Arnold O. DeHart

The Design of an Engine-Flywheel Hybrid Drive System for a Passenger Car

The quest to improve the fuel economy of General Motors passenger cars has led to the investigation of an engine-flywheel hybrid powertrain at the GM Research Laboratories (GMR). An engine-flywheel system was designed for a compact car and its performance was predicted analytically. The sytem was estimated to achieve an improvement in EPA composite fuel economy of 13 per cent ooer a 1984 production compact car. This margin of improvement was judged insuficient to justify the complex drivetrain, and, therefore, a prototype system was not built. However, the current potential of engine-flywheel hybrids for GM passenger car applications has been defined, and the technology areas requiring additional research attention have been identified.

SCORE RESISTANCE, HARDNESS AND PERFORMANCE OF DIFFUSED COPPER-NICKEL-TIN BEARINGS

Current production steel-back, copper-lead bearings contain a nickel-barrier layer between the lead-tin babbitt overplate and copper-lead intermediate layer. When these bearings are used in heavy-duty engines, the nickel-barrier layer changes composition via diffusion of tin into the nickel. When the journal wears through the thin babbitt into the modified nickel-barrier layer, scoring distress occurs. The copper-nickel-tin ternary system was studied. Its liquidus isothermal phase diagram was developed; intermetallic compounds were located; hardness and score resistance maps were generated; and the copper-nickel-lead-tin quaternary composition of actual field bearings as a function of depth through the barrier layers was examined. A new tri-metal, nickel-tin-copper barrier was developed which changes the composition of the barrier to have acceptable score resistance and hardness. An engine test, in which coolant is added to the engine oil until scoring distress occurs, was devised to simulate the distress encountered in service. The new tri-metal barrier bearing outperformed all other materials tested.

A Radiometric Test to Determine the Lubricant Effect on Journal Bearing Load Capacity

Radiometric techniques were developed and successfully applied to journal bearing studies in a unidirectional bearing test machine. These techniques involve the detection of wear debris from a radioactive test bearing and were used to determine bearing load capacity with both Newtonian and non-Newtonian lubricants. Results show that the radiometric method of determining bearing load capacity correlates with engine field tests and laboratory film thickness measurements. The method is more rapid and less costly than engine field tests and provides a more direct measure of load capacity than film thickness measurements. Slight changes in bearing geometry due to wear which occur during testing can be corrected by a linear compensation factor. A method for the electrodeposition of radioactive tin on a journal bearing surface is appended.