Abstract: A housing of an exhaust valve is provided for an exhaust port communicating with a combustion chamber. The housing has a plate-shaped portion formed with a plurality of fixed slits radially extending from the central axis of the port. A valve element is provided adjacent to the plate-shaped section, is rotatable around a central axis, and has formed with a plurality of movable slits radially extending from the central axis. Due to the action of electromagnets and a permanent magnet attached to an annular member, the valve body is rotationally displaced around the central axis of the port, and the relative positional relationship between the fixed slits and the movable slits is changed to open and close the exhaust valve. The same is also true for an intake valve.

Abstract: A housing of an exhaust valve is provided for an exhaust port communicating with a combustion chamber. The housing has a plate-shaped portion formed with a plurality of fixed slits radially extending from the central axis of the port. A valve element is provided adjacent to the plate-shaped section, is rotatable around a central axis, and has formed with a plurality of movable slits radially extending from the central axis. Due to the action of electromagnets and a permanent magnet attached to an annular member, the valve body is rotationally displaced around the central axis of the port, and the relative positional relationship between the fixed slits and the movable slits is changed to open and close the exhaust valve. The same is also true for an intake valve.

Abstract: An engine has a combustion chamber and a fuel injection valve for directly injecting a fuel into the combustion chamber. An assist air supplying apparatus supplies assist air to atomize the fuel injected by the fuel injection valve. Assist air supply pressure is controlled so that a given pressure difference is secured between the assist air supply pressure and pressure in the combustion chamber. The assist air, therefore, is supplied under proper pressure for an entire period of fuel injection, to adequately micronize the injected fuel and improve combustion efficiency.

Abstract: An improved electrically-operated backup alarm for use on mobile construction and industrial machinery, including selectable lower and higher loudness levels, automatically adjustable loudness level with respect to varying ambient noise level in which the alarm is operating, high and low frequency compensation to substantially eliminate high and low frequency signal components of the sensed ambient noise, and compensation for responding to transient signal components of the sensed ambient noise.