INSTRUMENT HEAD WITH LEVER MECHANISM FOR CLAMPING A TREATMENT TOOL

Description

[0001] The invention relates to a medical, in particular dental, hand instrument with an instrument head and a medical treatment tool received in the instrument head, wherein the treatment tool is detachably coupled to the instrument head via a holding mechanism.

[0002] Such hand instruments usually consist essentially of a handle sleeve and an instrument head, also referred to as the headpiece, which is arranged at a front end of the handle sleeve for easy and precise operation of the hand instrument. Figure 61 shows such a conventional headpiece 20, which is arranged at one end of a handle sleeve 10 of a medical hand instrument 1. The headpiece 20 has a tool receiving opening 240 so that different medical or dental treatment tools 7 can be inserted into the headpiece 20 and coupled to the hand instrument 1, depending on the application. For this purpose, a holding means 230 for rotatably holding the respective treatment tool 7, for example a dental drill, is provided inside the headpiece 20. A release element 210 is also coupled to the holding means 230, which, when actuated accordingly, releases the holder of the treatment tool 7 in the holding means 230. During operation, the treatment tool 7 and the components coupled to the treatment tool 7, such as the release element 210 and the holding means 230, rotate at up to 450,000 revolutions per minute.

[0003] To date, a collet 230 has typically been used to hold the treatment tool 7, which is actuated by means of the wedge-shaped release element 210 by pressing a push button 1000, so that the holder of the treatment tool 7 is released. For this purpose, the push button 1000 typically has a pressure element 1001 and a compression spring 1040, which pushes the push button 1000 away in the opposite direction to the actuation of the push button 1000. Upon actuation of the push button 1000, the compression spring 1040 is compressed, whereby the pressure element 1001 then contacts the release element 210 and pushes it further into the holding means 230. If the push button 1000 is actuated sufficiently and the release element 210 is thus displaced correspondingly, the holder of the treatment tool 7 in the holding means 230 is released and the treatment tool 7 can be removed from the tool channel 240 of the head piece 20.Such push-button mechanisms are usually implemented in a cover that can be screwed onto the head part 20 of the hand instrument 1.

[0004] However, this previous arrangement with the push button 1000 and the compression spring 1040 for releasing the holding mechanism requires a correspondingly high amount of force, since in addition to the spring force of the compression spring 1040, the interaction between the holding means 230 and the release element 210 also requires a certain force—usually approximately 50 Newtons. This makes this previous mechanism difficult to operate and cumbersome.

[0005] Furthermore, with this known mechanism, even a slight actuation of the push button 1000 results in contact between the pressure element 1001 and the release element 210, whereby only the spring force of the compression spring 1040 needs to be overcome. However, contact between the push button 1000 and the release element 210 represents a significant hazard during operation, since contact between the pressure element 1001 and the release element 210, which rotates at high speed, creates considerable friction, causing the push button 1000 to become extremely hot extremely quickly, which in turn poses a significant risk of injury. Such slight indentation can occur even through unintentional contact between the push button 1000 in a patient's mouth and a tooth or cheek, posing a risk of burns to the patient.There is also a risk of burns for the treating physician, as it is quite conceivable that he or she could accidentally press the push button 1000 slightly during the treatment.

[0006] Such known instrument heads with a push-button mechanism for releasing the holder of a treatment tool are therefore heavy and unwieldy to use and also pose a potential danger to both the treating physician and the patient.

[0007] Furthermore, EP 1 627 611 A1 describes a handpiece head for a medical handpiece, in which a reciprocating movement along an axis is transmitted to a tool arranged in the handpiece head. The tool can be fixed in any position with respect to rotation about the axis. Depending on the requirements, the tool can rotate about its own axis or be prevented from rotating by a locking mechanism.

[0008] The locking mechanism is designed to create a clamping connection. For this purpose, the handpiece head has a sleeve for receiving the tool, on which a first clamping part is arranged. Furthermore, a second clamping part is provided as part of an attachment on a grip portion of the handpiece. This second clamping part can be pushed toward the handpiece head and interacts with the first clamping part to create the desired clamping connection. The clamping mechanism described here therefore primarily serves to lock the sleeve holding the tool with respect to the rotation axis, but not to releasably hold the tool.

[0009] US 5,090,906 A describes a dental handpiece in whose head a cutting shaft of an instrument is received and clamped with a push-button control device. The push-button control device is movable against a tension spring. The control device generally consists of at least one reversing element for receiving pressures responsive to movements of the push-button and for converting these movements into a pulling movement exerted by the reversing element on the plunger, which serves to control the collet chuck that holds the shaft of the instrument.

[0010] US 5,040,980 A shows a dental handpiece having a bur chuck with spring-loaded jaws that exert a clamping force on the shank of a bur to operatively secure the bur to the handpiece rotor, such a handpiece also having a lever-operated bur release mechanism to force the jaws apart when a bur is to be removed and replaced.

