GB2072779A

GB2072779A - Couplings for dental tools

Info

Publication number: GB2072779A
Application number: GB8106627A
Authority: GB
Original assignee: Micro Mega SA
Current assignee: Micro Mega SA
Priority date: 1980-03-27
Filing date: 1981-03-03
Publication date: 1981-10-07
Also published as: AT372598B; JPS56139742A; ATA117681A; DE3109938A1; IT8120624A0; FR2478994B1; FR2478994A1; BR8101818A; DD157596A5; CH642249A5; IT1135674B

Abstract

A dental drive unit 5 is equipped with a hollow ferrule 9 to which coolant is supplied. A dental instrument for example a drill, having a handpiece 1 and head 4, for attachment to the drive unit incorporates a tube 7 which mates with the ferrule when the instrument and drive unit are assembled. <IMAGE>

Description

SPECIFICATION Improvements in dental equipment In dentistry, it is conventional to drive a variety of hand held instruments by means of a drive unit incorporating a motor to which the instruments may be coupled in turn. In the case of certain instruments, for example a dental drill, the high speed of the tool carried by the head of the instrument leads to frictional forces being applied to the tooth and the generation of large amounts of heat. It is therefore preferred to feed a coolant to the head of the instrument and to eject the coolant towards the tooth, generally in the form of an air/water spray. The coolant may be supplied through a supply duct associated with the drive unit into a feed duct associated with the instrument, the latter duct leading to the head of the instrument and terminating in spray nozzles.

The need to join and separate the ducts associated with the drive unit and instrument when assembling and disassembling the drive unit and instrument presents certain problems. Not merely is it necessary to make and break the connection efficiently and without wasting time, but whatever arrangement is employed must not obstruct the view or work of the dentist.

The prior art has attempted to solve this problem in two main ways. In accordance with a first solution, the supply duct associated with the drive unit is in the form of an external flexible tube, while the feed duct associated with the instrument is in a form of a metal tube onto which the flexible tube is fitted during assembly of the instrument and drive unit. Each time that the instrument is removed from the drive unit for the purposes of replacement or cleaning, it is necessary to remove the flexible tube from the metal tube before disconnection of the instrument from the drive unit can take place. Conversely, when fitting a new instrument, the flexible tube must be sleeved over the metal tube before operation can begin.

The steps of applying the flexible tube to the metal tube and removing it therefrom, are carried out as operations separate from those of assembling and disassembling the instrument and drive unit. This arrangement is therefore not very practical from the point of view of handling. Another problem is that the flexible tube may become jammed on the metal tube so that it cannot be promptly removed during the disassembly of the instrument and drive unit. The arrangement for supplying the coolant to spray nozzles in the head of the instrument may take either of two different forms irrespective of the way in which the supply and feed ducts are interconnected.In one known arrangement, the feed duct extends externally of the instrument and is in the form of a welded-on metal tube in order to ensure optimum heat exchange at the head of the instrument, and in the other form, this duct extends internally of the instrument.

The problems of the prior art arrangement described above have, to some extent, been overcome by arranging for the coolant supplied through the supply duct to be discharged to an annular chamber in the region where the drive unit and instrument meet, the coolant escaping from the chamber through a feed duct extending at least partially within the instrument as far as its head, as proposed in French Patent No.

2 235 670. Although this arrangement possesses some advantages compared with the prior art previously discussed, it has the disadvantage of requiring numerous relatively complex machining operations for producing inclined bores. Secondly in order to achieve a fluid-tight connection, it is necessary to use seals of small diameter in accordance with the effectively standardised dimensions of the coupling between drive units and instruments.

To overcome these problems, there is proposed herein a device for rigidly coupling ducts for the passage of coolant between a dental drive unit and dental instrument, said device comprising two hollow metal parts through each of which extends an internal duct, one part being carried by the drive unit and being connected with a coolant supply duct, and the other metal part being carried by the instrument and being connected with a feed duct through which coolant is fed to the head of the instrument, one of the parts comprising a ferrule, and the other comprising a tube adapted to fit into the ferrule.

At least one of the metal coupling parts may be supported in such a way that it is adjustable angularly about the axis of the drive unit and the associated instrument. Advantageously, it is the part which is carried by the drive unit which is free to rotate, this part preferably being the ferrule. The parts may be connected with the instrument and drive unit, respectively, by clamping rings or clips, although other means may be employed for this purpose, for example welding, or a screwed connection.

The feed duct extending from the coupling part carried by the instrument may extend either externally of the latter, being for example in the form of a flexible tube, or be in the form of an internal duct. The construction now proposed has a number of advantages, in particular being very simple and requiring no sophisticated technology for mass production. Assembly when in use is easy, since it is only necessary to align the metal tube of one coupling part and that orifice in the ferrule of the other before bringing the instrument and drive unit together. The disadvantages of the seals required by the device disclosed by the above-mentioned French Patent are hereby avoided.

