Abstract: An internal combustion engine includes an engine body defining a combustion chamber, an ignition device configured to ignite mixture in the combustion chamber, an operation device configured to receive a stop operation to stop the internal combustion engine, a controller configured to stop the ignition device from igniting the mixture in response to reception of the stop operation by the operation device, a carburetor configured to supply fuel to an intake passage that communicates with the combustion chamber, a switching valve provided in the intake passage, and an adjustment device configured to adjust an opening degree of the switching valve, wherein the adjustment device is configured to close the switching valve in conjunction with the reception of the stop operation by the operation device.

Abstract: An internal combustion engine includes an engine body defining a combustion chamber, an ignition device configured to ignite mixture in the combustion chamber, an operation device configured to receive a stop operation to stop the internal combustion engine, a controller configured to stop the ignition device from igniting the mixture in response to reception of the stop operation by the operation device, a carburetor configured to supply fuel to an intake passage that communicates with the combustion chamber, a switching valve provided in the intake passage, and an adjustment device configured to adjust an opening degree of the switching valve, wherein the adjustment device is configured to close the switching valve in conjunction with the reception of the stop operation by the operation device.

Abstract: In an automotive carburetor, the time delay in the response of the engine to the change in the cross sectional area of the air passage is minimized, and a high level of freedom in selecting the communication cross section area of the air passage and the air fuel ratio for the given load of the engine. The carburetor (1) comprises a fuel passage (13) including a fuel nozzle (16) for supplying fuel to the intake passage, a first air passage (14) communicating with the fuel passage to supply air to the fuel passage, a variable communication unit (21, 41) provided in a part of the first air passage and moveable between an open position for communicating the first air passage and a closed position for shutting off the first air passage and a switch mechanism (22, 43) for moving the variable communication unit between the open position and the closed position in dependence on a load of the engine.

Abstract: In an automotive carburetor, the time delay in the response of the engine to the change in the cross sectional area of the air passage is minimized, and a high level of freedom in selecting the communication cross section area of the air passage and the air fuel ratio for the given load of the engine. The carburetor (1) comprises a fuel passage (13) including a fuel nozzle (16) for supplying fuel to the intake passage, a first air passage (14) communicating with the fuel passage to supply air to the fuel passage, a variable communication unit (21, 41) provided in a part of the first air passage and moveable between an open position for communicating the first air passage and a closed position for shutting off the first air passage and a switch mechanism (22, 43) for moving the variable communication unit between the open position and the closed position in dependence on a load of the engine.

Abstract: A general-purpose engine fuel tank fuel vapor treatment system includes: a canister mounted on a peripheral part of a fuel filler opening of a fuel tank mounted on a general-purpose engine, the canister housing a fuel adsorbent for adsorbing fuel vapor generated in the interior of the fuel tank; and an air vent provided in a tank cap fitted into the filler opening of the fuel tank. The air vent has an inner end opening in the interior of the fuel tank, and an outer end opening to the atmosphere. The canister is connected to the air vent. The interior of the fuel tank is made open to the atmosphere via the canister and the air vent. Thus, need for special piping is eliminated and fuel vapor within the fuel tank is treated while always stably maintaining the interior of the fuel tank at atmospheric pressure.

Abstract: A general-purpose engine fuel tank fuel vapor treatment system includes: a canister mounted on a peripheral part of a fuel filler opening of a fuel tank mounted on a general-purpose engine, the canister housing a fuel adsorbent for adsorbing fuel vapor generated in the interior of the fuel tank; and an air vent provided in a tank cap fitted into the filler opening of the fuel tank. The air vent has an inner end opening in the interior of the fuel tank, and an outer end opening to the atmosphere. The canister is connected to the air vent. The interior of the fuel tank is made open to the atmosphere via the canister and the air vent. Thus, need for special piping is eliminated and fuel vapor within the fuel tank is treated while always stably maintaining the interior of the fuel tank at atmospheric pressure.

