BUILT-IN MIXER FOR SPRAYING

Abstract

The present invention relates to a dental handpiece (1) equipped with an integrated internal spray device comprising a first, water-conveying channel (171) and a second, air-conveying channel (172), and also a combined outlet channel (14) which opens onto a single spray orifice (15) for spraying a mixture of air and water, characterized in that it comprises an air-water mixing element (2) having a first, water supply duct (21) capable of being connected to the first, water-conveying channel (171) and a second, air supply duct (22) capable of being connected to the second, air-conveying channel (172), and in that the first, water supply duct (21) and the second, air supply duct (22) open into a main duct (24) of the air-water mixing element (2) at a junction zone (23) between the first, water supply duct (21) and the second, air supply duct (22).

Description

[0001] Integrated mixing device for spray

[0002] Technical field of the invention

[0003] The present invention relates to the field of handpieces provided with a mixed air-water spray, and more particularly to contra-angles provided with such an integrated spray device.

[0004] State of the art

[0005] Dental devices (turbines, contra-angles and straight handpieces) are generally equipped with internal sprays, allowing the working area to be cooled, i.e. the region of the tooth subjected to the action of the cutting, milling or prophylaxis / cleaning tool. Since friction between the working tool and the dental tissue (enamel and dentin) is a significant source of heat, the presence of sprays is essential to avoid necrosis of the dental tissue and / or burning of the patient's oral mucosa. The internal sprays of dental devices are therefore intended to protect the patient during treatment. In addition, the spray allows the debris generated during treatment to be evacuated, allowing for better quality work.If the user (dentist or dental assistant) does not have a device equipped with an internal spray, he or she is forced to use an external irrigation system, which considerably complicates dental treatment (management of two independent instruments, lack of space in the patient's oral cavity).

[0006] High-speed devices (air turbines or motorized contra-angles with speed multipliers) of the mid- and high-end range are generally equipped with 3 or 4 spray outlets, in which air and water are supplied in dedicated channels (typically for the mid-range) or mixed (high-end). In the case of separate sprays in the head of the device, there are 3 or 4 openings for the water outlet and 3 or 4 openings for the air outlet: the presence of several openings directed in an optimized way allows to obtain an effective irrigation of the tool (bur) attached to the head of the dental device thanks to the fact that the air separates the water jet into droplets that are deposited on most of the surface of the bur and flow inside the milled dental tissue. However, the presence of macroscopic water droplets can reduce the visibility of the dental practitioner in the working area.

[0007] For this reason, the irrigation and cooling efficiency, as well as the visibility, are logically improved by mixed sprays: in this case, the water-air mixture is made inside the head of the device, in a component called "diffuser" which also integrates the 3-4 openings allowing the water-air mixture to exit. In this case, the spray (which is a stationary mixture of water and air) manifests itself rather as a relatively homogeneous mist or aerosol, where the water is present in the form of microscopic droplets or micro-droplets.

[0008] These types of systems with multiple spray outlets are effective, especially for mixed sprays, created directly in the head of the device through the diffuser. However, they are also expensive and difficult to manufacture. Furthermore, the diffuser design is very complex because it is necessary to ensure that the flow rate of the 3 or 4 spray outlets is relatively uniform, avoiding excessive turbulence.

[0009] For lower speed devices, especially direct drive contra-angles (multiplication ratio 1:1) and / or entry-level devices, the internal spray is often reduced to a single air outlet and a single water outlet at the head, without adopting a diffuser integrated into the head of the device. This is mainly due to the fact that the lower rotation speed does not require such efficient cooling of the working tool (bur). It is therefore permissible to carry out direct irrigation of a single angular sector of the working area, relying solely on the diffusion generated by the rotation of the bur.

[0010] These systems with two independent outlets, i.e. one for air and one for water respectively, are significantly less expensive and much simpler to design and manufacture, but they are functionally limited because the irrigation quality is modest: the air and water cannot mix effectively outside the device before reaching the cutter and therefore the water jet is not separated into droplets, which makes the cooling of the cutter inhomogeneous and generates a significant obstacle to the visibility of the work area.

[0011] For this reason, a compromise was sought by providing an air-water mixture inside the handpiece, thus not needing to integrate a diffuser housed in the head of the device, and where single outlets of mixed air-water spray are provided in the head or near the head of the device. Patent document WO95 / 12361 describes such a solution where the air-water mixture is made via an adapter housed at the rear of the handpiece body, at the connection with the motor. This component integrates two inlet tubes for air and water, and a conduit having a "V" shaped section, the two tubes opening into the conduit which communicates with an outlet channel opening obliquely into the head and spraying the air-water mixture towards the bottom of the bur.

