Analysis of automotive load simulation techniques

The object of this thesis is to show how it is possible to provide simulated running conditions to a prime mover in the laboratory and to develop test a faculty to to provide such conditions. Ageneralised mathematic model is developed for prime mover/ dynamometer combinations which is used for the design of a wide range of load simulation systems. The mathematical model is validated by experiemental investigations of a low power simulation system for which the prime mover is a d.c.trcation motor and the dynamometer is of the hydrostatic transmission system type. A full scale engine test cell is constructed in which a 70kw diesel engine may be loaded by two types of hydraulic dynamometer to enable comparisons to be made between each system. One of these is a hydrostatic dynamometer having the same operating principles as the low power system. The other is based on the operation of a unique hydraulic valve, the design of which is based upon theoretical and experimental analysis of several low power prototypes. The generalised mathematical model and design method is used to predict the performance of these engine/ dynamometer systems for a range of load simulation methods. The theoretical analysis is also extended to petrol engines and electric prime movers, for a range of dynamometer systems and load simulation methods, in order that the most suitable dynamometer and simulation method may be determined for each prime mover. To aid the supervision of the engine test cell under running conditions, a low cost microprocessor-based monitoring system is developed to allow early warnings of any large changes from the required operating conditions.