Abstract: Provided is a backpack working machine with excellent operability and durability, the machine having a configuration in which a blower is mounted on a backpack frame with a vibration isolation device interposed therebetween, and a drive source and a fuel tank are attached to the blower. The machine includes a backpack frame with a backrest portion, the backrest portion being adapted to abut an operator's back, a blower mounted on the backrest portion with a vibration isolation device interposed therebetween, an engine attached to the blower for driving the blower, and a fuel tank that stores a fuel to be supplied to the engine. The fuel tank is attached to the blower such that the fuel tank is located at at least one of a position below the engine or on a lateral side of the engine.

Abstract: To improve the effect of preventing contamination of an element in an air cleaner. An air cleaner includes a first inlet (60) through which air is fed to an intake system air passage and a second inlet (62) through which air is fed to an intake system air-fuel mixture passage. An extended passage (72) leads to the second inlet (62), for example. A passage forming member (70, 204) forming the extended passage (72) is shaped to surround a periphery of the first inlet (60). The passage forming member (70, 204) forms a blown-back fuel diffusion preventing region (74) leading to the first inlet (60).

Abstract: An amplitude of a pressure fluctuation in a vicinity of a main nozzle of a carburetor (32) is decreased. An air cleaner (30) has a first inlet (60) that feeds air to an intake system air channel, and a second inlet (62) that feeds air to an intake system air-fuel mixture channel. A channel formation member (70) is attached to the second inlet (62). A channel length (L2) of an extension channel (72) formed by the channel formation member (70) is 110 mm or more.

Abstract: An air blower discharges an air flow generated by rotation of a fan from an outlet port of a fan case. An engine and a carburetor are disposed opposing to an outer surface of the fan case. An engine cover (partition) for separating a space in which the engine is disposed from another space in which the carburetor is disposed is provided. The outer surface including a region having a ventilation hole formed through a wall of the fan case, the region opposing to the space in which the carburetor is disposed and the ventilation hole being directed toward the carburetor.

Abstract: To enhance responsivity of temperature sensor detecting an engine temperature. A temperature sensor component 40 includes a metal washer 42. The temperature sensor component 40 transfers the engine temperature to a sensor body 46 via the heat transfer washer 42. A cylinder portion 8 of a cylinder block 64 has two bosses 30. The washer 42 of the temperature sensor component 40 is fixed to the boss 30 together with the electronic control unit 20.

Abstract: To enhance responsivity of temperature sensor detecting an engine temperature. A temperature sensor component 40 includes a metal washer 42. The temperature sensor component 40 transfers the engine temperature to a sensor body 46 via the heat transfer washer 42. A cylinder portion 8 of a cylinder block 64 has two bosses 30. The washer 42 of the temperature sensor component 40 is fixed to the boss 30 together with the electronic control unit 20.

Abstract: In a carburetor, three downstream body passages in the body communicate with three valve passages in the valve element, and the valve element rotates between a closed position and an opened position. The carburetor is a one-bore type carburetor in which the body passages and the valve passages are respectively partitioned with the body partitions and the valve partitions. When rotating the valve element from the closed position to the opened position, the second body passage and the second valve passage for mixture start to communicate in advance than the first and third body passages and the first and third valve passages for air.

Abstract: Provided is a structure for preventing the falling of a fastening nut of a portable power work machine, the structure reliably preventing loss of the nut and containing assembly cost, manufacturing cost, and component cost while reducing the possibility of damage, failure or the like and increasing the nut fastening and loosening workability and durability. A nut anchor member comprises a single bent wire or bar of elastically deformable material, and includes: a split ring-shaped portion externally retained in a circular groove provided at the outer periphery of a nut; a pair of left and right leg-like piece portions continuous with both ends of the split ring-shaped portion; and hook piece portions continuous with lower portions of the leg-like piece portions. A cover includes a locking portion that locks the hook piece portions so as to prevent the nut and the nut anchor member from falling from the cover when the nut is detached from the bolt.

Abstract: A grip for a backpack-type air blowing machine which performs a work by using air discharged from a distal end of an air blowing pipe that is coupled to a blower body driven by a power source while the air blowing pipe is manipulated by an operator with the power source and the blower body being carried on a back of the operator. The grip comprises a base section that constitutes an attachment section to the air blowing pipe, a vertical grip section that is provided with a proximal end portion provided continuously to the base section, and that extends in a direction away from the air blowing pipe, and a lateral grip section that extends backward along the air blowing pipe from a free end of the vertical grip section. The lateral grip section is located adjacent to a back of a hand of the operator holding the air blowing pipe.

Abstract: The certainty of supplying air to a scavenging channel through a piston groove is improved. In a cylinder wall 2, a gas venting port 10 is formed below and adjacent to a scavenging port 6a. The gas venting port 10 is independent from the scavenging port 6a, and is opened/closed by a piston as each of an air port 4a and the scavenging port 6a is. Upon a piston groove 8 being brought into communication with the gas venting port 10 as a result of the piston moving up (FIG. 1(II)), blown-back gas in a piston groove 8 can move to a crankcase through the gas venting port 10. Along with this, air can enter the piston groove 8 from the air port 4a.

Abstract: The efficiency of charging air to a scavenging channel is enhanced by generating a gas flow in a piston groove simultaneously with the piston groove coming into communication with an air port. A piston groove 8 formed in a peripheral surface of a piston includes a pressure transmission through hole 10, and the pressure transmission through hole 10 consistently communicates with a crankcase. In the course of the piston moving up, upon a pressure in the crankcase becoming negative, the negative pressure in the crankcase affects the piston groove 8through the pressure transmission through hole 10. Consequently, a pressure in the piston groove 8 is released to the crankcase through the pressure transmission through hole 10. Upon the piston moving up and the piston groove 8 being thereby brought into communication with the air port 4a, air enters the piston groove 8 through the air port 4a ((III) of FIG. 1).

