Medical turbine handpiece

Abstract

A medical turbine handpiece (100) has a holding mechanism (19) for rotatably holding a treatment tool in a head member (10), wherein a release element (48) is also provided, which is designed to interact with the holding mechanism (19) in order to release the holding of the treatment tool. The release element (48) can be actuated by means of a cover (40), wherein a sealing element (5) is also arranged in the head member (10), which acts between the cover (40) and a stationary bearing element (30) which encloses the holding mechanism (19) in a ring.

Description

[0001] This invention relates to a turbine handpiece for medical, particularly dental, use, having a handle sleeve and a head member disposed at the front end of the handle sleeve. Specifically, this invention relates to a method by which the head region of the handpiece can be effectively sealed relative to the environment.

[0002] To prevent the spread of bacteria, dental instruments intended for examination or treatment within a patient's mouth must be cleaned and sterilized before use. Accordingly, it is known that after use, these instruments are cleaned within their respective devices and sterilized to remove dirt particles and kill any bacteria present. This reprocessing is designed to be effective not only on the outer surfaces of the dental instruments but also in their internal areas.

[0003] Despite these measures, it is important to prevent bacterial intrusion into the internal areas of the handpiece from the outset. This problem is particularly evident in the aforementioned dental turbine handpieces, where the rotor housed in the handpiece head area is driven by compressed air. Such handpieces typically also have a holding mechanism for releasably holding treatment tools, along with an associated actuation system that selectively holds or releases tools, such as dental drill bits. In this case, potentially bacteria-laden fluids should be kept away from the internal rotor space and actuation system within the instrument, as such aspirated fluid can be partially expelled at a later point, posing a particular risk of bacterial transmission. Furthermore, foreign matter intruding into the internal space, along with corrosive fluids, can shorten the lifespan of the rotatable bearings and all other moving parts housed in the handpiece head assembly.

[0004] The problem with the dental turbine handpiece mentioned is that, during use, there may be at least temporary overpressure, but also partial negative pressure, within its internal space relative to the environment. When the handpiece is activated, i.e., when the turbine rotor is driven by pressurized fluid, there is typically some overpressure in the head region, resulting in the expulsion of air from that area, which is not inherently problematic. However, if the compressed air supply is stopped to interrupt operation, a temporary negative pressure occurs in the head region during the rotor's brief braking phase, potentially leading to the inhalation of ambient air. This results in the risk of repeatedly inhaling and expelling potentially bacteria-laden air, which should be avoided under any circumstances.

[0005] Therefore, some measures are known from the prior art to attempt to seal the internal space of the head region of a dental turbine handpiece relative to the environment. As will be explained in more detail below, in this context, the use of lip seals or sealing sleeves is known, forming a sealing lip that acts on the outer periphery of a rotatably mounted retaining element of the treatment tool. These sealing lips have a valve function, meaning they open during handpiece operation due to overpressure present in the internal space, i.e., they do not function relative to the rotating retaining element. This is not a problem in this respect, as there is no risk of inhaling ambient air due to the overpressure in the handpiece head component. If the compressed air supply is now stopped, the result is that the sealing lip closes and abuts against the outer periphery of the retaining element due to the pressure drop in the internal region. This not only achieves a seal, but the rotor is also briefly braked by the abutting sealing lip. Such lip seals are made, for example, of nitrile rubber or silicone, and are subject to a certain degree of wear due to the mechanism described above. Dental handpieces with such lip seals are known, for example, from DE 69201 133. EP 3 653 896 B1 also shows a dental turbine in which a sealing lip of the type described above is provided between the outer bearing ring and the inner bearing ring of the bearing for the rotatable tool holder.

[0006] Furthermore, CN 106 344180 discloses a dental turbine in which an elastic sealing element is installed in the housing on the cover side, i.e., the side opposite to the treatment tool, which acts as a so-called anti-backflow device. This sealing element, like the aforementioned lip seal, rests against the rotor, which in turn causes an abrasive effect during turbine start-up or braking, resulting in wear of the sealing element.

