range
real
0,1
integer
11,106
integer
11,53
integer
1,10
integer
2,2
real
0,5
real
0,3
integer
11,53
integer
11,53
real
1.01,10
real
-1,1
real
.25,1.5
real
0,15
real
0,200
N/A
Roller
N/A
Constant V
integer
1,2
real
-100,100
N/A
Single
real
0,120
real
0,200
real
0,150
Kinematics
33
Velocity
5
1.2
4
1
3
0.6
1
0
0
50
100
150
200
250
300
350
400
0.4
-1
0.2
-2
0
-3
-4
Follower 1 Velocity
Speaker: Tom Gentry
-0.2
Cam Angle (Degrees)
Follower 2 Velocity
Follower 1 Lift
Follower 2 Lift
Lift (in)
Follower Velocity (ft/s)
0.8
2
Kinematics
34
Acceleration
2000
1.2
1500
1
0.8
500
0.6
0
0
50
100
150
200
250
300
350
400
0.4
-500
0.2
-1000
0
-1500
-2000
Acceleration Follower 1
Speaker: Tom Gentry
-0.2
Cam Angle (Degrees)
Acceleration Follower 2
Lift Follower 1
Lift (in)
Follower Acceleration (ft/s^2)
1000
Kinematics
36
Follower Angle
0.5
0.4
Angle (rad)
0.3
0.2
0.1
0
0
50
100
-0.1
150
200
250
300
350
Cam Angle (deg)
Follower 1 high gear
Speaker: Tom Gentry
Follower 1 low gear
Follower 2 low gear
Follower 2 High gear
400
Cam Profile
37
Cam Profile
3
2
Y (in)
1
-3
0
-2
-1
0
1
2
-1
-2
-3
X ( in)
Pitch Curve
Speaker: Tom Gentry
Base Circle
Cam Surface
Roller
3
Output Analysis
38
Output Velocity
5
1.2
4.5
1
0.8
3.5
3
0.6
2.5
0.4
2
1.5
0.2
1
0
0.5
0
-0.2
0
50
100
150
200
250
Cam Angle (Degrees)
Equivalent Follower Output Velocity
Speaker: Tom Gentry
Lift Follower 1
300
350
400
Lift (in)
Output Follower Velocity (ft/s)
4
Output Analysis
39
Clutch Torque
180
160
140
Torque (ft-lbf)
120
100
80
60
40
20
0
0
50
100
150
200
250
Cam Angle (Degrees)
High Gear
Speaker: Tom Gentry
Low Gear
300
350
400
Output Analysis
40
Inertial Force on Cam
0.4
0.3
0.2
Force (lbf)
0.1
0
0
50
100
150
200
250
-0.1
-0.2
-0.3
-0.4
Cam Angle (deg.)
Follower 1
Speaker: Tom Gentry
Follower 2
300
350
400
Design Outputs
41
Variable
Total Lift (in)
Minimum Case Height
w
Output Travel per rise (high) (deg)
Output Travel per rise (low) (deg)
Final ratio (high)
Final ratio (low)
Total Ratio
Max Lead Screw Force (lbs)
Speed (mph) (low)
Speed (mph) (high)
Gearbox Input Torque (Low) (ft-lb)
Output Gear Torque (Low) (ft-lb)
Rear Wheel (Low) (ft-lb)
Gearbox Input Speed (low) (rpm)
Output Gear Speed (low) (rpm)
Rear Wheel Speed (low) (rpm)
Gearbox Input Torque (high) (ft-lb)
Output Gear Torque (high) (ft-lb)
Rear Wheel Torque (high) (ft-lb)
Gearbox Input Speed (high) (rpm)
Output Gear Speed (high) (rpm)
Rear Wheel Speed (high) (rpm)
Minimum Spring Constant (lbf/in)
Concave Profile?
Maximum Pressure Angle (deg)
Allowable Radius of Curvature? (roller)
Minimum Concave Radius of Curvature (in)
Spring Force %
Spring Compression (in)
Speaker: Tom Gentry
Value
0.985925926
11.0726239
111.0029404
0.466063428
0.140719761
4.678624042
1.412629302
3.311997023
36.37085325
12.08386649
40.02172982
11.91625811
170.0913578
103.9447186
110
1060
94.96008084
11.91625811
47.89929041
29.27178858
110
1060
314.507505
2.893935408
1
1.504222056
1
9999
3.843095842
3.750327639
Unit
inches
inches
rad/s
deg
deg
ratio
ratio
ratio
lbs
mph
mph
ft-lb
ft-lb
ft-lb
rpm
rpm
rpm
ft-lb
ft-lb
ft-lb
rpm
rpm
rpm
lbf/in
boolean
deg
boolean
in
%
in
Efficiency
42

