Abstract: According to one implementation, a hole finishing tool includes a reaming cutter and a holder. The reaming cutter has a first detaching structure. The first flow path for ejecting cutting oil is formed inside the reaming cutter. The holder has a second detaching structure. The second detaching structure is detached from and attached to the first detaching structure. The second flow path for supplying the cutting oil to the first flow path is formed inside the holder. The holder has a shank. The shank is held by a tool rotating device. The holder has a sliding portion. The sliding portion has no back taper. The sliding portion is inserted into a positioning bush and slid inside the positioning bush. The sliding portion has a concave portion for storing lubrication oil.

Abstract: A tool driving device for cutting includes a spindle and an electric motor. A user carries the tool driving device by hand to use the tool driving device. The spindle has a holder for holding a tool for the cutting. The holder is disposed at a distal portion of the spindle. The electric motor rotates the spindle. A thrust bearing is attached to a housing of the electric motor. The spindle is contacted to the thrust bearing so that cutting resistance in a rotation axis direction of the spindle, transmitted from the tool to the spindle, is applied to the thrust bearing.

Abstract: A collet bush includes a tapered cylindrical outer surface, a cylindrical inner surface and a flow path. The collet bush is to be inserted into a concentric collet that is attached to a handheld tool driving device in order to position the tool driving device to a workpiece. The tool driving device holds, rotates and feeds a tool. The tool driving device has a function to suck chips. The outer surface is for expanding the concentric collet. The inner surface forms a through hole for slidably fitting the tool. The flow path is for taking in air used for sucking the chips inside the collet bush. The tool driving device includes the above-mentioned collet bush and the concentric collet.

Abstract: A tool driving device for hole processing includes a spindle, an electric motor, a guide, an electric actuator, a sensor and a controller. The spindle has a holder for holding a tool for the hole processing. The holder is disposed at a distal portion of the spindle. The electric motor rotates the spindle. The guide has a positioning member for positioning the tool driving device to the workpiece. The electric actuator advances and retreats the spindle relatively to the guide in a rotation axis direction of the spindle. The sensor measures cutting resistance transmitted from the tool to the spindle. The controller is configured to control the electric motor and the electric actuator based on the cutting resistance measured by the sensor so that a rotating speed and a feeding speed of the spindle become a rotating speed and a feeding speed according to the cutting resistance.

Abstract: According to one implementation, a tool driving device includes a drill chuck, a motor, a casing and a vibrating mechanism. The drill chuck holds a drill. The motor is configured to rotate the drill chuck. The casing houses the motor. The vibrating mechanism is configured to periodically reciprocate the drill chuck relatively to the casing in a tool axis direction during rotation of the drill chuck. The vibrating mechanism is configured to distance the drill chuck from the casing at a first speed smaller than a second speed for bringing the drill chuck close to the casing.

Abstract: An engine system is provided, which includes a cylinder block, a cylinder head, a piston, a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, a subspark plug that ignites the mixture gas inside the subchamber, and a controller electrically connected to the injector, the main spark plug and the subspark plug. When an engine speed is above a given reference engine speed, the controller controls, in a low-load range below a given reference load, the ignition devices so that the subignition is performed after the main ignition, and the controller controls, in a high-load range exceeding the reference load, the ignition devices so that only the subignition is performed, or so that the main ignition is performed at the same timing as or after the subignition.

Abstract: A fuse includes: an element including a plurality of narrow portions each of which becomes a starting point of fusion cutting; a pair of terminals connected by the element; and a case housing the element, in which the element has a curved surface, and is disposed in a tube shape.

Abstract: To meet both a request to improve the thermal efficiency in the medium load operation of an engine and a request to suppress knocking in the high load and high rotation operation of the engine, the engine includes a main combustion chamber including a cylinder block, a cylinder head, and a piston; a pre-chamber having a plurality of injection holes that are open into the main combustion chamber; and a spark plug that ignites an air-fuel mixture in the pre-chamber. A compression ratio of the main combustion chamber is not less than 14 and not more than 24. A second index that is a product between a volume of the pre-chamber and the compression ratio is not less than 1.03 cm3 and not more than 5.92 cm3.

Abstract: To meet both a request to improve the thermal efficiency in medium load operation of an engine and a request to suppress knocking in high load operation of the engine, the engine includes a main combustion chamber including a cylinder block, a cylinder head, and a piston; a pre-chamber having a plurality of injection holes that open into the main combustion chamber; and a spark plug that ignites an air-fuel mixture in the pre-chamber. A compression ratio of the main combustion chamber is not less than 14 and not more than 24, an aperture ratio, which is the ratio of a total cross-sectional area of the plurality of injection holes to a volume of the pre-chamber, is not less than 0.0078 mm?1 and not more than 0.0145 mm?1, and the volume of the pre-chamber 15 is not less than 0.0430 cm3 and not more than 0.5631 cm3.

Abstract: An engine system is provided, which includes a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, a subspark plug that ignites the mixture gas inside the subchamber, an exhaust gas recirculation (EGR) device and a control device. In a specific range where EGR is performed, the ignition devices are controlled so that a subignition timing is retarded from a main ignition timing, and an ignition phase difference that is a retard amount of the subignition timing from the main ignition timing becomes larger under a high EGR condition than a low EGR condition, the EGR conditions being conditions in the specific range where engine speeds are the same and EGR rates are different, and the high EGR condition being larger in the EGR rate than the low EGR condition.

