GB2301288A

GB2301288A - Dental drilling device

Info

Publication number: GB2301288A
Application number: GB9617566A
Authority: GB
Inventors: Nicholai Ivanovich Kulikov; Sergei Ivanovich Patlasov
Original assignee: MO G AVIAT I
Current assignee: MO G AVIAT I
Priority date: 1994-12-22
Filing date: 1994-12-22
Publication date: 1996-12-04
Anticipated expiration: 2014-12-22
Also published as: GB9617566D0; GB2301288B; WO1996019156A1

Description

DENTAL DRILLING ENGINE

Technical Field

The present invention relates in general to medical engineering and more specifically to devices used in dental 5 prosthetics.

Background Art

Known in the present state of the art are dental drilling engines, comprising an enclosed electric motor whose shaft is linked, through a clutch, to a collet adapted to receive the working tool, current supply, control, and cooling systems (cf. USSR Patent 871,795, Cl. A61C 1/00).

The nearest to the technical solution proposed herein is the dental drilling engine as disclosed in USSR Inventor's Certificate No.158,376, Cl. A61C 1/00, which comprises a small-size d.c. commutator motor enclosed in a casing closed with a cover and a bush. A spindle accommodating a gripping collet is connected to the motor shaft through a clutch member, a pin, and a spring- actuated pusher. The dental engine in question, however, features an inadequately high tool rotation speed, too a high noise and vibration level, and insufficient cooling of the motor and casing.

Disclosure of the Invention

The present invention has for its principal object to provide a high-speed dental drilling engine convenient in use and having a low noise and vibration level, whose construction allows of an efficient cooling of both the motor and casing.

The foregoing object is accomplished due to the fact that in a dental drilling engine, comprising a casing which accommodates a drive electric motor whose shaft is journalled in bearing units and is connected, through a clutch, to a collet for gripping the working tool, a detachable cover with a power cable brought to a wiring board located on the rear bearing, unit, according to the invention, used as the drive electric motor is a brushless d.c. motor whose armature stack and stator winding are 2 provided with vent ducts and are located on the interior surface of the casing provided with a skirt that forms a vent duct together therewith. The shaft of the motor rotor carries a blower fan, and a number of vent holes are provided in the casing and the detachable cover. Rotor angular position sensors make a clearance with the rotor which carries an electromagnet.

The herein-proposed construction arrangement of the dental drilling engine that makes use of a brushless electric motor and specially provided vent ducts is substantially advantageous over the heretofore-known dental engines, that is, a speed restriction inherent in dental engines driven by commutator motors is obviated, heat losses, noise and vibration level are reduced, service life is extended, and cooling of the motor and exterior surface of the engine casing is ensured.

Brief Description of the Drawing

In what follows the present invention is illustrated in a detailed description of a specific exemplary embodiment thereof taken in conjunction with the accompanying drawing, wherein a general schematic view of the dental drilling engine is presented.

Best Method of Carrying Out the Invention The dental drilling engine of the present invention comprises a cylindrical casing 1 whose interior surface carries the motor stator with the stack of an armature 2 and a winding 3 (e.g., a three- phase one). The stack of the armature 2 is provided with coaxial vent ducts 4. A shaft 5 of a motor rotor 6 is journalled in two bearing units 7. A blower fan 8 (e.g., a centrifugal one) is set on the shaft 5 between the rotor 6 and the front bearing unit for sucking in the ambient air to cool the motor. A number of rows of vent holes 9 are provided opposite to the blades of the blower fan 8 round the periphery of the casing 1, intended for the cooling air to pass along a vent duct established by a skirt 10 mounted on the casing 1 and the exterior surface of the casing, towards a circular extension of the shaft 5 is joined, with a collet, wherein a working tool i omitted in the drawing). Vent holes detachable cover 13 for is slit 11. The tail through a clutch 12, s gripped (both being 14 are provided in a the ambient air to suck into the interior of the casing 1. A power cable 15 electrically insulated from the cover 13 runs therethrough to a wiring board 16 which is built into the rear bearing unit 7. Supply voltage is fed along the power cable 15 to the wiring board 16 and further, via the motor speed control system, to the motor stator winding 3.

The control system is instrumental in converting a primary mains voltage (220 V 50 Hz) into a preset d.c. voltage, followed by its inverting into an a.c. voltage (e.g., a three-phase one) whose frequency is strictly proportional to the rotation speed of the rotor 6 which is determined by signals from sensors 17 of the rotor angular position (e.g., Hall elements) making a clearance with an electromagnet 18 held to the rotor 6. The motor armature 2 is of the smooth (toothless) design, which simplifies the dental engine construction, reduces iron losses (which is special importance at high rotor rotation speeds), decreases tooth ripple and hence acoustic noise. Provision of the skirt 11 contributes not only to better cooling conditions but also effects holding of the front bearing unit to the casing 1 without using screws, bonding with adhesives, etc., thus simplifying the engine production technology and adds to its maintainability.

Industrial Applicability

The dental drilling engine proposed herein can find extensive application, depending on the type of working tool gripped in the collet, in medical engineering for dental prosthetics, in jewelry practice for treating and polishing of precious stones, in engraving practice for making patterns on articles, in dies-and-tools production for fine treatment of casting moulds.

Claims

1. A drilling engine, comprising a casing (1) which accommodates a drive electric motor whose shaft (5) is journalled in bearing units (7) and is connected, through a clutch (12), to a collet for gripping the working tool, a detachable cover (13) with a power cable brought to a wiring board (16) located on the rear bearing unit, CHARACTERIZED in that used as the drive electric motor is a brushless motor whose stack of an armature 2 and a winding (3) are provided with vent ducts and are located on the interior surface of the casing (1) provided with a skirt (10) that forms a vent duct together therewith, a number of vent holes (16) being provided in the casing (1) and in the detachable cover (13), while sensors (17) of an angular position of a rotor (6) make a clearance with an electromagnet (18) held to the rotor (6)