[0007] Finally, EP 0 689 801 A2 also describes a dental turbine in which the ball bearings for rotatably holding the tool retainer are sealed. However, the sealing or blocking elements used here primarily function between the mutually rotating parts and are therefore subject to wear, or simply form a labyrinth seal, which is rather ineffective in preventing the intrusion of bacteria-laden air.

[0008] Based on the prior art, the objective of this invention is to provide an improved solution for sealing the head region of a medical turbine handpiece.

[0009] This task is solved by a turbine handpiece having the features of claim 1. Advantageous improvements of the invention are the subject of the dependent claims.

[0010] The solution of the present invention particularly relates to a measure disposed in the head region on the cover side of the handpiece to achieve a seal relative to the environment. As already mentioned, treatment tools (e.g., dental drills) are typically not fixedly fastened to the handpiece, but are releasably held by a rotating holding mechanism, wherein a release element is arranged inside the head member along the axis of rotation, the release element being designed to interact with the holding mechanism such that the release element releases the holding of the treatment tool upon interaction with the holding mechanism. Here, actuation of the release element is typically performed via a cover of the head member arranged opposite the tool receiving opening, the cover being adjustable along the axis of rotation between a rest position and an actuated position, in which the cover is spaced apart from the release element, and in the actuated position, the cover presses against the release element to release the holding of the treatment tool.

[0011] The solution of the present invention now specifies sealing in this area, wherein a sealing element is used for this purpose, which acts between the cap and the stationary bearing element of the annular surrounding retaining mechanism. Here, the sealing element is fastened to one of these two components and presses against the sealing surface of the other element with a preload, wherein the sealing element is designed as a valve and configured to disengage from the sealing surface in the activated state of the handpiece. The advantage of the solution of the present invention is that the sealing element itself does not rotate and does not contact any rotating component. Therefore, unlike solutions known to date, no material removal wear occurs, thereby achieving an effective seal on the one hand and preventing wear of the seal on the other.

[0012] According to the present invention, a turbine handpiece for medical use, particularly dental use, is provided, comprising a handle sleeve and a head member, wherein the head member is disposed at the front end of the handle sleeve and has a tool receiving opening, wherein the handle sleeve has a fluid conduit for supplying fluid to drive a turbine wheel, wherein a turbine wheel and a holding mechanism for rotatably holding a treatment tool are disposed within the head member, wherein the holding mechanism is arranged along the rotation axis of the treatment tool, wherein a release element is also disposed within the head member along the rotation axis, the release element being designed to interact with the holding mechanism, wherein the release element releases the holding of the treatment tool upon interaction with the holding mechanism, and wherein the head member further comprises a cover opposite the tool receiving opening, the cover being adjustable along the rotation axis between a rest position and an actuated position, wherein in the rest position the cover is spaced apart from the release element, and in the actuated position the cover presses against the release element to release the holding of the treatment tool.

[0013] According to the invention, a sealing element is arranged in the head member, which acts between the cover and the stationary bearing element of the annular surrounding retaining mechanism, wherein the sealing element is fastened to the cover or bearing element and presses against the sealing surface of the bearing element or cover with a preload, and wherein the sealing element is designed as a valve and configured to disengage from the sealing surface in the activated state of the handpiece.

[0014] Here, the sealing element is preferably designed as a so-called umbrella valve with a circular outer circumference, which then presses against the corresponding sealing surface of the element that is not fastened to the sealing element. The sealing element is preferably designed such that it opens when the fluid overpressure is approximately 0.3 bar. This value ensures that the sealing element opens during operation of the handheld device (at which time there is an overpressure of approximately 0.5 bar relative to the outside atmosphere). On the other hand, it ensures that the head area is reliably sealed during braking and when the handheld device is stationary.

[0015] Here, the sealing element of the present invention is preferably designed as an annular shape with a central opening, the edge of which rests against the cover or bearing element. For example, the cover or bearing element may have a circumferential groove, into which the sealing element is pressed with the edge region of the central opening. In this way, a reliable and simultaneously sealing fastening of the sealing element to the corresponding component is achieved. Alternatively, the sealing element can also be clamped and held on the cover or bearing element by means of a separate, particularly annular, fastening element.

[0016] Preferably, the sealing element extends from the cover or bearing element on which it is attached toward the sealing surface of the bearing element or cover, such that the edge region of the sealing element abuts against the sealing surface when the valve is closed. In particular, for this purpose, the sealing element can be designed as a concave arch or a concave angle.

