Effort prizes

Development of gears for a wastegate valve in a turbocharged engine

Fig. 6 An Effort Prize was presented to Sumitomo Electric Industries Ltd. for a gear set for use in a turbocharged engine component (Courtesy JPMA)

The first of the Effort prizes went to Sumitomo Electric Industries Ltd. for a gear set for a decelerating mechanism in a turbocharged engine, used for opening and closing a wastegate valve.

The use of sintering technology for the manufacture of the gears was investigated as an alternative to adopting high strength resin. Although high strength resin was initially chosen, it was replaced due to its insufficient strength in this application.

The predicted drawback, caused by replacing light weight resin with sintered materials, was a considerable increase in gear weight. However, this issue was eliminated by optimising the gear design by introducing holes for reduced gear weight.

Although forming large holes in the gear contributes to weight reduction, the thickness of tools to form the holes in the gear inevitably becomes thin and breakable. As a measure to combat this, the shape of tooth profile of the gear was improved to avoid stress concentration in the gear.

This development has succeeded in the mass production of gears for a wastegate valve, while meeting characteristics required by customers.

Development of a pressure sensor holder in a gasoline direct injection system

Fig. 7 Sumitomo Electric Industries Ltd. received a prize for a sensor holder for an automotive application (Courtesy JPMA)

Sumitomo Electric Industries Ltd. secured a second Effort prize for a component used to fix a pressure sensor onto a delivery pipe in a gasoline direct injection system. The pressure sensor is a critical device for improving fuel efficiency and is used to measure pressure inside the engine, controlling the injection timing and pressure.

Sensor holders have previously been manufactured by forging and machining, which can be costly in high volume production. The required characteristics of the sensor holder include airtightness, strength, corrosion resistance and high dimensional accuracy. The component also has thin walls in part.

The use of PM was investigated primarily to reduce cost. The production method included compaction and sintering of a high strength material, machining, heat treatment, resin impregnation and plating. In most cases, the blank/material cost of sintered parts can be more expensive than that of forged parts. However, the machining cost of the sintered part was successfully reduced, compared with conventional forged parts, by optimising the shape of blank/material.

This takes advantage of PM’s capability to offer a high degree of design freedom, and a 20% reduction in manufacturing cost for sintered sensor holder was achieved. This enabled the replacement of conventional forged parts with sintered ones, while maintaining all the necessary functions for required by the customers.

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