HK1199194B - Cannula and adapter for multi-function syringe - Google Patents

Description

Cannula and adapter for a multi-function syringe

Technical Field

The present invention relates to the field of dental equipment and instruments.

Background

Dentist offices are often outfitted with dentist chairs that include a number of instruments that are accessible while a practitioner bends over on a patient. In these instruments, the central element of the device is the injector for injecting air, water and air/water mixtures (multifunctional injector or air/water injector).

The function of the air/water injector is to deliver a constant flow of a selected fluid or fluid mixture to enable the practitioner to rinse and dry areas in the mouth depending on how the practitioner's intervention is performed. When using the air-only function of the syringe, it is particularly important that the blow air is completely dry to ensure good quality of the intervention.

There are a variety of different air/water injectors depending on the manufacturer of the dentist chair. These syringes are typically made of stainless steel, sometimes aluminum or synthetic resin. They have respective end pieces having a shape adapted to be inserted into the mouth of a patient and to point in the appropriate direction. Said end pieces are movable but not consumable, so that between two interventions, once they have been removed, it is therefore necessary to clean and sterilize the end pieces, which naturally constitutes an expensive and time-consuming task, but is not entirely reliable in terms of its results.

It has been proposed to replace the use of such non-consumable endpieces, which are difficult to clean and sterilize, by the use of disposable endpieces for single use only, which are easily mounted on the syringe between two patients. The use of such end-pieces has become more widespread in recent years, thus allowing the hygiene to be improved to the benefit of the patient and the practitioner.

Document WO92/04878 (which is directed to the problem of reducing the cost of manufacturing such a disposable end piece) therefore describes an assembly of a cannula and a metal adapter suitable for connection at a first end to a syringe of a given type and at a second end to a connection hub of a disposable cannula made of moulded plastic material. Male channels extending side by side project from the adaptor and during assembly are inserted into the openings of the female channels within the sleeve to deliver water and air thereto.

Those two components (i.e., the sleeve and the adapter) are oriented relative to one another by aligning the axial splines carried by the inner wall of the sleeve's liner with complementary grooves formed in the outer wall of the adapter. Once arranged in this way, the parts engage each other by means of a translational movement and, after a short stroke, the male channel engages in the female channel.

Nevertheless, said system shows the following drawbacks: initial set-up of the cannula and syringe is performed substantially only by eye by aligning the splines and grooves. If they are only aligned in a rough manner and if the user applies pressure too quickly, the parts engage each other while being slightly offset, thereby having the consequence that the male channel contacts the wall of the female channel. This can lead to the formation of shavings of plastic material which can block the passage and possibly cause deformation of the male passage, thus leading to malfunction of the multi-functional syringe.

Furthermore, the system assumes that the two parts (cannula and adapter) have an excellent dimensional fit to ensure that the pressure of the fluid does not separate the cannula from the syringe and out of the syringe, or even swallow by the patient. One option described in document WO92/04878 is to provide a plurality of resiliently deformable projections on the inner surface of the connection bush which are received in peripheral grooves of the adapter. Nevertheless, this solution makes it more difficult to place the cannula in the proper position.

Finally, the system of document WO92/04878 has the risk of twisting the male channel of the adaptor when removing the cannula. In view of the need to securely fasten the cannula to the syringe, the user needs to apply a certain amount of force to remove the cannula. The user may attempt to grip the tube proximate the hub and twist the tube to increase the grip on the cannula. This also has the consequence of twisting the male channel which engages in the female channel of the tube.

A cannula for a dental syringe is also known from document WO90/07912, said cannula being adapted to be fixed to the syringe with the aid of a bayonet-type coupling projecting radially outwards carried by the syringe or by an adapter. Such bayonet-type couplings cooperate with L-shaped tracks formed in the sleeve. More precisely, the track has an inlet section parallel to the longitudinal direction and a second section extending over an angular sector of the circumference of the casing at 90 ° to the inlet portion.

The practitioner initially assembles the bayonet coupling by: the cannula and syringe are moved relative to each other in the longitudinal direction until a butt joint is formed against the intersection between the two sections of track. Thereafter, the cannula and syringe are rotated relative to each other to the end of the second section.