[0017] As an alternative to the above-described embodiments, it is also conceivable to design the sealing element as a rotating shape with an angled, annular circumferential profile. Here, the first, preferably outwardly oriented leg of the profile is substantially parallel to the cap orientation and fastened to the cap, while the second leg of the profile extends substantially perpendicular to the first leg and is designed to press against the side of the bearing element forming the sealing surface with a preload. This second leg then performs the valve function and laterally deflects in the activated state of the handpiece, which, as described above, preferably occurs under an overpressure of approximately 0.3 bar.

[0018] Here, on the one hand, the sealing element can be integrally formed from a suitable flexible material. On the other hand, it is also conceivable to design the sealing element as a multi-piece, having an internal region for fastening to a cover or bearing element and an annular sealing region made of flexible material fastened to the internal region. This flexible material can be formed, in particular, of an elastomer, preferably of a temperature-resistant elastomer, and especially preferably of a fluoroelastomer, wherein the thickness of the flexible material is particularly in the range of 0.2 mm + / - 0.1 mm.

[0019] The bearing element may, for example, be formed from the stationary outer bearing ring of a rotating bearing that rotatably retains the retaining mechanism. Alternatively, it is conceivable that the bearing element be formed from a so-called bearing housing element that holds the rotating bearing for rotatably retaining the retaining mechanism.

[0020] As explained at the beginning, the cover, which is also used as an actuating element to actuate the release element, is preferably pre-supported in a resting position by means of a spring element, particularly a helical spring, wherein the sealing element, or in the case of an annular angular profile, is a second leg perpendicular to the orientation of the cover, arranged within the spring element in a projection perpendicular to the axis of rotation. This measure ensures that the sealing mechanism of the present invention does not impair the function of the cover as an actuating element for actuating the release element. Furthermore, this measure ensures that the sealing of the handheld head member does not lead to an increase in the size of the handheld member. On the contrary, the solution of the present invention allows for an extremely compact design of the handheld head member.

[0021] On the side of the head member of the dental handpiece opposite the cap, a similar comparable sealing scheme cannot be achieved because, in principle, the seal must be relative to a moving, particularly rotating, component. Accordingly, it can be specified that another annular sealing element is provided opposite the cap, which then functions as a sealing lip between the outer periphery of the retaining mechanism or the rotating part of the retaining mechanism and the surrounding wall area of ​​the head member, similar to the scheme described in the prior art. This seal will inevitably undergo some wear, but as a supplement to the inventive sealing measure at the opposite end of the head member, it ensures that the head area of ​​the dental handpiece is sealed as optimally as possible relative to the environment, especially during the braking phase of the handpiece and in a stationary state.

[0022] The invention will now be explained in more detail with the aid of the accompanying drawings. In the drawings:

[0023] Figure 1 A cross-sectional view of a first embodiment of the medical turbine handpiece of the present invention is shown, wherein the valve formed by the sealing element is open;

[0024] Figure 2 Another cross-sectional view of the handheld component of the present invention is shown, wherein the fastening portion of the sealing element corresponds to Figure 1The valve is securely fastened, and the valve formed by the sealing element is closed;

[0025] Figure 3 An enlarged view of a portion of the handpiece of the present invention is shown, illustrating a second possibility for securing the sealing element;

[0026] Figure 4 A cross-sectional view showing a third embodiment of the turbine handpiece of the present invention;

[0027] Figure 5 and Figure 6 A view showing a fourth embodiment of the turbine handpiece is provided, wherein valves formed by sealing elements are respectively open and closed; and

[0028] Figure 7 A cross-sectional view showing a fifth embodiment of the turbine handpiece of the present invention is shown.

[0029] Figure 1 The front region of the dental handpiece 100 of the present invention is shown in cross-section. The handpiece is formed by an elongated handle sleeve 50 and a head member 10 disposed at the front end. As already mentioned, this is a turbine handpiece, i.e., driven by compressed air supplied by a dental supply unit. For this purpose, a fluid conduit 51 extends along the handle sleeve 50, through which compressed air is guided from the rear end to the head region 10, which has a turbine disposed therein. In a similar manner, an air conduit leading from the head region 10 also extends along the handle sleeve 50, through which air leaving the turbine space is again exhausted. This exhaust conduit is not visible in the selected illustration here.