[0012] The solution for a dental irrigation system in document FR2570268 similarly includes air and water inlet pipes opening into an air and water mixing pipe, the mixture also being conveyed to a spray orifice provided in the head. However, these pipes are provided outside the body of the handpiece, which makes this solution relatively unergonomic.

[0013] These last two solutions, operating on the basis of a mixture of air and water, make it possible to obtain a mist at the spray outlet, but only for very specific air and water pressure conditions. This technical limitation is due to the fact that the air-water mixture pipe is either too long, or the relative orientation of the pipes and the arrangement of their junction is not suitable and thus generates turbulence. The output spray flow rate can thus be considerably reduced and prove insufficient to ensure effective irrigation. It then becomes necessary to force the practitioner to regulate his dental unit specifically for such devices, which is inconvenient. There is therefore a need for solutions free from these known limitations.

[0014] Document JP2011097984 further discloses a spray solution with a mixing zone between the air and water channel at the spray orifice near the head; document CA1166490 similarly relates to a mixed delivery system via a spray chamber located near the head.

[0015] Document FR2570268 concerns a dental irrigation system conveying a mixture of air and water for diffusion via a spray nozzle directly into the head; the channels are however arranged outside the body of the handpiece.

[0016] Summary of the invention

[0017] An aim of the present invention is to provide a spray of improved quality compared to the solutions of the prior art.

[0018] Another object of the present invention is to provide a mixing device which does not require enlargement of the head size and which is simple in design.

[0019] Yet another object of the present invention is to provide a spray solution using a single outlet mixer having a more optimized operating range with respect to air and water pressure.

[0020] These aims are achieved by the features of the main claim, and in particular by a dental handpiece equipped with an integrated internal spray device comprising a first water delivery channel and a second air delivery channel, as well as a mixed outlet channel opening onto one or more single spray orifices for a mixture of air and water.The integrated internal spray device is characterized in that it comprises an air-water mixing element comprising a first water supply pipe capable of being connected to said first water supply channel and a second air supply pipe capable of being connected to said second air supply channel, and that the first water supply pipe and the second air supply pipe open into a main pipe of the air-water mixing element capable of being connected to the mixed outlet channel at a junction zone between the first water supply pipe and the second air supply pipe.

[0021] An advantage of the proposed solution is that it ensures the formation of a more homogeneous mist compared to existing solutions using a single spray orifice of an air-water mixture.

[0022] Another advantage of the proposed solution is to achieve quality mixing outside the head of a contra-angle, a straight handpiece or a dental turbine according to a relatively simple and modular design compared to existing standards, in particular for coupling to the motor parts of a contra-angle or for coupling a turbine to the air injection hose or a quick connector. Furthermore, such a configuration allows both to reduce the size of the head and therefore facilitate access to the patient's oral cavity, but also to simplify the conception and design of a handpiece with integrated diffuser.

[0023] Yet another advantage of the proposed solution is that it allows for an extended operating range, allowing the same air and water pressure settings of a dental unit to be used for several different devices.

[0024] According to a preferred embodiment for the dental handpiece equipped with an integrated internal spray device according to the invention, at least one pipe among the first water supply pipe and the second air supply pipe of the air-water mixing element has a bent portion forming an angle of between 10° and 80° relative to the other pipe among the first water supply pipe and the second air supply pipe at the junction zone. Such a configuration allows for better fluid flow, in particular at the junction zone, i.e. the confluence of the two air and water supply pipes, and also improves the efficiency of cleaning and degreasing of machining oils.

[0025] According to an even more preferred embodiment for the dental handpiece equipped with an integrated internal spray device according to the invention, the second water supply pipe has a bent part and opens directly into said first air supply pipe arranged in a completely rectilinear manner.

[0026] Such an implementation variant has shown surprisingly effective results in terms of stability of the air-water mixture compared to a solution or vice versa, where the air pipe is bent and the air is injected into the water. It generates a minimum of turbulence and provides maximum flexibility in terms of parameterization for regulating the flow rate of the resulting mixture.

[0027] According to another even more preferred embodiment for the dental handpiece equipped with an integrated internal spray device according to the invention, the first water supply line and the second air supply line each have respectively a first bent part and a second bent part and form, with the main duct of the mixing element, a totally symmetrical Y.

[0028] Such a variant has the advantage of being the easiest to machine, and, thanks to the minimization of the angles of each of the bent parts, of remaining particularly easy to clean and degrease from machining oils.

