Thermal Management

Thermal management for heavy duty engines (whether stationary, mobile equipment or heavy duty vehicles) is the process of maintaining the engine temperature through the use of engine accessories (coolant pump or fan drive). These engine accessories are powered by the engine they are trying to cool and can have a significant impact of the overall system efficiency. These accessories must be over sized to provide the adequate cooling output at all engine speeds (from idle to maximum) in all operating environments.

On heavy duty engines, the thermal management engine accessories are connected to the engine by a belt that runs at a speed proportional to the output of the engine. As engine temperature increases, the engine accessories will engage and cool the engine. They will remain engaged until the engine reaches the lower temperature limit and shut down. Due to the on/off nature of the devices, there is a cycle of engine heating and cooling that results in significant parasitic power consumption.

Orbital Traction’s adjustable speed drive (ASD) has a simple, modular design that has been designed to act as a variable speed drive for engine accessories. The controlled velocity accessory drive (CVAD) is placed between the engine/belt and the engine accessory. The CVAD maintains a constant speed for the accessory, regardless of the engine speed. This results in a much smoother application of power and appropriate levels of cooling output to maintain a consistent engine temperature.

Orbital has worked with the US Department of Defense (DoD) and the Small Business Innovation Research (SBIR) program to develop and test a CVAD for a heavy duty engine fan drive and water pump. The prototypes were successfully designed, constructed and installed on an ACV and MTVR. During this testing, it was shown that there was a >3% decrease in fuel consumption per accessory.

The CVAD system is designed to be retrofittable on any heavy duty engine, within current space confines without specialized training or personnel. This system can be installed on any type of heavy duty engine whether it provide stationary power (standby generator, frac pump, etc), mobile equipment (tractors, bulldozers, etc) or commercial and military vehicles.

The benefits of using the CVAD system are:

  • Fuel consumption reductions of approx. 3% to 10% based on the number of engine accessories aligned with CVADs
  • Three times reduction in engine temperature variation
  • Significant ambient noise reduction as engine accessories will not operate at full power. Consistent output levels will result in overall lower ambient noise
  • Reduced maintenance events due to lower variations in engine loads and engine temperatures