[0030] A so-called turbine rotor 15 is arranged in the head region, which is driven by compressed air supplied via a supply line 51, thereby rotating a dental treatment tool (e.g., a dental drill). The turbine rotor 15 is formed by a generally hollow cylindrical rotating component 17 extending along the axis of rotation I, which is surrounded by a turbine wheel 16 at approximately the middle height. If desired, the rotating component 17 and the turbine wheel 16 can also be implemented integrally, wherein in any case there is a fixed connection such that the rotation of the turbine wheel 16 caused by the compressed air is transmitted to the rotating component 17 and ultimately to the treatment tool (not shown). The rotatable support of the components just described in the head component 10 of the handpiece is here by means of two bearings 20 and 25, which are arranged on both sides of the turbine wheel 16 when viewed in the direction of rotation I, and have outer bearing rings 21 and 26, inner bearing rings 22 and 27, and rolling elements 23 and 28 in the form of balls arranged between them.

[0031] Treatment tools, such as dental drills, are replaceably housed in the rotating component 17, for which a so-called clamping sleeve 19 is provided. The tool is introduced into the tool receiving opening 18 of the rotating component 17 from below the handpiece head member 10 with its shank, until its end region is positioned within the clamping sleeve 19. The clamping sleeve 19, rotating with the rotating component 17, then surrounds the end region of the treatment tool, causing the treatment tool to rotate with the rotating component 17.

[0032] To allow the treatment tool housed in the clamping sleeve 19 to be retrieved again, a release element 48 is arranged in the upper region of the rotating member 17, having a wedge-shaped or pyramidal protrusion 49 on its lower side. The release element 48 rotates with the rotating member 17 but is movable along the axis of rotation I, such that when the actuating element 40 is pressed down accordingly, the wedge-shaped protrusion 49 engages in the upper region of the clamping sleeve 19. This slightly expands the clamping sleeve, loosening or at least reducing the clamping force applied to the handle of the treatment tool to allow for its removal.

[0033] Actuation of the release element 48, specifically pressing the release element 48 downward to interact with the clamping sleeve 19, is accomplished by means of a cover 40 disposed at the upper end of the head member component 10. This cover closes the upper side of the head member component housing and is received within the housing of the head member 10 by a circumferential edge region 43, allowing it to be pressed downward against the force of the coil spring 35. Figure 1 In the unloaded state, as visible in the diagram, the cover 40 is pressed to the upper stop by the coil spring 35, where the cover 40 is arranged spaced apart from the release element 48 by the central protrusion 41. This avoids friction between the cover 40 and the release element 48 when the handpiece is activated, i.e., when the rotating part 17 rotates together with the release element 48. This friction would cause undesirable braking and very rapid wear of the cover 40. Only when the cover 40 is pressed down (which is typically done in the deactivated state of the handpiece) does the central protrusion 41 abut against the upper side of the release element 48, so as to finally release the clamping hold of the treatment tool as described.

[0034] The features of the handheld component 100 of the present invention described so far are also incorporated in handheld components known from the prior art. The inventive measures for effectively sealing the internal region of the head member 10 will be explained in more detail below.

[0035] A sealed head assembly region 10 is desirable because cleaning and sterilizing the internal region is significantly more difficult than cleaning the outer surface of the handpiece 100. Furthermore, as explained at the outset, during handpiece operation—specifically when compressed air for driving the turbine wheel 16 is introduced into the head assembly 10 via fluid conduit 51—a certain overpressure exists within the handpiece's internal space compared to the ambient environment. Typically, such turbine handpieces operate at speeds up to 300,000 revolutions per minute, generating an overpressure of approximately 0.5 bar.

[0036] On the other hand, if the compressed air supply is stopped, the turbine rotor 15 brakes from high speed to 0, and during this braking phase, a negative pressure may occur inside the handpiece head assembly 10 for a period of approximately 1 second. This will cause outside air to be drawn in, which should be avoided under any circumstances. Because the handpiece 100 is usually still located in or near the patient's oral cavity at this time, this poses a risk of potentially bacteria-laden air entering the interior space of the head area 10. Besides the higher cost associated with cleaning and effective sterilization as already mentioned, there is also a risk of damage to components of bearings 20 or 25 by air thus drawn in.

