Executive Summary
Introduction
Problem Objective
Ignition System
Adjustable mechanism
Shield
Other Modifications
Final Design

 

Ignition System

 

The operation and efficiency of an internal combustion (IC) engine is strongly linked to its ignition timing. Dr. Horatio Perez-Blanco of the Texaco Energy Systems Laboratory at Penn State University is interested in being able to carry out experiments relating to this linkage on a Wisconsin Robin single cylinder IC engine (seen in Figure 1). The goal of this project was to modify the existing ignition to enable the spark location to be adjusted, so experimental research can be conducted in a laboratory environment.


Figure 1: Wisconsin Robin Engine

Research was conducted on current ignition modifications. This research was used to formulate three designs that met the specifications set forth by the sponsor. The optimal design was then selected using a design selection matrix which incorporated not only the needs of the sponsor, but also fit within the guidelines determined by the group.

Once the optimal design was chosen using an ignition system based on a Hall Effect sensor, refinements and alterations were made to the design until it was finalized. Detailed drawings of the selected system were constructed and the necessary measurements to assemble the apparatus were taken. Materials were chosen and together with the drawings and measurements, an adjustable mechanism was constructed as shown in Figure 2.


Figure 2: Final Design

be used to cause a spark to occur, the group decided on using a system based on a Hall Effect switch, which is commonly used in engine applications. The Hall Effect switch (see Figure 3) is a very small electronic device which can be used to open and close electronic circuits by exposing the switch to a magnetic field. The advantage to using the Hall Effect switch is that its size is considerably smaller than that of the existing magneto. By using a smaller device the group will have much more room to utilize when designing the adjustable mechanism. The Hall Effect switch will also induce less stress in the adjustable device, since the switch is much smaller than the existing magneto and therefore won’t experience as large of a magnetic pull from the magnet fixed to the flywheel.

Hall Effect Switch
Figure 3: Hall Effect Switch

As mentioned above, the Hall Effect Switch can only be used to open and close circuits, and thus an electrical circuit was created in order to generate the needed spark. During this phase of the project Mr. Steven Wagner was consulted. He suggested that if possible, the group should try to purchase an electronic ignition system from a supplier, which has already been tested, known to work, and would be easily replaced. This ignition system, along with a power supply and a spark coil provide the group with the needed spark intensity at any given location. Mr. Wagner then purchased the needed ignition system (Velleman Kit, part number K2543) from the Jameco catalog. The group then helped Mr. Wagner build the circuit and mount it as seen in Figure 4.

Figure 4: Ignition System


Key
A. Power Supply
B. Spark Plug
C. Spark Plug Wire
D. Spark Coil
E. Electronic Ignition System
F. Hall Effect Wire


The aforementioned system works as follows:
As the magnet on the flywheel approaches the Hall Effect switch, the sensor recognizes the magnetic field and closes. This completes the ignition system circuit and allows the current, generated by the voltage source, to flow through the spark coil. A spark coil consists of two coils. One coil has many small turns and the other consists of a few large turns. When the current flows through the large coil a charge is built up. Then once the magnet on the flywheel leaves the sensor, the switch opens the circuit causing the system to break. Upon breakage, the charge in the larger coil is transferred to the smaller coil and dissipated quickly which results in a spark in the plug.