[0011] The invention is based on the object of providing a medical hand instrument with an improved mechanism for operating the release element and the holding means for releasing the holder of a treatment tool inserted into the hand instrument, and a cover with such an improved mechanism for a medical hand instrument.

[0012] This object is achieved according to the invention with the subject matter recited in the independent claims. Particular embodiments of the invention are specified in the dependent claims.

[0013] According to the invention, a medical, in particular dental, hand instrument is provided with a grip sleeve and a head piece, which is arranged at a front end of the grip sleeve and has a tool receiving opening, wherein a holding means for rotatably holding a treatment tool (for example, a dental drill) is arranged inside the head piece. Furthermore, it is provided that the holding means is arranged along an axis of rotation for the treatment tool, and that a release element is arranged inside the head piece along this axis of rotation, which is designed to interact with the holding means, wherein the release element releases the holder of the treatment tool upon interaction with the holding means.According to the invention, the headpiece further comprises a lid, wherein the lid comprises a lever mechanism having a first lever and a second lever which cooperate to release the holder of the treatment tool.

[0014] As a result, the mechanism for releasing the holder of the treatment tool is realized by means of a lever mechanism, whereby the force required to release the holder is greatly minimized, in particular by the design of two interacting levers.

[0015] In addition to the hand instrument according to the invention, a cover for a head piece of a medical, in particular dental, hand instrument is also provided according to the invention.

[0016] This allows the lid to be attached, in particular, to older and already known medical hand instruments, such that the associated improved mechanism for releasing the retaining mechanism can also be used with other, particularly older, hand instruments. Thus, the advantages of greater safety and easier operation of the lid according to the invention can also be experienced by users of older hand instruments.

[0017] The following explanations and designs of the lid are therefore equally valid for the lid according to the invention as well as for the hand instrument according to the invention.

[0018] According to the invention, the first lever acts upon a free end of the second lever when actuated. This results in a particularly efficient leverage effect through the interaction of the first and second levers, thus greatly easing the force required to release the holder by means of the release element and holding means.

[0019] Preferably, a pivot axis of the first lever and a pivot axis of the second lever are arranged parallel to each other and perpendicular to a plane that runs along the axis of rotation. Such a design allows for a particularly space-saving arrangement and a particularly advantageous force transmission from the first lever to the second lever.

[0020] Preferably, the pivot axis of the first lever and the pivot axis of the second lever are arranged opposite one another on the cover with respect to the rotation axis. This allows for a particularly advantageous arrangement of the two levers. Furthermore, both pivot axes are preferably offset from one another in the direction of the rotation axis. With this additional offset arrangement, a correspondingly increased leverage effect can be achieved, since the two pivot axes are positioned at a corresponding distance from one another, thus increasing the potential lever length.

[0021] Preferably, the second lever has a deflection which presses against the release element to interact with the release element, whereby the deflection limits the force acting on the release element. In particular, it is provided that the second lever has elasticity due to the deflection, so that, above a certain existing lever force, the force acting on the release unit is limited and excessive force is prevented. This increases the safety of use of the hand instrument, as damage to components of the hand instrument is avoided.

[0022] Preferably, the second lever is provided in the region of its pivot axis with a return spring, in particular a leg spring, which is designed to transfer the first and second levers into a rest position if the first lever is not actuated, wherein in the rest position the second lever is spaced apart from the release element. This easily ensures that after actuation of the lever mechanism—with the first and second levers—both levers automatically return to their rest position, thus preventing, in particular, contact between the second lever and the release element. This implementation thus further improves user safety.

[0023] Preferably, the first lever is provided with lateral protrusions at its end region facing the pivot axis. These protrusions serve to mount the first lever in the cover and laterally overlap the end region of the second lever. This configuration of the first lever ensures that the second lever is securely mounted when the lever mechanism is not in use (rest position), while also fixing the position of the second lever relative to the first lever. These lateral protrusions of the first lever also increase the stability of the first lever.

[0024] Preferably, the first lever is provided with a grip element at its end region remote from the pivot axis. This simplifies the operation of the lever mechanism for releasing the holding mechanism, while also improving the force transmission to the first lever. The grip element also further stabilizes the first lever.

[0025] Preferably, the first lever is provided with a recess on its underside facing the second lever, which accommodates at least part of the second lever when the two levers are in a resting position. This prevents the second lever from slipping, and the cover can also be realized with a lower overall height since the two levers are arranged in a space-saving manner.

[0026] Preferably, the lid can be reversibly coupled to the headpiece of the hand instrument, with the lid preferably having a thread and the headpiece having a corresponding counter-thread. This allows maintenance, cleaning, and repair work to be carried out particularly easily and conveniently inside the headpiece and on the lid, while also providing particularly easy access to the individual components of both the lid and the headpiece.

[0027] Preferably, the lid has a locking device, wherein the lever mechanism can be selectively locked in a desired orientation relative to the rotation axis by means of the locking device. This allows the actuation direction of the lever mechanism to be adjusted to a user-preferred orientation, making the lever mechanism particularly easy and convenient to customize.