[0037] As explained in more detail later, it is known from the prior art to use a sealing lip to achieve the desired seal, the sealing lip being arranged between the housing of the head member 10 and the outer periphery of the rotating member 17. Therefore, such sealing elements function both between stationary members and between rotating members, which is considered disadvantageous due to the inevitable wear that occurs therein. With the present invention, a solution is now provided that enables an effective seal, at least in the area of ​​the cover 40, of the head region of the handheld member 10, while avoiding the disadvantages of solutions known from the prior art.

[0038] According to the present invention, it is now specified that the sealing element 5 is used again, particularly for sealing the upper region of the handheld head member 10. However, the sealing element 5 is now designed such that it only functions between the stationary, i.e., non-rotating parts of the handheld member 100, thereby avoiding the aforementioned problem of increased wear.

[0039] exist Figure 1 and Figure 2 In the first embodiment shown (in) Figure 2(Only the right side of the sealing element 5 corresponds to the first embodiment), where the sealing element 5 is designed as an annular seal made of flexible material. Therefore, the sealing element 5, shown only in cross-section, has a central opening, through which it is fastened to the cover 40 in this embodiment. Specifically, the aforementioned protrusion 41 of the cover 40 is provided with a circumferential groove 42 or a corresponding cutout, into which the sealing element 5 is pressed with the edge region of the central opening, thereby achieving a form-locking connection. Here, the sealing element 5 is clamped and thus sealably abutted against the circumference of the protrusion 41 of the cover 40, thereby achieving a corresponding seal in this respect.

[0040] Simultaneously, the sealing element 5 extends outward from the fastening area on the protrusion 41 of the cover 40 in a concave arch, or, if necessary, a concave angle, such that the circular edge region 7 extends toward the so-called bearing seat element 30, whose function is primarily to retain the upper bearing 20. Specifically, the annular bearing seat element 30, for example, screwed into the upper region of the head member housing, serves to retain the outer race 21 of the bearing 20, which, unlike the inner race 22, does not rotate with the rotating component 17. Therefore, the bearing seat element 30 is also a stationary component within the head member 10 of the handheld member 100. Thus, the seal 5, acting between the cover 40 and the bearing seat element 30, is not subject to wear, as is sought in this invention.

[0041] However, the sealing effect is not permanent as specified herein. Accordingly, the sealing element 5 should also function as a valve, which, while temporarily allowing air to flow out, prevents ambient air from entering the head area. Here, the sealing element 5 forms a so-called umbrella valve or rain valve, which opens in the event of overpressure inside the head member 10 and closes in other circumstances, thereby achieving a seal between the cover 40 and the bearing housing element 30 as described above.

[0042] Accordingly, the size and material of the sealing element 5 are selected to achieve the aforementioned valve function, particularly aiming for the valve to open under an overpressure of approximately 0.3 bar, but close under other conditions, and thus rest against the bearing housing element 30 with a corresponding preload. In addition to the concave curved design visible in the figure, the outer diameter of the valve element 5 is correspondingly specified to be approximately 7 mm to 8 mm, and the width of the sealing element 5, i.e., the distance from the edge region of the central opening 6 to the outer perimeter 7, is approximately 2 mm to 2.5 mm. However, these parameters can also vary depending on the selected material and the dimensions of the handle 100.

[0043] The material of the sealing element 5 is preferably a sterilizable material. As already mentioned, this material must have a certain degree of flexibility, and therefore it is particularly an elastomer, especially a heat-resistant elastomer. The use of so-called fluoroelastomers (e.g., PTFE) has proven to be particularly preferred, wherein the sealing element 5 has a thickness of about 0.2 mm + / - 0.1 mm.

