Siemens Aktiengesellschaft

Juergen Wohlgemuth

Manfred Franetzki

Hermann Landgraf

Eugen Hohmann

A dental turbine drive contains a rotor disk which is mounted for rotation in a rotor chamber in a head housing of a dental handpiece and is driven by compressed air from a nozzle in the known way. A control element for regulating the speed is arranged in the flow path of the exhaust air and is constructed to change shape or position upon rotation of the rotary disk as a consequence of centrifugal force so that the effective cross section of the exhaust path decreases with increasing speeds and will increase with decreasing speeds. In addition, an additional or second element is provided and includes a pressure chamber connected by channels to the rotor chamber so that the additional element will respond to changes in the pressure in the rotor chamber to support the effect of the control element. The second element can be a diaphragm valve having a valve member extending into either an exhaust channel or a delivery channel. The additional or second element can be a disk coacting with a resilient ring of the control element to form the control chamber in a recess on the rotor which receives the control element.

Dental turbine drive having means for automatic speed control

A regulatable dental turbine includes an actuator arrangement which is provided for regulating the speed by varying the amount of an essentially constant volume stream of drive fluid striking a turbine wheel of the dental turbine. The change of the direction based on the actuator arrangement may bypass a portion of the volume hitting the blades of the dental turbine or may create a portion of the stream as a deceleration force acting on the turbine wheel. The actuator arrangement can operate in a speed-dependent fashion based on the flow deflected by the blades of the wheel on an impact surface or can act with a speed sensor determining the rate of rotation of the turbine wheel.

Controllable dental turbine

A dental turbine drive which is provided with an arrangement to prevent suctioning of particles after deactivation of the drive air into the return air line. To accomplish this, the turbine space is closed during a run-out phase of the rotor except for an outflow channel that is arranged close to the axis of the rotor shaft adjacent the tool side and is connected to a return air channel. The return air channel can discharge directly into the outflow channel at a point spaced from the main portion of the rotor and a valve arrangement may be presented for closing the air opening once the input air has been interrupted.

Dental turbine drive

A controllable turbine drive for a dental handpiece has an adjustment member which rotates with the rotor disc and is deformable due to the centrifugal forces to constrict an exhaust channel extending along the disc to change the effective cross section of the channel so that with an increased speed of rotation, the effective cross section decreases and with a decreased speed, the effective cross section is increased. The member may be an elastic ring which is restrained by a rim formed by a recess on one side of the rotor disc or it may be an elastic spring washer, which has an upturned peripheral flange and which is bent or elastically deformed.

Dental handpiece having an automatically controlled turbine drive

A regulatable dental turbine includes an actuator arrangement which is provided for regulating the speed by varying the amount of an essentially constant volume stream of drive fluid striking a turbine wheel of the dental turbine. The change of the direction based on the actuator arrangement bypasses a portion of the volume hitting the blades of the dental turbine. The actuator arrangement operates in a speed-dependent fashion based on the flow deflected by the blades of the wheel on an impact surface.

A dental instrument having an active tool for treating a hard dental substance includes an arrangement for spraying water to cool the preparation location with the water either forming an envelope surrounding the tool or being a finely atomized stream of a solid angle directed onto the preparation location. The volume proportion of cooling air relative to the volume of the water in both versions is not greater than the volume of the water so that the envelope or spray are substantially free of air.

Dental instrument having a nozzle for cooling

A test device for dental instruments, which have a movably seated ram that moves toward the test subject in free flight with constant speed and after impact against the subject will return to initial position, characterized by a test member which is situated externally of the instrument and has a seating surface for engagement by the ram and an arrangement for positioning the test member on a carrier member so that it would have the elasto-mechanical properties which correspond to those of a test subject. The device includes the carrier member being a cap having the test element held by a resilient material in the cap so that the cap can be inserted onto the end of the instrument. The test element can also be a resilient tongue on the carrier member, which can have a plurality of resilient tongues forming a plurality of test members. In another embodiment, the carrier member has a slot so that the test element or member is a component part separated by the slot from the remainder of the solid body of the carrier member.

Test device for a dental percussion instrument

A percussion instrument suitable for use in dental practice for determining the degree of looseness of teeth has a movably seated ram which is accelerated to a defined velocity by an electromagnetic drive means and is subsequently moved toward a test subject (such as a tooth) in free flight. The electromagnetic means also controls return of the ram to a rest position. The ram is comprised of a non-magnetic section and a section of low magnetic retentivity passing through a magnetic coil. Control electronics supplies current pulses to the coil. The velocity of the ram is detected by a measuring and evaluation unit and is maintained at a constant value after a comparison of a rated value with the actual velocity value. The current feed to the coil is discontinued when the rated velocity is reached.

Percussion instrument

A rotatable socket for supporting a tool for rotation in a head housing of a dental handpiece. The socket includes a cylindrical or hollow tubular shaft for supporting a tool extending out of one end and having a dog for engaging a flattened surface on the shank of the tool for transmitting torque. To hold the tool in the socket, the socket has a catch device comprising at least one resilient element with a catch nose being disposed in the interior of the shaft to extend parallel to the axis of the shaft with the catch nose releasably engaging an annular groove in the shank of the tool. To disengage the tool, the catch device also includes a pressure element, which is disposed on the housing adjacent the free end of each resilient support element and which is urged into engagement with the free end of the support element to cause disengagement of each of the catch noses when a purchase has been actuated by pressure from the operator's thumb.

Rotatable socket for a dental handpiece

For adjusting the rpm with the assistance of mechanical regulators consisting of low-retentivity magnetic material, the air gap between the rotor and the stator, and/or the magnetic return between the stator field poles of opposite polarity, and/or a magnetic shunt is adjusted. The illustrative embodiments are particularly provided for d.c. subfractional horsepower motors for the drive of dental tools.

Growing community of inventors

Darmstadt, Germany

Juergen Wohlgemuth