View
133
Download
7
Category
Preview:
Citation preview
Generic EPS DVP and Robustness
Plan
Costas Chrysochoidis
1
CONTENTS
O REDPEPR
O Reliability Growth Plan
2
OBJECTIVE
LAUNCH
A
VALIDATED
&
ROBUST
PRODUCT
3
VALIDATION REQUIREMENTS
O Specified in OEM subsystem specification:
Tier 1 supplier:
O Vehicle End of travel test
O Steering Gear End of travel test
O EPS Unit tests
O Steering Gear tests (gear, ITR,OTR, Bellows)
O Other validatable requirements
OEM:
O Vehicle tests (Durability, Thermal, NVH, Water Intrusion)
O Lab tests (gear to cradle/frame durability, 445 N strg rim pull)
4
Robustness Performance Monitoring thru
CV/DV/PV
O Monitor Reliability growth in terms of: O Global and O LOA, NVH, Sealing, other
O Monitor with metrics performance relative to the
decided High Impact Error States: O Friction O Noise (running, rattle, clunk, buzz) O Excessive SRS O Lack or Loss of assist O Poor on center precision O Water Ingress O Mechanical Failure
5
REDPEPR Program: GM Epsilon
Author: Costas Chrysochoidis_5MAR10
System/Function: BD REPS VERIFICATION METHODS
IDEAL FUNCTIONS
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52
HIG
H I
MP
AC
T
ER
RO
R S
TA
TE
S
VM TYPE
K K K
X J Mechanical Failure J J X X X X X X X X X X X X X X
X I water ingress I I X X X X X X X X
X H Transfers poor on center precision to driver H H X X X X X X X X X X X X X
X G Lack or Loss of Assist G Cat Strategy G X X X X X X X X X X X X X X X X
X F Excessive SRS F I Change Technology F X X X X
X E NVH - IPA Buzz noise E II Apply Parameter Design E X X X
X D NVH - reversal noise D III Upgrade Design Spec. D X X X X
X C NVH - rattle noise C IV Reduce / Remove Noise C X X X X
X B NVH - Running noise/zipper noise (tonality) B V Add Compensation Device B X X X X X X
X A Friction A VI Disguise / Divert A X X X X X X X X X X X
VII Other HIGH
X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X X IMPACT
A B C D E F G H I J K L M N O NFMS Descriptions
NOISE 1: Piece to Piece Variation NF1
a) a) X X X X X X X
b) b) X X
c) c) X X X X X X X X X X X X X X
d) d) X X X X X X
e) e) X X X X X X X X
f) f) X X
g) g) X X
h) h)
I) I) X X X X X X X X X X X
j) j) X X X X X X X X X X X X
k) k) X X X X
l) l) X X X X X X X
m) m) X
n) n) X X X X X X X X X X X X X X X X
o) o) X
p) p) X X X X X X X X X X X X
q) q) X
r) r) X X X
s) s) X X X X X X X
t) t) X X X X X X X X X X X X
u) u) X X X X X X X X X
v) v) X X X X X X X X X X X X X
w) w) X X X X
x) x) X X X X X X X X X X
y) y) X X X
z) z) X X X X X X X X X
aa) aa) X X X
ab) ab) X X
ac) ac) X
ad) ad) X X
ae) ae) X X
af) af) X X
NOISE 2: Change Over Time NF2
a) a) X X X X X X
b) b) X X X X X X X X X
c) c) X X X X X
d) d) X X X X X X X X X X X
e) e) X X X X X X
f) f) X X X X X
g) g) X X X X X X
h) h) X X X X X
I) I) X X X X X
j) j) X X X
k) k) X X X X X
l) l) X X X X X X
m) m) X
n) n) X X X X X
NOISE 3: Customer Usage NF3
a) a) X X X X X X X X X X X X X
b) b) X X X X
c) c) X X
d) d)
e) e) X X X X X
f) f) X X X X
g) g) X X X X X X X X
h) h) X X X X X X X X X X X X
I) I) X X X X X X
j) j)
k) k)
l) l) X X X
m) m) X X X
n) n) X X X
o) o) X X X X
p) p) X X X X X X
q) q) X X
r) r) X X
s) s) X X X X X X
t) t) X X X X X X
u) II u) X X X X X X X X
v) v) X X X X X X X X
NOISE 4: External Environment NF4
a) a)
b) b) X X X X X X X