Major Contributions:
 Kinematics
~94% (High), ~99.8% (low)
 2 Chains ~98% each
 Follower Sliding Friction ~7.5% (High), ~1.8% (Low)
 Roller Follower Rolling Resistance ~3.2%
 Spring Energy ~3.2%


High Gear Efficiency – 80%
Low Gear Efficiency – 86%
Speaker: Tom Gentry
Losses
43
Major Losses
Due To:
9.00%
- Friction and
Rolling
8.00%
7.00%
- Chain
6.00%
5.00%
Loss %
- Spring
4.00%
- Cam Pressure
Angle
3.00%
2.00%
- Follower
Pressure Angle
1.00%
0.00%
0
50
100
150
200
250
300
350
Cam Angle
Chain Losses
Spring Losses
Speaker: Tom Gentry
Cam Pressure Angle Losses
Follower Pressure Angle Losses
Friction and Rolling Resistance Losses
400
Efficiency
44
Total Efficiency
100.00%
90.00%
80.00%
System Efficiency
70.00%
60.00%
50.00%
High Gear
Low Gear
40.00%
30.00%
20.00%
10.00%
0.00%
0
Speaker: Tom Gentry
50
100
150
200
Cam Angle
250
300
350
400
Design Optimization
45


Parametric Model
Optimization method
 Gradient
based
 Non gradient based

Inputs
 Ranges/types

Outputs
 Maximize/Minimize/Target
Speaker: Tom Gentry
Excel Parametric System Model
46
Speaker: Tom Gentry
Isight Capabilities
47
Speaker: Tom Gentry
Isight Capabilities
48
http://www.simulia.com/download/products/Fiper_Isight35_web.pdf
Speaker: Tom Gentry
Gear Ratio
49
Low Gear (1:1)
Speaker: Andrew Shaw
High Gear (3.5:1)
Output Analysis – Gear Ratios
and Torques
50
Gear Ratios:
Start angle
End Angle
Output Travel per rise
Output Travel per rise
Output Travel per crank
Back wheel per crank
Final ratio
Total Ratio
Shaft
Input Shaft
Gearbox Input
Output Gear
Rear Wheel
Speaker: Andrew Shaw
High Gear
0.0
0.5
0.5
26.7
1029.3
1684.3
4.7
3.3
Torque (low Gear) (ft-lb)
114.8293963
11.9
170.1
103.9
Low Gear
0.0
0.1
0.1
8.1
310.8
508.5
1.4
Unit
rad
rad
rad
deg
deg
deg
:1
Follower Type
51
Translating Roller Follower

Pros:
Flexibility with cam
profile (positive radius of
curvature)
 Multiple rises
 Less wear
Oscillating Flat Faced Follower



Cons:
More Parts
 Slightly more contact
stress

Speaker: Andrew Shaw
Pros:



Lower number of parts
Pressure angle is always 0
Cons:



