Abstract: A blade mounting structure of a lawn mower includes a blade holder including a shaft-mounted section connected to an output shaft of an engine, and a blade mounting section having a grass cutting blade mounted thereto. The blade holder further includes a connecting leg section located between the shaft-mounted section and the blade mounting section and interconnecting the shaft-mounted section and the blade mounting section. The connecting leg section has a wall thickness dimension gradually decreasing in a direction from the shaft-mounted section toward the blade mounting section.

Abstract: A blade mounting structure of a lawn mower includes: a drive hub mounted on an output shaft of a power source and protruding radially outward beyond an outer periphery of the output shaft; a friction member for transmitting driving force from the drive hub to a blade holder, the drive hub and the friction member having respective curved surfaces slidable on each other when the drive hub and the friction member are in abutting engagement with each other; a grass cutting blade attached to the blade holder; and an energy absorbing member disposed in a space defined by the blade holder and members peripheral to the blade holder, the energy absorbing member being constructed to maintain its shape during normal grass cutting condition but deform when a load exceeding a predetermined value acts on the energy absorbing member.

Abstract: A blade mounting structure of a lawn mower includes: a drive hub mounted on an output shaft of a power source and protruding radially outward beyond an outer periphery of the output shaft; a friction member for transmitting driving force from the drive hub to a blade holder, the drive hub and the friction member having respective curved surfaces slidable on each other when the drive hub and the friction member are in abutting engagement with each other; a grass cutting blade attached to the blade holder; and an energy absorbing member disposed in a space defined by the blade holder and members peripheral to the blade holder, the energy absorbing member being constructed to maintain its shape during normal grass cutting condition but deform when a load exceeding a predetermined value acts on the energy absorbing member.

Abstract: A blade mounting structure of a lawn mower includes a blade holder including a shaft-mounted section connected to an output shaft of an engine, and a blade mounting section having a grass cutting blade mounted thereto. The blade holder further includes a connecting leg section located between the shaft-mounted section and the blade mounting section and interconnecting the shaft-mounted section and the blade mounting section. The connecting leg section has a wall thickness dimension gradually decreasing in a direction from the shaft-mounted section toward the blade mounting section.

Abstract: A pipe handle holding structure wherein force for holding a bar handle in a holder is minimized, the holding performance whereby the bar handle is held by the holder is improved, and the bar handle and holder are maintained in an appropriate state even in cases in which the bar handle is frequently attached to and detached from the holder. The pipe handle holding structure comprises a round pipe-shaped bar handle, and a holder for holding an external peripheral surface of the bar handle. The holder has a plurality of concealing parts for concealing the external peripheral surface of the bar handle and elastically deforming the external peripheral surface in a pipe diameter direction.

Abstract: A walk-behind work machine having a foldable operating handle is disclosed. The operating handle is swingable and foldable about a first linking pin relative to a handle-attachment part of a work-machine body from a usage position to a storage position and can be locked in a usage position by a second linking pin. The second linking pin is present on one of the operating handle and the handle-attachment part, and the distal end part of the second linking pin is formed in a tapered shape. The other of the operating handle and the handle-attachment part has a second pin-fitting hole allowing insertion and retraction of the distal end part. When the distal end part is fit into the second pin-fitting hole, no gap is present in the second pin-fitting hole due to the tapered surface of the distal end part, and the operating handle is locked in the usage position.

Abstract: A walk-behind work machine having a foldable operating handle is disclosed. The operating handle is swingable and foldable about a first linking pin relative to a handle-attachment part of a work-machine body from a usage position to a storage position and can be locked in a usage position by a second linking pin. The second linking pin is present on one of the operating handle and the handle-attachment part, and the distal end part of the second linking pin is formed in a tapered shape. The other of the operating handle and the handle-attachment part has a second pin-fitting hole allowing insertion and retraction of the distal end part. When the distal end part is fit into the second pin-fitting hole, no gap is present in the second pin-fitting hole due to the tapered surface of the distal end part, and the operating handle is locked in the usage position.

Abstract: A pipe handle holding structure wherein force for holding a bar handle in a holder is minimized, the holding performance whereby the bar handle is held by the holder is improved, and the bar handle and holder are maintained in an appropriate state even in cases in which the bar handle is frequently attached to and detached from the holder. The pipe handle holding structure comprises a round pipe-shaped bar handle, and a holder for holding an external peripheral surface of the bar handle. The holder has a plurality of concealing parts for concealing the external peripheral surface of the bar handle and elastically deforming the external peripheral surface in a pipe diameter direction.