It should be observed that the bayonet coupling system is not compatible with the channel of the sleeve as described in document WO92/04878, since in the case of channels arranged side by side in the sleeve, it is necessary to align the two parts before they are moved relative to each other in the longitudinal direction. Document WO90/07912 provides a different channel compatible with its proposed subsequent rotation, since it describes two channels that are coaxial.

Nevertheless, the two passages are only present in the outer part of the sleeve, not in the part connected to the syringe and/or to the adapter, so that it is necessary to have a gasket in an attempt to keep the air and water completely separated. Thus, depending on the arrangement of the gasket (which may differ with each time a new sleeve is put in place), and depending on the state of ageing of the gasket, it may become impossible to obtain completely dry air. Unfortunately, this completely dry air is necessary for performing certain operations of dentistry, which therefore causes significant problems when using the device.

Disclosure of Invention

In order to solve the various problems described above, a cannula for a multifunctional dental syringe is provided, the cannula comprising a fastener bushing defined by a circular opening, an end wall and a side wall comprising a circular cylinder, the cannula also comprising at least two channels enabling the passage of a fluid separately or together from the end wall to a fluid injection orifice, the two channels being adjacent to each other starting from the end wall, the cannula being characterized in that the circular cylinder comprises, in the thickness of the wall, a cut comprising at least one transverse segment (i.e. a segment disposed crosswise with respect to the axis of the cylinder) (in other words extending in a direction different from the direction of the axis of the cylinder) starting at the opening, followed by a longitudinal segment parallel to the axis of the cylinder and oriented towards the end wall.

A cutout in the thickness of the wall is used to receive a peg carried by the side wall of the fastening cylinder of the multi-purpose syringe or adapter. The longitudinal section serves to guide the rotation of the cannula about the axis until the male passage carried by the syringe is perfectly positioned on the cylinder with respect to the plug and aligned with the female passage in the cannula. This may potentially overcome a user's potentially poor verification of how the components are joined together. Once the transverse segments have performed their guidance, the longitudinal segments enable the components to engage until the components are secured together. In summary, the male and female channels are aligned by a mechanical and therefore more reliable means than prior art eye-only examinations.

These characteristics avoid any scrap of plastic material formed when the sleeve is put in place, and also any deformation of the passage protruding from the syringe. The working life of the syringe is extended and the operations performed by the practitioner are simplified.

Finally, the quality of various fluids is completely met. The system is therefore more reliable, more hygienic, simpler and more reliable to use.

These advantages constitute a significant improvement over the disclosure of document WO92/04878, which cannot be obtained on the basis of the teachings available elsewhere, in particular on the basis of the teachings of document WO 90/07912. In particular, WO90/07912 proposes coaxial channels, which is very different from parallel channels that open adjacent to each other in the bushing of the invention. Furthermore, WO90/07912 does not propose abutment positions that resist translational movement, nor does it propose two distinct abutment positions as in certain embodiments of the invention.

Advantageously, the cut-out comprises an abutment opposing movement in a direction away from the end wall.

By means of said abutment, any risk of the sleeve separating under the effect of the pressure generated by the injected fluid is avoided, even if the manufacturing tolerances of the diameter of the bush are high. This avoids any risk of the cannula being swallowed by the patient.

For example, the abutment that resists translational movement comprises a local constriction in the cut-out. Thus, the cannula is locked on the syringe and does not move when it is used by the practitioner. This serves to facilitate manufacturing since tolerances in the diameters of the components can be greater.

Preferably, the width of the cut-out varies more sharply alongside the second position relative to the abutment against translational movement of the local constriction than alongside the opposite side. This makes it easier to place the sleeve in place.

Advantageously, the cut-out has a chamfered opening. This enables the adapter bolts to be guided towards the inside of the cut-outs even if the user poorly aligns the components by quickly handling them.

Advantageously, the sleeve comprises a reinforcement on the outside of the bush aligned with the opening of the cut. Such reinforcements are used to ensure the mechanical cohesion of the part.

It is also advantageous that the opening of the passage in the end wall is chamfered. Thus, even if the male channel of the adaptor is poorly positioned relative to the female channel of the sleeve, interengagement is facilitated by the guidance provided by the chamfer.

In an advantageous embodiment, the passage is reinforced in the vicinity of the bushing, for example by a bracket. Thus, when the male channel is engaged in the female channel, the male channel is not at risk of being twisted by a user who intends to detach the sleeve and twist it in an untimely manner: the bracket serves to prevent any such twisting.