Abstract: A general-purpose engine includes a canister which adsorbs fuel vapor that has evaporated within a fuel tank. The fuel vapor is desorbed from the canister and guided to an intake system communicating with an engine main body. The engine main body includes a crankcase and a cylinder block joined to the crankcase to have an upwardly inclined cylinder axis (C). The canister is disposed to one side of the crankcase and beneath the cylinder block to avoid any increase in the dimensions of the general-purpose engine.

Abstract: A general-purpose engine includes a canister which adsorbs fuel vapor that has evaporated within a fuel tank. The fuel vapor is desorbed from the canister and guided to an intake system communicating with an engine main body. The engine main body includes a crankcase and a cylinder block joined to the crankcase to have an upwardly inclined cylinder axis (C). The canister is disposed to one side of the crankcase and beneath the cylinder block to avoid any increase in the dimensions of the general-purpose engine.

Abstract: The present invention provides a working machine having an internal combustion engine. The working machine includes a single operation unit comprised of a rotatable body adapted to be selectively rotated between an engine-stop position, engine-start position and choke-activation position, a valve to be rotated about an rotation shaft, an arm attached to the rotation shaft and a link member adapted to be moved in its longitudinal direction to transmit the movement of the rotatable body to the arm. The link member has a distal end coupled with the arm and a proximal end coupled with the rotatable body, and extends between the distal and proximal ends. The rotatable body is formed with an elongated slot receiving the proximal end therein. When the rotatable body is rotated from the engine-stop position to the engine-start position, the proximal end is allowed to displace relative to the rotatable body along the elongated slot without causing any movement of the link member in the longitudinal direction.

Abstract: A muffler for an internal combustion engine is disclosed which is capable of effectively enhancing its muffling effect without any substantial increase in size, weight or manufacturing cost. The exhaust gas ejected from an exhaust port of the internal combustion engine is divided in the muffler into at least two flows. The divided exhaust gas flows are subsequently impinged against each other before the divided exhaust gas flows are finally discharged from a final exhaust port to the external atmosphere. More specifically, this muffler comprises an expansion chamber into which the exhaust gas is to be introduced from the exhaust port, and the expansion chamber is provided with at least two impingement openings for enabling the exhaust gas to be divided into at least two exhaust gas flows which are designed to be subsequently impinged against each other.

Abstract: A carburetor is supported on a casing by the air-fuel mixture discharging port thereof and by the portion of the adjustment screws thereof. A first vibration isolating member is interposed between the casing and the air-fuel mixture discharging port, and a second vibration isolating member is interposed between the casing and the adjustment screws. These vibration preventing members prevent the direction transmission of the vibration of the casing to the carburetor side. A reasonable and compact carburetor support structure can be provided because the air-fuel mixture discharging port and the adjustment screws are intrinsically provided with the carburetor itself.

Abstract: A chain saw with vibration-isolating devices, capable of providing a desirable vibration-isolating effect over a wide frequency range and reducing accidental deviation from a desired cutting line in a cutting operation. The chain saw includes a main body containing an engine, a frame member mounting a grip handle thereon, and at least two vibration-isolating devices each interposed between the main body and the frame member to support the main body with respect to the frame member. Two of the vibration-isolating devices are disposed spaced apart from each other in the longitudinal direction of the chain saw. Each of the two vibration-isolating devises includes a pair of first and second vibration=isolating members which are different in frequency range for providing a vibration-isolating effect. The two vibration-isolating devices are disposed such that the respective first or second vibration-isolating members are positioned in a first or second diagonal relationship with respect to one another.