Abstract: An exhaust circulation lawnmower is disclosed in which grass clippings are sent, along with carrier air, from a cutter housing to a grass bag; the grass clippings are held in the grass bag; and the carrier air is returned to the cutter housing as exhaust. A surface area A1 of a grass clippings discharge opening and a surface area A2 of a recirculation opening have a relationship of A2?{1/(1??N)0.5}A1, where A1 is the surface area of the grass clippings discharge opening through which the grass clippings and carrier air are discharged from the cutter housing to the grass bag, A2 is the surface area of the recirculation opening through which the carrier air is recirculated from the grass bag to the cutter housing, N is the number of bends having an angle of ? degrees in the space between the grass clippings discharge opening and the recirculation opening, and ? is a pressure loss coefficient for each of the bends.

Abstract: An outboard motor has an internal combustion engine installed in an engine compartment defined by an engine cover. The engine's intake air inlet is formed by an air intake duct, which communicates with an air intake space outside the engine compartment. The engine cover includes an upper cover with a receiving ring fitted on the air intake duct. The receiving ring and the intake duct form an overlapping part in which the ring and the duct overlap each other in the direction of flow of combustion air. The overlapping part has a sealing member therein which forms a seal between the air intake space and the interior space of the engine compartment. The sealing structure does not require high dimensional precision to form a required sealing property between the engine cover and the air inlet of the engine intake system. The sealing structure minimizes any influence of engine vibrations.

Abstract: An internal combustion engine installed in an engine compartment 15 covered with an engine cover C is provided with an intake air passage P. The intake air passage P extends continuously from an intake air inlet Pi to intake air outlets Pe in the engine compartment 15 and has a first down passage 62, a reversing passage 63, an up passage 64 and a second down passage 67c arranged in the order in the flowing direction of combustion air. The combustion air taken through the intake air inlet Pi into the intake air passage P flows down through the first down passage 62, the reversing passage 63 reverses the flowing direction of the combustion air that has flowed down through the first down passage 62 such that the combustion air flows up, flows up through the up passage 64 to a position at a level higher than that of an uppermost intake air outlet Pe. Then, the combustion air flows down through the second down passage 67c and flows through the intake air outlets Pe into combustion chambers 30.

Abstract: An outboard motor S includes an internal combustion engine E having a crankshaft 7, and an alternator G having a shaft 81 and a housing 82. The engine E and the generator G are disposed in an engine compartment 15 with the crankshaft 7 of the engine E and the shaft 81 of the alternator G spaced a center distance d apart from each other. The housing 82 is provided with air inlets 83 through which cooling air for cooling the interior of the alternator G flows into the housing 82 and air outlets 84 through which cooling air that has cooled the alternator G is discharged as exhaust air. An exhaust air duct 91 surrounds the outlets 84 of the housing 82 and carries the exhaust air to a predetermined position from which the exhaust air cannot easily flow again through the inlets 83 into the housing 82. The alternator G spaced the center distance apart from the internal combustion engine E can be cooled at improved cooling efficiency.

Abstract: An internal combustion engine installed in an engine compartment 15 covered with an engine cover C is provided with an intake air passage P. The intake air passage P extends continuously from an intake air inlet Pi to intake air outlets Pe in the engine compartment 15 and has a first down passage 62, a reversing passage 63, an up passage 64 and a second down passage 67c arranged in the order in the flowing direction of combustion air. The combustion air taken through the intake air inlet Pi into the intake air passage P flows down through the first down passage 62, the reversing passage 63 reverses the flowing direction of the combustion air that has flowed down through the first down passage 62 such that the combustion air flows up, flows up through the up passage 64 to a position at a level higher than that of an uppermost intake air outlet Pe. Then, the combustion air flows down through the second down passage 67c and flows through the intake air outlets Pe into combustion chambers 30.

Abstract: An outboard motor S includes an internal combustion engine E having a crankshaft 7, and an alternator G having a shaft 81 and a housing 82. The engine E and the generator G are disposed in an engine compartment 15 with the crankshaft 7 of the engine E and the shaft 81 of the alternator G spaced a center distance d apart from each other. The housing 82 is provided with air inlets 83 through which cooling air for cooling the interior of the alternator G flows into the housing 82 and air outlets 84 through which cooling air that has cooled the alternator G is discharged as exhaust air. An exhaust air duct 91 surrounds the outlets 84 of the housing 82 and carries the exhaust air to a predetermined position from which the exhaust air cannot easily flow again through the inlets 83 into the housing 82. The alternator G spaced the center distance apart from the internal combustion engine E can be cooled at improved cooling efficiency.

