HK1131734A - Dental handpiece - Google Patents

Description

Dental handpiece

RELATED APPLICATIONS

The application is a divisional application of Chinese patent application with the application date of 2003, 12 and 22 months, and the application number of 200380107011.X, and the title of the application is dental handpiece.

Technical Field

The present invention relates to a handpiece for a rotary tool, in particular a turbine driven medical or dental handpiece.

Background

There are a variety of handpieces for rotary tools. Turbine-driven handpieces are widely used in dental offices and medical laboratories on a global scale. Most cell phones include a handle portion, a connector at one end of the handle portion, and a tool carrying a drive head at the other end. The connector provides the connection of the handset to various air, water, light and electricity supply lines, which are often combined in so-called umbilical cords (umbilical cord). The drive head houses a tool rotating component, which typically consists of a tool base or chuck and a motor or turbine, rotatably mounted in the head for driving the chuck.

Various different types of turbine arrangements may be used, all of which include a turbine in a turbine housing, pressurized air supplied into the housing for driving the turbine, and a set of bearings for rotatably supporting the turbine and head within the housing. Since conventional dental handpieces are manufactured to rotate the bur or burr at speeds up to 500,000rpm, the bearings are subjected to significant stresses. This stress is in turn increased by the bearings that must otherwise support the chuck during operation and the tool resisting lateral forces applied to the tool. Furthermore, the asymmetric thrust generated by the tangential impingement of the drive air on the turbine creates additional stresses on the bearings.

In existing handsets, ball bearings are mainly used, which usually have a service life of up to 3 months and must be lubricated after each sterilisation. Ceramic bearings, which are more durable and do not require maintenance, are currently marketed, and do not require lubrication after each sterilization. However, the service life is still unsatisfactory.

US patent US 3,906,635 relates to a dental handpiece using an air bearing. In the handpiece, a center rod supporting a turbine and having an axial burr receiving bore is supported in the drive head of the handpiece by a pair of cylindrical bearing sleeves which are adjacent to and spaced from the rod to form a narrow air passage or air gap therebetween. The bearing sleeves are respectively installed in pressure chambers to which pressurized driving air is supplied. Each bearing sleeve includes a plurality of air passages that allow pressurized air to flow from the pressure chamber into the air gap between the rod and the bearing sleeve. Drive air is supplied to both the turbine and the air bearing. Pressurized drive air supporting the stem enters the bearing cavity, passes through the bearing housing into the air passage, and is discharged therefrom to the ambient environment or into the turbine cavity. It is clear that operating the air bearing and the turbine with the same drive air results in a major drawback. When the drive air is turned off, the turbine is still rotating and the air pressure is no longer sufficient to fully support the rod in the bearing housing. This can cause severe damage to the bearings, which in turn limits the useful life of the turbine drive unit. Furthermore, while the cylindrical air cushion may properly support the rod in the radial direction, it provides little support in the axial direction. In this prior art construction, an axial thrust washer is provided for axially supporting the stem. Although annular air pads are provided around the thrust washers, the overall surface of these air pads is significantly too small, given the potentially large axial thrust forces acting on the spindle when the burr is in contact with the tooth. In addition, the acute angle of the transition from the cylindrical air cushion to the annular air cushion prevents the flow of cushion air. Accordingly, there is a need for improved bearing designs.

There are many different air turbine designs and configurations, but in a typical turbine design, the drive air is blown tangentially onto and around the turbine wheel. This tangential air supply creates asymmetric thrust and subjects the bearings to asymmetric loads thereby increasing stress and wear. Furthermore, the torque produced by the turbine is low, since only partial drive air is provided. Furthermore, when the driving air is provided tangentially around the turbine, the parasitic air flow (drag) is high.

Various air turbine designs are known in the art in which a paddle wheel turbine rotor is driven by drive air impacting the outer ends of the turbine blades in a direction tangential to the turbine circumference. Representative of prior art designs are US patent US 6,120,291 and US patent application US 2001/0002975. Although U.S. Pat. No. 4,470,813 discloses an air driven turbine arrangement in which the drive air changes direction slightly radially before striking the turbine, the drive air still strikes the turbine blades at one location and in a substantially tangential direction. Accordingly, there is a need for improved turbine structures that produce higher torque output and less bearing stress.

The chucks of prior art dental handpieces are mostly designed to hold the dental burr by a friction fit only. Examples of such structures appear in US 4,595,363, US5,549,474 and US5,275,558. In this configuration, only a low torque transmission is possible between the chuck and the burr, and a higher torque will result in slippage of the burr. In us patent 6,065,966, a spring loaded pin is used to engage in a recess in a dental tool. However, the use of this device in an air turbine handpiece is not disclosed. In fact, the disclosed structure cannot be used at all for fixing a dental burr, since the engagement between the pin and the chuck is designed for a non-rotating tool, which is not easily used for a rotating tool per se.

A detent connection is known from US patent 4,370,132, which teaches the use of a burr with a shank and a flat end portion at the upper shank end of the shank. The jaws, rigidly connected to the burr receiving sleeve, are adapted to engage the flat end of the burr shank. The burr cannot be fully inserted into the chuck until the burr end fits into the jaws, and therefore the burr must be rotated relative to the chuck until these interlocking portions are aligned. A disadvantage of this prior art arrangement is that the burr must be rotated in the chuck until the keying features are mated together. Since the chuck also provides a friction fit with the burr, rotating the burr almost fully inserted into the chuck will necessitate some mechanism to prevent the chuck from rotating in the drive head, or the burr must be repeatedly removed and reinserted in a slightly different angular position. Positioning the interlock mechanism deeper within the handpiece drive head is not possible for the user to visually pre-align the catch structure prior to insertion of the burr. Thus, insertion of the burr is subject to trial and error.

The handpiece air turbine is normally shut off by stopping the supply of pressurized drive air. However, since the turbine rotates at a high speed, it takes some time to gradually decelerate and stop. For safety reasons, the dentist must wait until the turbine has completely stopped before removing the handpiece from the patient's mouth, which is highly undesirable. Furthermore, during so-called shut-down, the continuous rotation of the turbine creates a vacuum in the turbine chamber, which may cause contaminants to be drawn into the chamber.

US patent 5,507,642 discloses an exhaust air shut-off device for a dental handpiece turbine unit which automatically prevents air from being exhausted through the lower bearing during turbine shutdown to prevent vacuum build-up. This can be achieved by using a flexible Belleville washer (Belleville washer) which maintains a planar configuration with the drive air and automatically flexes upward when the drive air is turned off, thereby closing the air discharge passage. US patent 5,782,634 discloses an automatic stopping device comprising a valve in the exhaust air conduit which is operated by the drive air pressure and closes the exhaust air conduit when the air pressure falls below a certain level. However, the valve structure of both patents only closes the exhaust air conduit and not the drive air and trace air/water conduits. Thus, a vacuum may still be created and contamination may occur. As a result, it is desirable to provide a mechanism for reliably and quickly stopping the turbine and preventing contamination of the turbine chamber as much as possible.

Dental turbine handpieces typically include a straight or curved neck that is easily and conveniently accessible behind the patient's teeth. However, the tooth clearance achievable with this configuration is limited by the length of the burr. In some cases, better tooth clearance is required. Furthermore, in use, the treatment area is often partially obstructed by the drive head and neck. U.S. Pat. nos. 1,984,663 and 4,820,154 disclose dental handpieces having an adjustable neck angle and dental appliances (scalers) having a neck portion including two bends, respectively. Accordingly, there is a need for a handpiece neck design that provides additional tooth clearance and improved visibility of the treatment area.