Wear
Friction Losses
Spring Packaging
Roller Follower Selection
52
Stud Bending Stress
Max Allowable stress of
100 kpsi given by
manufacturer
Speaker: Andrew Shaw
Cam Contact Stress
Follower Bearing Fatigue
Contact Stress
53
Max Contact Pressure
Principle Stresses
Speaker: Andrew Shaw
Contact Stress cont.
54
σx=
σy=
σz=
taumax=
-34922.175525717
-23696.480153326
-96310.995880065
36307.257863370
Cam
Roller
AISI 4140
AISI 52100
Processing
Quenched & Tempered Quenched & Tempered
@ 425°C
Tensile Strength(kpsi)
181
325
Yield Strength(kpsi)
165
295
Brinell Hardness
370
518
Factor of Safety
1.87
3.73
Normally contact strength is a factor of 2 more than
Sut
Speaker: Andrew Shaw
PSI
PSI
PSI
PSI
Contact Stress cont.
55
To reduce the contact force:
 Change the transmission kinematic parameters
Increase cam rotation speed
 Increase amount of rise
 Increase number of cam rises

To reduce contact stress:
 Reduce the contact force
 Increase the diameters of the contacting bodies
 Reduce the modulus of elasticity of the materials
involved
 Change the geometry of the contact region
Speaker: Andrew Shaw
Contact Fatigue
56
Factor of Safety Theoretical
Factor of Safety
1.6
1.4
1.2
1
0.8
Factor of Safety
0.6
0.4
1000
1500
Hours
2000
Factor of Safety
Factor of Safety Needed K
1.4E+17
1.2E+17
1E+17
8E+16
6E+16
4E+16
2E+16
0
1000
Speaker: Andrew Shaw
Factor of Safety
1500
Hours
2000
•This is with an experimental
K = 9000 for 4150 steel.
Our calculated K needed is
108.
•Take away is we can use a
weaker material but for
yielding we are using a
harder material, which gives
an infinite life for contact
fatigue.
Follower Arm Stress
57
Critical plane at the
end near fillet.
 a  K f  a ,nom
Se  0.5Sut
 m  K f  m ,nom
ka  aSutb
Se  ka kb kc kd ke k f Se
K f  1
nf 
Kt  1
1 a
r
1
 a / Se   m / Sut
ny 
Factor of safety=2.55
Speaker: Andrew Shaw
Sy
( a   M )
Spring Force
58
A spring is used to
keep the follower in
contact with cam and
must be capable of
applying a force
equal to inertia force.
F - mfg - S(X - xo) = mf Af
F = contact force, mf =
mass of the follower,
Af = acceleration of
the follower.
Neglect gravity

Spring Constant
Speaker: Andrew Shaw
Force (lbf)
Inertial Force on Cam
0.4
0.3
0.2
0.1
0
-0.1 0
-0.2
-0.3
-0.4
100
200
400
Cam Angle (deg.)
Follower 1
Preload
Follower Mass
Minimum Spring Constant
Minimum Net Force
Spring Force/min net force %
Spring Compression
300
Follower 2
8
0.00621118
2.893935408
282.4
3.8
3.8
lbf
slug
lbf/in
lbf
in
Sprag Clutch
59



Selected based on torque, speed and
axial load
Transmits high torque compared to
other devices
Similar to a bearing but allows only
one way rotation
Speaker: Andrew Shaw
Bearing Selection
60
L  60 LD nD
nD  rpm
LD  hrs
L10  RatingLife
xD 
L
L10
1/ a


xD
C10  FD 
1/ b 
x

(


x
)(1

R
)
0
D
 0

RD  0.9
x0 , , and b
Wiebull Parameters
a3
•No Axial Load
•Sealed single row deep groove ball bearings
•Bearings are available in suitable sizes for this project
Speaker: Andrew Shaw
Material Selection
61
Cam
AISI 4140
Processing
Roller
AISI 52100
Tensile Strength(kpsi)
Quenched & Tempered Quenched & Tempered
@ 425°C
181
325
Yield Strength(kpsi)
165
295
Brinell Hardness
370
518
Endurance Limit Strength
(kpsi)
Modulus of Elasticity(106
psi)
Poisson’s Ratio
90.5
100
29.2
29.5
.29
.3
Machinability
.65
.40
Speaker: Andrew Shaw
Packaging
62






