Embedded Files
The final design of the temperature control device is described here in further detail.
Hardware
Hardware
Airflow Manifold
The manifold is the first step in the redirection of the airflow from the contactor to the valve system. The undercut of the manifold guides the flow towards a tunnel sized 2mm which is the inner diameter of the PTFE tube. The PTFE tube itself is secured using a set screw that has is held into place on the side tapped hole.
4mm OD PTFE Tubing
The soft PTFE tubing allows a flexible flow redirection in the Cohu Matrix, which has very limited space available. The high melting temperature and the shape memory of PTFE makes it a prime candidate for this purpose.
Custom-made Butterfly Valve
The butterfly valve was made in-house due to market valves being too expensive. The valve was also designed to be compact for easy manufacturability.
TowerPro MG29B Servo Motor
This motor was chosen due to its metal gearing and high compatibility with the Arduino. It also offers enough torque (3.5 kg/cm) to open and close the valve and allows for incremental control.
Aluminum Coupler
Standard 5mm to 8mm aluminum couplings is used to connect the valve to the shaft of the motor. The couplings also adds some space between the valve and the motor so that heat entering and exiting the valve would not affect the motor.
Mounting Bracket
The mounting bracket serves the simple purpose of holding the valve system together. Machined from aluminum, the bracket uses its weight to hold the systems securely in place while the precision of machining allows the user to position the valve and the servo motor with a tight fit.
Electronics
Electronics
Circuit Diagram
Arduino Mega 2560
The Arduino Mega was used due to its programmable versatility and our familiarity with it. The Arduino is able to be programmed specifically for our needs and had an appropriate number of pins to control four valves.
PT100 RTD Temperature Sensor
The PT100 is one of the most accurate temperature sensors in the industry. It provides excellent stability and repeatability and is able to work with our controller.
MAX31865 Amplifier Board
In order to get good precision and accuracy out of the PT100 RTD, the Max amplifier board is designed to read the PT100 low resistance. This board is the connection between the Arduino and the temperature sensor. It is also essential for the controller read temperature changes.
16x2 Character LCD
This LCD screen is used to display the status of the controller. Without it, we would have a difficult time figuring out what the controller was doing.
Software
Software
Arduino Code
Located here, the programming of our device was done using the C++ coding language through an Arduino. The device can handle multiple types of control algorithms, but we decided to use incremental control since it worked the best and caused the least errors while tuning.
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