Transcript Final Design Review

Jonathan Brooks
Matthew Piatkowski
Spencer Herendeen
Ultimate Tailgate Prototype
2

Project Background and Scope
◦ Customer Needs
◦ Engineering Specifications
◦ Risk Management





Design Changes from MSD I
Final System
Budget
Project Shortfalls
Recommendations for future prototypes

Project is to create a functional tailgate
work surface with
◦
◦
◦
◦
◦

Workmate style clamp
Auxiliary clamp
Storage Bins
120 VAC power
12 VDC power
The intention of this project is to generate
an initial proof of concept. This is the main
concern, and as such drives much of how
the project progressed








Meet or exceed stock tailgate performance capabilities
Flat work surface, level with truck bed
Two clamps: one primary Workmate style, and one auxiliary
bar style
Two storage drawers
Structure to conform to a 2001 Chevrolet Silverado 2500
System capable of providing 120 VAC outlet power, and 12 VDC
accessory power
System power failsafe to shut down when vehicle is engaged
out of park or neutral and when vehicle battery voltage
becomes too low.
System power to be limited to 10 AAC when vehicle is off and
limited to 15 AAC when the vehicle is on.
Engr. Spec. #
Source
Specification (description)
Unit of Measure
Marginal Value
Ideal Value
ES31
Mechanical
Secure to a 2001 Chevrolet 2500
(interference)
Binary
0
0
ES33
Mechanical
Compatible with Cap or cover
(interference)
Binary
0
0
ES34
Mechanical
Truck Bed Preservation (interference)
Inches
6
0
ES35
Mechanical
Work surface level with bed
inches
± 0.50
0
ES26
Mechanical
Rigid work surface when in the down
position
inches
<1
0
ES27
Mechanical
Lock in place while up
Degrees
<1
0
ES28
Mechanical
Lock in place while down
Degrees
<5
0
ES36
Mechanical
Weight to support
lbs
250
500
ES29
Mechanical
Black and Decker Workmate clamp force
lbs
250
500
ES30
Mechanical
Auxiliary clamp force
lbs
100
200
ES37
Mechanical
Tie Down force
lbs
250
500
ES1
Electrical
Voltage at tailgate plug
V (AC)
100 - 125
120
ES8
Electrical
Inverter total harmonic distortion
%
<30%
<25%
17
2
13
22
Risk Item
Effect
Cause
Likelihood
Severity
Importance
ID
Action to Minimize Risk Owner
Components and
Assisted lift mechanism
features too heavy
Tailgate too heavy to lift Assistance required for
3 3 9 designed externally as MP, JP
manually
lifting
Drawer capacity too
an independent study
high
Poor design, structure
Assess customer need
No storage bins
impedes space for
for depth of storage bin
Tailgate too thin for
drawer
3 2 6
JB
drawers
Relocate Storage
Customer need not met Needs too restrictive
Reassess needs
Wire too long and/or
thin
Battery drained
Choose proper wire
Excessive Losses in wire
3 2 6
SH
prematurely
diameter
Wire unable to carry
sufficient power
Measure the draw of
the truck with all
Electrical draw from Inverter must be turned
Too many accessories
normal truck circuits is
off earlier than
1 2 2 accessories running
running at once
too high
expected
Design proper cutoff
circuitry
4
Workmate interferes
with work surface space
Insufficient work
surface
30
Parts difficult to
fabricate
Excessive time spent
creating parts
Tailgate dimension
limitations
SH
Open/Clos
ed?
Closed
Closed
Closed
Closed
Pop-up Workmate
1 2 2
JB
More complicated
design
Ensure all intricate parts
Poorly designed parts 1 2 2
JB, MP
are fabricated early
Closed
Closed

Mechanical
◦ Drawer Slides have integrated catch to prevent drawer from
opening unexpectedly
◦ Workmate Clamp has added rotation feature
 Workmate can be rotated in 90 degree increments
 When operated parallel to the direction of truck, workmate is
elevated to allow work to extend into truck bed
 Workmate dimensions reduced to allow for rotation
◦ Automated actuation added as an independent study to
work in conjunction with MSD II P10811
 Drawers shortened to account for automated actuation system
◦ Tube structure made of 0.083 steel tubing instead of 0.065
due to availability

Electrical
◦ No DC side relays were used in order to save on
implementation complexity, safety, and cost
◦ No external low voltage shutdown circuitry was used
because the innate inverter circuitry was found to be
sufficient
◦ No starter relay was used because the vehicle will draw
current away from the inverter to start. The inverter has a
shutdown mechanism if the current becomes too low.