As described above, fluid and power are supplied to the handpiece through the umbilical cord, which is typically removably connected to the handpiece at the rear end. Such connections are typically made by a rotating connection of the umbilical cord that prevents the cable from being twisted around. However, this connection typically extends straight through the deployment range of the handpiece, creating a relatively high torsional tension on the user's wrist, since the straight swivel connection combined with the inherent rigidity of the umbilical cord acts as a kind of lever which adds to the actual downward force created by the weight of the cord. This problem has plagued dentists for many years, and there is no solution available for dental handpieces. Various rotary connectors for releasable connection of a dental handpiece including a working fluid supply and a fiber optic conduit to an umbilical cord are known in the art. Examples of rotary connectors are shown in US5,057,015, US 6,033,220 and US 6,319,003. However, all of these connectors provide only a direct connection between the umbilical cord and the handpiece. There is therefore a need for a connector that reduces wrist strain.

Disclosure of Invention

It is an object of the present invention to obviate or mitigate at least one disadvantage of existing handset designs.

In a first aspect, the present invention provides a turbine design and method of operation in which drive air is evenly distributed in an annular cavity extending around the turbine cavity before the air is directed generally radially towards the turbine blades. To obtain a high torque and self-centering turbine, the latter being particularly important for the long life of the bearings used.

In another aspect, the invention provides an air bearing for a turbine and a chuck, the bearing comprising a substantially hemispherical bearing stator and a bearing rotor of complementary shape for fitting into the bearing stator, respectively, the bearing rotor being shaped and configured to fit into the bearing stator and having an intermediate air gap for bearing air.

In another aspect, the present invention provides an air bearing device that includes a magnet portion in the bearing portion for levitating the bearing at all times whether or not sufficient air is provided to levitate the air bearing at the desired air cushion. This provides the advantage of substantially preventing contact of the bearing parts even at low rotational speeds and when the handpiece is shut down, thereby reducing wear of the bearings. The floating bearing also has advantages in the event that the handpiece is stopped or shut down during sterilization, since the possibility of ingress of contaminants between the various contacting bearing portions is generally reduced.

In another aspect, the present invention provides a method of solving the problem of burr slippage in a chuck under high torque conditions. The burr/chuck (burr/spindle) combination according to the present invention provides a shaft portion having a non-circular cross-sectional shape, while the chuck or spindle has a protruding portion that engages the shaft portion to prevent rotation of the burr in the chuck/spindle.

In another aspect of the invention there is provided a burr locking arrangement which, in accordance with the invention, includes a chuck having a central bore for receiving a standard burr and a socket portion at the outer end of the bore for receiving a locking portion on the burr. The socket and the locking portion are non-circular in cross-section and are complementarily shaped to prevent rotation of the locking portion in the socket. This prevents rotation of the chuck relative to the burr and allows reliable torque transmission. The chuck is preferably configured to allow visual alignment of the complementary shapes of the socket and locking portion during insertion of the burr.

In another aspect of the invention, a burr locking structure is provided which includes a burr having a non-circular shaft end portion for insertion into the chuck/spindle, the spindle having a radially inwardly extending projection for engaging the shaft end portion to prevent rotation of the burr relative to the chuck. The nose is preferably shaped to self-align the burr with the nose as the burr is inserted.

In another aspect of the invention, a handset construction is provided that solves the problem of excessive wrist strain by providing an angled swivel connector and brings the point of impact of the downward force generated by the weight of the umbilical cord closer to the user's wrist so that the torsional strain on the user's wrist (user wrist strain) is significantly reduced.

In a preferred embodiment, the present invention provides a medical or dental turbine handpiece including a handle portion for gripping by a user, a drive head connected to the handle portion and forming a turbine housing, a turbine in the turbine housing for rotation about an axis of rotation and having an axial tool bore for receiving a shaft of a rotary tool inserted into the handpiece, and a pair of axially spaced bearings for rotatably supporting the turbine in the turbine housing, characterised in that the handpiece further includes torque transfer means for transferring torque generated by the turbine to a tool having a shaft portion with a non-circular cross-section, the torque transfer device comprises a locking socket for receiving the shaft portion and having a complementary cross-section, for locking the shaft portion against rotation in the socket, while allowing the shaft portion to be axially inserted into the locking socket, which is connected to the turbine for rotation therewith.

The locking socket may be separate from the turbine and fixed or integrated into the turbine as an extension of a tool bore for receiving a tool having a shaft portion in the form of a radially extending locking head having a diameter greater than the shaft diameter of the tool.

The locking socket may also be configured to receive a shaft portion of triangular cross-section, thereby providing the locking socket with a complementary cross-section to the shaft portion.

The locking socket is preferably a hollow rod received and secured in the tool bore when the locking socket is disengaged from the turbine section, the rod having a cylindrical bore for receiving the shaft section of the tool and having a torque transmission for locking the shaft section in the rod against rotation while allowing axial insertion of the shaft section into the locking socket. The torque transfer member is preferably a projection extending radially inwardly into the bore of the cylinder, more preferably a portion of the shaft is bent radially inwardly to extend into the bore, and most preferably a portion of the shaft wall is hammered radially inwardly to extend into the bore. The projection which engages the shaft portion during insertion of the tool into the shank preferably has a circular arc shape for automatically guiding the shaft portion through the projection to achieve self-alignment of the shaft portion in the locking socket during tool insertion.

Preferably, the handpiece further includes tool retaining means for releasably retaining the tool in the tool bore against axial movement when the tool is fully inserted in the bore, the burr retaining means comprising a pair of complementary, interengaging elements which feed into the shank and tool shaft respectively. The retaining means preferably comprises a first interengaging element in the form of a resilient tongue incorporated into the shank and a circular groove in the tool shaft, whereby the resilient tongue and groove are positioned on the shank and tool shaft so that the resilient tongue engages the groove when the tool is fully inserted into the tool bore.

In another preferred embodiment, the present invention provides a torque transfer device for a dental handpiece having a turbine for rotatably driving a burr about an axis of rotation, the burr having a burr shaft with a non-circular shaft portion and the turbine having an axial tool bore for receiving the burr shaft, and the torque transfer device including a locking socket having an axial bore for receiving the shaft portion of the burr shaft, the locking socket being connectable with the turbine for rotation therewith and a torque transfer member connected with the locking socket for locking the shaft portion against rotation relative to the locking socket.

In a variant, the locking socket can preferably be inserted into the tool bore. Preferably, the locking socket is a hollow stem that can be inserted into the tool bore to connect with the turbine wheel, and the torque transmitter is a wall portion of the stem that extends radially inwardly into the axial bore. In the most preferred form, the locking portion of the burr shaft is an end portion of the burr shaft, and the locking socket is a hollow stem having a cylindrical bore for receiving the burr shaft, and the torque transfer member is a projection extending radially inwardly into the cylindrical bore for preventing rotation of the locking portion of the burr shaft relative to the stem while permitting axial insertion of the burr shaft into the stem. To achieve self-alignment of the end of the relative projection during insertion of the burr into the spindle, the end faces of the projection and the end which contact each other during insertion of the burr shaft into the spindle are preferably rounded for alignment with the end faces of the end which pass through the projection. To release a burr retained in the tool bore, preferably the shank further includes a burr retaining member extending into the cylindrical bore for releasably engaging a complementary retaining member on the burr shaft to releasably lock the burr shaft in the cylindrical bore against axial movement.

In another variation, the locking socket fits into the turbine and is an extension of the tool bore for receiving the shaft portion, where the shaft portion is a locking boss on the burr shaft having a diameter greater than the diameter of the burr. In this variant, the locking socket preferably has a cross section complementary to the triangular cross section of the shaft portion.

In another preferred embodiment, the invention provides a medical or dental turbine handpiece for a rotary tool having a handle portion for gripping by a user, a drive head connected to 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 tool shaft, a pair of axially spaced 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, the bearings being air bearings, and the handpiece including a bearing air conduit for supplying pressurized bearing air to the air bearings independently of the turbine drive air. The handpiece also preferably includes a controller for controlling pressurized drive air through the drive air conduit separate and independent from the bearing air flow through the bearing air conduit.