Abstract: The present invention provides a working machine having an internal combustion engine. The working machine includes a single operation unit comprised of a rotatable body adapted to be selectively rotated between an engine-stop position, engine-start position and choke-activation position, a valve to be rotated about an rotation shaft, an arm attached to the rotation shaft and a link member adapted to be moved in its longitudinal direction to transmit the movement of the rotatable body to the arm. The link member has a distal end coupled with the arm and a proximal end coupled with the rotatable body, and extends between the distal and proximal ends. The rotatable body is formed with an elongated slot receiving the proximal end therein. When the rotatable body is rotated from the engine-stop position to the engine-start position, the proximal end is allowed to displace relative to the rotatable body along the elongated slot without causing any movement of the link member in the longitudinal direction.

Abstract: A muffler for an internal combustion engine is disclosed which is capable of effectively enhancing its muffling effect without any substantial increase in size, weight or manufacturing cost. The exhaust gas ejected from an exhaust port of the internal combustion engine is divided in the muffler into at least two flows. The divided exhaust gas flows are subsequently impinged against each other before the divided exhaust gas flows are finally discharged from a final exhaust port to the external atmosphere. More specifically, this muffler comprises an expansion chamber into which the exhaust gas is to be introduced from the exhaust port, and the expansion chamber is provided with at least two impingement openings for enabling the exhaust gas to be divided into at least two exhaust gas flows which are designed to be subsequently impinged against each other.

Abstract: A carburetor is supported on a casing by the air-fuel mixture discharging port thereof and by the portion of the adjustment screws thereof. A first vibration isolating member is interposed between the casing and the air-fuel mixture discharging port, and a second vibration isolating member is interposed between the casing and the adjustment screws. These vibration preventing members prevent the direction transmission of the vibration of the casing to the carburetor side. A reasonable and compact carburetor support structure can be provided because the air-fuel mixture discharging port and the adjustment screws are intrinsically provided with the carburetor itself.

Abstract: A chain saw with vibration-isolating devices, capable of providing a desirable vibration-isolating effect over a wide frequency range and reducing accidental deviation from a desired cutting line in cutting operation. The chain saw includes a main body containing an internal combustion engine which has a crankshaft extending in the lateral direction of the chain saw, a saw chain extending from the main body in the forward direction of the chain saw, a frame member mounting a grip handle thereon, and at least two vibration-isolating devices each interposed between the main body and the frame member to support the main body with respect to the frame member. Two of the vibration-isolating devices are disposed spaced apart from each other in the longitudinal direction of the chain saw. Each of the two vibration-isolating devices includes a pair of first and second vibration-isolating members which are different in frequency range for providing a vibration-isolating effect.

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: A two-stroke internal combustion engine having a crankcase provided with a crank chamber, a suction port which opens to the crank chamber, a scavenging passage opening into the crank chamber, and a crankshaft is provided with a flow control surface formed on an inner peripheral wall portion of the crank chamber which is capable of retarding the flow rate of unatomized raw fuel and which extends from the vicinity of the suction port to the vicinity of the scavenging passage. The flow control surface is comprised of a large number of intersecting unit ribs.

Abstract: A two-cycle internal combustion engine including a carburetor, a crankcase provided with a crank chamber and a suction port, an insulator attached to the crankcase and provided with a suction passage for introducing the air-fuel mixture from the carburetor to the suction port, and a reed valve whose proximal end portion is fixed to the insulator so as to allow a free end portion thereof to be optionally press-contacted with the downstream side end face of the insulator, wherein the downstream side end face of the insulator is slanted by a predetermined angle, while the suction port is contiguously connected with the slanted downstream side end face of the insulator without substantially forming a stepped portion therebetween.

Abstract: A two-cycle internal combustion engine including a carburetor, a crankcase provided with a crank chamber and a suction port, an insulator attached to the crankcase and provided with a suction passage for introducing an air-fuel mixture from the carburetor to the suction port, and a reed valve whose proximal end portion is fixed to the insulator so as to allow a free end portion thereof to be optionally press-contacted with the downstream side end face of the insulator, thereby opening or closing the suction passage, wherein a rib is formed on a portion of the downstream side end face of the insulator which is in the vicinity of the free end portion of the reed valve in such a manner as to protrude into the suction port.