[0044] The key is, in Figure 1 In the activated state of the handheld component 100, as already mentioned, overpressure exists in the internal region of the head component 10, causing the sealing element 5 to open. Figure 1 As can be seen, in this configuration, the outer edge region 7 of the sealing element 5 has a small distance from the end face sealing surface 33 of the bearing housing element 30. Therefore, in the activated state of the handheld component 100, air can flow from the inside to the outside. At the same time, the overpressure in the internal region prevents potentially contaminated air from intruding from the outside.

[0045] If the compressed air supply is stopped now, the pressure in the internal region of the handheld head component 10 will drop, and a negative pressure compared to ambient pressure will exist even briefly during the braking phase. Here, if the pressure drops, in particular, to a value below approximately 0.3 bar (compared to ambient pressure), the sealing element 5 will... Figure 2 The seal is closed, and its outer periphery 7 now abuts against the annular sealing surface 33 of the bearing housing element 30. This seal exists not only during the braking phase but also in the inactive state of the handpiece 100. In other words, the sealing element 5 is only open in the active state of the handpiece 100, ensuring an effective seal of the upper head region 10 during all other time periods. This ensures that no ambient air can enter the area of ​​the upper bearing 20, as desired.

[0046] exist Figure 1 as well as Figure 2 In the embodiment shown on the right, the sealing element 5 is integrally implemented and directly and lockingly fastened to the protrusion 41 of the cover 40. Figure 2 left side or Figure 3 The enlarged view shows alternative fastening possibilities for the sealing element 5, where an annular so-called clamping element 44 is used as the fastening element. This clamping element is press-fitted onto or otherwise connected to the protrusion 41 of the cap (e.g., adhesive), and here clamps and holds the sealing element 5 in the position shown. The clamping element 44 (which can also be connected to the sealing element 5, e.g., adhesive, if desired) is in this case made of a more stable material than the actual sealing element 5, where plastic or metal can be envisioned again. In this case, the sealing element 5 can be designed with an angled inner edge region, such as... Figure 3 This is to further improve the seal relative to cap 40. Regarding its further design and function, this variant is similar to... Figure 2 A variant of .

[0047] In addition, such as Figure 4The third embodiment shown indicates that it is also conceivable to design the sealing element 5 as a multi-piece unit. In this case, the sealing element 5 first consists of an annular inner region 8, which is arranged and secured to the central protrusion 41 of the cover 40 in the manner described above. An annular sealing region 9 is subsequently formed on the outer periphery of the inner region 8, which is formed of a more flexible material and is similar to a bonding element. Figure 1 and Figure 2 The described scheme works in conjunction with the annular sealing surface 33 of the bearing housing element 30.

[0048] In the illustrated embodiment, the sealing region 9, as shown, is designed to be angled, wherein the web formed on the outer periphery and aligned with the bearing housing element 30 then presses its end face against the corresponding sealing surface 33 of the bearing housing element 30, as shown. Figure 4 Visible on the left. As already mentioned, this state exists during the braking phase of the handpiece 100 or in the inactive state of the handpiece 100. Conversely, in the active state, the overpressure present in the head region 10 causes the sealing element 5 to open within the range of valve function, so that the circumferential web is now spaced apart from the upper side of the bearing housing element 30. This situation is... Figure 4 The right side is visible. The above applies to the material of sealing region 9. Therefore, it is particularly suitable for flexible, heat-resistant materials, such as fluoroelastomers, to achieve valve function.

[0049] Figure 4 It is also shown that a seal for the head component 10 can also be provided on the side of the rotating component 17 opposite to the cover 40. However, compared to the solution of the present invention, there is no possibility of sealing between the two stationary components of the handheld head component 10. Instead, an annular sealing lip 60 is now provided on the inner wall region of the head component housing below the bearing 25, which engages with the outer periphery of the rotating component 17. This sealing lip 60 also preferably has a valve function, such that when there is sufficient overpressure inside the handheld component 100, it is spaced apart from the outer periphery of the rotating component 17, as... Figure 4 The right side is shown again. Conversely, the sealing contact shown on the left side occurs only during the braking phase and in the inactive state.

[0050] However, since the seal 60 now cooperates with the rotating member (in this embodiment with the rotating component 17), the sealing lip 60 inevitably experiences some wear, which is not the case in the seal of the present invention in the upper region of the handheld head member 10. Nevertheless, the sealing lip 60 provided in the insertion opening 18 region represents a meaningful supplement in order to achieve a satisfactory overall seal of the handheld head member 10. Accordingly, this additional sealing lip 60 can also, in principle, be provided in other embodiments of the sealing element 5 of the present invention.