Mounts to existing bike frame with clamps
Provides adequate clearances
Aluminum case
Chain tensioner
Translucent side to see operation
Low center of gravity
Follower length
Minimum Case Height
Including Followers
Speaker: Andrew Shaw
8.3
5.6
11.1
inches
inches
inches
BOM
63
CONCEPT 1 BOM
ITEM
COMPANY
RBC Follower
Bearing Engineering
Rail Guide
Grainger
Carriage
Grainger
Sprag Clutch
VXB
Shaft 8x1/2
McMaster-Carr
Bearing
McMaster-Carr
Sprocket
McMaster-Carr
Chain
Price Point
Aluminum for Housing
Metal Depot
Follower Arms AL 6061 1'x1.5"x.5"
McMaster-Carr
Springs
McMaster-Carr
Retainer Clips for 1/2" Shaft
McMaster-Carr
Aluminum Carriage 5"x2"x2"
Woodruff Key
4140 Steel for Cam
Miscellaneous
Metal Depot
Home Depot
McMaster-Carr
Speaker: Andrew Shaw
PART #
S16LWRBC
2CRR8
2RLE4
Kit8182
6061K103
6384K49
6280K661
25068
S318
6023K251
9657K128
(12ct.)
9590A122
(10ct.)
SQ32
79758
8960K61
QUANTIT
Y
2
2
2
2
2
4
2
2
1
1
Price
Line Cost
$13.80
$19.25
$27.80
$19.95
$4.33
$8.33
$11.05
$12.98
$37.40
$15.92
$27.60
$38.50
$55.60
$39.90
$8.66
$33.32
$22.10
$25.96
$37.40
$15.92
1
$6.97
$6.97
1
$8.94
$8.94
1
2
2
1
$26.94
$0.25
$23.96
$100.00
Total =
$26.94
$0.50
$47.92
$100.00
$496.23
64
Control System
Concept Selection
-Functional Diagrams
-Equipment Selection
-
System Control Concept
Selection
65
Mechanical
Electro-Mechanical
Electrical
High
Medium
Medium
Output Force
Very Low
High
High
Adjustability
Very Low
Medium
Very High
High
Low
Very High
Medium
Low
High
Rider
Battery
Battery
Medium
High
Very Low
Weight
Accuracy
Cost
Power Source
Position Control Difficulty
Speaker: Brian Pigman
Functional Diagram
66
Encoder
PLC Controller
Optimal
Cadence
Wheel Speed
Speaker: Brian Pigman
Desired Gear
Ratio/Position
Drive and
Motor
Power
Source
Gear Position
Electrical Control Components
67
-
-
Optical Encoder- Transduces wheel speed to pulse
PLC- Produces output voltage based on
programmed input signal conditions
Motor Drive- Delivers power to motor
Motor- Provides output position
Lead Screw- Converts Rotary Positioning to Linear
Speaker: Brian Pigman
Motor Selection
68
Stepper
Servo
Holding Torque
X
Price
X
Encoder Required
X
Continuous
X
Accuracy
Speaker: Brian Pigman
X
X
Lead Screw Force
69
http://www.smallmotors.com/html/lead_screws.html
F
x
0
Fx  Fcam * sin( )
 The follower arm and output shaft are
supported by a track.
 There are no moments and Fx is the only force
on the lead screw
Speaker: Brian Pigman
Fy
Fcam
Ѳ
Fx
Tout
Lead Screw Force
70
Lead Screw Force
40
1.2
35
1
30
0.8
Force (lbf)
25
20
0.6
Lead Screw Force
Lift Follower 1
Lift Follower 2
15
0.4
10
0.2
5
0
0
0
50
100
150
200
Cam Angle (deg)
Speaker: Brian Pigman
250
300
350
400
Motor Torque
71




η- Efficiency
P- screw pitch (revolutions/inch)
F- axial load on lead screw
T – required motor torque
Speaker: Brian Pigman
Motor Torque
72