In another advantageous aspect, the sleeve comprises a gripping area around the tube in which the channel is embedded, thereby providing a larger gripping surface than the tube itself. Thus, when the cannula is removed, the user applies a force in a controlled manner.

In a second aspect of the invention, there is provided an adapter for fastening a disposable cannula to the end of a multi-function dental syringe, the adapter having an end with the general shape of a circular cylinder and terminating at a portion where at least two channels project adjacent to each other, the adapter being characterized in that a peg projects partially from a side wall of the end. Such adapters are used to secure the above-described disposable cannulas to multi-function syringes.

Drawings

The present invention is described with reference to the following drawings.

FIG. 1 is a three-quarter view of a cannula in one embodiment of the invention.

FIG. 2 is an interior view of the fastener bushing of the bushing of FIG. 1.

Fig. 3 is a view of a first embodiment of the adapter of the present invention.

Fig. 4 is a view of a second embodiment of the adapter of the present invention.

Fig. 5 is a detailed view of a cut-out of a liner of the cannula of fig. 1 and 2.

Fig. 6 is a second detailed view of the same incision.

Fig. 7 is a view of the cannula of fig. 1, 2, 5 and 6 from a different angle.

Fig. 8 shows a second embodiment of the invention.

Fig. 9 is a second view of the bushing of fig. 1-7.

Detailed Description

Fig. 1 shows a cannula 1000 in one embodiment of the invention. It is a molded plastic part, the individual elements of which are made as a single piece. For fastening to a multi-function dental syringe via an adapter. For example, its overall length is about 5.5 centimeters (cm).

In a first approach, the casing 1000 is made up of two main parts, namely a tube 1100 and a liner 1200.

The tube 1100 has an elongated cylindrical shape. It is oval in cross-section, containing two parallel holes extending along its entire length, forming channels 1120 and 1125 for the fluid injected by the syringe. The channels are of similar diameter and they are arranged side by side.

The end of the tube 1100 remote from the bushing 1200 is free and may have a rounded chamfered shape (see cross-section of fig. 9). The surface of the end constitutes a section of the tube 1100 inclined with respect to the axis of the tube 1100. The end has two orifices for injecting air and water as fluids from the cannula into the patient's mouth. In certain embodiments, the channels 1120 and 1125 have specific internal structures proximate to the injection orifice suitable for forming a combined air and water spray when air and water are injected together.

The bushing 1200 is generally in the form of a hollow circular cylinder having the same axis as the tube 1100 and having two ends with circular portions 1210 and 1220, a first end being hollow and a second end being solid. The sidewall of the bushing 1200 has a thickness of, for example, about 1 millimeter (mm). The diameter of the bushing is slightly larger than 1cm, and these dimensions may vary.

The tube 1100 is fastened at right angles to the centre of the portion 1220 of the bushing 1200.

The sleeve 1000 also has reinforcing and engagement members with reference numerals 1290, 1300 and 1400 which are described with reference to the following figures. The sleeve 1000 has in a significant way a cut D in the wall of the bushing. The incision is described in more detail below.

Fig. 2 shows the interior of the fastener bushing of the sleeve 1000. Which is viewed through its open portion 1210. The tube 1100 is visible from the rear.

The side walls of portion 1220 are visible at the bottom of bushing 1200. The wall 1220 is pierced by the openings 1230 and 1235 of the channels 1120 and 1125. These openings 1230 and 1235 are disposed near the center of wall 1220, aligned with tube 1100.

Advantageously, openings 1230 and 1235 are also chamfered, for example, at an angle of about 45 °.

There are splines 1240 on the interior of the bushing 1200, which splines 1240 act as a snap member to more easily place the cannula in place on the syringe. The splines begin in contact with the wall 1220 and extend longitudinally, terminating approximately two-thirds along the liner 1200. Spline 1240 has a width of about 10. The splines are terminated by rounded ends. The splines also have a flat surface facing the axis of the bushing 1200.

The sidewall of the bushing 1200 has a cut-out D radially therethrough in a particularly pronounced manner. The cut is limited to a small angular sector of the bushing 1200, occupying about 20 °. The origin of the cut D in the open part 1210 can be seen by reference numeral 1250, which reference numeral 1250 denotes the opening of the cut in the open part 1210. On each side of said opening 1250, the walls of the bushing 1200 are chamfered, for example, at an angle of 45 °.