[0051] The fourth embodiment of the present invention is in Figure 5 and Figure 6 This is shown in the image. This is consistent with... Figure 1 and Figure 2 The embodiments are very similar, but now the sealing element 5 is fixedly arranged on the bearing seat element 30 and depends on the pressure in the internal space of the handpiece head member 10 and the lower side of the cover 40.

[0052] Therefore, the sealing element 5 is again designed as an umbrella valve, extending concavely and curved from the fastening area on the bearing housing element 30 toward the cover 40, but in the event of overpressure in the handpiece head member 10, the edge region of the sealing element 5 is spaced apart from the cover 40. Figure 5 ), while sealing occurs during the braking phase or when the handpiece 100 is in an inactive state ( Figure 6 In this context, it is also conceivable that something similar to... Figure 4 The variant in the design makes the sealing element 5 a multi-piece type, or corresponds to Figure 3 The embodiment uses another element to hold it clamped on the bearing housing element 30.

[0053] Finally, the fifth embodiment is in Figure 7 As shown, the sealing element is now designed with a rotating shape having an angled, annular circumferential profile. Here, the first, flange-shaped, outwardly pointing leg 151 of the profile is oriented substantially parallel to and fastened to the cover 40, wherein the cover 40 may have a circumferential annular recess or receiving portion if necessary. Inside the first leg 151, a second leg 152 extends substantially perpendicularly thereto, and this second leg is designed to press with a preload against the side of the bearing seat element 30 forming the sealing surface 33. Thus, the second leg 152 achieves the required seal while also fulfilling the valve function. That is, as... Figure 7 As shown on the left (on the right, the second leg 152 acts as a sealing lip against the bearing housing element 30), the second leg 152 deflects laterally under a corresponding overpressure and disengages from the bearing housing element 30. This preferably requires an additional overpressure of approximately 0.3 bar. The dimensions of the legs 151 and 152 are chosen such that the second leg 152 is located within the coil spring 50, thus not impairing its function.

[0054] In this case, the sealing element 5 may also be composed of the same material continuously, or alternatively formed of different materials, such as the variation described above, in which case the second leg 152 is then preferably composed of a slightly more flexible material.

[0055] In all the embodiments shown, it is also conceivable that the sealing element 5 functions between the outer bearing ring 21 and the cover 40 of the equally stationary upper bearing 20. In this case, it is also ensured that no external air can enter the area of ​​the bearing 20 from the top.

[0056] As already mentioned, the size and shape of the sealing element 5 can be designed to be variable, provided the desired valve function is achieved. However, the sealing element 5 is preferably designed so that it is completely contained within the helical spring 30, thus not compromising its function. This helical spring is housed in the circumferential groove 31 of the bearing housing element 30 and should preload the cover 40 to its initial upper position without failure. Figure 7 In the fifth embodiment, as already mentioned, at least the second leg is located within the helical spring 50.

[0057] In summary, the measures of the present invention significantly improve the feasibility of sealing the head region of a dental turbine handpiece. Furthermore, it ensures that wear on the sealing element located therein is minimized or preferably even completely eliminated.

Claims

1. A dental turbine handpiece (100) having a handle sleeve (50) and a head member (10) disposed at the front end of the handle sleeve (50) and having a tool receiving opening (18). in, The handle sleeve has a fluid conduit (51) for supplying fluid to drive the turbine wheel (16). The turbine wheel (16) and a holding mechanism (19) for rotatably holding the treatment tool are arranged inside the head member (10). The retaining mechanism (19) is arranged along the rotation axis (I) of the treatment tool. A release element (48) is further arranged inside the head member (10) along the axis of rotation (I). The release element (48) is designed to interact with the holding mechanism (19), wherein the release element (48) releases the holding of the treatment tool when interacting with the holding mechanism (19). Furthermore, the head member (10) also has a cover (40) opposite to the tool receiving opening (18), the cover being adjustable between a rest position and an actuated position along the direction of the rotation axis (I), in the rest position the cover (40) is spaced apart from the release element (48), and in the actuated position the cover (40) presses against the release element (48) to release the retention of the treatment tool. The feature is that a sealing element (5) is arranged in the head member (10), the sealing element acting between the cover (40) and the stationary bearing element (30), the stationary bearing element (30) surrounding the retaining mechanism (19) in annular shape. The sealing element (5) is fastened to the cover (40) or the bearing element (30) and presses against the sealing surface (33) of the bearing element (30) or the cover (40) with a preload force. The sealing element (5) is designed as a valve and is configured to detach from the sealing surface (33) when the handpiece (100) is in the activated state.

