Abstract: A blower fan includes: an impeller having a predetermined number of blades; a fan casing having an air-intake port disposed to face a central portion of base of the impeller and eccentrically housing the blower fan and defining a spiral scroll passageway between an inner wall thereof and an external circumference of the impeller, the spiral scroll passageway having an inlet portion constituting a narrow nose portion and an outlet portion constituting a wide discharge port; and a driving source for rotating the impeller. In order to minimize the noise to be released from the nose portion, the blower fan further includes a sound-reflecting means which is disposed to cover a portion of the air inlet port at a location spaced away from the nose portion by a distance corresponding to ½ of wavelength of noise in an emanating direction of noise.

Abstract: To achieve improved cooling in a power unit, a first fan is coupled with an end of a crankshaft of an internal combustion engine to cool at least a cylinder of the internal combustion engine, and a second fan is coupled with another end of the crankshaft to cool at least the cylinder. The cylinder is cooled by the air supplied from the first fan and the second fan.

Abstract: To achieve improved cooling in a power unit, a first fan is coupled with an end of a crankshaft of an internal combustion engine to cool at least a cylinder of the internal combustion engine, and a second fan is coupled with another end of the crankshaft to cool at least the cylinder. The cylinder is cooled by the air supplied from the first fan and the second fan.

Abstract: It is the object of the present invention to provide a centrifugal blower fan capable of reducing a noise in an operating rotational speed range without degradation in blàwer performance. A centrifugal blower fan comprises a base plate, and a plurality of fan blades arranged on the base plate in a radial pattern to define a plurality of air passages between the pairs of adjacent fan blades, respectively. A portion of the base plate serving as a bottom wall of each of the air passages is formed with a plurality of through-holes.

Abstract: A blower fan includes: an impeller having a predetermined number of blades; a fan casing having an air-intake port disposed to face a central portion of base of the impeller and eccentrically housing the blower fan and defining a spiral scroll passageway between an inner wall thereof and an external circumference of the impeller, the spiral scroll passageway having an inlet portion constituting a narrow nose portion and an outlet portion constituting a wide discharge port; and a driving source for rotating the impeller. In order to minimize the noise to be released from the nose portion, the blower fan further includes a sound-reflecting means which is disposed to cover a portion of the air inlet port at a location spaced away from the nose portion by a distance corresponding to ½ of wavelength of noise in an emanating direction of noise.

Abstract: A power blower includes a frame, and a blower mounted on the frame. An air intake port of the blower faces the frame. There is provided an air intake space between the blower and the frame. A debris-catching cover is constructed between the frame side and the blower side in a state in which it is mounted on both the frame and blower sides. The debris-catching cover inhibits debris from being sucked from the air intake space into the air intake port.

Abstract: There is provided a portable air blowing working machine capable of obviating frequent operation for the maintenance of air cleaner and hence capable of improving working efficiency. This working machine includes an internal combustion engine having the air cleaner disposed in the air-intake system thereof, and an air blower to be rotationally driven by the engine; which is characterized in that the air cleaner is provided with a suction port for in drawing in external air, with a filter member for cleaning air drawn from the suction port to thereby permit the cleaned air to be introduced into the engine, and with a discharge port for enabling part of the air drawn from the suction port to be discharged out of the air cleaner without permitting part of the air to pass through the filter member; and that an air flow directed to flow from the suction port to the discharge port is permitted to generate inside the air cleaner by making use of the suction force of the air blower.

Abstract: A power blower having a frame, a blower, and a loop-shaped filter member. In an embodiment of the invention, the blower is disposed apart from the frame by an air intake space and has an air intake port facing the frame, and the loop-shaped filter member is disposed around a periphery of the air intake port and is adapted to catch debris on an upstream side of the air intake port.

Abstract: It is the object of the present invention to provide a centrifugal blower fan capable of reducing a noise in an operating rotational speed range without degradation in blàwer performance. A centrifugal blower fan comprises a base plate, and a plurality of fan blades arranged on the base plate in a radial pattern to define a plurality of air passages between the pairs of adjacent fan blades, respectively. A portion of the base plate serving as a bottom wall of each of the air passages is formed with a plurality of through-holes.