c) c) X X X X X X X X X
d) d) X X X
e) e) X X X X X X X X X X X
f) f) X X X X X X X X X X X
g) g)
h) h) X X X X
I) I) X X X X X X X X X X X X
j) j) X X X X X X X
NOISE 5: System Interaction NF5
a) a) X X X
b) b) X X X X X
c) c) X X X X X X X X X
d) d) X
e) e) X X X X
f) f) X
g) g) X X X X X X X
h) h) X X X X
I) I) X X X
j) j) X X
k) k)
l) l) X
m) m) X X X X
n) n)
o) o) X X X X
p) p)
q) q) X X X X X X X X X
CONTROL FACTORS NF1
a) a) X X X X X
b) b) X X
c) c) X X X X X X X X
d) d) X X X X X
e) e) X X X X X X
f) f) X X X X X X X X X X X X X X X X
g) g) X X X X X
h) h) X X X X X X X X X
I) I) X X X X X X
j) j) X X X X X X X X X
k) k) X X X X X X X X
l) l) X X X X X X X X X X X X X X X
m) m) X X X X X
n) n) X X X X X
o) o) X X X X X X X X X
p) p) X X X X X X
q) q) X X X X
r) r) X X X X X X X X X X X
s) s) X X X X X X X X X X X
t) t)
u) u) X X
v) v)
w) w) X
x) x) X X X
y) y) X
z) z) X X X X
aa) aa) X X
ab) ab) X X
ac) ac) X X
ad) ad) X X
ae) ae) X X X X
af) af) X
ag) ag) X
ah) IV ah) X X
ai) ai) X X
aj) aj) X X X
ak) ak) X X X
SEALING CONTROL FACTORS NF2
a) III a) X
b) III b) X
c) III c) X
d) III d) X
e) III e) X
f) f) X
g) III g) X
h) III h) X
I) III I) X
j) III j) X
k) k) X
l) l) X
m) m) X
n) n) X
o) o) X
EPP to pinion housing
Threaded yoke cover to pinion housing ISO fit
Yoke plug (rubber) to yoke cover (as cast hole) mmmax yoke ID
(min fill)max yoke ID (min fill)
Seals between female and male connectors (TRW TS, GM power and comm)
ECU lid to motor casting and plastic connector header to motor casting mm
Radial clamp over Santoprene bellow to inner tie rod mm
ITR groove
min OD/max
width (min fill)
ITR groove min OD/max width (min fill)
Oetiker clamp over Santoprene bellow to pinion housing mm, N
min hsg OD,
max groove,
min clamp
min hsg OD, min bellow thickness,
max groove, min clamp force (min
fill)
harness to pinion housing mmmax PH ID
(min fill)max PH ID (min fill)
Input shaft to torque sensor cover mm
min IS OD-
max TSC
ID/height
min IS OD-max TSC ID/height (min fill)
Pinion plug threaded interface to pinion housing ISO fit
o-ring-Pinion plug to pinion housing mm
plug min
OD&max
height/max
plug min OD&max height/max hsg OD (min fill)
o-ring groove width-Torque sensor cover to pinion housing mm max (min fill) max (min fill)
o-ring groove depth-Torque sensor cover to pinion housing mm max (min fill) max (min fill)
face seal groove width-Pinion to Outboard Housing Face Seal mm max (min fill) max (min fill)
face seal groove depth-Pinion to Outboard Housing Face Seal mm
max (min fill)
and min
(stability)
max (min fill) and min (stability)
bias to be used for the mule build based
on Eng'g judgement
OBJ lash
IBJ lash
Yoke o-rings compression
t-bar bearing design (bearing vs.bushing)
Yoke radial clearance mm 0.008 - 0.052
Yoke axial clearance mm 0.050 - 0.110
Yoke spring rate/ mesh load setting - spring force N 340 +/-10%
4-pt bearing surface finish Ra microns tbd
RBNA nut surface finish Ra microns tbd
RBNA rack race waviness tbd tbd
RBNA rack race surface finish Ra microns 0.4
Gear set tolerance - Rack/Pinion mesh tbd tbd
4-point bearing lash microns 10 - 25
RBNA lash microns 15 - 21
Alignment of pinion housing to TSC (concentricity)
4-point clearance between bearing OD and hsg ID
T-bar rate Nm.deg 2.5 +/-