2. The dental turbine handpiece according to claim 1, Its features are, The sealing element (5) is designed as an umbrella-shaped valve with a circular outer perimeter. The sealing element (5) is designed to open when the fluid is overpressured by approximately 0.3 bar.

3. The dental turbine handpiece according to claim 2, Its features are, The sealing element (5) is designed to be annular and has a central opening, the central opening of which rests against the cover (40) or the bearing element (30) with its edge (6).

4. The dental turbine handpiece according to claim 3, Its features are, The cover (40) or the bearing element (30) has a circumferential groove (42), and the sealing element (5) is pressed into the circumferential groove with the edge region of the central opening.

5. The dental turbine handpiece according to claim 3, Its features are, The sealing element (5) is held in place on the cover (40) or the bearing element (30) by means of a separate annular fastening element (44).

6. The dental turbine handpiece according to claim 4, Its features are, The sealing element (5) extends from the cover (40) or the bearing element (30) on which the sealing element (5) is attached, toward the sealing surface of the bearing element (30) or the cover (40), such that the edge region (7) of the sealing element abuts against the sealing surface (33) when the valve is closed.

7. The dental turbine handpiece according to claim 6, Its features are, The sealing element (5) is designed to be concave or angularly concave.

8. The dental turbine handpiece according to claim 1, Its features are, The sealing element (5) is designed with a rotating shape having an angled, annular, surrounding profile. The first outward-pointing leg (151) of the outline is oriented substantially parallel to the cover (40) and fastened to the cover. The second leg (152) of the profile extends substantially perpendicular to the first leg (151) and is designed to press against the side of the bearing element (30) forming the sealing surface (33) with a preload and be deflected in the activated state of the dental turbine handpiece (100).

9. The dental turbine handpiece according to claim 1, Its features are, The sealing element (5) is integrally formed from a flexible material.

10. The dental turbine handpiece according to claim 1, Its features are, The sealing element (5) is designed as a multi-piece unit, having an inner region (8) for fastening to the cover (40) or the bearing element (30) and an annular sealing region (9) for fastening to the inner region (8), the sealing region being made of a flexible material.

11. The dental turbine handpiece according to claim 9 or 10, Its features are, The flexible material is an elastomer. The thickness of the flexible material is in the range of 0.2 mm + / - 0.1 mm.

12. The dental turbine handpiece according to claim 1, Its features are, The bearing element (30) is formed by a stationary outer bearing ring of a rotating bearing (20) that rotatably supports the retaining mechanism (19).

13. The dental turbine handpiece according to claim 1, Its features are, The bearing element (30) is formed of a bearing housing element that holds a rotary bearing (20) for rotatably holding the retaining mechanism (19).

14. The dental turbine handpiece according to claim 1, Its features are, The cover (40) is preloaded and supported in the rest position by means of a spring element (35), wherein the sealing element (5) is arranged inside the spring element (35) in a projection perpendicular to the axis of rotation (I).

15. The dental turbine handpiece according to claim 1, Its features are, The dental turbine handpiece has another annular sealing element (60) opposite the cap (40), which acts between the outer periphery of the retaining mechanism (19) or the rotating part (17) that holds the retaining mechanism (19) and the surrounding wall region of the head member (10).

16. The dental turbine handpiece according to claim 11, Its features are, The flexible material is a temperature-resistant elastomer.

17. The dental turbine handpiece according to claim 11, Its features are, The flexible material is a fluoroelastomer.

18. The dental turbine handpiece according to claim 14, Its features are, The cover (40) is preloaded and supported in the rest position by means of a helical spring.

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