Typical lead screw efficiency – around .4
Screw Pitch – 10rev/1in
Axial Load – 50lb
Gives a required T = 20.7 oz-in
Speaker: Brian Pigman
Maximum Torque RPM
73

Assume
 Maximum
acceleration or deceleration will occur when
braking from full speed (~35mph) to zero
 Braking within 6 seconds
 Neglect inertia of motor and shaft
At Maximum, carriage needs to travel 6” in 6 seconds
Speaker: Brian Pigman
Maximum Torque RPM
74



6 in/6sec = 1 in/sec
1 in/sec * (10 rev/in) = 10 rev/sec
Maximum Torque of 20.7oz-in needed at 10rps
24Vdc at
10rps
http://www.omega.com/Auto/pdf/2035.pdf

Speaker: Brian Pigman
At the given parameters the motor produces around 42
oz-in of torque
Hardware
75




Motor – Stepper Motor OMHT17-275
Drive – 2035
Programmable Logic Controller - ELC-PB14NNDR
Encoder - RB-Cyt-39
http://www.omega.com/pptst/ELC_PLC.html
http://www.hurst-motors.com/hybridstepper.html
Speaker: Ernie Stoops
http://www.omega.com/pptst/2035.html
http://www.robotshop.com/cytron-simplerotary-encoder-kit.html
Lead Screw Buckling Analysis
76




F – Force to cause
buckling
E – Modulus of Elasticity
I – Area Moment of
Inertia
K – End Conditions
Speaker: Ernie Stoops
Force (lb)
Buckling Force vs. Diameter
100000
90000
80000
70000
60000
50000
40000
30000
20000
10000
0
F
0


0.2
0.4
0.6
Diameter (in)
0.8
1
At .5”, 5,800 lbf is needed
to buckle
Max force is just over 40
lbf
Power & Weight
77

24 V System
Running 56 W
Battery is 5 A-h

Gives a battery life of just over 1.7 hours



Weight of major components
Speaker: Ernie Stoops
Object
Weight (lbs)
PLC
0.348
Battery
4
Motor
0.79
Motor Drive
0.5625
5.7005
TOTAL
Controls BOM
78
ITEM
Stepper Motor
Motor Drive
PLC
Rotary Encoder
24 V Rechargeable Battery
Battery Charger
DIN Rail
Lead Screw
Platform Nut
PLC Software
PLC-PC Cable
Coupler
Thrust Bearing
Speaker: Ernie Stoops
COMPANY
Omega
Omega
Omega
Cytron Technologies
All-Battery
All-Battery
McMaster-Carr
McMaster-Carr
Fine Line Automation
Omega
Omega
Servo City
McMaster-Carr
PART #
QUANTITY
OMHT17-275
1
2035
1
ELC-PB14NNDR
1
RB-Cyt-39
1
11809
1
1007
1
8961K13
1
93255A431
1
GRP108-00
1
ELCSOFT
1
ELC-CBPCELC1
1
CSC-.250-.375
1
5909K31
1
Total =
PRICE
$49.50
$170.10
$181.80
$11.29
$99.99
$12.87
$4.74
$8.96
$16.50
$247.50
$38.70
$12.99
$2.76
$857.70
79
DESIGN OVERVIEW
Secondary Design: Variable Cam
Assembly Models
80
Speaker: Andrew Shaw
Assembly Models
81
Speaker: Andrew Shaw
Assembly Models – Low Gear
82
Speaker: Andrew Shaw
Assembly Models – High Gear
83
Speaker: Andrew Shaw
Assembly Models
84
Speaker: Andrew Shaw
Assembly Models
85
Speaker: Andrew Shaw
Cam Profile
86