Frame constructed as tube structure
Tubes are 1-1/4 inch X 0.083 square mild
steel tube stock
Tubes are cut to length and MIG welded
together to provide required strength
External frame dimensions match those of
stock tailgate, except thickness which is
increased to 4-1/2 inches to provide
additional room for features






Drawers are constructed from 16 guage mild
steel sheet
Drawer size is 15 X 12 X 2 inches
Parts are cut to size with shears and bent if
required using a break
Parts are MIG welded together
Drawer slides are sourced from Ovis Online
and are 14 inch 100 lb load capacity
Drawer slides are welded to drawer and frame




Wood surfaces are milled to size
Screw system is constructed on lathe
Frame constructed from 16 gauge sheet steel
in same fashion as drawers
Workmate mounts to frame by quarter turn
fasteners allowing easy changing of
orientation in 90 degree increments



Irwin one handed bar clamp purchased from
Lowes
Slots fabricated from mild steel to allow for
insertion into frame for clamping directly to
tailgate work surface
Clamp modified with stronger dowel pin to
allow for mounting to slots welded on frame



Designed as an independent study
Provides motors to raise and lower the
tailgate electronically
Incorporates latching mechanism to prevent
tailgate from opening during vehicle
operation




Inverter was pre-designed and
manufactured by the Whistler
Group, Inc.
Inverter has a high power
rating to tolerate up to a
continuous 16 AAC with a 94%
efficiency under 66% load.
Inverter has safety shutdowns
if the input and output
voltages become too high or
low.
Model has a robust
mechanical design to tolerate
temperature and above
general usage.

The electrical relay system provides the
failsafe conditions of
◦ Immediate shutdown when the vehicle
is out of neutral or park
◦ Switching of the allowable currents
dependent upon whether the vehicle is
on or off

System is shutdown if current
exceeds 10 A when vehicle is off
Fast switching time of relays (< 1 s)
and passable 10 A breaker cutoff time
(~ 9 s)
All components can tolerate at least a
worst case maximum of 120 VAC, 20
AAC.
All components have a low profile in
order to reduce complexity of
integration, cost, and space.

◦
◦
◦
10 A for when the vehicle is off and
full draw (15 A) when the vehicle is
on.




LED bank provides an
interface between the
tailgate and the rest of the
electrical system
LEDs indicate whether the
system is on or off, if the
inverter is overloaded, when
the truck should start, and
what mode of current limit
the system is in.
All LEDs are high intensity
to provide a wide viewing
angle, and far distance of
sight.
All LEDs are fitted with a
current limiting resistor for
component protection
Estimate Mechanical Total
$995.61
Estimate Electrical Total
$485.07
Estimate Total
$1,480.68
Actual Total
$1,141.32
Difference
$339.36
Mechanical




Excessive weight when fully
loaded
Self-actuated lifting subsystem
left to independent study
Weatherproof enclosure for
electronic components not
implemented
Interference with truck bed
when closing tailgate
Electrical



LED to indicate the right time to
start the truck is not included
◦ Future Solution: The inverter LED
is a multi-purpose LED that
indicates when the truck should
be started.
LED to indicate an overload does
not function properly
◦ Future Solution: The inverter LED
also has the ability to indicate
when an overload condition has
occurred
Relay circuitry not placed in end
user housing
◦ Future Solution: Encase and
mount relay circuitry in non
conductive housing
•
Mechanical
– Self-actuating lifting
subsystem integration
– Lighter weight materials
for drawers
– Weatherproof enclosure
for electrical components
– Reduce tubing size
– Allow for more room for
tailgate features
– Reduce tailgate weight
•
Electrical
– Isolated and devoted
battery
– More robust relays
– LCD interface to replace
LED interface bank
– Traced board for LED
bank
– Removing inverter from
cab for safety
regulations
– Self-actuating lifting
subsystem integration