The precise shape of the cut D is described in more detail below with reference to the following drawings.

The reinforcement 1290, which in the depicted embodiment is shown as perfectly circularly symmetric, is present on the outer surface of the bushing 1200, particularly over the opening 1250, in alignment with the portion 1210. The reinforcement may have a thickness of about 1mm in the longitudinal direction and about 1mm in the radial direction.

Fig. 3 shows a first embodiment of the adapter of the present invention for cooperation with the sleeve 1000 shown in fig. 1 and 2. The adapter is made of stainless steel, or aluminum, or indeed synthetic resin. Which is composed of two parts arranged consecutively in the longitudinal direction.

The first part 2100 is a part for fastening to a multi-function dental syringe. Which is dedicated to a given type of multi-functional dental syringe as provided by a given manufacturer of dentists chairs.

The second part, designated 2200, is a part intended to be fastened to a bushing of the type shown in figures 1 and 2. It is a generally rotating body, generally cylindrical, with a free end constituting a flat part of the right side of the cylinder. Male metal channels protrude from this end and are adapted to engage in openings 1230 and 1235 of the channels in sleeve 1000. Longitudinal slot 2230 is adapted to receive spline 1240 of sleeve 1000.

Finally, the pegs 2240 project in a conspicuous manner locally over a given angular sector of the cylinder and radially from the wall of the portion 2200. The pegs 2240 are adapted to engage in the cutouts D of the sleeve 1200 via the openings 1250.

In fig. 4, there can be seen an adaptor 3000 according to a second embodiment of the present invention. In a similar manner to the adapter 2000 shown in fig. 3, the adapter 3000 has a first portion 3100 that enables it to be fastened to the end of a particular multi-function dental syringe supplied by a given dental chair manufacturer.

Adapter 3000 also has a section 3200 for securing to cannula 1000. Section 3200 is substantially similar to section 2200 described with reference to figure 3.

Referring to fig. 5 and 6, a detailed description of the shape of the cutout D existing in the wall of the bushing 1200 is as follows. The cutout is approximately diametrically opposite spline 1240.

The cut D starts at the portion 1210 via the opening 1250 and has a first section of constant width extending in the longitudinal direction of the bushing. The segment is labeled 1260 in fig. 6. Followed by a second segment 1265 at right angles to the first segment 1260, and thus extends circumferentially relative to the liner over a sector of liner angles occupying about 10 degrees. The segment 1265 continues to be of constant width. Followed by a third elongate section, designated 1270, which is at right angles to the second section and extends in a longitudinal direction towards the tube 1100 similar to the first section 1260.

The third segment 1270 has a length that is substantially twice the length of the first segment 1260. Terminating in a closed end 1272. The segment 1270 has a constant width over a substantial portion of its length. However, as the end 1272 is approached, it has two projections in its two walls which produce a narrowing of the cut width at the location of the projections.

The angle 1262 between segments 1260 and 1265 defines an abutment position where the pegs 2240 or 3240 that penetrate into the cut move translationally when the practitioner places the cannula on the syringe. The abutment position may cause the male passageway carried by the syringe or adapter to remain unengaged during initial engagement of the two components, which may be poor for the user, particularly in terms of angular alignment between the sleeve and the syringe.

The angle 1267 between the segments 1265 and 1270 also defines an abutment location that is a location that prevents rotational movement of the pin when the cannula is set in place. Said abutment positions, which represent the guiding function of the segments 1265, make it possible to ensure the angular alignment of the cannula and the syringe and, consequently, of the male and female channels, which is achieved mechanically in a more efficient manner than the purely visual alignment of the prior art.

The segments 1270 enable the male channels to be inserted into the female channels provided they are correctly positioned at this stage.

The angle 1267 between the segments 1265 and 1270 also defines the abutment position that resists translational movement of the peg when the cannula 1000 is detached from the syringe. This aspect constitutes a safety feature to prevent a poorly installed cannula from falling into the patient's mouth driven by an injected stream of liquid or air.

Fig. 7 shows the cannula 1000 in a side view. The tube 1100 and liner 1200 can be seen. The following is a description of the engaging and reinforcing elements that can be seen in the above-mentioned figures.

