Abstract: An air compressor includes: a motor actuating a mechanism to generate compressed air; a tank part in which the compressed air is stored; a pressure detector detecting a pressure value in the tank part; and a controller driving the motor when the pressure value is equal to or smaller than an ON pressure value and to stop drive of the motor when the pressure value is equal to or greater than an OFF pressure value. The controller executes processing for detecting a continuous drive time or a continuous stop time of the motor and changing at least one of the ON pressure value, the OFF pressure value and an output of the motor, and the controller detects a change amount of the pressure value, and to determine an execution cycle of the processing or a change amount of a value in the processing, based on the detected change amount.

Abstract: An air compressor includes: a motor actuating a mechanism to generate compressed air; a tank part in which the compressed air is stored; a pressure detector detecting a pressure value in the tank part; and a controller driving the motor when the pressure value is equal to or smaller than an ON pressure value and to stop drive of the motor when the pressure value is equal to or greater than an OFF pressure value. The controller executes processing for detecting a continuous drive time or a continuous stop time of the motor and changing at least one of the ON pressure value, the OFF pressure value and an output of the motor, and the controller detects a change amount of the pressure value, and to determine an execution cycle of the processing or a change amount of a value in the processing, based on the detected change amount.

Abstract: An electric tool includes a motor, an operation part provided to be operable by a user, a motor drive control unit configured to perform control of driving the motor in response to the operation part being operated, a temperature sensor, and a temperature determination unit configured to determine overheating of the motor. The temperature determination unit is configured to estimate a temperature of the motor based on a drive situation of the motor and a detection result of the temperature sensor, and to determine the overheating of the motor based on the estimated temperature.

Abstract: An air compressor includes: a motor actuating a mechanism to generate compressed air; a tank part in which the compressed air is stored; a pressure detector detecting a pressure value in the tank part; and a controller driving the motor when the pressure value is equal to or smaller than an ON pressure value and to stop drive of the motor when the pressure value is equal to or greater than an OFF pressure value. The controller executes processing for detecting a continuous drive time or a continuous stop time of the motor and changing at least one of the ON pressure value, the OFF pressure value and an output of the motor, and the controller detects a change amount of the pressure value, and to determine an execution cycle of the processing or a change amount of a value in the processing, based on the detected change amount.

Abstract: An electric tool includes a motor, an operation part provided to be operable by a user, a motor drive control unit configured to perform control of driving the motor in response to the operation part being operated, a temperature sensor, and a temperature determination unit configured to determine overheating of the motor. The temperature determination unit is configured to estimate a temperature of the motor based on a drive situation of the motor and a detection result of the temperature sensor, and to determine the overheating of the motor based on the estimated temperature.

Abstract: This invention provides a coolant-containing hollow poppet valve, which, in use, in consideration of a temperature distribution caused in each pert of the valve, causes a lowering in fatigue strength and creep strength in the valve at its site exposed to high temperatures falling within the tolerante of design standard, and, in consideration of required properties at the other valve sites, holds abrasion resistance and strength, and a process for producing the same.

Abstract: Objects: To provide a direct-acting type valve lifter that is simple in structure, involves a small number of components, and is capable of switching its valve lift between a high and a low lift. Means for Carrying Out the Invention: The valve lifter is mounted between a cam unit (20) and a valve stem (15). The cam unit (20) comprises a high-lift cam (22) and a low-lift cam (24) integrated to the high-lift cam. The valve lifter (30) is equipped with a side lifter (32) for slidably lifting the low-lift cams (24), a center lifter (40) for slidably lifting the high-lift cam, and hydraulic means (oil groove) (11b) for sliding the center lifter (40) so as to switch the valve lift in two levels, i.e. to switch between a high and a low lift. A cylindrical body of the valve lifter is provided on the top end thereof with a slit (33) for allowing the high-lift cam to freely rotate therein, and with sliding surfaces (32a) serving as a side lifter (32) to be in sliding contact with the low lift cam.