In another preferred form, the invention provides 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 the pressurized bearing air. The method preferably comprises the steps of: pressurized bearing air is supplied to the air bearings, and pressurized drive air independent of the bearing air is supplied to the turbine. The step of supplying bearing air is preferably started before supplying drive air and continued for at least as long as the step of supplying drive air.

In another preferred embodiment, the invention provides a medical or dental turbine handpiece for a rotary tool having a handle portion for gripping by a user, a drive head connected to 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 tool, and a pressurized turbine drive air supply conduit, with the drive head including a turbine drive air supply chamber connected to the drive air supply conduit for receiving drive air, and with the supply chamber extending around the turbine chamber at least two spaced locations distributed about the axis of rotation to supply turbine drive air to the turbine. The turbine drive air supply chamber is preferably an annular chamber extending concentrically about the axis of rotation. In a more preferred form, the supply chamber supplies drive air to the turbine at a plurality of locations evenly distributed about the axis of rotation. The handpiece may also include a Venturi (Venturi) passage in the drive head connecting the drive air supply chamber to the turbine chamber for accelerating the drive air prior to impinging on the turbine. The venturi passage preferably includes a plurality of air guide vanes for directing turbine drive air to the turbine wheel generally in a direction radially inwardly toward the axis of rotation.

In another preferred embodiment, the invention provides a medical or dental turbine handpiece for a rotary tool having a handle portion for gripping by a user, a drive head connected to 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 tool shaft, and a pair of axially spaced bearings for rotatably supporting the turbine in the turbine housing for rotation about the axis of rotation, and the bearings are air bearings. Each air bearing preferably comprises a bearing stator having a spherical cross-sectional shape, and a complementary shaped bearing rotor. In a more preferred form, the bearing stator and rotor are shaped to form an intermediate bearing gap of uniform width throughout.

In another preferred embodiment, the invention provides a medical or dental turbine handpiece having a handle portion for gripping by a user, a drive head connected to the handle and forming a turbine chamber, an air driven turbine in the turbine chamber for rotatably driving a tool and which is manipulated by turbine drive air, and a rotary connector for rotatably connecting the handle to a steering cable including at least one supply conduit for turbine drive air, the rotary connector having a slanted connector body for connecting the handle and steering cable at an angle of less than 180 degrees to reduce wrist strain on the user. The handle and steering cable are preferably connected at an angle of 90 to 180 degrees.

In another preferred embodiment, the present invention provides a medical or dental turbine handpiece for a rotary tool with 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 bearings for rotatably supporting the turbine in a turbine chamber, a pressurized drive air conduit connected to the turbine housing for providing pressurized turbine drive air to the turbine, and an exhaust conduit connected to the turbine housing for exhausting spent turbine drive air from the turbine housing, the handpiece further including a shut-off valve for reducing turbine downtime when the turbine drive air supply is stopped, the shut-off valve being connected to the drive air conduit and the exhaust air conduit, and the shut-off valve including a closure member normally biased in a closed position, wherein the closure member closes the drive air conduit and the exhaust conduit, and is moved to an open position by drive air pressure wherein the closure member allows passage of drive air and exhaust air through the drive air and exhaust air conduits, respectively. The bearing is preferably an air bearing and the handpiece preferably further includes a bearing air supply conduit connected to the drive head for supplying pressurized bearing air to the air bearing, wherein the supply conduit supplies bearing air independent of the position of the closure member closing the valve. The shut-off valve is preferably incorporated into the handle portion and the closure member is preferably a sleeve that moves axially along the handle portion between open and closed positions.

In another preferred embodiment, the present invention provides a medical or dental turbine handpiece for a rotary tool having a working tip, the handpiece including a handle portion for gripping by a user, a drive head connected to the handle portion by an intermediate neck 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 tool shaft, and a pair of axially spaced bearings for rotatably supporting the turbine in the turbine housing, the handle portion having a longitudinally central first axis, and the neck portion having a longitudinal central second axis, the drive head, neck portion and handle portion being interconnected in such a manner that the axis of rotation of the tool encloses an angle of greater than 90 degrees with the first axis, and encloses an angle of less than 90 degrees with the second axis, and the second axis is at an angle to the first axis such that the tool tip is coincident with the first axis.

In another preferred embodiment, the invention provides a medical or dental turbine handpiece for a rotary tool, comprising a handle portion for gripping by a user, a drive head forming a turbine housing, an intermediate neck portion connecting the drive head and the handle portion, a turbine in the turbine housing for rotating the drive tool about an axis of rotation and having an axial tool bore for receiving the tool shaft, and a pair of axially spaced bearings for rotatably supporting the turbine in the turbine housing, wherein the handpiece further comprises neck attachment means for releasably attaching the neck portion to the handle portion, the neck attachment means comprising 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 the handle portion, the plug and socket portions being of complementary shape for non-rotatably attaching the neck and handle portions. In a preferred form, the neck connecting means further comprises a snap lock for releasably locking the plug portion in the socket portion.

In another preferred embodiment, the present invention provides a dental burr for a dental turbine handpiece, the burr having a working tip and a shaft for insertion into the handpiece, characterized in that the shaft includes a shaft portion of non-circular cross-section for torque-transmitting engagement with a burr receiving locking socket in the handpiece. The shaft portion preferably has a cross-section of a geometric shape other than a circle, preferably a triangle. The cross-sectional shape of the shaft portion is preferably symmetrical to the axis of rotation of the burr. If the shaft portion has a cross-section that is asymmetrical with the axis of revolution, the cross-sectional shape is preferably complementary to the cross-sectional shape of the locking socket to prevent rotation of the shaft portion in the locking socket while allowing axial movement of the shaft portion in the locking socket. The burr also preferably has a circumferential retaining groove for releasable engagement with a flexible retaining member in the locking socket when the shaft portion is fully inserted into the locking socket.

Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.

Drawings

Embodiments of the invention are described in detail below with reference to the following figures and examples, wherein:

FIGS. 1a-c and 2 illustrate the shape and design of a turbine and bearing combination for one embodiment of a handpiece of the present invention;

figures 3a-d show various cross-sections of the handpiece drive head of figure 2 and illustrate the interlocking configuration of the chuck and burr;

FIGS. 4a-e illustrate the shape and design of another turbine bearing assembly of the present invention;

FIGS. 5a-b illustrate another burr locking structure of the present invention included in the embodiment of FIGS. 4 a-e;

FIGS. 6a-k illustrate specific configurations of components in a preferred embodiment of the bearing structure shown in FIGS. 4 a-e;

FIGS. 7a-c show perspective, partial cut away and cross sectional views of the handle and neck quick connect of the present invention, and FIG. 7c shows a cross sectional view of the quick connect taken along line A-A of FIG. 7 b;

FIG. 8 illustrates an automatic closing mechanism according to an embodiment of the present invention;

FIG. 9 illustrates the automatic shutoff mechanism of FIG. 8 in a different operating state;

FIG. 10 is a perspective view of one embodiment of a dental handpiece of the present invention;

FIGS. 11 and 12 illustrate the ergonomics of the handset of the present invention;

FIG. 13 illustrates a lighting system of one embodiment of the handset of the present invention; and

fig. 14 is an exploded view of the handle portion shown in fig. 8 and 9.

Detailed Description

In general, the present invention provides a handpiece for a rotary tool, in particular a medical or dental handpiece, and a method of operating and controlling the handpiece. Although reference is made below to a dental handpiece for reasons of simplicity, all structural and functional features of the present invention are equally applicable to medical handpieces and other handpieces for supporting high speed rotary tools.

