Ignition System

Components

Spark Plugs

Ignition Coils

Relay

The relay is used in conjunction with another microcontroller that is set to trigger the relay on and off at a certain rate. The rate of 100 milliseconds works best to build the magnetic field within the coils to give the spark plug enough voltage to ignite the air around it at a larger magnitude.

Control / Data Acquisition Box

Top Circuit Layer 3

The picture to the left is a preview of what the initial menu looks like as well as what will be the physical user inputs. The top circuit layer will be responsible for handling the displays and communicating the user inputs as well as receiving the sensor value and displaying them on screen.

Data acqusition Circuit Layer 2

The picture to the left displays the pulse jet and the data acquisition circuit layer that will in the future be mounted inside the control box. This layer will be responsible for powering and monitoring all of the sensors on the pulse jet. The microcontrollers on this layer can be interchangeable to allow one microcontroller to be the main sensing controller and the other one to communicate the signals. The purpose is to include more analog and digital inputs to eventually add more sensors and other devices like control valves.

Spark plug Circuit Layer 1

The sides of the Control box will host the ignition coils. The circuits on the bottom layer will be responsible for activating the ignition coils on and off to spark the spark plug. A separate microcontroller will handle this feature.

A 12-Volt battery connects to the first-layer circuit and the spark plug is activated using a switch and a switching relay controlled by an esp32.

Fly-back diodes are used to separate the esp32 circuit from the 12 Volt switching relay circuit.

Recent tests show that the spark plug and the glow plug are not capable of igniting the Air/Propane mixture. These ignition options might be capable of igniting liquid fuels. The results of this hypothesis is yet to be tested.

recorded-278906301192.MP4

Second iteration

The second design includes two ignition coils in series with the outputs of the second coils in parallel to power the spark plug.

IMG_1620.MOV

Initial design

The initial design consisted of a 12-volt battery, ignition coil, Arduino, relay, switch, diode, and a sparkplug.

Since the spark plug requires 15,000 V - 35,000 V an ignition coil powered by a 12-volt lawn mower battery was used in series with a relay control by the Arduino. The ignition coil is turned on and off by the relay to instantaneously create and dissipate a magnetic field that travels through the second coil of ignition coil to the spark plug to ionize the air in the spark gap. The Arduino is protected against any unexpected flyback voltage by using a diode. This system failed in igniting the air fuel mixtures of gasoline and propane so another ignition coil might solve the problem for ignition.

C++ to activate the spark

SparkPlug_ Switch

// the setup function runs once when you press reset or power the board

void setup() {

// initialize digital pin LED_BUILTIN as an output.

pinMode(4, OUTPUT);

pinMode(5, INPUT);

}

// the loop function runs over and over again forever

void loop() {

if (5 == HIGH)

{

digitalWrite(4, HIGH); // turn the LED on (HIGH is the voltage level)

delay(100); // wait for a second

digitalWrite(4, LOW); // turn the LED off by making the voltage LOW

delay(100); // wait for a second

}

else

{

}

Configurations & considerations

Spark Plug Mount Configuration:

The spark plug is attached with alligator clips to the positive side of the ignition coil set. The spark plug is wrapped in copper wire from the positive of one ignition coil and the negative of the other ignition coil.

Spark Plug Design Considerations:

The Spark Plug has yet to ignite the air propane mixture due to the health of the available 12-volt battery. There could be an alternative method to generate 12 volts for the ignition coils or viable alternative methods to generate a high voltage in general but those are outside the scope of this project for now.

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