Abstract: An engine system is provided, which includes a cylinder block, a cylinder head, a piston, a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, a subspark plug that ignites the mixture gas inside the subchamber, and a controller electrically connected to the injector and the main spark plug and the subspark plug. In a low-load range where an engine load is below a given reference load, the controller controls the main spark plug and the subspark plug so that the subignition is performed after performing the main ignition, and the controller retards the timing of the subignition in a high-speed range where an engine speed is above a given reference engine speed, compared with a low-speed range below the reference engine speed.

Abstract: To meet both a request to improve the thermal efficiency in the medium load operation of an engine and a request to suppress knocking in the high load and high rotation operation of the engine, the engine includes a main combustion chamber comprising a cylinder block, a cylinder head, and a piston; a pre-chamber having a plurality of injection holes that open into the main combustion chamber; and a spark plug that ignites an air-fuel mixture in the pre-chamber. A compression ratio of the main combustion chamber is not less than 14 and not more than 24. A first index, which is the product between a total cross-sectional area of the plurality of injection holes and the compression ratio, is not less than 0.1496 cm2 and not more than 0.8449 cm2.

Abstract: An engine system is provided, which includes a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, and a subspark plug that ignites the mixture gas inside the subchamber, an throttle valve, and a control device. In a first range, compression self-ignition combustion of the mixture gas inside the main combustion chamber is performed. In a second range, flame propagation combustion is performed while setting an air-fuel ratio of the mixture gas lower than that in the first range. Immediately after the transition from the first range to the second range, only the subignition is performed, or the subignition and the main ignition are performed while setting a timing of the main ignition to a timing same as or retarded from the subignition.

Abstract: An engine system is provided, which includes a cylinder block, a cylinder head, a piston, a main combustion chamber, a subchamber, an injector that injects fuel into the main combustion chamber, a main spark plug that ignites a mixture gas inside the main combustion chamber, a subspark plug that ignites the mixture gas inside the subchamber, and a control device. In a low-speed high-load range, a fuel injection timing is set in compression stroke and the main ignition and the subignition are performed after the fuel injection timing, and the fuel injection timing under a low-speed condition becomes later than that under a high-speed condition, and the ignition devices are controlled so that the subignition timing is retarded from the main ignition timing and an ignition phase difference that is the retard amount of the subignition timing becomes larger under the low-speed condition than under the high-speed condition.

Abstract: To meet both a request to improve the thermal efficiency in medium load operation of an engine and a request to suppress knocking in high load operation of the engine, the engine includes a main combustion chamber including a cylinder block, a cylinder head, and a piston; a pre-chamber having a plurality of injection holes that open into the main combustion chamber; and a spark plug that ignites an air-fuel mixture in the pre-chamber. A compression ratio of the main combustion chamber is not less than 14 and not more than 24, an aperture ratio, which is the ratio of a total cross-sectional area of the plurality of injection holes to a volume of the pre-chamber, is not less than 0.0078 mm-1 and not more than 0.0145 mm-1, and the volume of the pre-chamber 15 is not less than 0.0430 cm3 and not more than 0.5631 cm3.

Abstract: To meet both a request to improve the thermal efficiency in the medium load operation of an engine and a request to suppress knocking in the high load and high rotation operation of the engine, the engine includes a main combustion chamber comprising a cylinder block, a cylinder head, and a piston; a pre-chamber having a plurality of injection holes that open into the main combustion chamber; and a spark plug that ignites an air-fuel mixture in the pre-chamber. A compression ratio of the main combustion chamber is not less than 14 and not more than 24. A first index, which is the product between a total cross-sectional area of the plurality of injection holes and the compression ratio, is not less than 0.1496 cm2 and not more than 0.8449 cm2.

Abstract: To effectively suppress strong knock that occurs in the operating region of high load and high rotation in a specific engine having a pre-chamber in a combustion chamber, the engine includes a piston that defines a combustion chamber together with a cylinder block and a cylinder head. The combustion chamber includes a sub-chamber and a main chamber separated from the sub-chamber by a pre-chamber. The specific ratio obtained by dividing a volume of the sub-chamber by a stroke volume of a cylinder is greater than or equal to 0.00005 and less than or equal to 0.00045.

Abstract: To effectively suppress strong knock that occurs in the operating region of high load and high rotation in a specific engine having a pre-chamber in a combustion chamber, the engine includes a piston that defines a combustion chamber together with a cylinder block and a cylinder head. The combustion chamber 6 includes a sub-chamber and a main chamber separated from the sub-chamber by a pre-chamber having through-holes. The specific ratio obtained by dividing the ratio ?p/Vpc of a hole diameter ?p of the through-holes to a volume Vpc of the sub-chamber by a compression ratio is greater than or equal to 0.26 mm/cm3 and less than or equal to 2.30 mm/cm3.

Abstract: To effectively suppress strong knock that occurs in the operating region of high load and high rotation in a specific engine having a pre-chamber in a combustion chamber, the engine includes a piston that defines a combustion chamber together with a cylinder block and a cylinder head. The combustion chamber includes a sub-chamber and a main chamber separated from the sub-chamber by a pre-chamber. The specific ratio obtained by dividing a bore/stroke ratio of a cylinder by the volume of the sub-chamber is greater than or equal to 6.6 cm?3 and less than or equal to 57.6 cm?3.

Abstract: To meet both a request to improve the thermal efficiency in the medium load operation of an engine and a request to suppress knocking in the high load and high rotation operation of the engine, the engine includes a main combustion chamber including a cylinder block, a cylinder head, and a piston; a pre-chamber having a plurality of injection holes that are open into the main combustion chamber; and a spark plug that ignites an air-fuel mixture in the pre-chamber. A compression ratio of the main combustion chamber is not less than 14 and not more than 24. A second index that is a product between a volume of the pre-chamber and the compression ratio is not less than 1.03 cm3 and not more than 5.92 cm3.