Rack Travel tolerance
Flatness tolerance of gear mounting
Position tolerance of gear mounting
Housings porosity
Soft stop stiffness
Fastener Torques (inner & outer spanner nut, hsg bolts, harness, connector, ITR to rack)
clamp loads
ITR Buckle strength
Gear mounting bushes
Control algorithms
Housings strength
Belt design (including mass? )
Rack strength
Pinion strength
Lubrication properties
Rack Liner to rack clearance
rack liner wear properties
Motor design
Gear reduction ratio (column to motor ratio) ratio GMX: 22.4 / XTS 24
Torque sensor accuracy / precision / resolution /redundancy
Tires and Wheels (Modes and mini spare) tread, Hz
Non uniformity TBD
Alignment input shaft to steering column mm
AC Evaporator drip / cowl drainage (Water) gr/min
EMC interference / ESD V/microsec
CAN signal availability and quality logic, tbd
CAN connector and harness resistance mohms
Upper steering loads, stiffness, friction, and modes Nm, Hz
Powertrain modes Hz
Heat (powertrain exhaust) deg C
Subframe flatness of gear mounts mm
Voltage spikes V/micro sec
Power supply voltage (Battery) V
Power Connector and harness resistance mohms
Suspension loads, friction modes N
Subframe structure loads and modes kN, Hz
Body structure modes Hz
Driving on extremely crowned road type
Road surface type
EMC interference / ESD V/micro sec
Agressive industry polution (Ozone / SOx, etc.) mgr/cc
Water/Humidity (as noises only relevant after failed sealing or cut boot) outside design windowgr, RH TBD, 5 - 100%
Dust and Dirt (as noises only relevant after failed sealing or cut boot) outside design windowtype, mgr/cc
Mud/Slurry (as noises only relevant after failed sealing or cut boot) outside design windowtype, mgr/cc
Saltwater (as noises only relevant after failed sealing or cut boot) outside design windowtype, mgr/cc
Ambient Temperature outside the vehicle deg C -40 to 130
Vehicle Shipment - Shock exposure logic
Loose BNA ball logic true/false
Cut boot logic true/false
Damaged PH datum (handling) logic true/false
Broken PH (IPA tower) logic true/false
TS bent finger logic true/false
TS wire harness damage logic true/false
Vehicle Load incl. Trailer (weight) kN spectrum
Engine idling for a long time in very hot environment hrs, degC 1 hr?, 130 degC
Low mu end lock impact (power on) motor rev/min~2000
Workshop Misuse motor rev/min~2000
Car wash cleaning agents and spray list SSTS
Reverse polarity V
Jump starting vehicle with non 12V system V
Submerged driving water temp deg C0 - 5
Extreme off road driving kN spectrum
Vehicle loads (max load) kN spectrum
High Loads impacts kN 20+
Tire/Wheel Change tread sizes
Improper service interval (bellows/tie rods)
Customer fluids/chemical compatibility list SSTS
Extreme handwheel torque (while power off) Nm
Temperature range deg C -40 to 125
4-pt bearing lash increase over time mm
Compression set or plastic creep of rubber seals %
Outer Spanner nut pre-torque decay Nm
Inner Spanner nut pre-torque decay Nm
Leak rate (correlation to water leak paths following operation cycles) ccm
RBNA efficiency decay %
EPP efficiency decay %
Ball nut lash increase mm
Sealing degradation (->Corrosion) ccm
Yoke clearance increase mm
Belt tension decay Hz
Lubrication property changes
Friction decay IS Nm
Pinion Nut torque Decay Nm
