A Dynamic Test Facility with Motoring Using a Digital Computer

A computer controlled engine research and testing facility is described which has the capability to motor the engine via a unique hydraulic motoring system. The facility provides a highly reproduceable and accurate response to arbitrary schedules of engine speed and dynamometer torque versus time. The development of a proportional plus integral plus derivative control scheme for direct digital control of speed and torque is presented in detail, along with a set of vehicle modeling equations which allows test cell simulation of road tests.

A simple experimental driving cycle is described, and fuel flow results obtained from tests of alcohol/gasoline blends are compared to actual road and chassis dynamometer tests. The agreement of the various result supports the use of the facility with the simple driving cycle as an alternative to chassis dynamometer or road testing.