Produce single profile and shrink down by factor
Speaker: Tom Gentry
87
Design Analysis
Secondary Design: Variable Cam
Cam Profile
88
Low Gear
High Gear
Cam Profile
Cam Profile
2.5
3
2
2
1.5
1
1
v (in)
v (in)
0.5
-3
0
-2.5
-2
-1.5
-1
-0.5
0
0.5
1
1.5
2
0
-2
-1
0
1
2
2.5
-0.5
-1
-1
-2
-1.5
-2
u ( in)
Pitch Curve
Speaker: Tom Gentry
Base Circle
-3
u ( in)
Cam Surface
Roller
Pitch Curve
Base Circle
Cam Surface
Roller
3
Kinematics
89
Low Gear
High Gear
Follower Angle
Follower Angle
0.12
0.4
0.35
0.1
0.3
0.08
0.25
Angle (rad)
Angle (rad)
0.06
0.04
0.2
0.15
0.1
0.02
0.05
0
0
50
100
150
200
250
300
350
400
0
0
-0.02
Cam Angle (deg)
Follower 1 high gear
Speaker: Tom Gentry
Follower 2 High gear
-0.05
50
100
150
200
250
Cam Angle (deg)
Follower 1 high gear
Follower 2 High gear
300
350
400
Output Analysis
90
Low Gear
High Gear
Clutch Torque
300
250
250
200
200
Torque (ft-lbf)
Torque (ft-lbf)
Clutch Torque
300
150
150
100
100
50
50
0
0
0
50
100
150
200
250
Cam Angle (Degrees)
High Gear
Speaker: Tom Gentry
Low Gear
300
350
400
0
50
100
150
200
250
Cam Angle (Degrees)
High Gear
Low Gear
300
350
400
Output Analysis
91
Low Gear
High Gear
Inertial Force on Cam
Inertial Force on Cam
0.1
0.4
0.08
0.3
0.06
0.2
0.04
0.1
0
0
50
100
150
200
-0.02
250
300
350
400
Force (lbf)
Force (lbf)
0.02
0
0
50
100
150
200
250
-0.1
-0.04
-0.2
-0.06
-0.3
-0.08
-0.1
Cam Angle (deg.)
Follower 1
Speaker: Tom Gentry
Follower 2
-0.4
Cam Angle (deg.)
Follower 1
Follower 2
300
350
400
Output Analysis – Spring Rate
92
High Gear
Preload
Follower Mass
Minimum Spring Constant
Minimum Net Force
Spring Force/min net force %
Spring Compression
Speaker: Tom Gentry
8
0.00621118
3.750161675
270.9
4.3
3.1
Low Gear
lbf
slug
lbf/in
lbf
in
8
0.00621118
0
1263.4
0.6
0.0
lbf
slug
lbf/in
lbf
in
Output Analysis – Gear Ratios
93
Gear Ratios:
Start angle
End Angle
Output Travel per rise
Output Travel per rise
Output Travel per crank
Back wheel per crank
Final ratio
Speaker: Tom Gentry
High Gear
0.0
0.3
0.3
19.2
766.8
1254.8
3.5
Low Gear
0.0
0.1
0.1
6.0
241.8
395.6
1.1
Unit
rad
rad
rad
deg
deg
deg
:1
Output Analysis – Torques
94
Shaft
Input Shaft
Gearbox Input
Output Gear
Rear Wheel
Speaker: Tom Gentry
Torque (High
Torque
Gear)
(low
(ft-lb)
Gear) (ft-lb)
Torque (low Gear) (ft-lb)
114.8293963
114.8293963
114.8293963
11.5
11.5
11.5
66.8
66.8
219.3
40.8
40.8
134.0
BOM
95
ITEM
CONCEPT 2 BOM
COMPANY
PART #
QUANTITY
Price
Line Cost
RBC Follower
Bearing Engineering
S16LWRBC
2
$13.80
$27.60
Cam
Bevel Gear Set
Lead Screw Nut
Sprag Clutch
Shaft 8x1/2
Ball Spline Shaft
Ball Spline Nut
Bearing
Sprocket
Chain
Aluminum for Housing
Follower Arms AL 6061 1'x1.5"x.5"
Springs
Retainer Clips for 1/2" Shaft
32 Tooth Spur Gear
65 Tooth Spur Gear
Aluminum 2"x1"x1"
Aluminum 3"x5"x1"
Aluminum 1'x2"x2"
Woodruff Key
Miscellaneous
McMaster-Carr
Grainger
McMaster-Carr
VXB
McMaster-Carr
Gridline Industrial
Grainger
McMaster-Carr
McMaster-Carr
Price Point
Metal Depot
McMaster-Carr
McMaster-Carr
McMaster-Carr
McMaster-Carr
McMaster-Carr
McMaster-Carr
McMaster-Carr
Metal Depot
Home Depot
9034K69
3ZP64
6350K42
Kit8182
6061K103
SSP6S150mm
3HVC3
6384K49
6280K661
25068
S318
6023K251
9657K128 (12ct.)
9590A122 (10ct.)
6325K85
6325K73
9008K141
8975K313
SQ32
79758
1
1
1
2
2
1
1
6
2
2
1
1
1
1
3
1
1
1
1
2
1
$149.04
$115.15
$23.58
$19.95
$4.33
$102.58
$101.00
$8.33
$11.05
$12.98
$37.40
$15.92
$6.97
$8.94
$23.98
$37.14
$10.41
$23.16
$26.94
$0.25
$100.00
Total =
$149.04
$115.15
$23.58
$39.90
$8.66
$102.58
$101.00
$49.98
$22.10
$25.96
$37.40
$15.92
$6.97
$8.94
$71.94
$37.14
$10.41
$23.16
$26.94
$0.50
$100.00
$1,004.87
Speaker: Ernie Stoops
96
Design Comparison
Final Results
Comparison of Concepts
97
Non- Variable Cam
Variable Cam
Pros:
-Easier to Machine
-More efficient
-Lighter weight
-Cheaper ($1360)
Cons:
-Moving output shaft
Pros:
-Possible neutral gear
-Multiple input and output
configurations
Cons:
-More Shift Force
-Heavier
-Larger Package
-Cost ($1870)
Speaker: Ernie Stoops
Schedule
98
Legend
On Time
Scheduled
A
Approval
Task
Organization
Team Name
Team Logo
Mission Statement
Goals
Concept Design
Design Criteria
Concept Sketches
Preliminary Design Review
Critical Design Review
Fabrication
Assembly & Integration
Testing
Delivery
Speaker: Ernie Stoops
SHIFT GANTT CHART
Week 1 Week 2 Week 3 Week 4 Week 5 Week 6 Week 7 Week 8 Week 9 Week 10 Week 11 Week 12 Week 13 Week 14
A
A
A
A
A
A
Risk
99

