Abstract: The present invention relates to a four-stroke cycle internal combustion engine in which lubrication oil is atomized to generate oil mist so as to lubricate an internal mechanism of the engine with the oil mist. The four-stroke cycle internal combustion engine includes an oil-mist breather in fluid communication with a fuel tank of the engine. Any oil mist remaining after the lubrication of the internal mechanism is discharged into the fuel tank 14 through the oil-mist breather 22. Since no oil mist remains in the oil-mist breather the air filter of the engine is not contained by the oil mist.

Abstract: A reciprocating pump includes a chamber, a reciprocating member arranged to induct a fluid into the chamber and discharge the fluid from the chamber to a delivery side of the pump, and a piezoelectric element attached to the pump and arranged to detect pressure fluctuations on the delivery side of the pump so as to sense any abnormality in the inducting and discharging of fluid.

Abstract: A two-stroke internal combustion engine that emits exhaust gases with reduced amounts of noxious components, such as HC, and has less blow-by of unburned air-fuel mixture has a crank chamber located below a piston and a combustion actuating chamber located above the piston. Either one pair or two pairs of scavenging passageways communicate the crank chamber with the combustion actuating chamber, the scavenging passageways of the one pair or of each of the two pairs being disposed symmetrically with respect to a plane that bisects an exhaust port so as to form a Schnürle-type scavenging system. Each scavenging passageway is throttled at a location proximate to a scavenging inlet port thereof.

Abstract: A starter that is capable of minimizing fluctuations in the pulling force of a starter rope so as to make it possible to perform a smooth pulling operation when starting an internal combustion engine includes a driving section (A), a driven section (B), and a buffering/power-accumulating device (15) interposed between the driving section (A) and the driven section (B).

Abstract: A cutting blade safety cover for covering a rear portion of a cutting blade of a portable trimmer. The safety cover includes a roof plate portion and a skirt portion suspended from the roof plate portion. The roof plate portion is separated at a radially middle location thereof into a radially inner portion and a radially outer portion. The radially inner portion and the radially outer portion are detachably attached to each other so that the radially outer portion is replaceable with another radially outer portion having a dimension suitable for covering a cutting blade of a different dimension.

Abstract: In a compression stroke and an exhaust stroke, a part of a mixture in a downstream intake passage 30b is introduced through a branch intake passage 50a into a crank chamber 20. The mixture introduced into the crank chamber 20 flows into a valve chamber 16 during the expansion stroke and the intake stroke. From which it flows back to an intake port 9 through a circulation passage 71, and is eventually charged into a combustion chamber 7 during the intake stroke. As the mixture passes through a first communicating passage 55 which allows fluid communication between the crank chamber 20 and the valve chamber 16, a gasoline component which is vaporized with comparative easy is vaporized by a heat released from a cylinder block 3 so that the mixture is separated into the lubricating oil and gasoline components.

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 two-stroke internal combustion engine which is capable of minimizing the quantity of blow-by or the quantity of air-fuel mixture to be discharged without being utilized for the combustion, of improving the fuel consumption and power of the engine, of reducing the content of poisonous components in the exhaust gas, and of reducing the manufacturing cost, without extensively altering the conventional engine. A through-hole or a communication groove is provided at the skirt portion of a piston to thereby enabling a scavenging inlet port to be communicated with the crank chamber. In the descending stroke, combustion exhaust gas from the combustion actuating chamber is enabled to be introduced, via a scavenging outlet port provided at a downstream end of the scavenging passageway, into the scavenging passageway while closing the scavenging inlet port at the skirt portion of the piston.

Abstract: An engine intake control mechanism has a throttle valve that can be rotated to a cold-starting position in response to the closing movement of a choke valve and, even if the throttle valve is opened beyond the cold-starting position, the choke valve is retained at the cold-starting position. Only when the throttle valve is subsequently actuated to return to its original closed position is the choke valve automatically returned to its original opened position. The engine intake control mechanism is especially useful in top handle type portable power working machines, which are subject to undesirable movements of the throttle control lever on the top handle when the engine is being started.

Abstract: A two-stroke internal combustion engine has an air passageway for introducing air into a scavenging passageway communicating a combustion/actuating chamber disposed above a piston with a crankcase and an air-fuel supply passageway for introducing an air-fuel mixture from a carburetor into the combustion/actuating chamber. On the descending stroke of the piston, an exhaust port opens before a scavenging port formed at an upper end of the scavenging passageway opens, and an air-fuel mixture-feeding port disposed at a downstream end of the air-fuel supply passageway is opened a moment after the scavenging port is opened. Thus, air is introduced into the combustion/actuating chamber prior to the introduction of the air-fuel mixture.