As is apparent from FIG. 10, one embodiment of a dental handpiece 10 of the present invention includes a handle/handle portion 11, a plug 12 for connection to an umbilical cord 13 (see FIG. 5), and a neck/drive head 16 having a drive head 14 for rotatably supporting and driving a rotary tool 15. The inventors have identified several structural features of currently marketed dental handpieces that require improvement. The turbine unit, bearing unit, burr (drill) and chuck interconnection, and the overall ergonomics, construction and connection capability of the handpiece.

Air bearing

One embodiment of the handpiece 10 of the present invention includes an improved drive head 14, a chuck 40 and an air turbine 50 housed in a turbine chamber 60, wherein the drive head 14 has a housing 13, the housing 13 forming the turbine chamber 60 and housing a drive unit 20 formed by a pair of spaced apart air bearings 30 (see fig. 1a-c and 2). The bearing 30 is preferably a hydrostatic air bearing, but a hydrodynamic air bearing may also be used. Each bearing 30 comprises a bearing cap or bearing stator 31 and a complementary shaped bearing body or bearing rotor 32. The bearing rotor 32 is sized to be mounted to the stator 31 with sufficient movement to create an air gap 33 (bearing gap) of average thickness between the two bearing parts. Adjusting the width of the bearing gap 33 for optimal operation of the air bearing 30 will be readily understood by those skilled in the art of air bearing technology. During use, compressed air is blown into the bearing gap 33 to support the bearing rotor 32 at an even spacing from the stator 31. Many forms and types of air bearings are known to those skilled in the art of air bearing technology and need not be described in greater detail herein. The supply of drive air, bearing air and a small amount of air/cooling liquid is controlled such that the bearing air supplied to the drive head 14 is independent of the turbine drive air and independent of whether the drive unit 20 is rotating or not. The bearing air supply is preferably controlled by a well known handset stand or support (not shown). Preferably, a bearing air supply switch (not illustrated) is provided in the cradle which switches off the bearing air supply when the handset is in the cradle and switches on the bearing air supply when the handset is removed from the cradle. This means that the bearing 30 is resting on an air cushion (levitated) and is in a ready-to-operate state at all times when the handpiece 10 is lifted off its stand (not shown). This will ensure that the bearing 30 is always active before the turbine 50 rotates to prevent damage to the bearing and significantly reduce wear. Various embodiments of handset controls are known to those skilled in the art of air bearing technology and need not be described in greater detail herein. Any controller may be used to ensure that bearing air (buffer air) is constantly supplied to the bearings 30 when operating the handpiece, regardless of the supply of turbine drive air. As explained in more detail with reference to fig. 8 and 9, control of the bearing air within the handset may also be achieved by diverting a constant flow of turbine drive air to the bearings while separately controlling the supply of turbine drive air to the turbine.

The bearing is preferably a ball air bearing in which the bearing rotor 32 and complementary bearing stator 31 parts have a spherical curvature (in other words a spherical cross-sectional shape) to provide a smooth bearing air flow in the bearing gap 33 and to allow the bearing to support the turbine against axial thrust exerted by the tool 15 (see figure 10) as well as thrust acting in other directions than axial, for example thrust caused by side or oblique loads acting on the tool tip. This has a significant advantage over prior art flat pad type air bearing arrangements in which the air bearing surface is substantially flat and extends only axially or radially relative to the axis of rotation of the tool, creating significant turbulence and hence air resistance at the transition between the axial and radial bearing surfaces.

In a preferred embodiment of the handpiece of the present invention as shown in fig. 4a-d and 6a-1, the turbine wheel and the upper and lower bearing rotors of the upper and lower air bearings 30 are combined into a turbine rotor unit 100, the unit 100 including a wheel portion 110, a lower bearing rotor portion 130 and an upper bearing rotor portion 120 (see fig. 6e-6 g). The air bearing 30 is a ball air bearing. In addition, the upper and lower bearing rotors 121, 131 are respectively connected to upper and lower housing covers 122, 132 which respectively close the top and bottom ends of the housing 13. The respective opposite bearing surfaces of each bearing rotor and associated bearing stator are complementary and the spherical portion is smoothly curved in shape. The bearing bodies 120, 130 each preferably have a convexly curved bearing surface and the bearing stators 121, 131 each preferably have a concavely curved bearing surface. Of course, the curvature of the upper bearing rotor 120 may be concave, the curvature of the lower bearing rotor may be convex, or both may be the same type of curvature, i.e., concave or convex. Preferably, however, the bearing surfaces of the upper and lower bearings are oppositely curved. The use of a pair of ball bearings having opposite curvatures will make the guidance of the components supported by the bearings more accurate and efficient. The bearing stators 121, 131 are shaped and sized to sealingly engage the housing 13 along their peripheries. This is achieved by an annular sealing flange 124 on the upper bearing stator 121 and an annular sealing flange 134 on the lower bearing stator 131, which are each sealingly engaged with the inner surface of the housing 13. The bearing stators each have at least one air passage 125, 135 for bearing air. Preferably, each stator has a plurality of air passages 125, 135 (see fig. 6c, 6d, 6h, 6i) extending from an outer surface of the stator 121, 131 opposite the associated casing cover 122, 132, through the stator, to an inner surface of the stator 121, 131 opposite the associated bearing rotor 120, 130. The air passages 125, 135 are preferably evenly distributed over the bearing surface of the stator, but may also be distributed in a geometric arrangement or randomly. The inner surface of the bearing stators 121, 131 has at least one recessed air distribution groove 126, 136 for one air passage 125, 135, respectively. Preferably, each stator has a plurality of pocketed air distribution slots 126, 136. Each air passage 125, 135 preferably has at least one air distribution groove 126, 136. The grooves 126, 136 preferably curve along a circular path concentric with the axis of rotation of the bearing rotors 120, 130. This ensures that the bearing air is supplied and distributed more evenly within the bearing gap 33.

The upper housing cover 122 has a cylindrical side wall 126 for sealing engagement with the housing 13 and spacing the cover and the bearing stator 121 to create an upper bearing air cavity 142. The upper housing cover 122 includes an air supply passage 123 for supplying bearing air to the upper bearing stator 121. Bearing air entering through the air supply passage 123 from the bearing air supply conduit 140 (see fig. 4b, 4d) is distributed throughout the upper bearing air chamber 142 and enters the bearing gap 33 through the air passage 125. Spent bearing air exits bearing gap 33 by flowing from around upper bearing stator 120 into turbine chamber 60 and through bearing air exhaust port 148 in outer edge 149 of upper stator 121. The lower housing cover 132 and lower bearing stator 131 have central burr receiving channels 144, 145, respectively. The shape and configuration of the lower housing cover 132 and the lower bearing stator 131 form an annular lower bearing air supply chamber 143. To this end, the lower bearing stator 131 is provided with a cylindrical spacer wall 146 which is preferably sealingly insertable into a spacer receiving annular groove 147 in the lower housing cover 132. The spacer wall 146 and the receiving groove 147 both concentrically surround the burr receiving passageway 144 and the axis of rotation of the burr 80 and turbine wheel 50. Bearing air entering the lower bearing air supply chamber 143 from the bearing air supply conduit 140 is distributed throughout the lower chamber 143 and enters the bearing gap 33 through the air passage 135 and exits the bearing gap 33 through the burr receiving passage 144. Bearing air is supplied to the housing 13 of the drive head 14 separately from the turbine drive air via a separate air conduit 140 to allow operation of the handpiece as described above, wherein during rotation of the turbine unit 100 and after the turbine drive air is turned off, the bearing air is supplied to the drive head 14 before the turbine drive air is turned on to keep the turbine unit 100 levitated during rotation. This will be further explained with reference to fig. 8 and 9.