[0029] According to another preferred embodiment for the dental handpiece equipped with an integrated internal spray device according to the invention, at least one element chosen from the first water supply line and the second air supply line does not have a constant section and has a narrowing at the junction zone. Such a variant aims to maximize the Venturi effect at the junction, and is therefore to be favored with a variant where it is the air supply line which is bent, and not the water line, in order to maximize the efficiency of the air suction.

[0030] According to another preferred embodiment for the dental handpiece equipped with an integrated internal spray device according to the invention, the air-water mixing element is arranged in the form of a modular part held in a rear body of a rear gripping part of the dental handpiece.

[0031] Such an implementation variant is particularly advantageous because it allows a modular arrangement of the air-water mixing element as a wear part that can be easily replaced during use if necessary, and also easily mounted and dismounted. Furthermore, this wear part is advantageously arranged far from the tool head in order to minimize the space requirement at this point of the handpiece.

[0032] According to an even more preferred variant for the dental handpiece equipped with an integrated internal spray device according to the invention using a modular air-water mixing element, the latter is suspended by an O-ring seal.

[0033] This implementation variant is therefore particularly simple, as the O-ring is only intended for sealing purposes.

[0034] According to an even more preferred variant for the dental handpiece equipped with an integrated internal spray device according to the invention using a modular air-water mixing element, an outlet pipe intended to convey the air-water mixture to the spray orifice is driven into the main spray pipe. In this case, a second O-ring seal can advantageously be positioned around the outlet pipe at the location of the driving, to ensure the sealing of the connection between the main spray pipe and the outlet pipe. Such an implementation variant greatly facilitates assembly and disassembly operations as a replacement for the air-water mixing element, and it also guarantees optimal interoperability with respect to standard parts such as tubes or channels usual for handpieces which can constitute the outlet pipe.

[0035] According to yet another more preferred variant for the dental handpiece equipped with an integrated internal spray device according to the invention using a modular air-water mixing element, the latter is fixed to the rear body of the dental handpiece and an outlet pipe made of an elastic material is glued to said modular air-water mixing element (2).

[0036] Such a variant further facilitates assembly operations and makes it easy to recover operating clearances between the different parts to be assembled.

[0037] According to yet another more preferred variant for the dental handpiece equipped with an integrated internal spray device according to the invention using a modular air-water mixing element, the latter is oblong in shape, extending in a direction substantially perpendicular to that defined by the air-water mixture outlet pipe.

[0038] Such a configuration makes it possible to minimize the radial size in the handpiece as much as possible, in order to be able, for example, to have other channels provided for example for optical fiber or even a cooling channel for the kinematic chain in the context of a contra-angle; moreover, the minimization of the size necessary to produce the mixed internal spray device according to the invention makes it possible to maximize the size of the teeth and therefore the transmission efficiency, still in the context of a contra-angle.

[0039] According to yet another more preferred variant for the dental handpiece equipped with an integrated internal spray device according to the invention using a modular air-water mixing element, the latter is characterized in that it is produced as a single-piece part. Such a configuration significantly improves the ease and simplicity of machining such a part essential for the implementation of the invention.

[0040] According to an even more preferential variant for the production of an air-water mixing element in monobloc form, the latter can preferably be produced by 3D printing.

[0041] This variant allows to further optimize the geometric shape and cross-section of the pipes better than by molding and / or hollowing operations, and with any type of material, i.e. not only with plastic materials, but also with metallic materials.

[0042] According to an even more preferred variant for the implementation of the invention, not only the air-water mixing element by 3D printing, but also a chassis provided with integrated pneumatic lines are produced by 3D printing, as a single piece.

[0043] Such a configuration thus makes it possible to optimize the geometric characteristics of all the parts likely to be provided with pipes, and to preferably make them all from metallic materials and not just plastics. It may be noted that according to such a variant, it is possible to make not only the chassis and the mixing element separately each in a single piece, but possibly even to configure almost the entire handpiece in a single piece, that is to say a mixing element integrated directly into the chassis, and the latter possibly coated with external caps provided for the gripping of the tool by the dental practitioner. Such a variant thus makes it possible to considerably simplify the assembly operations of the handpiece.

[0044] According to yet another preferred embodiment for the dental handpiece equipped with an integrated internal spray device according to the invention, the air-water mixing element is preferably positioned substantially equidistant from the two ends of said handpiece. According to such a variant, the positioning of the air-water mixing element is optimized to the extent that the transit time of the air-water mixture is not too long with respect to the head, but its location is sufficiently far from the motor connection interface at the rear despite everything to allow coupling to standard tools (the coupling nose of dental motors is a few centimeters, generally between 1.5 and 3.5 centimeters). Such a configuration is also advantageous because it makes it possible to minimize vibrations and noise generated at the head because the air-water mixing element is isolated towards the center of the handpiece.