Abstract: The air-blow working machine comprises a fan provided in a fan casing and a drive unit to drive the fan, and discharges an airflow generated by the rotating fan. The fan casing has an inner wall disposed between the fan and the drive unit. A smooth surface is formed on the face of the inner wall on the side of the fan. A first concavo-convex portion is formed on the face of the inner wall on the side of the drive unit. Thereby, a noise is reduced without an influence upon performance for blowing air.

Abstract: A shoulder harness for a portable work machine comprises a back member that is to be located on a back of an operator, said back member including a main frame, to which a downward extension frame connected with a waist belt is detachably attached; right and left shoulder belts that respectively extend from right and left upper end portions of said back member; a joint buckle that is to be located on a chest of said operator, distal ends of said right and left shoulder belts being connected to said joint buckle; a hip pad that is to be located on a side of a waist of said operator, and is provided with a locking device, to which a work machine is connected; a relay member that is located above said locking device, and is connected to said locking device by a hanging member; a rear suspension belt that is connected to said relay member and said back member; and a front suspension belt that is connected to said relay member and said joint buckle.

Abstract: A carburetor achieves better emission characteristics while improving a combustion state by increasing a delivery ratio of a stratified scavenging engine and reducing intake resistance. No dividing wall is provided between a throttle valve 204 and a choke valve 242, and a gap 244 between the valves 204 and 242 is opened. Intake air in both of an upper region and a lower region of the choke valve 242 flows into an air-fuel mixture passage 246 in a lower region of the fully-open throttle valve 204. A main nozzle 202 is arranged so as to be inclined toward the throttle valve 204.

Abstract: The present invention is to prevent mixing of fresh air and an air-fuel mixture when a throttle valve is fully opened and increase a delivery ratio. A main nozzle (30) is surrounded by a tunnel-like air flow guiding member (52). The air flow guiding member (52) is opened at its front and back sides. A whole amount of fuel discharged via a main nozzle (30) is sent to a downstream side by an air flow created by the air flow guiding member (52). When a throttle valve (22) and a choke valve (24) are both in a fully-opened state, fresh air flows into an air-fuel mixture passage (12) through a gap between these valves (22, 24).

Abstract: A pipe-shaped fixture (100) to be attached to a housing (120) of a work machine includes a fixture body (102) having a front-end projection (110) and a rear-end projection (112) that make front and rear limits of a rubber cushion (104) that encloses the fixture body (102) closely and circumferentially. The front- and rear-end projections (110, 112) are connected to each other by a plurality of longitudinally extending ridges (114) formed at circumferential intervals. The ridges (114), front- and rear-end projections (110, 112) define a plurality of concavities (116) surrounded thereby on the outer circumference of the fixture body (102). The front- and rear-end projections (110, 112) cause longitudinal vibration of an operation rod (130) relative to the housing (120) to act as a compression force on the rubber cushion (104), and thereby suppress longitudinal vibration of the operation rod (130) while maintaining effects of suppressing horizontal and vertical vibrations.

Abstract: An engine includes a cylinder block, and a piston slidably mounted in a cylinder, with the cylinder block being formed with an exhaust passage leading to a combustion chamber through an exhaust port, a first scavenging port opened to an inner circumferential surface of the cylinder, a first communication passage formed from the first scavenging port in a radial direction of the cylinder, and a first scavenging passage formed with an opening on a bottom surface of the first communication passage, in which a side surface on a far side from the exhaust port forming the communication passage is formed towards the far side from the exhaust port in the combustion chamber, and the opening portion of the first scavenging passage and a landing portion formed in the periphery of the opening portion are formed at a bottom portion of the communication passage.

Abstract: A grip for a backpack-type air blowing machine which performs a work by using air discharged from a distal end of an air blowing pipe that is coupled to a blower body driven by a power source while the air blowing pipe is manipulated by an operator with the power source and the blower body being carried on a back of the operator. The grip comprises a base section that constitutes an attachment section to the air blowing pipe, a vertical grip section that is provided with a proximal end portion provided continuously to the base section, and that extends in a direction away from the air blowing pipe, and a lateral grip section that extends backward along the air blowing pipe from a free end of the vertical grip section. The lateral grip section is located adjacent to a back of a hand of the operator holding the air blowing pipe.

Abstract: It is intended to effectively prevent blow-by with no need for large changes in typical structures of two-cycle internal combustion engines. A main scavenging passage (24) for supplying air-fuel mixture from a crankcase to a combustion chamber for scavenging purposes has a branch scavenging passage (26) that extends upward aslant toward an intake port (14). The main scavenging passage (24) communicates with a first scavenging port (20) located nearer to an exhaust port (16). The branch scavenging passage (26) communicates with a second scavenging port (22). A mean cross-sectional area of the branch scavenging passage (26) is smaller than that of the main scavenging passage (24). Cross-sectional area of a portion (24b) next to an inlet port (24a) of the main scavenging passage (24) opening to the crankcase is smaller than the sum of cross-sectional areas of the first and second scavenging ports (20, 22).

Abstract: The scavenging passage includes a wall surface that defines an orientation direction of a main scavenging gas flow spouting from the scavenging port to the cylinder chamber. In a boundary portion between the scavenging port and the scavenging passage, a wall surface located on an opposite side of the exhaust port is composed of an inclined surface inclined in a direction further away from the exhaust port than a wall surface of a deep portion of the scavenging passage. The scavenging port includes a rear wall surface located in a portion on the opposite side of the exhaust port. The rear wall surface continues to the inclined surface to extend in the direction away from the exhaust port and generates an incidental scavenging gas flow incidental to the main scavenging gas flow and higher in speed than the main scavenging gas flow.