Recently, in the automobile industry, the reduction of the size and weight of the engine starter motor has become an important issue. We think that an engine starter with a planetary gear reduction system would be the best method to achieve this goal. However, a planetary gear system as such would need a heavy duty sintered bearing that has a combination of a high PV (Pressure, Velocity) value, a low and stable coefficient of friction in a wide range of temperatures and operating conditions, good wear resistance, strength, dimensional tolerance, reliability after assembly, and more. As there is no quantitative data base for the development of a sintered bearing, we were dependent upon experience of engineers to accomplish this development. However, this is a time consuming and elaborate method. In order to overcome this, we developed a data base for the design and material selection on sintered bearings, and we were able to develop a new and effective bearing for the planetary gear type starter. We determined that the best material for this type of bearing in a Cu-9/10 Sn-2/4MoS2-<1X alloy with a density of 6.7/7.4 g/cc. This bearing has an excellent PV-value of 500 MPa.m/min and a stable coefficient of friction (0.06) under condition of up to PV=500. Dimensional tolerance and reliability after assembly were also improved by optimizing the cocking and fitting conditions. This new bearing is currently being used in a new starter motor which is more compact, lighter and less noisy than conventional ones.
Development of sintered bearings for planetary-type engine starters
Entwicklung gesinterter Lagerteile für Maschinenanlasser vom Planetentyp
1991
15 Seiten, 22 Bilder, 5 Tabellen
Conference paper
English
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