In a preferred embodiment of the air bearing structure as shown in fig. 4a-e and 6a-1, the bearing stators 121, 131 and the upper and lower bearing rotor portions 120, 130 of the turbine unit 100 are provided with magnet means for suspending the turbine unit 100 in the turbine chamber at all times independently of any air supply in the handpiece. This means that the turbine unit 100 is able to float even when the handpiece is not connected to the umbilical cord at all, such as during storage, transport and sterilization of the handpiece or at least the neck/head portion 16 of the handpiece. This will reduce damage to the turbine unit and bearing structure due to vibrations etc. caused in shut down or turbine and handpiece separation conditions. But also minimizes contact of the turbine unit 100 with the bearing stators 121, 131 during sterilization, thereby minimizing the chance of contaminants being trapped between the mutually contacting surfaces, thereby improving the effectiveness of sterilization. The magnet arrangement comprises one or more magnet inserts 150 (fig. 4c) in the bearing rotors 120, 130 and the bearing stators 121, 131, which inserts are positioned into the bearing parts, respectively, in such a way that the poles of the same polarity are oriented opposite each other in each bearing rotor/bearing stator combination. Since the poles of the same polarity repel each other, the magnet insert 150 causes the turbine unit 100 to be pushed away from the two bearing stators 121, 131, thus remaining levitated therebetween. The magnet inserts 150 are preferably in the form of circular magnet discs 151 embedded in the bearing stators 121, 131 and annular magnet rings 152 embedded in each bearing rotor 120, 130. The magnet discs 151 are preferably evenly spaced from each other and arranged along a circle concentric with the axis of rotation of the turbine unit 100, which circle preferably has a radius equal to the average radius of the annular magnet ring 152, so that the magnet discs 151 are preferably positioned on the center line of the magnet ring 152 for maximum repulsion forces. As mentioned above, the polarity of the respectively opposite magnet discs and magnet rings is chosen such that their respectively opposite faces are of the same polarity and repel each other. One possible polarity orientation of the magnet insert 150 is shown in fig. 4e, which is an enlarged view of the drive head shown in fig. 4 c. Of course, it is also possible that each insert 150 be of diametrically opposite polarity orientation. The respective polarity directions of the two magnet rings 152 on the upper and lower bearing rotors 120, 130 are chosen such that mutually opposite poles are of opposite polarity. This causes the magnet rings 152 to attract each other, reducing the potential for pushing the magnet rings 152 out of the associated bearing rotor. Furthermore, arranging the polarity of the magnet rings in this way will potentially lead to an overlap and strengthening of their respective magnetic fields rather than weakening them.

The turbine unit 100 and the bearing stators 121, 131 are preferably made of metallic materials well known to those skilled in the art. The magnet inserts 150 are preferably commercially available permanent magnets that are inserted into and secured in receiving pockets in the bearing stators 121, 131 and bearing rotors 120, 130, preferably with an adhesive. The connecting surfaces of the bearing stator and the bearing rotor are preferably polished to provide the best possible bearing air cushion. The magnet inserts are preferably inserted into the stator and rotor prior to the polishing operation to prevent any bearing surface irregularities. As will be readily understood by those skilled in the art of air bearings. The connecting surface may also be anodized to provide a smoother bearing surface.

Radial gas flow turbine

The drive unit 20 of the handpiece according to the present invention as shown in fig. 1-3e generally includes an air turbine 50 and a dental tool (burr) receiving chuck 40 supported in the handpiece drive head 14 by bearings 30. The air turbine wheel 50 is connected with the bearing rotor 32 of the lower bearing 30 for torque transmission. It will be obvious to a person skilled in the art that this connection can be realised in many ways, all connections being possible within the scope of the invention, as long as the connection is a coaxial connection and prevents the turbine from rotating relative to the bearing rotor. Examples of types of connection applications are adhesive connections, interlocking connections between two parts (latch type), meshing connections of complementary non-circular parts, press-fitting of the bearing rotor 32 and turbine 50, etc. The bearing rotor 32 of the lower bearing 30 may also be integrally manufactured with the air turbine 50 as a single turbine body of unitary construction, such as the turbine body of the embodiment of fig. 6e-6 g. In a preferred embodiment shown in fig. 3a-c, the bearing rotor 32 comprises an axially protruding connection flange 34 which is received in an axial bore 53 in the turbine wheel 50. In this embodiment, the flange 34 and the bore 53 preferably include respective complementary and preferably engaging axially extending radial projections 55 to allow axial insertion of the flange 34 into the bore 53 while preventing rotation of the flange in the groove. The improved drive unit of the present invention comprises a radial air flow turbine as opposed to the commonly known paddle wheel type turbines. The design of radial flow turbines requires that the drive air be fed radially inward rather than tangentially to the turbine. This is achieved in the illustrated embodiment of the invention by providing an annular drive air supply chamber 70 in the housing 13, the air supply chamber 70 extending concentrically about the axis of rotation of the turbine. The air supply chamber 70 is connected radially inwardly to the turbine chamber 60 by a Venturi (Venturi) passage 72 (see figures 1a, 1 c). The venturi passage 72 preferably extends continuously about the axis of rotation and provides a restriction or nozzle for accelerating the drive air supplied from the air supply chamber 70 to the turbine chamber 60. The air supply chamber 70 is supplied with pressurized drive air through a drive air supply conduit 75 that extends through the handpiece and umbilical cord. The drive air is evenly distributed within the annular air supply chamber 70 and redirected radially inwardly toward the axis of the turbine 50 by a plurality of stationary radial air vanes 74 positioned in the venturi passage 72. Directing the drive air radially inward will significantly reduce parasitic airflow (obstructions) as compared to a paddle wheel type turbine where the drive air is fed tangentially around the turbine 50. The radial drive air supply also generates additional torque due to the extended engagement time of the air with the turbine 50 and the drive air engaging all of the turbine blades simultaneously rather than only one as with the tangential flow configuration. The torque output of the turbine 50 is also improved by utilizing the annular venturi air supply nozzle 72, since it accelerates the drive air immediately prior to impact with the turbine 50. The venturi passage 72 also creates a back pressure in the annular cavity 70. This compensates for the pressure of the drive air throughout the air supply chamber 70, and then, evens out the drive air pressure throughout the circumference of the turbine 50. The radial and uniform supply of drive air around the turbine also overcomes the significant problem of asymmetric loading of the turbine bearings caused by the tangential drive air supply in prior art designs. The even distribution of drive air to the handpiece of the present invention provides automatic centering of the turbine 50, greatly reducing radial stress on the bearings 30, particularly the top bearing. The turbine blades 54 in axial cross-section are convexly curved in the direction of rotation to deflect impinging drive air radially relative to the direction of rotation of the turbine. The turbine blades are also preferably tilted in the axial direction of the wheel and in accordance with the driving air flow away from the direction of rotation to produce additional torque. Pressurized turbine drive air is supplied to the drive head 14 through a drive air supply conduit 62 (see fig. 4c) connected to an annular air supply chamber 70 and extending through the handpiece and umbilical cord to a source of pressurized air (not shown) as is well known to those skilled in the art. Drive air entering turbine chamber 60 through venturi passage 72 impinges upon all of the turbine blades 54, flows radially inwardly along the blades and axially downwardly along blades 54 toward the center of turbine 50 to be collected in annular drive air exhaust chamber 68 and exhausted through air exhaust conduit 64.

Chuck and burr lock

The embodiment of the handpiece 10 of the present invention shown in fig. 3a-3e is equipped with a torque transfer arrangement for transferring torque generated by the turbine to a tool having a shaft portion with a non-circular cross-section, the torque transfer arrangement including a locking socket for receiving the shaft portion and having a complementary cross-section for locking the shaft portion in the socket against rotation while allowing axial insertion of the shaft portion into the locking socket. The locking socket is connected to and rotates in the turbine. This torque transfer arrangement transfers torque generated by the turbine 50 to the burr 80, preventing the problem of slippage of the burr 80 in the tool receiving bore of the turbine as is typical with prior art handpieces.