TSC bearing to IS clearance mm 0.040 - 0.072
belt teeth misalignment (axial offset & fleeting angle-pulleys assy related) mm & deg CARS 10-00364
Misalignment of RBNA nut races to rack races mm & deg CARS 10-00364
Boot stiffness N/mm 1.05 - 1.10
IS Seal friction (RSS) mNm
Strength of Assist reduction mechanism (belt/pulleys) Nm
Efficiency of Assist reduction mechanism (belt/pulleys) %
Compliance of Assist reduction mechanism (belt/pulleys) deg/Nm
Friction of Assist reduction mechanism (belt/pulleys) Large Pulley Nm
BNA friction p-p @ x mm/s N
RBNA mean friction @ x mm/s N
Large pulley runout in assy Hz deg +/-25 +/-4
Small pulley runout in assy Hz deg +/-50 +/-2
Belt mass gr
EPP torque ripple (9th order) mNm
EPP friction p-p (cogging) @x rpm, power on currently not measured
EPP mean friction @x rpm, power on mNm
EPP cogging (friction p-p) @x rpm power off mNm
EPP mean friction @x rpm power off mNm
System natural frequency (modal alignment) Hz >>34
Transmission error mm/rev 0 - 0.30
Motor Inertia 10 -̂4 kg.m 2̂69:2.25/78:2.54 +/- 5%
TS functionality (ASIC jitter, short, solder Joint) logic true/false
EPP functionality logic true/false
IPA natural frequency (IS to Pinion gap, other gaps/lashes) Hz
Kinematic Hysteresis deg 0 - 0.5
BNA noise m/s 2̂
RBNA efficiency %
Leak rate (correlation to water leak paths) cc/min tbd
Belt tension N 80 - 100
EPP housing vibration (9th order) m/sec 2̂ tbd
STRATEGY (NFMS)
Metric Range
EPP efficiency %
10 years of environmental exposure and 160900 km of extreme customer usage (99.9 percetile)
ERROR STATES
NOISE FACTOR MANAGMT
Power assist
On center precision (Vehicle Dynamics Attribute)
GM
Veh
Dyn
am
ics
TR
W V
eh
Ratt
le N
ois
e t
est
Revers
al
No
ise t
est
Bu
zz n
ois
e t
est
GM
Veh
Th
erm
al
GM
Veh
NV
H
GM
Veh
wate
r in
tru
sio
n
GM
Veh
En
d o
f tr
avel
Cu
t B
oo
t
GM
ste
eri
ng
to
cra
dd
le
GM
100 l
bs r
im p
ull
GM
Veh
Du
rab
ilit
y
Imp
act
En
d o
f T
ravel
Test
Vacu
um
/Pre
ssu
re a
ir l
eak t
est
BU
LL
Y
Vib
rati
on
Gear
En
vir
on
men
tal
Wear
an
d W
ate
r S
ub
mers
ion
Co
rro
sio
n
Tem
p S
ho
ck W
ate
r S
ub
mers
ion
/hig
h p
ressu
re S
pra
y
EP
S U
nit
Wear
Test
Gear
Wear
an
d F
ati
gu
e (
Du
rab
ilit
y)
Gear
Hig
h L
oad
Fati
gu
e
Gear
Wear
(po
wer
on
)
EP
S U
nit
Lash
Ch
em
ical
Exp
osu
re -
Un
derh
oo
d
Du
st
Han
dw
heel
To
rqu
e
Co
ld S
tart
Eff
ort
s
Du
ty C
ycle
Cap
ab
ilit
y/P
ark
ing
du
rati
on
Max P
oth
ole
(kic
k b
ack)
Ste
eri
ng
Eff
ort
- P
ow
er
Assis
t O
ff (
EE
C92/6
2)
Sta
tic E
ffo
rt V
ari
ati
on
wit
h T
em
p a
nd
Vo
ltag
e
Dyn
am
ic E
ffo
rt V
ari
ati
on
wit
h T
em
p a
nd
Vo
ltag
e
Co
ld S
tart
No
ise
Ho
t T
em
pera
ture
No
ise
Axia
l/R
ad
ial
Ste
eri
ng
Gear
Inp
ut
Sh
aft
Co
mp
lian
ce
Dete
rmin
ati
on
of
C-F
acto
r
Ela
sti
cit
y/B
ackla
sh
rack t
o p
inio
n
Inert
ia C
om
pen
sati
on
Ste
eri
ng
No
ise A
llo
wan
ce
SC
F
SR
S
Kin
em
ati
c H
yste
resis
Po
wer
On
Displacement (mm) of tie rods/rack bar
Force (N) on tie rods/rack bar
Ste
eri
ng
Eff
ort
Ch
an
ge w
ith
Han
dw
heel
Sp
eed
Ste
eri
ng
To
rqu
e P
ow
er
On
/Off
R+
P I
nte
rface C
om
pli
an
ce (
yo
ke c
leara
nce)
Retu
rnab
ilit
y P
ow
er
On
On
-Cen
ter
Retu
rnab
ilit
y P
ow
er
On
Retu
rnab
ilit
y P
ow
er
Off
Bo
ost
Ch
ara
cte
risti
csUSEFUL LIFE PERIOD
B - Bogey
D - Degradation
F - Failure
VM Types
