Design Ideas

transcript

Design History

Brainstorm, Pros and Cons, Top Design Ideas

Pros Cons• Eliminates most tubing • Not very exciting

• Simple • Have to make a connector

• Can design manifold similar to CasMed

• Separate module gives more flexibility

Pros Cons• All components completely integrated • Might be a little bulky

• Relatively small • Complex

• Interesting design

Pros Cons• Integrates all components • Not most compact design

• “Valve bundle” allows for easy storage of valves beneath pump

• Too much tubing

Pros Cons• Smallest design in size • Doesn’t completely integrate all

• Integrates valves and circuit board

• Manifold design might be a bit difficult

• Separate pump allows more flexibility

Top Three Initial Design Ideas

Criteria for Picking Top three designs

Combined concepts Least Complex (can do in 10 weeks) Least amount of tubing Most compact

Criteria for Picking Top Design

Integrated connector can easily be added Neat appearance Compact system (length, width and height small

as can be) that can easily become completely integrated in the future

Interesting

Top Design Idea Version 1.0

Comments

Pros Cons • All ports in one area, minimized

friction between pump outlet and pressure sensor/cuff inlet

• Walls prevented access to the pump outlet

• Walls kept all parts contained • Walls added extra thickness

• Distance between sensor port and cuff port was acceptable

• Port to transducer was too close to pump, couldn’t put a tube completely over it.

• Port was designed as a barbed tube fitting to form a tight seal (tube ID 3/32”)

Comments

Pros Cons• Decreased size by removing

majority of walls and created a wall that can be inserted to keep bottom of the pump from sliding

• Two parts

• Repositioning sensor port (while maintaining the same port-to-port distance) allowed tube to fit completely over the ports

• No support for upper part of pump

• Added channels (details of design explained later)

Comments

Pros Cons• Added snap and clip for support

(removed all walls)• Clip too thin towards middle

(snapped)• More compact package • Snap too stiff

• Tooth of snap too long

• Slit on either side of snap too narrow

• Channel edges too sharp

Comments

Pros Cons Added strength to clip by adding triangular support

Tube doesn’t quite fit into pump and cuff outlet due to clip

Widened the slit ?

Rounded off all edges of channel ?

Redesigned snap ?

Air channels

Comments

Added seal around channels Removed extra materials Lengthened the snap (less load)

Channel Design

Wanted to find channel width (b) and depth (a) that would minimize friction loss through channels

Defined a range for width and constant values for depth

Plotted data to find the smallest head loss.

Channel Design (Calculations)Inputs

* 0.965

0.17 – 0.27

0.1 / 0.3 / 0.7

*Flow rate was half of the one from rolling air pump data sheet.

Equations

Channel Design (Calculations)

0.17 66636.22818 0.17 2742.232 0.17 259.0330.18 59254.41998 0.18 2425.62 0.18 227.30710.19 53033.9358 0.19 2160.642 0.19 201.0033

0.2 47743.46924 0.2 1936.684 0.2 178.96340.21 43206.53733 0.21 1745.719 0.21 160.32110.22 39286.60128 0.22 1581.586 0.22 144.41770.23 35876.69259 0.23 1439.497 0.23 130.7460.24 32892.05057 0.24 1315.682 0.24 118.910.25 30264.8125 0.25 1207.144 0.25 108.59770.26 27940.12765 0.26 1111.473 0.26 99.55990.27 25873.275 0.27 1026.717 0.27 91.59635

Depth (a) = 0.01 Depth (a) = 0.03 Depth (a) = 0.07

0.15 0.2 0.25 0.30

20000400006000080000

Varying Width (a=0.01)

Width (b) [in]

0.15 0.2 0.25 0.30

50010001500200025003000

Varying Width (a = 0.03)

Width (b) [in]

0.15 0.2 0.25 0.30

Varying Width (a=0.07)

Width (b) [in]

Channel Design (Results)

Optimal depth: 0.07 in Optimal width: 0.27 in : ~91.6 in Velocity: ~51.1

Snap Design

Used it to secure bottom of pump as a replacement for the wall.

Takes up less space Had to make sure strain was below 1.3% to

prevent my snap from breaking

Snap Design (Calculations)

Note: Formulas based on Snap Fit Design Manual from BASF Chemical Company‐

Inputs:

Outputs:

Strain is about 0.8% which is less than 1.3% and less than the limit (typically 3-6%) recommended in design guides for PC/ABS.

Design Ideas

Documents