Dental handpiece

Abstract

A dental handpiece is disclosed including a turbine construction creating a radial in flow of air onto the impeller blades about the whole circumference of the turbine. This generates additional torque and avoids asymmetrical thrust on the impeller wheel. A pair of axially spaced air bearings support the turbine. Air supply to the bearings is controlled in such a way that the air bearings are floated before drive air is supplied to the turbine and after drive air to the turbine has been shut off. This ensures that the air bearings are always operational irrespective of the operational state of the turbine. The handpiece has an improved ergonomic shape, especially the shape and configuration of the front or drive head, which provides additional tooth clearance and a better field of view. An angled swivel connection to the umbilical cord is provided which reduces physical strain on the dentist's wrist. A self adjusting lock and key type torque connection between the dental burr and the chuck is provided which accommodates both conventional burrs and the burr of the lock and key arrangement. An auto stop arrangement for the turbine is disclosed which prevents a vacuum buildup during rundown of the turbine. The specific construction of the auto stop valve in accordance with the invention closes both the drive and exhaust air conduits.

1 - 14 . (canceled)  
   
   
       15 . A medical or dental turbine handpiece for a rotatable tool, having a handle portion for gripping by a user, a drive head connected with the handle portion and forming a turbine housing, a turbine in the turbine housing for rotatably driving the tool about an axis of rotation and having an axial tool bore for receiving the shaft of the tool, a pair of axially spaced apart bearings for rotatably supporting the turbine in the turbine housing, and a pressurized drive air conduit for supplying pressurized turbine drive air to the turbine, characterized in that the bearings are air bearings, and that the handpiece includes a bearing air conduit for supplying pressurized bearing air to the air bearings independent of the turbine drive air.  
   
   
       16 . The handpiece of  claim 15 , characterized in that it further includes a controller for controlling a flow of the pressurized drive air through the drive air conduit separate and independent from a flow of the bearing air through the bearing air conduit.  
   
   
       17 . A method of operating a dental handpiece including an air turbine driven by pressurized drive air and a pair of air bearings for supporting the air turbine in the handpiece and operated by pressurized bearing air, characterized by the steps of supplying pressurized bearing air to the air bearings, and supplying pressurized drive air to the turbine independent of the bearing air, the step of supplying bearing air being commenced prior to supplying drive air and continued at least as long as the step of supplying drive air.  
   
   
       18 . A medical or dental turbine handpiece for a rotatable tool, having a handle portion for gripping by a user, a drive head connected with the handle portion and forming a turbine housing, a turbine in the turbine housing for rotatably driving the tool about an axis of rotation and having an axial tool fore for receiving the tool, and a pressurized turbine drive air supply conduit, characterized in that the drive head includes a turbine drive air supply chamber connected to the drive air supply conduit for receiving drive air, and that the supply chamber extends about the turbine chamber for supplying turbine drive air to the turbine at least at two spaced apart locations distributed about the axis of rotation.  
   
   
       19 . The handpiece of  claim 18 , characterized in that the turbine drive air supply chamber is an annular chamber extending concentrically about the axis of rotation.  
   
   
       20 . The handpiece of  claim 19 , characterized in that the supply chamber supplies drive air to the turbine at a multitude of locations evenly distributed about the axis of rotation.  
   
   
       21 . The handpiece of  claim 18 , characterized in that the drive head further includes a Venturi passage connecting the drive air supply chamber to the turbine chamber for accelerating the drive air prior to impinging on the turbine.  
   
   
       22 . The handpiece of  claim 21 , wherein the Venturi passage includes multiple air guide vanes for directing the turbine drive air onto the turbine in a direction generally radially inwardly towards the axis of rotation.  
   
   
       23 . A medical or dental turbine handpiece for a rotatable tool having a handle portion for gripping by a user, a drive head connected with the handle portion and forming a turbine housing, a turbine in the turbine housing for rotatably driving the tool about an axis of rotation and having an axial tool bore for receiving a shaft of the tool; and a pair of axially spaced apart bearings for rotatably supporting the turbine in the turbine chamber for rotation about the axis of rotation, characterized in that the bearings are air bearings.  
   