Gearbox
 Time
 Machining
 Packaging
Speaker: Ernie Stoops

Control System
 Time
 New Programming
Language
 Electrical failure
Conclusion
100



SHIFT’s CVT will provide fully automatic,
continuously variable gearing system that will
improve experience for all riders
Team SHIFT has skills, dedication and drive to
complete the development of the Bicycle CVT in
allotted time
Request approval to continue with design process
and begin Prototyping and preparing for Critical
Design Review
Speaker: Ernie Stoops
Acknowledgements
101
Professor Starkey
Professor Pennock
Professor Sadeghi
Mike Moya
Speaker: Ernie Stoops
102
Questions?
Problems encountered
103
Variable diameter pulley:

Low Efficiency

Requires High Rotational Speeds

Hard to Control

Unable to Shift while Stationary
Hydrostatic:

Heavy

Inefficient
http://cmgonline.com/content/view/2489/57/
http://auto.howstuffworks.com/cvt4.htm
Speaker: Nick Schwartzers
Problems encountered cont.
104
Toroidal:




High Contact Stress
Requires Traction Fluid
Tight Tolerances required
Balance of Friction(wear),
Normal Force(contact
stress), Radius(size), and
Angular Velocity(losses)
Speaker: Nick Schwartzers
P  T
P  Fr
P   Nr
http://www.nsk.com/products/auto
motive/drive/hcvt/