Abstract: There is provided a portable air blowing working machine capable of obviating frequent operation for the maintenance of air cleaner and hence capable of improving working efficiency. This working machine includes an internal combustion engine having the air cleaner disposed in the air-intake system thereof, and an air blower to be rotationally driven by the engine; which is characterized in that the air cleaner is provided with a suction port for inhaling external air, with a filter member for cleaning air inhaled from the suction port to thereby permit the cleaned air to be introduced into the engine, and with a discharge port for enabling part of the air inhaled from the suction port to be discharged out of the air cleaner without permitting part of the air to pass through the filter member; and that an air flow directed to flow from the suction port to the discharge port is permitted to generate inside the air cleaner by making use of suction force of the air blower.

Abstract: A portable power tool includes an internal combustion engine that includes a crankshaft in which a load applied thereto is unevenly distributed along the axis of the crankshaft with respect to the axis of the reciprocating movement of a piston. The portable power tool also includes operational members that are driven by the internal combustion engine, a rotational body fixed to an end of the crankshaft to which a smaller component of the load is applied, and a balancing weight provided on the rotational body for absorbing vibrations generated by the reciprocating movement of the piston. The centroid of the balancing weight is disposed at an angular position from 140 degrees to 180 degrees with respect to the axis of the reciprocating movement of the piston in a rotational direction of the rotational body, when the piston is positioned at a top dead center.

Abstract: A power blower includes a frame, and a blower mounted on the frame. An air intake port of the blower faces the frame. There is provided an air intake space between the blower and the frame. A debris-catching cover is constructed between the frame side and the blower side in a state in which it is mounted on both the frame and blower sides. The debris-catching cover inhibits debris from being sucked from the air intake space into the air intake port.

Abstract: A portable power tool includes an internal combustion engine that includes a crankshaft in which a load applied thereto is unevenly distributed along the axis of the crankshaft with respect to the axis of the reciprocating movement of a piston. The portable power tool also includes operational members that are driven by the internal combustion engine, a rotational body fixed to an end of the crankshaft to which a smaller component of the load is applied, and a balancing weight provided on the rotational body for absorbing vibrations generated by the reciprocating movement of the piston. The centroid of the balancing weight is disposed at an angular position from 140 degrees to 180 degrees with respect to the axis of the reciprocating movement of the piston in a rotational direction of the rotational body, when the piston is positioned at a top dead center.

Abstract: A power blower having a frame, a blower, and a loop-shaped filter member. In an embodiment of the invention, the blower is disposed apart from the frame by an air intake space and has an air intake port facing the frame, and the loop-shaped filter member is disposed around a periphery of the air intake port and is adapted to catch debris on an upstream side of the air intake port.

Abstract: A fuel tank-mounting structure for a portable power working machine, which has an internal combustion engine as a power source and a fuel tank received in a tank housing portion defined in a two-piece cover housing of the power working machine, includes cushioning members supporting the fuel tank in the tank housing portion of the two-piece cover housing. The cushioning members are interposed in spaces between the tank housing portion and all faces of the fuel tank, namely, the front and rear end faces, the right and left side faces, and the top and bottom faces of the fuel tank. The cushioning members prevent the vibration of the internal combustion engine from being easily transmitted to the fuel tank, thereby avoiding the generation of bubbles in the fuel as well as damage to the fuel tank, and also reduce the manufacturing cost of the fuel tank-mounting structure.

Abstract: A backpack frame for mounting a blower having an inlet port is provided with an intake air muffler on a surface facing the inlet port. The intake air muffler may be formed of a large number of through holes which are communicated with the backpack frame and have a small diameter and no angular portions, or a large number of dimples with a small diameter formed on the surface.

Abstract: A fuel tank-mounting structure for a portable power working machine, which has an internal combustion engine as a power source and a fuel tank received in a tank housing portion defined in a two-piece cover housing of the power working machine, includes cushioning members supporting the fuel tank in the tank housing portion of the two-piece cover housing. The cushioning members are interposed in spaces between the tank housing portion and all faces of the fuel tank, namely, the front and rear end faces, the right and left side faces, and the top and bottom faces of the fuel tank. The cushioning members prevent the vibration of the internal combustion engine from being easily transmitted to the fuel tank, thereby avoiding the generation of bubbles in the fuel as well as damage to the fuel tank, and also reduce the manufacturing cost of the fuel tank-mounting structure.