   
       24 . The handpiece of  claim 23 , characterized in that each air bearing includes a bearing stator having the shape of a spherical section and a bearing rotor of complementary shape, and that the bearing rotor and stator are shaped to define an intermediate bearing gap of even width throughout.  
   
   
       25 . A medical or dental turbine handpiece having a handle for gripping by a user, a drive head attached to the handle and forming a turbine chamber, an air driven turbine in the turbine chamber for rotatably driving a tool, the turbine being operated by turbine drive air, and a swivel connector for rotatably connecting the handle to an umbilical cord including at least a supply conduit for the turbine drive air, characterized in that the swivel connector has an angled connector body for connecting the handle and the umbilical cord at an angle of less than 180 degrees to reduce user wrist strain.  
   
   
       26 . The handpiece of  claim 25 , characterized in that the handle and the umbilical cord are connected at an angle between 90 and 180 degrees.  
   
   
       27 . A medical or dental turbine handpiece for a rotatable tool having a shaft including a drive head for rotatably supporting the tool and forming a turbine housing, a turbine in the turbine housing for rotatably driving the tool about an axis of rotation, a pair of axially spaced apart bearings for rotatably supporting the turbine in the turbine housing, a pressurized drive air conduit connected to the turbine housing for supplying pressurized turbine drive air to the turbine, and an exhaust conduit connected to the turbine housing for removing spent turbine drive air from the turbine housing, characterized in that the handpiece further includes a shut-off valve for reducing turbine run down time when the supply of turbine drive air is stopped, that the shut-off valve is connected to the drive air conduit and the exhaust air conduit and that the shut-off valve includes a closure member normally biased into a closed position wherein the closure member closes both the drive air and exhaust conduits and movable by drive air pressure to an open position wherein the closure member permits passage of drive air and exhaust air through the drive air and exhaust conduits respectively.  
   
   
       28 . The handpiece of  claim 27 , characterized in that the bearings are air bearings, that the handpiece further includes a bearing air supply conduit connected to the drive head for supplying pressurized bearing air to the air bearings, and that the supply conduit supplies the bearing air independent of the position of the closure member of the shut-off valve.  
   
   
       29 . The handpiece of  claim 28 , characterized in that the shut-off valve is incorporated into the handle portion and that the closure member is a sleeve axially movable in the handle portion between the open and closed positions.  
   
   
       30 . A medical or dental turbine handpiece for a rotatable tool having a working tip, the handpiece including a handle portion for gripping by a user, a drive head connected with the handle portion by an intermediate neck portion, the drive head forming a turbine housing, a turbine in the turbine housing for rotatably driving the tool about an axis of rotation and having an axial tool bore for receiving the shaft of the tool, and a pair of axially spaced apart bearings for rotatably supporting the turbine in the turbine housing, characterized in that the handle portion has a longitudinal central first axis and the neck portion has a longitudinal central second axis, that the drive head, neck portion and handle portion being interconnected in such a way that an angle enclosed by the axis of rotation of the tool with the first axis is larger than 90 degrees and with the second axis is less than 90 degrees, and that the second axis is oriented at an angle to the first axis such that the tool tip coincides with the first axis.  
   
   
       31 . A medical or dental turbine handpiece for a rotatable tool, including a handle portion for gripping by a user, a drive head forming a turbine housing, an intermediate neck portion connecting the drive head with the handle portion, a turbine in the turbine housing for rotatably driving the tool about an axis of rotation and having an axial tool bore for receiving the shaft of the tool, and a pair of axially spaced apart bearings for rotatably supporting the turbine in the turbine housing, characterized in that the handpiece further includes a neck connecting arrangement for releasably connecting the neck portion to the handle portion, that the neck connecting arrangement includes a socket portion on one of the neck portion and the handle portion and a plug portion on the other of the neck portion and handle portion, and that the plug and socket portions are of complementary shape for non-rotatably connecting the neck and handle portions.  
   
   
       32 . The handpiece of  claim 31 , characterized in that the neck connecting arrangement further includes a snap lock for releasably locking the plug portion in the socket portion.  
   
   
       33 - 34 . (canceled)