The torque transfer structure generally includes a non-circular cross-section torque transfer shaft portion on the shaft of the burr 80 and a locking socket 35 non-rotatably connected to the turbine and having a shape complementary to the shaft portion to prevent rotation of the shaft portion relative to the turbine in the socket. The locking socket may be separate from the turbine and connected thereto by an intermediate part, such as the bearing rotor 32, or may be connected directly to the turbine.

In the preferred embodiment shown in fig. 3a-d, the torque transfer structure includes a chuck 40, a bearing rotor 32 and a locking socket 35 integrated with the bearing rotor 32 of the lower bearing. The burr 80 is received in an axial tool passage extending through the bearing rotor 32, the chuck 40 and the turbine wheel 50. The burr 80 and chuck 40 are designed so that the burr is held in the chuck by friction. This may be accomplished by pressing the chuck 40 against the burr 80. The chuck 40 includes an inclined shoulder 42 extending along the outer circumference of the chuck 40 at a bottom end 43 of the chuck 40. The turbine 50 has a corresponding inclined seat 52 in the bore 53. The chuck 40 is axially movable in the bore 53 between a locked position in which the shoulder 42 engages the seat 52 and the bottom end 42 of the chuck 40 is urged radially inwardly to be locked, and an open position in which the shoulder 42 is axially spaced from the seat 52 and the burr 80 is freely insertable into and removable from the chuck 40. Of course, the chuck 40 is made of a material having a desired degree of flexibility to allow the chuck 40 to deform sufficiently to frictionally grip an inserted burr 80. The chuck 40 is normally urged into the locked position by a Belleville washer 44, which Belleville washer 44 extends around the chuck 40 below a radial top flange 45 and urges the top flange 45 away from the turbine 50. The flexible button actuator 21 allows the operator to move the chuck 40 to the open position by means of an intermediate actuating ball 22 received in a complementary seat 46 in the top end 47 of the chuck 40. Depressing the button 21 will push the ball 22 and chuck 40 downward until the shoulder 42 no longer engages the seat 52. This type of friction burr locking and chuck release arrangement is standard in the art and need not be described in further detail.

Rotation of the burr 80 relative to the chuck 40 and the turbine wheel 50 may be prevented by interlocking or intermeshing structures that include complementary portions such as lock and key portions on the bearing rotor 32 and the burr 80, respectively. The burr 80 has a generally constant cross-section shaft 81 for insertion into the burr receiving tool bore of the bearing rotor 32, chuck 40 and turbine wheel 50. The shaft includes an enlarged locking boss 82 of non-circular cross-section. The bearing rotor 32 of the lower bearing 30 includes a locking socket 35 that is complementary in shape to the locking boss 82 of the shaft 81. The socket 35 properly receives the locking boss 82 to reliably prevent the burr 80 from rotating relative to the bearing rotor 32 and the turbine wheel 50. The axial position of the boss 82 on the shaft is selected so that when the burr 80 is fully inserted into the chuck 40, the boss 82 non-rotatably engages the socket 35. Thus, the problem of burr slippage at high torque commonly observed in prior art handpiece constructions can be overcome. The boss 82 and the socket 35 may have any cross-sectional shape other than circular, so long as the respective shapes reliably prevent rotation of the burr 80 relative to the socket 35 when the burr 80 is fully inserted into the chuck 40. The socket 35 is preferably located on the bearing rotor 32 for easy viewing by a user. This allows the user to align the shape of the boss 82 with the shape of the socket 52 to facilitate insertion of the burr 80.

In another preferred embodiment, as shown in fig. 4a-d and 5a-b, the locking socket is designed as a two-piece lever 200, the lever 200 including a torque lock 210 and an alignment sleeve 220. The alignment sleeve 220 is sized and shaped for insertion into the central tool bore 170 of the turbine unit 100. The alignment sleeve and torque lock may also be made in one piece. Thus, a torque transmission device for a dental handpiece with a turbine unit 100 for rotationally driving a burr 80 about an axis of rotation, the burr 80 having a burr shaft 81 with a non-circular shaft portion 83 (see fig. 5), the turbine having an axial tool bore for receiving the burr shaft 81, the torque transmission device comprising a locking socket 200 with a shaft bore for receiving the shaft portion 83 of the burr shaft 81, the locking socket being connectable to the turbine for rotation therewith, a torque transmission member 210 being connected with the locking socket for locking the shaft portion 83 against rotation relative to the locking socket 200. In the preferred embodiment shown in fig. 5a and b, the locking socket is a two-piece socket comprising a hollow stem 220 and a torque lock 210. The locking socket 200 is connected to the turbine for rotation therewith. This may be achieved by an adhesive or frictional connection between the torque lock 210 and the lever 220 and the connection of the lever 220 to the turbine unit 100 (see fig. 4 a-d). The stem 220 may be non-rotatably connected to the turbine unit 100 for reliable torque transfer by press-fitting the stem into the turbine, but an adhesive connection is preferred. Thus, the locking socket 200 is inserted into the tool hole 101 of the turbine unit 100 and connected with the turbine. The locking socket 200 includes a hollow stem 220 that is inserted into the tool bore 101 for connection to the turbine wheel, and a torque transfer member 230 that fits into the torque lock 210 and extends radially inward into an axial bore 221 of the stem. While the torque lock 210 and the spindle 220 are shown as separate pieces in the illustrated embodiment, once connected to each other, they function as one piece, preferably by being adhesively connected together to form a burr receiving spindle. However, they may also be made as one piece in the form of a rod 220, the rod 220 being capable of properly receiving the burr shaft 81 and having an inwardly extending transfer member 230 attached directly into the rod. The torque transfer member 230 is a projection that extends radially inwardly into the cylindrical bore 221 of the spindle for preventing rotation of the locking portion 83 of the burr shaft 81 relative to the spindle 220 while allowing axial insertion of the burr shaft into the spindle. The lever 220 and the torque lock 210 are preferably made of metal and the torque transfer member is preferably stamped from the torque lock or lever. As is apparent from fig. 5a, the ends of the nose portion 230 and the terminal portion 83 that contact each other during insertion of the burr shaft 81 into the spindle 220 have a rounded shape for guiding the end face of the terminal portion 83 automatically through the nose portion to achieve automatic alignment of the terminal portion relative to the nose portion during insertion of the burr 80.

Like the lever 220, the configuration of the locking socket 200 also allows the use of the locking socket in conventional drive head configurations that include a turbine and a pair of mechanical bearings, such as ball bearings. The rod 220 may be used for coaxial adjustment of the bearing and turbine when the rod 220 is rigidly connected to the turbine (e.g., by bonding) to reliably transmit torque from the turbine to the burr. Therefore, the problem of burr slippage that occurs with conventional handpieces at high torque can be ameliorated by the torque transfer structure of the present invention.

The torque transmitting structure of the embodiment shown in fig. 5a and b further includes a burr retaining member 240 of the shank 220 extending into the cylindrical bore 221 for releasably engaging the complementary retaining member 85 to the burr shaft 81 in the form of a circular groove to releasably lock the burr shaft 81 in the cylindrical bore 221 against axial movement. The retaining member or tab 240 is preferably formed by pressing a portion of the wall of the stem 220 radially inward. The projections 240 preferably have sufficient flexibility and durability to allow repeated insertion and removal of the burr. The projections 240 also preferably have sufficient strength to provide a noticeable biting feel to the user of insertion into the burr 80 when the projections bite into the burr grooves 85.