[0045] According to yet another preferred embodiment for the dental handpiece equipped with an integrated internal spray device according to the invention, the air-water mixing element is positioned in the rear body of the rear gripping part at a predetermined distance from the rear end of said handpiece. This predetermined distance is preferably equal to at least 2 centimeters.

[0046] In this way, whether the mixing element is arranged as a wear part or directly in a single piece with respect to the rest of the handpiece casing, it is then advantageously arranged on the one hand sufficiently far from the head of the tool to minimize the space requirement at this location, but also sufficiently far from the motor connection interface to guarantee full compatibility with existing standards.

[0047] Brief description of the drawings

[0048] The present invention will be better understood on reading the following description, given by way of example and with reference to the drawings in which:

[0049] - Figure 1A is a sagittal half-sectional view of a handpiece provided with a mixing element according to a preferred embodiment for the present invention, where only the rear body of the rear gripping part of the handpiece comprising the mixing element arranged here in the form of a modular part is seen in section (the front of the handpiece, including the head and the cutter which is to be mounted thereon, being shown in the form of an external view);

[0050] - Figure 1B is a sagittal sectional view of the handpiece of Figure 1A, showing the detail of the mixing zone M surrounding the mixing element which is represented therein in dotted lines;

[0051] - Figure 1C is a view of the handpiece of Figures 1A and 1B from the rear, highlighting the section plane EE used for Figure 1A;

[0052] - Figure 2A is a sagittal sectional view of a mixing element according to another preferred embodiment for the present invention, the latter being in the form of a fully symmetrical Y;

[0053] - Figure 2B is a sagittal sectional view of a mixing element according to a variant for implementing the present invention, in which the water and air supply pipes do not have a constant section and have a narrowing at the junction zone;

[0054] - figure 3A illustrates a mixing element produced according to a particularly preferred embodiment where it is produced in a single piece via 3D printing and has an oblong shape, seen in profile in three dimensions;

[0055] - Figure 3B illustrates the same single-piece mixing element as that illustrated in Figure 3A, but seen from the side and highlighting the internal conduits (shown in dotted lines);

[0056] - Figure 3C illustrates a three-dimensional external view of a handpiece in the rear portion of which is integrated the mixing element of Figures 3A & 3B; - Figures 4A and 4B illustrate an alternative embodiment for the present invention using a straight handpiece, Figure 4A constituting a half-sectional view - similarly to Figure 1A for a contra-angle - and View 4B a view from the rear, highlighting the section plane BB used for Figure 4A.

[0057] Detailed description of the invention

[0058] In the following, a preferred embodiment for the invention will be described in connection with Figures 1A, 1B and 1C which represent 3 different views of a handpiece 1 here taking the form of a contra-angle. Figure 1A is a sagittal half-sectional view of such a handpiece 1 provided with an air-water mixing element 2 arranged in the rear body 122 of the rear gripping part 12 of the contra-angle. The air-water mixing element 2 arranged here in the form of a modular part is seen in section at a mixing zone M detailed later in Figure 1B, while the front of the handpiece, including the head 13 and the cutter 10 which must be mounted therein, are shown in the form of an external view. Figure 1C is a view of the handpiece of Figures 1A and 1B from the rear, highlighting the section plane EE used for Figure 1A.

[0059] The left of Figure 1A highlights the fact that the handpiece 1 according to the invention comprises an integrated spray device with a single mixed outlet channel 14 into which air and water are introduced. This mixed outlet channel 14 is visible in dotted lines inside the front gripping part 11 of the handpiece 1, and it ends in a spray orifice 15 at the working area in the direction of the cutter 10. Positioning the air-water mixing element approximately in the middle of the handpiece 1, and in this case rather in the middle of its rear gripping part 12 and not in the head 13 or in the handle near the head, makes it possible to design an optimal solution without space problems.Indeed, the handle - that is to say the front gripping part 11 - and the head 13 of a dental device generally have a diameter of less than 1 cm because this part of the device must easily enter the patient's oral cavity, whereas the external cap 121 rear gripping part 12 has a diameter of 2 centimeters. Furthermore, arranging the air-water mixing element 2 too far to the rear of the handpiece 1, at the connection of the handpiece with the motor (that is to say the motor connection interface 120 illustrated in FIG. 1A) or more generally at the connection of the turbine to the pipe or to the quick connector, has the disadvantage of having to adapt the design of the mixing element to the design of the connection which is standardized (ISO3964 standard for motorized devices and ISO9168 for turbines).For this reason, it is advantageous to maintain two separate conduits between the connection zone and the middle of the handpiece 1, or at least the middle of the rear gripping part 121, in order to end up in the zone with the largest diameter.

