A high torque dual speed turbine rotor for a lightweight hand held tool for grinding and polishing or for use with a spindle mounted pneumatic machine. The high torque dual speed turbine rotor includes a two-piece shaft with flow control screw disposed within the shaft. The shaft includes a first set of hollow openings, at a first position from one end of the shaft, in fluid communications with a first annular chamber of a rotor. There is also a second set of hollow opening, at a second position from the one end of the shaft, in fluid communications with a second annular chamber of the rotor. The flow control screw moves inside a threaded axial bore of the shaft from an open position inside the axial bore to the closed position corresponding to the second set of hollow openings.

A compressed air-driven tool having an electromagnetically operated control element (27) for controlling a pneumatic control circuit in order to maintain a load-independent torque at a constant rotational speed. The tool includes a principal valve (5), which arranged in a drive housing (1) in a manner displaceable by the supplied compressed air against the force of a helical spring (13), and a generator (43), which is mounted on the shaft (49) of a turbine wheel (51). The rotational speed of the shaft (49) is measured with a speed sensor (75) and the supply of compressed air to the principal valve (5) is controlled in the event of a drop in rotational speed as a consequence of a load.

The overload protection device used on a high-speed dental handpiece includes a valve body, a piston, an elastic member, and a valve plug. The valve body is provided with an air chamber and an air intake passage in communication with each other. The piston is arranged in the air chamber. The valve plug is arranged at an end of the air chamber away from the air intake passage and is connected with the valve body. The elastic member is arranged between the piston and the valve plug. An outer surface of the valve body is provided with a plurality of air discharging holes which is in communication with the air chamber. The piston is capable of opening or closing the air discharging holes when moving vertically within the air chamber. The present invention further discloses a high-speed dental handpiece with an overload protection device.

A novel turbine motor spindle assembly for a spindle-mounted pneumatic tool, especially in a live tool environment is described. The novel turbine motor spindle assembly includes a manifold with a front end and a rear end. The manifold includes an air intake passage for receiving pressurized air. The pressurized air is directed axially through a drive shaft rotatably coupled to the front end. The pressurized air drives a turbine motor assembly and a drive shaft. The drive shaft is mounted inside a housing with self-lubricating. The turbine motor assembly includes tangential openings for expelling exhaust air therefrom. The turbine motor housing is mechanically coupled to the front end of the manifold with an exhaust air passage for directing exhaust air from the one or more tangential openings out through the rear end of the manifold. The combined overall length of the turbine motor spindle assembly is no more than 1.76 inches in length for live tooling applications.

The invention relates to a rotor (1) having a turbine wheel (3) driven by propellant (TG) in a turbine housing (2), a dental preparation instrument (20) having such a rotor (1) and a method (100) for operating such a preparation instrument (20), wherein at least one part of the propellant (TG) flows back to the gas outlet opening (51) in an inner wall (21) radially orbiting the turbine wheel (3) through a return flow channel (6) after impinging on at least one of the drive blades (31) of the turbine wheel (3) counter to the direction of rotation (DR) of the turbine wheel (3), the inner wall (21) in the segment of a circle (KS) comprises at least one return flow channel (6) extending at least from the gas inlet opening (41) as far as the gas outlet opening (51), which allows at least one part of the propellant (TG) to flow back to the gas outlet opening (51) through the return flow channel (6) after impinging on at least one of the drive blades (31) counter to the direction of rotation (DR) of the turbine wheel (3), wherein, in axial direction (AR), the turbine housing (2) has at least one cross-sectional extension (8) of a surface between drive blades (31) and inner wall (21) as far as the return flow channel (6).

A high torque dual speed turbine rotor for a lightweight hand held tool for grinding and polishing or for use with a spindle mounted pneumatic machine. The high torque dual speed turbine rotor includes a two-piece shaft with flow control screw disposed within the shaft. The shaft includes a first set of hollow openings, at a first position from one end of the shaft, in fluid communications with a first annular chamber of a rotor. There is also a second set of hollow opening, at a second position from the one end of the shaft, in fluid communications with a second annular chamber of the rotor. The flow control screw moves inside a threaded axial bore of the shaft from an open position inside the axial bore to the closed position corresponding to the second set of hollow openings.

A compressed air-driven tool having an electromagnetically operated control element (27) for controlling a pneumatic control circuit in order to maintain a load-independent torque at a constant rotational speed. The tool includes a principal valve (5), which arranged in a drive housing (1) in a manner displaceable by the supplied compressed air against the force of a helical spring (13), and a generator (43), which is mounted on the shaft (49) of a turbine wheel (51). The rotational speed of the shaft (49) is measured with a speed sensor (75) and the supply of compressed air to the principal valve (5) is controlled in the event of a drop in rotational speed as a consequence of a load.

The overload protection device used on a high-speed dental handpiece includes a valve body, a piston, an elastic member, and a valve plug. The valve body is provided with an air chamber and an air intake passage in communication with each other. The piston is arranged in the air chamber. The valve plug is arranged at an end of the air chamber away from the air intake passage and is connected with the valve body. The elastic member is arranged between the piston and the valve plug. An outer surface of the valve body is provided with a plurality of air discharging holes which is in communication with the air chamber. The piston is capable of opening or closing the air discharging holes when moving vertically within the air chamber. The present invention further discloses a high-speed dental handpiece with an overload protection device.

A novel turbine motor spindle assembly for a spindle-mounted pneumatic tool, especially in a live tool environment is described. The novel turbine motor spindle assembly includes a manifold with a front end and a rear end. The manifold includes an air intake passage for receiving pressurized air. The pressurized air is directed axially through a drive shaft rotatably coupled to the front end. The pressurized air drives a turbine motor assembly and a drive shaft. The drive shaft is mounted inside a housing is self-lubricating. The turbine motor assembly includes tangential openings for expelling exhaust air therefrom. The turbine motor housing is mechanically coupled to the front end of the manifold with an exhaust air passage for directing exhaust air from the one or more tangential openings out through the rear end of the manifold.