Abstract: A work machine wherein motive power of a drive part is transmitted to an operation part through a shaft, the shaft being inserted into a cylindrical part and supported by a plurality of bearing members. In the cylindrical part, the plurality of bearing members are disposed on the node side of vibration generated in the shaft or the cylindrical part.

Abstract: A vertical, multi-link, adjustable-stroke type engine includes a lubricating oil passage provided in a cylinder barrel for supplying lubricating oil to a lower shaft end portion of a crankshaft and at least a lower shaft end portion of an eccentric shaft, which changes an intake stroke and compression stroke of a piston, so as to pre-press the crankshaft and the eccentric shaft in a predetermined direction, or for supplying lubricating oil to the lower shaft end portion of the eccentric shaft so as to pre-press the eccentric shaft in a predetermined direction.

Abstract: A vertical, multi-link, adjustable-stroke type engine includes a lubricating oil passage provided in a cylinder barrel for supplying lubricating oil to a lower shaft end portion of a crankshaft and at least a lower shaft end portion of an eccentric shaft, which changes an intake stroke and compression stroke of a piston, so as to pre-press the crankshaft and the eccentric shaft in a predetermined direction, or for supplying lubricating oil to the lower shaft end portion of the eccentric shaft so as to pre-press the eccentric shaft in a predetermined direction.

Abstract: In a link type variable stroke engine in which a piston, a crankshaft and an eccentric shaft are linked by a linking mechanism, a counterweight part which is provided so that in a projection view on a plane orthogonal to an axis of a rotary shaft, a center of gravity of the counterweight part is located on an opposite side of the axis of the rotary shaft from an axis of the eccentric shaft rotates together with the rotary shaft. Accordingly, it is possible to effectively suppress and lessen half-order inertial exciting force occurring at the eccentric shaft.

Abstract: A muffler unit for a general-purpose engine includes a muffler (40) having a maze of sound-deadening chambers (101, 102, 103) defined therein and an inlet pipe (85) disposed inside the muffler. The inlet pipe has an open end (106) connected to an exhaust port of the engine via an exhaust pipe (43), a closed end (107) opposite to the open end, and perforations (108) provided near the open end and connecting an internal space of the inlet pipe and a first sound-deadening chamber (101). The closed end of the inlet pipe is exposed to the outside air, so that exhaust gasses are cooled when the gasses impinge on the closed end of the inlet pipe.

Abstract: In a stroke-variable engine, the position of a center of gravity of a subsidiary connecting rod is determined so that a distance between the position of the center of gravity of the subsidiary connecting rod and an axis of a crankpin is smaller than a distance between a point of connection of a main connecting rod to the subsidiary connecting rod and the position of the center of gravity as well as a distance between a point of connection of a control rod to the subsidiary connecting rod and the position of the center of gravity. Thus, 0.5-order vibration generated in the subsidiary connecting rod is lowered, engine vibration is suppressed, and noise generated with the vibration is suppressed.

Abstract: In a link type variable stroke engine in which a piston, a crankshaft and an eccentric shaft are linked by a linking mechanism, a counterweight part which is provided so that in a projection view on a plane orthogonal to an axis of a rotary shaft, a center of gravity of the counterweight part is located on an opposite side of the axis of the rotary shaft from an axis of the eccentric shaft rotates together with the rotary shaft. Accordingly, it is possible to effectively suppress and lessen half-order inertial exciting force occurring at the eccentric shaft.

Abstract: A muffler unit for a general-purpose engine includes a muffler (40) having a maze of sound-deadening chambers (101, 102, 103) defined therein and an inlet pipe (85) disposed inside the muffler. The inlet pipe has an open end (106) connected to an exhaust port of the engine via an exhaust pipe (43), a closed end (107) opposite to the open end, and perforations (108) provided near the open end and connecting an internal space of the inlet pipe and a first sound-deadening chamber (101). The closed end of the inlet pipe is exposed to the outside air, so that exhaust gasses are cooled when the gasses impinge on the closed end of the inlet pipe.

Abstract: In a stroke-variable engine, the position of a center of gravity of a subsidiary connecting rod is determined so that a distance between the position of the center of gravity of the subsidiary connecting rod and an axis of a crankpin is smaller than a distance between a point of connection of a main connecting rod to the subsidiary connecting rod and the position of the center of gravity as well as a distance between a point of connection of a control rod to the subsidiary connecting rod and the position of the center of gravity. Thus, 0.5-order vibration generated in the subsidiary connecting rod is lowered, engine vibration is suppressed, and noise generated with the vibration is suppressed.