SYSTEM LEVEL DESIGN REVIEW P16318 Gaseous Mass Flow Rate Controller Luke McKean, Lianna Dicke, Selden Porter, Schuyler Witschi ?

Agenda ● Phase I Review ○ Problem Statement ○ Updated Phase I Documentation ○ Review P15318’s Prototype ● Phase II Tasks ○ Shared Vision ○ Functional Decomposition ○ Concepts and Development ○ Feasibility Analysis ○ Proposed Test Plan ○ Risk Assessment ● Phase III Plans

Problem Statement Environmentally and economically CNG makes sense as an alternative fuel Delivering a precise portion of Compressed Natural Gas is necessary for an engine to operate Current device done by previous MSD team has functional limitations New design will deliver a precise amount of CNG Use a PID control algorithm Designed for use in an automotive environment

Updated Customer Requirements

Updated Engineering Requirements

Updated House of Quality

P15318’s Prototype Test Results

P15318’s Design Decomposition Temperature Sensor Position Sensor Rotational Actuator Pressure Sensor Output Fitting

P15318’s Design Decomposition Known Issue: Leak rate when fully closed Suspected Cause: Plastic on Metal face seal failure High mfg tolerances required

P15318’s Design Decomposition Known Issue: Slow response time Suspected Cause: Friction in the system due to face seal, Issues with microcontroller and software.

Shared Vision:

Functional Decomposition

Morphological Chart

Concept Generation Valve ideas in detail Ball/Cam

Concept Generation Valve ideas in detail Poppet Valve

Concept Generation Valve ideas in detail Rotational Disc

Concept Generation Valve ideas in detail Needle/Seat

Concept Selection

Pugh Analysis Results All concepts are variations of the same concept Each component type independent of the others Need to analyze components in detail in Subsystem Design Phase

System Architecture

System Level Flowchart

Feasibility Questions Will we be able to model the flow as incompressible? Incompressible flow is fairly accurate for M < 0.3 Spoke with Dr. Liberson Using: Calculated M at the outlet of the valve, resulted in M=1.709 To accurately model the flow it must be considered compressible, and it is supersonic at the exit. Need to verify next steps to flow modelling with Dr. Liberson

Feasibility Questions Will a metal-on-metal seal be able to prevent leak (< 25 sccm)? Experience with testing EGR valves: Steel poppet/seat was able seal with leakage much less than 25 sccm Need to determine how to model leakage Talk with ME faculty

Feasibility Questions If our system is required to ‘unseat’ a valve, will our current actuator have enough torque?

Feasibility Questions If our system is required to ‘unseat’ a valve, will our current actuator have enough torque? Assumptions Needed: ● Neglecting Friction (for now) ● Cam Profile is linear ramp ● Valve is sealed only by air pressure ● Cam diameter ● No spring assist

Feasibility Questions If our system is required to ‘unseat’ a valve, will our current actuator have enough torque?

Feasibility Questions Question: Are thermistors, or resistance temperature detectors feasible for our temperature sensing needs? *Thermocouples were not included in this feasibility study, but will be added for consideration in the sub-system design phase.

Feasibility Questions ˜Question: Is it feasible to use a general purpose, flush diaphragm, or PCB mountable pressure transducer?

Feasibility Questions Question: What technologies might be feasible for our positional sensing needs?

Feasibility Questions Question: How much power will our system consume?

Feasibility Questions Can a microcontroller be used for this project? Some requirements are: Operating Voltage: 1- 5V Temperature Range: -40 to 85 degrees Celsius Speed: > 20MHz I/O Pins: >20

Feasibility Questions: 049_full_img.jpg

Feasibility Questions Can a microcontroller be used for this project? We are still researching potential ways to optimize microcontroller response: the use of lookup tables vs real-time calculation processing speed/power vs available memory Careful attention to price

Proposed Test Plan

★ Test Valve ○ Run compressed air through device and open and close valve ★ Test Microcontroller ○ Generate values to simulate varying sensor readings ★ Test Response Time ○ Have the microcontroller open and close the actuator ★ Test with Installed Sensors ○ Vary sensor variables to test microcontroller response ★ Test Voltage Regulator ★ Test Leakage ○ Pressurized system and measure amount lost due to leakage ★ Test Flow Rate Accuracy and Repeatability ○ Connect device to compressed air tank and measure output

Risk Assessment

Risk Assessment continued

Next Phase Plans