[0060] Thus, according to the example illustrated, the air-water mixing element 2, that is to say more precisely the rear thereof, is located at a first predetermined distance D1 from the rear end of the handpiece 1 at the motor connection interface 120, which is preferably equal to at least 1.5 centimeters, and preferably 2 centimeters, in order to be compatible with the connection standards in force mentioned above (ISO3964 and ISO9168). In this figure, the first predetermined distance D1 is of the order of approximately 3 centimeters.

[0061] At the same time, the air-water mixing element 2, that is to say more precisely the front thereof, is also located at a second predetermined distance D2 from the front of the rear gripping part 12 of the handpiece 1, preferably equal to at least 2 centimeters, so that the air-water mixing element can be positioned substantially in the center of the rear gripping part 12 of the handpiece 1, where the space constraints are the lowest.

[0062] On the right of Figure 1A, it is thus easy to visualize the water conveyance channel 171 towards the mixing zone M in the middle of the rear gripping part 12 of the handpiece 1, and the air conveyance channel 171. According to the preferred embodiment described, the air-water mixing element 2 is mounted in the rear body 122 of the rear gripping part 12 of the handpiece 1, which constitutes the internal chassis, and around which is mounted the external cap 121 which is intended to be grasped and manipulated by the dental practitioner. On the left, the outlet pipe 16 is intended to convey the air-water mixture which has been generated thanks to the mixing element described later with the aid of Figure 1B, which shows the detail of the mixing zone M indicated in Figure 1A.Figure 1B shows that the air-water mixing element 2 is formed of a modular element, that is to say constituting a part intended to be mounted inside the rear body 122 of the handpiece 1. This air-water mixing element 2 allows the confluence between the two flows of air and water conveyed separately at the inlet via a water conveying channel 171 and an air conveying channel 172 arranged respectively in the rear body 122 of the handpiece. This confluence takes place at a junction zone 23 where a first water supply pipe 21 connected to the water conveying channel 171 and a second air supply pipe 22 connected to the air conveying channel 172 meet, to open at the outlet onto a main spray pipe 24, connected to a mixed outlet pipe 16 intended to convey the air-water mixture towards the head 13.The first water supply pipe 21, the second air supply pipe 22, and the main pipe 24 thus form an asymmetrical “Y”. The sealing of the system is guaranteed in a particularly simple manner by the presence of an O-ring seal 25 arranged in a peripheral annular groove 251.

[0063] According to the preferred embodiment described, the first water supply pipe 21 has a bent portion C while the second air supply pipe 22 is completely straight. Such a configuration makes it possible to improve the properties of the air-water mixture. Preferably, the angle α formed between the bent portion C of the first water supply pipe 21 and the second air supply pipe 22 at the junction zone 23 is preferably between 10° and 80°, and according to an even more preferred variant, between 20° and 70° in order to facilitate the flow of the fluid in the bent portion C and also facilitate the cleaning of the latter and degreasing after machining.According to the proposed configuration, it can be noted that the same angle a is also found at the top between the bent part C of the water supply pipe 21 and the connecting part of the latter with the second air conveying channel 172, the latter being parallel with the first water conveying channel 171 connected to the second air supply pipe 22 of the air-water mixing element 2 which is arranged in a completely rectilinear manner. Thus the level of angulation of all internal pipes of the air-water mixing element 2 remains sufficiently low so as not to disturb the flow of fluid and to allow easy and effective cleaning of the interior thereof.

[0064] As can be seen on the left of Figure 1 B, the main spray duct 24 is also completely rectilinear, and of a diameter slightly greater than that of the second air supply duct 22 into which the first water supply duct 21 opens. Nevertheless, this larger diameter is intended to allow the driving out, and / or the bonding of the outlet duct 16 where the air-water mixture will circulate towards the head 13. According to the embodiment illustrated in Figure 1 B, the outlet duct 16 consists for example of a non-flexible steel tube, but the latter could preferably be constituted entirely or partially by a flexible tube, so as to simplify the assembly and possibly recover slight operating clearances.

[0065] Figure 1C, which constitutes a view from the rear of the handpiece 1 of the preceding figures 1A and 1B, highlights the section plane EE corresponding to what is illustrated on the right part of figure 1A, and thus makes it possible to visualize the radial positioning of the air-water mixing element 2 in the rear gripping part 12 of the handpiece 1, the head 13 of which can be seen at the opposite end of the motor connection interface 120. The air-water mixing element 2 is thus preferably located at the bottom left of the rear body 122 of the rear gripping part 12 of the handpiece.