Quick connection of driving head

A conventional handpiece includes a neck/drive head that houses a drive unit and a dentist-operated handle/handle portion, wherein the handle portion includes at the rear end an umbilical cord coupling for housing air and water supply lines. The neck and shank portions are typically combined into one piece. This is disadvantageous because the coupling will be subjected to harsh sterilization conditions when the handpiece is sterilized, which often results in premature failure of the connection member (e.g., O-ring). The preferred embodiment of the handpiece of the present invention, shown partially cut away in fig. 4, is constructed in two parts so that the neck/drive head 14 can be separated from the handle/stem portion 11 and separately sterilized. The handle portion does not require heat sterilization in accordance with existing health standards. Thus, with the handpiece construction of the present invention, the drive head can be heat sterilized, while the handle portion can be sterilized by another method that is less damaging to sensitive components in the umbilical cord connection 12 (see FIG. 7). A quick connect coupling is provided between the two parts and is non-rotatable and comprises a connector socket 90 insertable into the handle sleeve 17 and a complementary connector plug 91 integral with the neck portion 14. The receptacle 90 and the plug 91 are of complementary shape so that the plug 91 may fit non-rotatably into the receptacle. The connection portion is configured to form a snap-fit connection by a pair of spring-loaded pins or balls 93 in the connector receptacle 90 respectively engaging one of a pair of snap-in recesses 94 in the plug 91 when the plug is fully inserted into the receptacle.

Turbine automatic stop

The handpiece is also provided with automatic shut-off valves for the turbine drive air and the turbine exhaust air and preferably also for small amounts of water/air mixture. This provides a quick on/off for the turbine and small amounts of water/air. This is a significant advantage since if current handpiece designs are used, the dentist must wait until the burr is slowly stopped before removing it from the patient's mouth in order to avoid injury to the patient's tongue or lips. As shown in fig. 8 and 9, the automatic shutoff includes a closure member, in this case a pair of cooperating valve sleeves 61a, 61b (see fig. 8, 9 and 14) operated by turbine drive air. As shown in fig. 8, the valve sleeves 61a, 61b are normally biased by a spring 66 into a closed position in which they close the drive air supply conduit 62, the turbine air exhaust conduit 64, and preferably also the chip water/air conduit 63. Thus, in the closed position of the valve sleeves 61a, 61b no air at all can be supplied to the turbine chamber 60 or discharged from the turbine chamber 60, which is able to rapidly slow down the turbine 50 because of the turbulence in the air that is trapped in the turbine chamber. The rapid stopping of the turbine prevents a vacuum from forming in the turbine chamber 60 during the shutdown of the turbine 50, and therefore prevents contaminants from being drawn into the turbine chamber during the shutdown. When turbine drive air is supplied to the handpiece by operation of a handpiece controller/variable resistor (not shown, typically a foot pedal) as is well known in the art, the valve sleeves 61a, 61b are moved from the closed position shown in fig. 8 to the open position shown in fig. 9 by the drive air pressure against the force of the spring 66. In the open position, the valve sleeves 61a, 61b do not block the turbine drive air supply conduit 62, the turbine air exhaust conduit 64, and the chip water/air supply conduit 63. Once the drive air supply is stopped, the biasing spring 66 moves the valve sleeves 61a, 61b back to their closed position again blocking the turbine drive air supply conduit 62, the turbine air exhaust conduit 64 and the chip water/air supply conduit 63. This will completely trap the air in the turbine chamber 60. Thus, no vacuum is created in the turbine chamber 60 and the turbine is brought to a substantially instantaneous stop due to the turbulence created in the chamber. It is important to note that if air bearings are used, the valve sleeves 61a, 61b are preferably configured so as not to interfere with the supply of bearing air. Bearing air is separated from the drive air supply by a cylinder air flow splitter 67 prior to the drive air supply engaging the valve sleeve. This ensures continuous easy operation of the air bearing regardless of the operating state of the turbine, preventing damage to the air bearing due to lack of bearing air supply during shutdown of the turbine. In a preferred method of operating a handpiece in accordance with the present invention, the bearing air supply trigger is connected to the handpiece cradle (not shown) so that bearing air is supplied to the handpiece at all times the handpiece is closed off the cradle.

Ergonomic neck portion

The shape of the neck portion of the handpiece has been redesigned in the handpiece of the present invention to provide additional tooth clearance and better visual clearance visibility. The neck portion of conventional handsets is designed to provide a certain amount of backlash. This may be achieved by bending the front end 17 of the neck portion 14 of the abutment 16 away from the longitudinal axis of the handle 11 at a fixed angle of deflection. However, since the upwardly curved portion of the neck 14 is substantially straight, the maximum tooth clearance is only achieved immediately behind the drive head 16. Furthermore, for ergonomic reasons, the tip of the burr 80 must be aligned with the longitudinal axis of the handpiece, and therefore, the maximum tooth clearance is limited by the length of the burr 80. This requires that the angle of attack of the burr 80 on the tooth surface be changed without moving the burr tip by simply rotating the handle portion about the longitudinal axis of the handpiece (see fig. 11 b).

Now, additional clearance and better visibility have been achieved in the preferred embodiment of the handpiece according to the invention (see fig. 11a, b and 12), which consists in the front portion 17 of the neck portion 16 having two different bending angles. The curved portion 18 includes a first portion 19a adjacent the handle 11, which portion 19a curves away from the longitudinal axis 10a of the handpiece 10 at a greater angle than in the prior art. The curved portion 18 also includes a second portion 19b, which portion 19b is curved away from the longitudinal axis 10a in an opposite direction so that it forms a smaller angle with the longitudinal axis 10a than the first portion 19a does with the longitudinal axis 10 a. In other words, the drive head 14 is fixed to the neck portion 17 relative to the handle portion 11 such that the tool axis 15a forms an angle α of less than 90 ° with the longitudinal axis 17a of the neck portion 17 and an angle β of greater than 90 ° with the longitudinal axis 11a of the handle portion 11, while the tip of the tool 15 coincides with the axis 11 a. This configuration allows the clearance area between the curved portion 18 and the axis to be greater than in the prior art design (see fig. 12). At the same time, it is ensured that the tip of the burr is still aligned with the longitudinal axis. This alignment allows the dentist to adjust the angle of the burr relative to the patient's teeth without changing the hand support position. Adjustment of the burr angle is achieved by simply scrolling the phone between the fingers, similar to a pen as shown in fig. 11 b. The alignment of the burr with the axis of the handpiece prevents lateral displacement of the burr relative to the teeth, as best seen in figure 11b, as long as the handpiece is rotated about the longitudinal axis 11a of the handle.

Rotary connector

As described above, conventional handpiece designs include a swivel connector for connecting the handpiece to the umbilical cord and preventing bending and kinking of the umbilical cord. The weight of the umbilical cord creates tension on the dentist's wrist. This is further exacerbated by the leverage provided by the relatively stiff steering cables extending from the rear of the handpiece. This problem has now been solved in a preferred embodiment of the handset according to the invention (see fig. 8, 10, 11), in that the swivel connector is tilted. The provision of a tilt swivel connection ensures that the umbilical cord is always suspended more or less vertically downwardly from the handpiece so as to overcome the leverage and significantly relieve the strain on the wrist. In the preferred embodiment shown in fig. 11, the connector is configured as a swivel connector 100 having an angled body 101 provided with a quick connect coupling at each end. The angled body provides less than 180 degrees of connection between the handpiece handle and the umbilical cord. The first quick connect coupling 102 is designed to provide a rotatable swivel connection to the handpiece coaxial with the longitudinal axis of the handpiece, while the second quick connect coupling 103 provides a rotatable swivel connection of the connector body 101 to an umbilical cord (not shown). The angled connector may also constitute an improved connector for insertion into a conventional swivel connection between the umbilical cord and the connector end of a conventional handpiece. Many different forms of rotational connection structures will be readily apparent to those skilled in the art that may be used to effect a rotational connection between the connector body 101 and the handpiece, such as a threaded, snap or quick connect (bayonet) type connection commonly used in the art. Accordingly, since one skilled in the art can select a known rotary-type connection for a variety of conduits, a detailed description of the rotary connection is not required. In principle, any prior art connection structure for multiple rigid pressurized conduits that allows for a sealed rotational connection may be used.