Further in accordance with the present proposa! is the provision of a dental drive unit and a dental instrument adapted to be fitted thereto upon movement of the instrument relative to the drive unit parallel to the axis of the latter, a metal ferrule mounted on the drive unit, a coolant supply duct opening into the ferrule, and a metal tube mounted on the instrument, at least a portion of said tube extending parallel to said axis for reception in the ferrule and a coolant feed duct connected directly or indirectly to said tube.

In the drawings:- Figure 1 shows diagrammatically a prior art dental instrument, illustrating in particular a receiving duct disposed internally of a dental instrument.

Figure 2 is a diagrammatic view of a dental instrument assembled with a drive unit, showing a coupling device in accordance with the present invention in partial longitudinal section.

Figure 3 is a view similar to Figure 2, but of a second embodiment.

Figure 4 is a perspective view of a further embodiment showing the dental instrument and drive unit disassembled.

Figure 5 shows a detail from Figure 4, and Figure 6 is a partial section taken on the line A-A of Figure 5.

Referring to Figure 1, a known hand held dental instrument, in particular a dental drill, has a hand piece 1 from which extends a head portion 4.

Coolant is sprayed during operation of the drill from nozzles in the head portion 4. The fluid is supplied to the nozzles by way of an internal feed duct, connected to a projecting metal tube 3, over which is sleeved a flexible supply tube 2, supported by a drive unit (not shown in Figure 1) incorporating a motor from which the rotatable parts of the instrument are driven in use. In an alternative prior art construction, the internal duct is replaced by an external tube connected to the metal tube 3, in a similar fashion to the tube 18 shown in Figure 3 in connection with the invention. The arrangements for feeding the coolant to the head and for discharging the coolant therefrom are well known to those skilled in the art and will not be described in further detail.

A first embodiment of the invention is shown in Figure 2, wherein the drive unit is shown at 5. As with the instruments, the drive unit has a construction which is well known to those skilled in the art, as is the coupling between the drive unit and the instrument. These parts are for the most part of standardised construction and, again, they will not be described in detail.

In accordance with the invention, the coupling for the supply and feed ducts comprises two metal parts one of which is carried by the drive unit and the other by the instrument. A first of these parts comprises a hollow metal component 6 mounted on the body of either the drive unit or instrument, the component having extending therefrom a metal tube 7 which projects beyond the end face of the said body and includes a linear terminal portion parallel to the axis of the assembled drive unit and instrument. A second of these parts comprises a hollow metal ferrule 9 supported by the body of the other of the drive unit and instrument and adapted to receive the tube 7. In the illustrated embodiment, the ferrule 9 is supported by the drive unit and the hollow component 6 by the instrument, although within the scope of the invention this association may be reversed.

The component 6 is fixedly secured to the instrument, while the ferrule 9 is carried by a collar 10 which encircles the drive unit and is free to rotate about the axis of the drive unit. In this way, angular adjustment of the instrument may take place relative to the drive unit to allow the instrument to be repositioned during use without interference from the motor. In an alternative construction, as will be described in greater detail with reference to Figure 4, the collar may encircle the drive unit only partially, to facilitate snap fit.

Alternatively, the ferrule may be screwed or welded to the drive unit and the component 6 supported on an adjustable collar. In the reverse case, the collar supporting the ferrule is applied to the instrument in a similar manner or the ferrule screwed or welded thereto. Stops or guides may be provided on the drive unit to limit or prevent movement of the collar in the axial sense.

The hollow component 6 may have a hollow, screw-threaded male portion which is screwed into the mouth of the feed duct in the body of the instrument, or be otherwise secured therein.

The ferrule 9 is of simple construction, consisting of a body through which a passage extends parallel to the axis of the drive unit. Tubes 15, 16 open into a chamber communicating with the passage, and in use have sleeved onto them flexible coolant supply tubes through which air and water are respectively supplied and mix before entering the tube 7. The internal surface of the passageway is undercut to form annular grooves at two axially spaced positions in order to receive toroidal sealing rings of known construction. During assembly of the instrument and drive unit, it is only necessary to align the coupling parts of both of these elements as well as tube 7 and ferrule 9, and push the two elements together. Fluid sealing of the tube 7 in the ferrule is achieved reliably by the contact of the rings 13 and 14 with its outer surface.

Instead of mixing the air and water in the ferrule, or in a chamber associated therewith, it is possible for a single tube to open into the ferrule and through which an air/water mixture is supplied from a mixing chamber elsewhere. It is also possible for there to be provided two separate ferrules to which air and water are respectively supplied and into which are inserted two parallel tubes 7 connected to a mixing chamber associated with the head of the instrument so that mixing of fluid is delayed until just before they are discharged.