[0066] The technical solution corresponding to the preferred embodiment of figures 1A-1 C described above makes it possible to propose an economical handpiece 1 with a mixed spray, of superior quality to separate sprays, and the integration of which does not require any particular adaptation in terms of motor coupling at the rear gripping part. Furthermore, the positioning of the air-water mixing element 2 substantially in the middle of the handpiece 1 with the air routing via a slightly bent part, i.e. bent with a relatively small angulation (preferably less than 20°) in a water supply line allows the maximization of the operating range in air and water pressure; the air-water mixture can thus be functional for a water pressure / air pressure ratio equal to or greater than 1 / 3 (for example 1 bar of water and 3 bar air).Finally, such positioning of an air-water mixing element arranged modularly in a rear body 122 of the rear gripping part 12 of the handpiece, i.e. well away from the head 13, makes it possible to minimize the vibrations and noise due to the generation of the mixture because the mixing can be carried out in a well-insulated part in the center of the handpiece 1.

[0067] According to a variant not illustrated, however, the air-water mixing element 2 could be arranged directly in the rear gripping part 12, without it being inserted into the rear body 122. In this way, the air-water mixing element 2 could be arranged in a more middle part of the rear gripping part 12, but still sufficiently far from the head 13 to guarantee the quality of the air-water mixture of the spray.

[0068] In the following, Figures 2A and 2B illustrate further alternative variants for the embodiment of the air-water mixing element 2, however still preferably arranged as a modular part separate from the rear body 122 of the dental handpiece 1 in which it is intended to be mounted.

[0069] In these figures, not all references identical to figure 1 B will necessarily be repeated in detail; we will in fact concentrate essentially on the differences compared to the preferred embodiment previously described.

[0070] The air-water mixing element 2 produced according to the variant corresponding to Figure 2A corresponds, unlike that of Figure 1B, to a symmetrical “Y”, that is to say where each of the water and air supply pipes referenced respectively 21 and 22 have respectively a first bent part C1 and a second bent part C2, having a mutual angle α at the junction zone 23 which is always less than 20°, and preferably 10°. Tests carried out in such a configuration have shown slightly poorer performance than that obtained with the previous embodiment; however, this has the advantage of being easier to machine and even easier to clean.Similar to Figure 1B, the diameter of the main conduit 24 at the outlet of the junction zone 23 of the mixing element 2 is always greater than that of the first water supply pipe 21 and the second air supply pipe 22, but the outlet pipe 16 for the air-water mixture will preferably be assembled in the same way, that is to say by driving and / or gluing inside the main conduit 24, so that the effective fluid flow diameter is slightly smaller and its cross-section corresponds to the sum of the cross-sections of the first water supply pipe 21 and the second air supply pipe 22. In the case where the outlet pipe 16 is simply driven into the main conduit, it is advantageous to insert an O-ring seal around the outlet pipe 16 to ensure the sealing of the assembly.

[0071] The air-water mixing element of Figure 2B corresponds in every respect to that of Figure 1B, except that the second air supply duct 22 does not have a constant section, and has a narrowing R at the inlet upstream of the junction zone 23, so as to accentuate the Venturi effect. This slightly complicates the machining of the air-water mixing element, but not too much impact for an injected or printed part. As can be seen on the left of Figure 2B, the main duct 24 has, at the outlet of the junction zone 23, a symmetrical enlargement A, or even slightly greater than the narrowing R of the second air supply duct 22 upstream of the junction zone 23. This makes it possible to optimize the fluid flow at the outlet of this zone.Furthermore, the ratio between the sections of the two pipes can be optimized to improve the quality of the mixture, as explained below in view of figures 3A and 3B of an air-water mixing element 2 manufactured in a single piece by 3D printing.

[0072] The choice to produce the air-water mixing element preferably by 3D printing, for example in plastic, is conditioned by the fact that one seeks to simplify as much as possible one's production process without having to dig pipes following a molding, while optimizing the quality of the dimensions obtained as well as the flexibility in terms of geometric shape to be produced (for example pipes which could alternately have curved shapes, etc.). Figures 3A and 3B illustrate the same part corresponding to the air-water mixing element 2 of oblong shape and extending in a direction D, here upwards, and which is perpendicular to that of the flow of the fluid mixture F corresponding to the direction of orientation of the rectilinear main conduit 24.Figure 3A shows such an air-water mixing element 2 in three-dimensional three-quarter face, thus highlighting the first section S1 of the first water supply pipe 21 and the second section S2 of the second air supply pipe 22, which are substantially identical, and each section profile being circular. The O-ring seal used for sealing purposes not being shown in this figure, one can only distinguish the annular groove 251 in which it is intended to be arranged.