The sleeve 1000 advantageously has an arch 1300 originating from two diametrically opposed points of the portion 1220 of the bushing 1200. The arch 1300 defines a plane perpendicular to the portion 1220. The long dimension of the portion of the tube 1100 lies in the plane. The interior of the dome 1300 includes a material surface surrounding the base of the tube 1100 which constitutes an additional grip for a user intended to manipulate the cannula, particularly to remove the cannula from the syringe. The user may place a thumb on one side of the arch and a finger on the other side of the arch, thereby providing a large surface for grasping the cannula.

Two corner brackets 1400 are provided perpendicular to the plane of the arch 1300 between the tube 1100 and the wall of the portion 1220. These braces constitute reinforcement at the junction between the tube 1100 and the liner 1200. They oppose twisting of the tube 1100 about an axis parallel to the long direction of the portion of the tube 1100. For example, the two brackets 1400 are disposed symmetrically to each other about the axis of the bushing.

The height of the arch 1300 is about one-fifth the height of the tube 1100. The height of the bracket 1400 is approximately one-quarter of the height of the arch 1300. These ratios may vary.

In one variation, the bushing 1200 is not only comprised of a hollow cylinder, but also includes a hollow frustum between the hollow cylinder and the tube 1100. Such a taper may match a complementary shape at the end of the adapter. The opening of the female passage is provided in the end wall of the vertebral body and the male passage of the adaptor is provided at the end of the complementary shape.

In another variant, possibly combined with the above variant, the cut in the wall of the cylinder does not pass through the wall, but only constitutes a groove in the inner surface of the wall.

In another embodiment, the cut-out is in the outer surface of the wall and the sleeve cooperates with an adapter having a further outer cylinder with inwardly directed pegs.

Furthermore, in another embodiment of the incision, as shown in fig. 8, the incision comprises only two segments: the segments 1260 and 1265 are replaced by a single segment 2265, which single segment 2265 extends transversely along the cylinder but not perpendicular to the axis of the cylinder (e.g., at an angle of 45 °). Similar to section 1265 in the embodiment of fig. 6, its function is to guide angular movement of the cannula and syringe relative to one another. A longitudinal segment 2270 similar to segment 1270 enables the components to engage one another until they are secured to one another. Splines 1240 and grooves 2230 are sized to be compatible with the travel defined by segments 2260 and 2270.

The invention is not limited to the described embodiments but extends to any variant which comes within the scope of the claims.

Claims (10)

1. A cannula for a multi-functional dental injector, the cannula comprising a fastener bushing defined by a circular opening, an end wall and a side wall comprising a circular cylinder, the cannula also comprising at least two channels enabling fluid to be conveyed separately or together from the end wall to a fluid injection orifice, the two channels being adjacent to each other starting from the end wall, the cannula being characterized in that the circular cylinder has a cut in the thickness of its wall, the cut comprising at least one segment starting from the opening extending in a direction different from the axial direction of the cylinder followed by a longitudinal segment extending towards the end wall.

2. The cannula of claim 1, wherein the cutout comprises an abutment adapted to resist movement away from the end wall.

3. The cannula of claim 2, wherein the abutment comprises a local constriction in the cut-out.

4. A cannula according to claim 3, wherein the longitudinal section has a constant width over a major part of its length, but when approaching its terminating closed end it has a protrusion from both walls which narrows the width of the slit in alignment therewith, the width of the slit changing more sharply on the locally narrowed end wall side than on its opposite side.

5. The cannula of claim 1, wherein the cutout has a chamfered opening.

6. The cannula of claim 1 including a reinforcement on an exterior of the bushing aligned with the opening of the slit.

7. A sleeve according to claim 1, wherein the opening of the passage in the end wall is chamfered.

8. The cannula of claim 1, wherein the passageway is reinforced adjacent the hub by a brace.

9. A casing according to claim 1, comprising a gripping zone around the tube in which the channel is embedded, adjacent the liner, thereby providing a greater gripping surface than provided by the tube itself.

10. An adapter for fastening a cannula according to any of claims 1-9 to the end of a multi-functional dental syringe, said adapter having an end having the general shape of a circular cylinder and ending at a portion where at least two channels project adjacent to each other, characterized in that a peg projects locally from the side wall of the end and is adapted to engage in a cut-out of a fastener bush of such a cannula, the cannula and the syringe being guided in mutual angular movement, after which the parts are mutually engaged in the longitudinal direction until they can be fixed to each other.