Abstract: A portable power working machine has an L-shaped top handle having a top grip portion that is attached to the front portion of the top of a main housing and extends longitudinally above and parallel to the top of the main housing and a rear coupling portion that is attached to the rear portion of the main housing. A side handle has a front grip portion that is connected directly to the front end of the top grip portion of the top handle and a diagonal grip portion that extends diagonally straight as viewed in side elevation from the front grip portion toward the lower end of the rear coupling portion of the top handle. The lower end of the diagonal grip portion of the side handle is connected directly to the rear coupling portion of the top handle.

Abstract: A portable power working machine has an L-shaped top handle having a top grip portion that extends longitudinally above and parallel to the top of a main housing and a rear coupling portion that extends along the rear portion of the main housing. A side handle has a front grip portion that is joined to and extends horizontally and laterally from the front end of the top grip portion of the top handle and a diagonal grip portion which curves out and down from the front grip portion and extends diagonally straight as viewed in side elevation from the front grip portion toward the lower end of the rear coupling portion of the top handle. A starting footstool contiguous to a lower end of the diagonal grip portion extends horizontally to the vicinity of and is joined to the lower end portion of the rear coupling portion of the top handle.

Abstract: A starter which is capable of smoothly and reliably starting an internal combustion engine even though an electric motor employed is relatively small in size and output, thereby making it possible to minimize power consumption of the electric motor, to miniaturize the capacity of battery, to reduce the total weight of the starter, to enhance the durability of the starter, and to suppress the generation of failure of the starter. This starter comprises a buffering/power-accumulating means disposed midway along a power transmission system between a driving member and a driven member, wherein the buffering/power-accumulating means is enabled, during the driving process, to accumulate the power supplied through the driving process while alleviating any impact to the driven member, the accumulated power being subsequently employed to drive the driven member, and wherein the driving member is an electric motor.

Abstract: The present invention relates to a four-stroke cycle internal combustion engine which is adapted to lubricate the inside of the engine using a mixed fuel composed of fuel and lubricant.

Abstract: An object of the present invention is to provide an improved lubricating method and device for the internal combustion engine, which allows the engine to be lubricated by taking advantage of engine vibration without using other power source. The lubricating device includes a crankcase separated into a crank chamber and an oil reservoir by a partition wall. The partition wall has an opening provided with a wire net for covering the opening. A coil spring is suspended within the oil reservoir so as to form a U-shape. During operation, an engine vibration induces a vibration of the coil spring, and the oscillating coil spring agitates and/or splashes up an engine oil contained in the oil reservoir, and whereby an entire oil surface is ruffled. The engine oil introduced into the crank chamber impinges on a crankshaft and finer droplets or oil mist is formed to thereby lubricate the crankshaft and other engine components.

Abstract: An air cleaner includes a cylindrical cleaning filter, and a case rotatably receiving the cleaning filter therein. A dust-removing brush is disposed to contact with a filter portion of the cleaning filter, and a manipulating device coupled to the cleaning filter and accessible from outside the case enables the cleaning filter to be rotated from outside of the case.

Abstract: A portable power working machine which is provided with an internal combustion engine (20) and is designed to minimize the clogging of an air cleaner (31) attached to the air intake system of internal combustion engine (20). For this purpose, part of air introduced into the main housing (12) by means of the cooling fan (25) is allowed to be sucked again by the cooling fan, thereby enabling it to be recirculated through the carburetor chamber (40) and a circulating air duct (50) disposed outside the carburetor chamber (40), and at the same time, part of air introduced into the carburetor chamber (40) is allowed to be introduced from the air cleaner (31) into the internal combustion engine (20).

Abstract: An air-fuel mixture generating device includes a main body equipped with a diaphragm-type fuel pump, a fuel injection valve attached to the main body, and a manual fuel pump attached to the main body for filling a fuel passageway with fuel when the diaphragm-type fuel pump is not operating. The manual fuel pump has an inlet port which communicates with the fuel passageway and a pressure-adjusting valve disposed at the inlet port of the manual fuel pump, thereby enabling it to act not only as an intake valve when the manual fuel pump is operated but also as a relief valve for allowing the fuel inside the fuel passageway to escape into a pump chamber of the manual fuel pump when the pressure of fuel inside the fuel passageway exceeds a predetermined pressure.

Abstract: A vacuum apparatus has a recessed portion which is provided at an appropriate position of a fan casing. When incoming materials frequently pass through the fan casing, the recessed portion wears more quickly than the rest of the inner surface of the fan casing. Hence, a user of the vacuum apparatus can easily know when to replace the fan casing by visually checking the recessed portion from outside the fan casing.

Abstract: A two-stroke cycle internal combustion engine has a quaternary Schnürle-type scavenging system that is configured such that the capacity of a pair of second scavenging passageways are made larger than the capacity of a pair of first scavenging passageways, so that during the descending stroke of the piston, air is allowed to be introduced into the combustion actuating chamber from the second scavenging passageways prior to the introduction of the air-fuel mixture and at the same time, a relatively large quantity of air is allowed to be introduced into the combustion actuating chamber from the first scavenging passageways over a longer period of time as compared with the period of time in which air is introduced from the second scavenging passageways.