Abstract: A dental handpiece configured to rotatably drive a dental treatment tool mounted in a chuck mechanism includes the chuck mechanism in which the dental treatment tool is mounted so as to be attachable and detachable. The chuck mechanism includes a hollow cylindrical sleeve, a cylindrical slide member, a plurality of divided movable pieces disposed in the sleeve, an elastic biasing member configured to bias the cylindrical slide member forward in an insertion direction of the dental treatment tool, and a stopper unit which restricts forward axial movement of the plurality of divided movable pieces in the insertion direction. The divided movable pieces are moved in a radial direction by relative movement between the divided movable pieces and the cylindrical slide member in the axial direction, so that fixation of the dental treatment tool and release of the fixation are performed.

Abstract: A gas turbine combustor of the pre-mixed combustion system in which the pre-mixed fuel and the air are combusted. The gas turbine combustor comprises main cylindrical nozzles provided in the end wall on the upstream side of a cylindrical combustion chamber, auxiliary nozzles formed to surround the main nozzles, a main pre-mixed gas supply for supplying a pre-mixed gas to the main nozzles, and an auxiliary pre-mixed gas supply for supplying a pre-mixed gas having an fuel/air ratio smaller than that of the main pre-mixed gas to the auxiliary nozzles, and wherein it is allowed to stably burn a lean pre-mixed gas having an fuel/air ratio of greater than 1 from a low-load condition through and up to a high-load condition of the gas turbine.

Abstract: A gas turbine combustor comprises a combustion chamber, a premixing chamber in which hydrocarbon fuel and air are premixed, a nozzle with swirler for swirling and injecting the premixed fuel and air into the combustion chamber, to effect premixed combustion, and a fuel nozzle projecting into the combustion chamber and adapted to inject fuel at region wherein the premixed combustion is completed, so as to effect low air-ratio diffusion combustion thereby to produce reducing substance. NOx produced by the premixed combustion is reduced by reducing reaction with the reducing substances, so that the NOx concentration in the combustion gas is reduced. The combustor further includes an after-air ports on a peripheral wall defining the combustion chamber to effect combustion of unburnt substances.