[0073] Figure 3B illustrates a three-dimensional figure but taken more from the side compared to Figure 3A, highlighting the profile of the internal pipes of the air-water mixing element 2, that is to say the first water supply pipe 21 and its bent part (C), the angle a of inclination at the junction zone 23 with the second air supply pipe 22, and the main spray pipe 24 at the outlet, oriented in the direction F of fluid flow, perpendicular to the direction of extension D of the oblong shape for the air-water mixing element 2.It can also be seen that the diameter of the third section S3 of the main spray conduit 24 is close to one and a half times that of the first section S1 of the first water supply pipe 21 and the second section S2 of the second air supply pipe 22, such that the cross-section ratio between the air-water mixture outlet pipe 16, which is substantially smaller than that of the third section S3, is of the order of twice that of each of the first and second sections S1 and S2, which, when they are identical, means that the fluid flow cross-section at the outlet of the junction zone 23 corresponds substantially to the sum of those of the two supply pipes, respectively air and water.

[0074] As can be seen in Figure 3C showing such an oblong air-water mixing element 2 mounted in the rear body of the handpiece, the purpose of using such a shape rather than a cylindrical shape is to reduce the radial bulk towards the outside and thus allow the arrangement of other elements (light channels, cooling channels, etc.). The fluid flow direction F, which had been materialized in Figure 3B as corresponding to the direction of extension of the main spray duct 24 of the air-water mixing element 2, now corresponds to the direction of extension of the outlet duct 16, the end of which is preferably driven into the main duct 24. This Figure 3C also illustrates, on the left, the front gripping part 11 and on the right, the motor connection interface 120 at the rear.In reality, only the outer cap 121 of the rear gripping portion 12 has been removed in this figure to show the integration of the air-water mixing element as a modular wear part in the rear body 122 of the handpiece; otherwise the view would have constituted a simple external view of the handpiece in three dimensions.

[0075] According to a preferred embodiment, it is possible to produce the frame of the handpiece via three-dimensional printing, so that all the fluid and / or light conduits are directly and automatically produced at the same time. In other words, it would be possible to produce both the rear body 122 with integrated air and water routing channels by 3D printing, as well as potentially the outlet pipe 16, and similarly the front gripping part 11 with the integrated mixed outlet channel 14 of the spray. More generally, according to a non-illustrated embodiment, it would be possible to produce almost the entire handpiece 1 by 3D printing, that is to say not only the internal parts (rear body 122 and water and air routing channels, respectively referenced 171 and 172) but external parts, including the motor connection interface 120 and the rear external cap 121.In such a configuration, it would be possible to directly produce the air-water mixing element 2 in a single piece inside the rear body 122.

[0076] In the embodiments illustrated above, the handpiece 1 used consisted of a contra-angle. However, the solution can be applied to all types of handpieces (straight handpieces, contra-angles and turbines), because the design of the mixer is not dependent on the specificities of each device: shape of the head, angled or straight shape of the handle, length of the device, type of connection (to the motor, to the turbine connector or directly to the hose). It is therefore possible to 'standardize' the air-water mixing element 2 and integrate it as a sub-module in products that are very different ergonomically and technically.

[0077] Figure 4A thus shows an example of a straight handpiece 1 comprising a cutter 10 fixed to the end of a head 13 inside which is arranged a mixed spray outlet channel 14 opening onto a spray orifice 15 of an air-water mixture generated in a mixing zone M via an air-water mixing element 2 in all respects similar to that illustrated in Figure 1A (and which for this reason will not be described again in detail). Figure 4A consists, like Figure 1A, of a semi-sectional view of the handpiece where the rear gripping part 12 is shown according to the section plane BB illustrated in Figure 4B showing the straight handpiece 1 from the rear. In this figure, only the motor connection interface 120 is thus referenced in addition to this section plane BB.Figure 4A shows that here again, the air-water mixing element 2 is sufficiently far from the motor connection interface 120 at the rear to not require any particular design not in accordance with existing standards, but as much as possible in the direction of the front gripping part 11 of the handpiece 1 in the rear body of the rear gripping part 12 of the handpiece 1 in order to minimize the length of the spray outlet pipe 16 where the air and water are mixed and conveying this mixture to the head 13.