Strong =
Weak =
None = Blank
Interaction
6
Parameter Design Applications …
A. FRICTION
Ensure NF/CF traceability to run capability and correlations
Measure tension at 4 positions
Record belt mass
B. RUNNING NOISE
DOE: 8 run 1/16 fractional Factorial – seven factors
C. RATTLE NOISE
DOE: 8 run full Factorial – three factors
D. CLUNK NOISE
DOE: 8 run full Factorial – three factors
E. BUZZ NOISE
Test max TSC bearing to IS clearance with nominal (centered) IPA and
Pinion Housing
7
Parameter Design Applications continued
F. SRS
DOE: 16 run 1/256 fractional Factorial – twelve factors
Simulation model: characterize gear components for damping/spring properties and solve for required properties
G. LOA
Evaluate with repetitive ignition cycling and other CV testing
H. OCP
Define the target dynamic S plot (Input torque vs. rack load)
DOE: 8 run 1/16 fractional Factorial – seven factors
I. WATER INGRESS
Define program specific leak testing and investigate correlation to water leak paths
Evaluate the most likely worst case condition for the sealing joints
J. MECHANICAL FAILURE
Evaluate with OEM Validation Testing
Apply Overstress Probing (four candidate tests) 8
CV Robustness Samples
ITEM # QTY PART REQUIREMENT USAGE
1 3 IPA MAX transmission error (MAX CRE) 1 CLUNK, 1 SRS, 1 OCP
2 3 IPA MIN transmission error (MIN CRE) 1 CLUNK, 1 SRS, 1 OCP
3 1 IPA ALL DIMS NOMINAL (ZERO runout) w /min IS OD (same as in sealing) BUZZ
4 2 IPA 1.5 Nm/deg MAX transmission error (MAX CRE) 1 SRS, 1 OCP
5 2 IPA 1.5 Nm/deg MIN transmission error (MIN CRE) 1 SRS, 1 OCP
6 1 IPA bearing t-bar MAX transmission error (MAX CRE) * OCP
7 1 IPA bearing t-bar MIN transmission error (MIN CRE) * OCP
8 1 IPA bearing t-bar 1.5 Nm/deg MAX transmission error (MAX CRE) * OCP
9 1 IPA bearing t-bar 1.5 Nm/deg MIN transmission error (MIN CRE) * OCP
10 1 YOKE MIN OD RATTLE
11 1 YOKE MAX OD RATTLE
12 1 YOKE MIN OD and MIN o-ring grooves SRS
13 1 YOKE MAX OD and MIN o-ring grooves SRS
14 1 YOKE MAX OD and MAX o-ring grooves SRS
15 1 YOKE MIN OD and MAX o-ring grooves SRS
16 2 Y- SPRING MAX rate 1 RATTLE, 1 SRS
17 2 Y- SPRING MIN rate 1 RATTLE, 1 SRS
18 1 TSC MAX IS bearing DIA (same as in sealing) and nominal (zero) concentricity BUZZ
19 2 PH MAX yoke bore 1 RATTLE, 1 SRS
20 2 PH MIN yoke bore 1 RATTLE, 1 SRS
21 1 PH NOMINAL (zero) concentricity IPA bores BUZZ
9
Parameter Design Leads
O NVH
1.Tonality / Running noise – DFSS project
2.Rattle
3.Clunk
4.Buzz
O Vacuum/pressure Leak test
Correlate leak rate to water leak paths by exploring test media (i.e. air,H2, Helium,
ultrasonic, etc) and parameters to create a dependable production test
O Friction
Including belt tensioning procedure for a capable production process
O SRS – DFSS project
O On center precision – DFSS project 10
Bayesian Prediction (method under investigation)
11
Bayesian reliability prediction for 68 mm steering gear is
98.1%R @ 50%C
= 1 part failing in 53
Likewise for 79 mm steering gear
97.1%R @ 50%C
= 1 part failing in 34
Combined reliability prediction for both is
98.8%R @ 50%C
= 1 part failing in 83 & is based on 51 parts tested
Seems a more reasonable value based on the limited number of parts tested
PROBLEM:
Model has not yet achieved universal acceptance
REDPEPR PROCESS (Ford tool)
12
Recommended