Abstract: An outboard motor S is provided with an internal combustion engine E installed in an engine compartment 15 which is defined by an engine cover C. The engine E has an intake air inlet Pi of an intake system of the engine. The intake air inlet Pi is formed by an air intake duct 54. The intake duct 54 communicates with an air intake space 42 located outside the engine compartment 15. The engine cover C includes an upper cover 14 formed with a receiving ring 14b which is fitted on the air intake duct 54. The receiving ring 14b and the intake duct 54 form an overlapping part W in which the receiving ring 14b and the intake duct 54 overlap each other in the direction F of flow of combustion air. The overlapping part W has a sealing member 55 therein which forms a seal between the air intake space 42 and the interior space of the engine compartment 15.

Abstract: A lawn mower has a machine body, a grass bag detachably attached to the machine body for collecting therein grass clippings, a driving power source mounted on the machine body, a cutter blade driven by the driving power source for rotation to cut grass, and a cutter housing covering the cutter blade. The cutter blade has air lifting sections disposed at opposite end portions thereof for producing carrier air during rotation of the cutter blade. The cutter housing has a grass clipping delivery passage for directing grass clippings to the grass bag with the carrier air produced by the air lifting sections of the cutter blade, and an exhaust air return passage for returning only the carrier air, as exhaust air, from the grass bag to the cutter housing. The grass clipping delivery passage extends in a front-and-rear direction of the cutter housing. The exhaust air return passage is disposed adjacent to and extends substantially perpendicular to the grass clipping delivery passage.

Abstract: An exhaust circulation lawnmower is disclosed in which grass clippings are sent, along with carrier air, from a cutter housing to a grass bag; the grass clippings are held in the grass bag; and the carrier air is returned to the cutter housing as exhaust. A surface area A1 of a grass clippings discharge opening and a surface area A2 of a recirculation opening have a relationship of A2?{1/(1??N)0.5}A1, where A1 is the surface area of the grass clippings discharge opening through which the grass clippings and carrier air are discharged from the cutter housing to the grass bag, A2 is the surface area of the recirculation opening through which the carrier air is recirculated from the grass bag to the cutter housing, N is the number of bends having an angle of ? degrees in the space between the grass clippings discharge opening and the recirculation opening, and ? is a pressure loss coefficient for each of the bends.

Abstract: Lawn mower includes a cutter housing covering a grass-cutting cutter blade, and a grass bag, detachably attachable to a rear portion of the cutter housing, for collecting therein grass clippings. The cutter housing includes a grass clipping delivery passage for directing grass clippings to the grass bag with carrier air produced by rotation of the cutter blade, and an exhaust air return passage for returning only the carrier air, as exhaust air, from the grass bag to the cutter housing. The exhaust air is caused to flow, through a netted member provided on an upper surface of the grass bag, back into the cutter housing via the exhaust air return passage provided adjacent to, and extending substantially perpendicularly to, the grass clipping delivery passage.

Abstract: A lawn mower includes a mower body and a grass bag provided at the rear of the mower body. The mower body has a cutter deck rotatably accommodating a cutter blade, a carrying passage for guiding grass clippings into the grass bag, and an air return passage for guiding only air from the grass bag into the cutter deck. Cutter deck-facing openings of the air return passage are opened in line with the rotating track of airlifts provided at the opposite ends of the cutter blade. A swirling airflow inside the cutter deck induced by the rotation of the cutter blade is in the same direction as that of air returned via the air return passage, resulting in a smooth airflow inside the cutter deck.

Abstract: A cutter blade for lawn mowers having an airlift curved from a cutting edge formed on a rotationally leading edge toward a rotationally trailing edge. The trailing edge of the airlift is shaped in a waveform comprising a plurality of protrusions and a plurality of depressions. The protrusion closest to an outer end where the centrifugal force is greatest during the rotation of the cutter blade, is greatest in width so as to improve the discharging capability of grass clippings. The depressions limit negative pressure generated rotationally behind the airlift. A plurality of vent holes formed in the airlift is arranged radially in lines.