In a preferred embodiment of the invention, the swivel connector body 101 is fixed directly to the end of the umbilical cord and has only one swivel means for connection to a handpiece (see fig. 10). The connector body 101 also has a fiber optic conduit extension 104 that separates the fiber optic line 105 from the turbine drive air, small amounts of air/water, and air exhaust conduits. This prevents contamination by oil (lubricating fluid for turbines and bearings) and fluid in the supply lines, thereby preserving fiber performance over the life of the fiber. The fiber optic catheter extension may also be modified to include a light source at its end. This may be accomplished by fitting an LED or bulb socket 162 for receiving the LED or bulb 16 into the free end of the extension 104 as a light source, while the cover 160 serves to protect the light source from damage during insertion or removal of the quick connect. In the preferred embodiment shown in fig. 13b, light is provided to the neck portion 16 of the handpiece through a fiber optic waveguide, and the waveguide end of the neck portion is covered with a protective convex lens cover 165 that forms a curved retaining arm to snap tightly around the neck portion. The convex mirror cover 165 is shown in a removed and installed condition.

The above-described embodiments of the present invention are intended to be examples only. Alterations, modifications and variations may be effected to the particular embodiments by those of skill in the art without departing from the scope of the invention, which is defined solely by the claims appended hereto and their equivalents.

Claims (18)

1. A medical or dental turbine handpiece for a rotary tool, the handpiece having a handle portion for gripping by a user, a drive head connected to the handle portion and forming a turbine housing, a turbine wheel in the turbine housing for rotatably driving the tool about an axis of rotation and having an axial tool bore for receiving a tool shaft, a pair of axially spaced bearings for rotatably supporting the turbine wheel in the turbine housing, and a pressurized drive air conduit for supplying pressurized turbine drive air to the turbine wheel, characterized in that: the bearing is an air bearing and the handpiece includes a bearing air conduit for supplying pressurized bearing air to the air bearing independently of turbine drive air.

2. The handset according to claim 1, wherein: the handpiece also includes a controller for controlling the flow of pressurized drive air through the drive air conduit separate and independent from the flow of bearing air through the bearing air conduit.

3. A method of operating a dental handpiece including a turbine driven by pressurized drive air and a pair of air bearings for supporting the air turbine in the handpiece and operated by the pressurized bearing air, comprising the steps of: supplying pressurized bearing air to the air bearings and pressurized drive air to the turbine independently of the bearing air, the step of supplying bearing air beginning before and continuing at least as long as the step of supplying drive air.

4. A medical or dental turbine handpiece for a rotary tool, the handpiece having a handle portion for gripping by a user, a drive head connected to the handle portion and forming a turbine housing, a turbine in the turbine housing for driving the tool in rotation about an axis of rotation and having an axial tool bore 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 extending around the turbine chamber for supplying turbine drive air to the turbine at least two spaced locations distributed about the axis of rotation.

5. The handset of claim 4, wherein: the turbine drive air supply chamber is an annular chamber extending concentrically about the axis of rotation.

6. The handset according to claim 5, wherein: the supply chamber supplies drive air to the turbine at a plurality of locations evenly distributed about the axis of rotation.

7. The handset of claim 4, wherein: 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 impingement on the turbine.

8. The handset of claim 7, wherein: the venturi passage includes a plurality of air guide vanes for directing turbine drive air to the turbine in a radially inward direction toward the axis of rotation.

9. A medical or dental turbine handpiece for a rotary tool, the handpiece having a handle portion for gripping by a user, a drive head connected to the handle portion and forming a turbine housing, a turbine in the turbine housing for driving the tool in rotation about an axis of rotation and having an axial tool bore for receiving a tool shaft, and a pair of axially spaced bearings for rotatably supporting the turbine in a turbine housing for rotation about the axis of rotation, the turbine having: the bearing is an air bearing.

10. The handset according to claim 9, wherein: each of the air bearings includes a bearing stator having a spherical cross-sectional shape and a complementary shaped bearing rotor, and the bearing stators and rotors are shaped to form a central bearing gap of uniform width throughout.

11. A medical or dental turbine handpiece having a handle portion for gripping by a user, a drive head connected to the handle and forming a turbine chamber, an air driven turbine in the turbine chamber for rotatably driving a tool, and the turbine being operated by turbine drive air, and a rotary connector for rotatably connecting the handle to a steering cable, the steering cable including at least a supply conduit for 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 strain on the user's wrist.

12. The handset according to claim 11, wherein: the handle and steering cable are connected at an angle between 90 and 180 degrees.

13. A medical or dental turbine handpiece for a rotary tool having a shaft, the handpiece including a drive head for rotatably supporting the tool and forming a turbine housing, a turbine wheel in the turbine housing for rotatably driving the tool about an axis of rotation, a pair of axially spaced bearings for rotatably supporting the turbine wheel in the turbine housing, a pressurized drive air conduit connected to the turbine housing for supplying pressurized turbine drive air to the turbine wheel, and a discharge conduit connected to the turbine housing for discharging spent turbine drive air from the turbine housing, characterized in that: the handpiece further includes a shut-off valve for reducing turbine downtime when the turbine drive air supply is stopped, the shut-off valve being connected to the drive air conduit and the exhaust air conduit, and the shut-off valve including a closure member normally biased into a closed position, wherein the closure member closes the drive air conduit and the exhaust conduit and is moved to an open position by the drive air pressure, wherein the closure member allows passage of the drive air and the exhaust air through the drive air conduit and the exhaust conduit, respectively.

14. The handset according to claim 13, wherein: the bearing is an air bearing and the handpiece further includes a bearing air supply conduit connected to the drive head for supplying pressurized bearing air to the air bearing, the supply conduit supplying bearing air regardless of the position of the closure member in the shut-off valve.

15. The handset according to claim 14, wherein: the shut-off valve is mounted in the handle portion and the closure member is a sleeve axially movable in the handle portion between open and closed positions.

16. A medical or dental turbine handpiece for a rotary tool having a working tip, the handpiece including a handle portion for gripping by a user, a drive head connected to the handle portion by an intermediate neck portion and forming a turbine housing, a turbine wheel in the turbine housing for rotatably driving the tool about an axis of rotation and having an axial tool bore for receiving a tool shaft, and a pair of axially spaced bearings for rotatably supporting the turbine wheel in the turbine housing, characterized in that: the handle portion has a central longitudinal first axis and the neck portion has a central longitudinal second axis, the drive head, neck portion and handle portion being interconnected such that the axis of rotation of the tool encloses an angle of greater than 90 degrees with the first axis and less than 90 degrees with the second axis, and the second axis being at an angle to the first axis such that the tip of the tool coincides with the first axis.

17. A medical or dental turbine handpiece for a rotary tool, the handpiece including a handle portion for gripping by a user, a drive head forming a turbine housing, an intermediate neck portion connecting the drive head and the handle portion, a turbine wheel in the turbine housing for rotating the drive tool about an axis of rotation and having an axial tool bore for receiving a tool shaft, and a pair of axially spaced bearings for rotatably supporting the turbine wheel in the turbine housing, characterized in that: the handset also includes neck connecting means for releasably connecting the neck portion to the handle portion, the neck connecting means comprising 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 the handle portion, the plug portion and the socket portion being of complementary shapes for non-rotatably connecting the neck portion and the handle portion.

18. The handset according to claim 17, wherein: the neck connecting means further comprises a snap lock for releasably locking the plug portion in the socket portion.