As an alternative to feeding the coolant from the hollow component 6 to the head of the instrument by way of an internal duct 17 as is shown in Figure 2, the supply may take place by way of an external flexible tube 18 as shown in Figure 3. The construction shown in this Figure may be identical to that shown in Figure 2 so far as the construction and support for the ferrule is -concerned. However, in this embodiment, the metal component 6 is supported in a simple fashion on the instrument and may, in the simplest case, consist of a projecting bracket supporting the tube 7 which has a forwardly projecting portion 19, onto which the end of the flexible tube 1 8 is sleeved. The other end of the tube 1 8 is sleeved onto a metal tube carried by the head portion of the instrument, and through which the coolant is supplied to the nozzle.

Figures 4 to 6 show in greater detail an embodiment in which the drive unit and hand instrument are shown separated. No detailed description will be given of those parts corresponding to parts already described and which have the same reference numerals. The ferrule 9 consists of a metal body 22 carried by a collar 11 of generally U-shaped cross-section which can be snapped or slid onto the body of the drive unit and is held in place by a shoulder 12 formed thereon. The collar is of resilient construction so that it grips the drive unit but is capable of being adjusted angularly in position relative thereto. The body 22 of the ferrule has a hollow chamber 21 into which opens a passage in which is secured a single tube 1 5 for the supply of previously mixed air/water coolant.The chamber 21 has a stepped opening in the forward end of the body 22 so as to receive one or more seal rings held in place by a hollow clamping screw 23 having a bore of the same diameter as the smaller diameter portion of the bore 21.

The instrument is provided with a tube 7 projecting beyond the rear end face of the instrument from a hollow adapter 6 which (as in the case of the embodiment shown in Figure 2) may be screwed into the mouth of a duct internal of the instrument and through which the coolant is supplied to the head of the instrument. To fit the instrument and drive unit, it is necessary only to align the tube 7 and ferrule 9, and then slip the instrument onto the nose 20 of the drive unit.

During this movement, the tube 7 enters the bore 21 and is sealed thereto by the seal ring.

Of course, the invention is not limited to the exemplary embodiments described and shown, and modifications may be made within the scope of the appended claims.

Claims

1. A device for rigidly coupling ducts for the passage of coolant between a dental drive unit and dental instrument, said device comprising two hollow metal parts through each of which extends an internal duct, one part being carried by the drive unit and being connected with a coolant supply duct, and the other metal part being carried by the instrument and being connected with a feed duct through which coolant is fed to the head of the instrument, one of the parts comprising a ferrule, and the other comprising a tube adapted to fit into the ferrule.

2. A device according to Claim 1, wherein a first of the parts is carried by the instrument and is a fixture with respect to the instrument.

3. A device according to Claim 2, wherein the said first part carried by the instrument includes a tube extending beyond the end face of the instrument and having a terminal portion substantially parallel to the axis of the drive unit.

4. A device according to Claim 2, wherein the feed duct comprises a flexible tube extending externally of the instrument and coupled to the said first part.

5. A device according to any of Claims 1 to 3, wherein the feed duct extends internally of the instrument.

6. A device according to Claim 4, wherein the first part comprises a unitary tube having a portion onto which the said flexible tube fits and a portion for reception in the ferrule.

7. A device according to any preceding claim, wherein a second of the parts is supported by the drive unit so as to be adjustable angularly about the axis of the drive unit.

8. A device according to any preceding claim, wherein the ferrule has an internal chamber, fitted with at least one toroidal seal.

9. A device according to any preceding claim, wherein the ferrule is mounted on a clamping ring extending throughout the periphery of the body of the drive unit.

10. A device according to any of Claims 1 to 8, wherein the ferrule is mounted on a collar, partially surrounding the body of the drive unit and abutting against a shoulder of the drive unit to limit axial movement of the ferrule relative to the drive unit.

11. A device according to any preceding claim, wherein separate tubes for the supply of air and water are connected to the ferrule.

12. A device according to any of Claims 1 to 10, comprising a second ferrule and a second tube adapted to fit into the second ferrule.

1 3. In combination, a dental drive unit and a dental instrument adapted to be fitted thereto upon movement of the instrument relative to the drive unit parallel to the axis of the latter, a metal ferrule mounted on the drive unit, a coolant supply duct opening into the ferrule, and a metal tube mounted on the instrument, at least a portion of said tube extending parallel to said axis for reception in the ferrule, and a coolant feed duct connected directly or indirectly to said tube.

14. A device substantially as hereinbefore described with reference to and as illustrated in any of Figures 2 or 3 or 4, 5 and 6 of the drawings.