Abstract: A transmission structure of a helicopter according to one aspect is a transmission structure that transmits power from a prime mover to a rotary wing in the helicopter. The transmission structure includes: a housing; an input shaft that transmits the power of the prime mover to a gear arranged in the housing; a bearing supporting the input shaft in the housing such that the input shaft is rotatable, the bearing including an annular inner ring that holds the input shaft, an annular outer ring that is arranged outside the inner ring in a radial direction and fixed to the housing, and rolling elements sandwiched between the inner ring and the outer ring; and a sleeve that is sandwiched between an inner peripheral surface of the inner ring and the input shaft and is lower in heat conductivity than the inner ring and the input shaft.

Abstract: A transmission cooling assembly of a helicopter includes: a transmission including a speed change structure that changes the speed of rotation produced by rotational power input from a prime mover and outputs the resulting rotational power and a housing accommodating the speed change structure; a cowl covering at least a part of an outer surface of the housing, with a gap defined between the cowl and the outer surface; and a flow structure that allows external air to flow through the gap.

Abstract: A transmission lubricating assembly of a helicopter includes: a transmission including a speed change structure that changes the speed of rotation produced by rotational power input from a prime mover and outputs the resulting rotational power and a housing accommodating the speed change structure; and a lubricator that lubricates the speed change structure. The lubricator includes a collector that collects a mist of a lubricating oil in an internal space of the housing and a dropper that is disposed below the collector and that applies droplets of the lubricating oil to the speed change structure, the droplets resulting from the collected mist being gathered under its own weight.

Abstract: In an electromagnetic fuel injection valve for in-cylinder injection, a fuel injection hole is an elongated hole having a major axis and a minor axis, the major axis being curved into an arc shape having a radius that is smaller than a radius of a pitch circle of an inlet of the fuel injection hole. Accordingly, the electromagnetic fuel injection valve can ensure a required flow rate even when a penetrating power is decreased.

Abstract: In an electromagnetic fuel injection valve for in-cylinder injection, a fuel injection hole is an elongated hole having a major axis and a minor axis, the major axis being curved into an arc shape having a radius that is smaller than a radius of a pitch circle of an inlet of the fuel injection hole. Accordingly, the electromagnetic fuel injection valve can ensure a required flow rate even when a penetrating power is decreased.