[0078] According to the example illustrated in Figure 4A, the air-water mixing element 2 is located substantially in the center of the rear gripping portion 12 of the handpiece 1, but however slightly further forward of the latter compared to the example of the contra-angle of Figures 1A-1C. The rear of the air-water mixing element 2 is always located at a first predetermined distance D1 from the rear end of the handpiece 1 at the motor connection interface 120 in order to be compatible with the connection standards in force mentioned previously (ISO3964 and ISO9168). In this figure, the first predetermined distance D1 is of the order of approximately 2.5 centimeters.At the same time, the air-water mixing element 2, i.e. more precisely the front thereof, is also located at a second predetermined distance D2 from the front of the rear gripping part 12 of the handpiece 1, here equal to approximately 2 centimeters, so that the air-water mixing element 2 can be positioned at a location of the rear gripping part 12 of the handpiece 1 where the space constraints are still acceptable despite the slight narrowing after the motor connection interface 120.

[0079] According to the preferred embodiments described in connection with the present invention, it will be noted that the reliability of the spray is systematically improved in the event of the handpiece being dropped, because the air-water mixing element 2 is now protected in the middle of the handpiece 1 or even the rear gripping part 12. On the contrary, in cases where the mixer / diffuser is located in the head 13 of the handpiece, it is common for it to be damaged during a drop and for the quality of the spray to be greatly reduced (involving a risk of burning for the patient) or, in the event of major damage, for it to be ejected into the patient's mouth, a risk which is completely excluded for the mixing system according to the invention.

[0080] Those skilled in the art will understand that it is also possible to adapt certain characteristics according to requirements (shape of the channels, adjustment of the position of the mixing element according to the longitudinal direction of the handpiece, etc.) without departing from the scope of the present invention.

Claims

1. A dental handpiece (1) equipped with a built-in internal spray device containing a first channel (171) for supplying water and a second channel (172) for supplying air, as well as a combined outlet channel (14) open into one spray hole (15) for spraying a mixture of air and water, characterized in that it comprises an air and water mixing element (2) held in the rear gripping portion (12) of the dental handpiece (1) and having a first water supply channel (21) configured to be connected to the first water supply channel (171), and a second air supply channel (22) configured to be connected to the second air supply channel (172), wherein the first channel (21) for supplying water and the second channel (22) for supplying air are open into the main channel (24) of the element (2) for mixing air and water, configured to connect to the combined outlet channel (14) in the connection zone (23) between the first channel (21) for supplying water and the second channel (22) for supplying air.

2. The tip according to claim 1, in which at least one of the elements (2) for mixing air and water, selected from the first channel (21) for supplying water and the second channel (22) for supplying air, has a curved section (C) forming an angle (α) from 10° to 80° relative to the other, selected from the first channel (21) for supplying water and the second channel (22) for supplying air in the connection zone (23).

3. The tip according to claim 2, in which the second water supply channel (21) has a curved section (C) and is open directly into the first air supply channel (22), located in a completely straight line.

4. The tip according to claim 2, in which each of the first channel (21) for supplying water and the second channel (22) for supplying air has a first curved section (C1) and a second curved section (C2), respectively, and forms a completely symmetrical Y-shape with the main channel (24) of the mixing element (2).

5. A tip according to any of the preceding claims, in which at least one element selected from the first water supply channel (21) and the second air supply channel (22) does not have a constant cross-section, but has a narrowing (R) in the connection zone (23).

6. A nozzle according to any of the preceding claims, wherein the element (2) for mixing air and water is designed as a modular part.

7. The tip according to claim 6, in which the element (2) for mixing air and water is suspended by means of a sealing ring (25).

8. A tip according to any one of paragraphs 6, 7, in which the outlet tube (16) supplying the air-water mixture to the spray opening (15) is inserted into the main channel (24).

9. A handpiece according to any one of claims 6, 7, in which the modular element (2) for mixing air and water is attached to the rear housing (122) of the rear gripping section (12) of the dental handpiece (1), and the outlet tube (16), made of an elastic material, is attached to the modular element (2) for mixing air and water.

10. A nozzle according to any one of claims 6 to 9, wherein the modular mixing element (2) has an elongated shape and extends in a direction (D) that is substantially perpendicular to the direction defined by the outlet tube (16) for the air-water mixture.

11. A tip according to any one of paragraphs 6-10, in which the modular element (2) for mixing air and water consists of a single piece.

12. The tip according to claim 11, in which the modular element (2) for mixing air and water is manufactured using 3D printing.

13. The tip according to claim 11, in which the frame equipped with built-in pneumatic lines, as well as the element (2) for mixing, are a single piece manufactured using a 3D printing method.

14. A tip according to any of the preceding claims, wherein the element (2) for mixing air and water is substantially equidistant from both ends of the tip (1).

15. A tip according to any one of paragraphs 6-13, in which the element (2) for mixing air and water is located in the rear housing (122) of the rear gripping section (12) at a first predetermined distance (D1) from the rear end of the tip (1).