Top Dead Center Application

In an internal combustion engine, determining the right moment to ignite the fuel is critical for maximum efficiency. To achieve this, it’s necessary to know when the piston is at the Top Dead Center (TDC) position and the angle of the crankshaft in that specific moment. Engine developers must conduct multiple tests and research on these exact events for correct engine performance. One of the most effective and precise options for these tests is using a top dead center measurement system along with a crankshaft angle encoder.

Crankshaft DiagramTop Dead Center (TDC) is the position of a piston in which its head is the farthest away from the crankshaft. In a reciprocating engine, the TDC of a piston is the point from which ignition system measurements are made and the firing timing is determined for all the pistons. When the TDC is known and the angle encoder determines the exact crankshaft angle, the spark plug can be fired at the exact moment for the most efficient burn. Additionally, knowing when TDC is reached can also help investigate energy conversion processes inside engines.

To determine the exact point at which TDC is reached, the best solution is to use a capacitive sensor that measures the distance between the piston head and the sensor. In most circumstances, the sensors are installed through the spark plug hole (located at the top of the chamber). The sensor will let the system know when the piston is at its highest point. At precisely that point, the system will know that TDC has been reached.

The benefit of using capacitive sensors instead of identifying the maximum pressure inside the chamber is that thermodynamic loss angle does not affect the measurement. You always get precise data despite the conditions.

Within our capacitive sensor product line, we have multiple options to choose the one that fits you best.

  • Sensing area diameter from 0.5 to 21mm
  • Varied measurement ranges (Fine, Standard or Extended) between 10µm and 12,500µm
  • Multiple resolution options depending on bandwidth (1kHz, 10 kHz, 15kHz)
  • Multiple body options
    • Shape: Cylindrical and rectangular
    • Size: Diameter (cylindrical) and longest side (rectangular)
    • Body style: Long, short or right angle

Additionally, all our drivers can be custom-built for your specific needs.

Contact us today for more information