[0028] In a special preferred embodiment, the lever mechanism is movably mounted along the axis of rotation and the lever mechanism is preloaded by spring force into a position spaced from the release element, wherein the lever mechanism can be pressed down against the spring force in order to contact the release element when the two levers are in a rest position in the pressed-down state. With this special embodiment, in addition to the lever mechanism with the first and second levers, an additional pressure mechanism for releasing the holding mechanism is implemented, wherein for this purpose the lid can be pressed down together with the levers remaining in the rest position in such a way that the second lever comes into contact with the release element, which in turn releases the holder in the holding means. In this respect, this embodiment offers two mechanisms for releasing the holding mechanism.

[0029] Preferably, the holding means is a collet chuck, and / or the release element is a wedge element with a wedge-shaped head area and a flat base area. This allows for a particularly simple yet robust holding mechanism consisting of the release element and holding means.

[0030] Furthermore, the first lever is preferably designed as a two-armed lever and the second lever as a single-armed lever. This increases the leverage of the lever mechanism, while simultaneously allowing the two levers to be positioned in the lid in a space-saving manner.

[0031] The invention is explained in more detail below using an exemplary embodiment and with reference to the drawings. They show: Fig. 1 is a schematic side view of an embodiment of a medical hand instrument according to the invention with a treatment tool inserted into the headpiece of the hand instrument; Fig. 2 is a schematic cross-sectional view of an exemplary first embodiment of a cover according to the invention and medical hand instrument; Fig. 3A is a schematic cross-sectional view of an exemplary second embodiment of a cover according to the invention for a medical hand instrument in an operating position of the lever mechanism; Fig. 3B is a perspective view of the embodiment of Figure 3A a cover according to the invention for a medical hand instrument in an operating position of the lever mechanism; Fig. 4A a schematic cross-sectional view of the embodiment from Figure 3Aa cover according to the invention for a medical hand instrument in the rest position of the lever mechanism; Fig. 4B a perspective view of the embodiment from Figure 3A a cover according to the invention for a medical hand instrument in the rest position of the lever mechanism; Fig. 5 a schematic cross-sectional view of an exemplary third embodiment of a cover according to the invention and medical hand instrument; Fig. 6 a schematic cross-sectional view of the head region of a medical hand instrument known from the prior art.

[0032] The Figure 1shows the basic structure of a medical, and in particular dental, hand instrument 1 according to the invention, which has a headpiece 20 at its front end 101, wherein the headpiece 20 is in turn coupled to the grip sleeve 10 of the hand instrument 1. At the rear end 102 of the hand instrument 1, a connection for a supply line 6 is usually provided, via which the hand instrument 1 can be coupled, for example, to a power supply source; in particular, it can be provided to supply the hand instrument 1 with electrical energy or mechanical energy (for example, rotational energy).

[0033] The part of the hand instrument essential for the invention is in the Figures 2 to 5shown in more detail, with the area of ​​the headpiece 20 being shown in more detail here. The invention aims at an improved mechanism for releasing the holding mechanism for a treatment tool 7 in the headpiece 20 of the hand instrument 1. This mechanism is built into a cover 30 of the hand instrument 1 and is designed as a lever mechanism 304. In the various exemplary embodiments shown here, the cover 30 can always be reversibly coupled to the headpiece 20.

[0034] The lever mechanism 304 has a first lever 320 and a second lever 330, which cooperate with each other to release the holder of the treatment tool 7. For this purpose, the lever mechanism 304 interacts with the release element 210, so that the release element 210 in turn actuates (or opens) the holding means 230 and a corresponding treatment tool 7 can be inserted into or removed from the head piece 20 of the hand instrument 1. The lever mechanism 304 minimizes the force to be applied by the user. Furthermore, the actuation B of the first lever 320 takes place in the opposite direction to the interaction of the second lever 330 with the release element 210, so that this required actuation movement B of the first lever 320, which spreads away from the cover 30, creates a lever movement, as shown by way of example in the Figure 3Ais illustrated, prevents unintentional triggering of the lever mechanism 304 to release the holding mechanism. This eliminates the risk of burns for the user or patient due to unintentional actuation, since exerting force on the lid 30 and in particular the lever 320 - for example, through contact with a cheek or tooth of a patient, or a finger of the attending physician - does not trigger the lever mechanism 304, thus preventing contact between the lever mechanism 304 and rapidly rotating components during operation of the hand instrument 1.

[0035] Regardless of the specific design of the cover 30, the lever mechanism 304 implemented therein is always designed to interact with the release element 210 upon actuation B, so that this in turn releases the holding means 230. The holding means 230 and the release element 230 form a so-called holding mechanism. As also in the Figure 2The holding means 230 is preferably a clamping tong - that is, a tubular sleeve which has a stepped bore and at least one slit. When actuated, the holding means 230 is spread by means of the release element 210, which preferably has a wedge-shaped head region 211 and a flat bottom region 212. For this purpose, for example, the wedge-shaped head region 211 of the release element 210 interacts with the slit of the clamping tong, and thus the sleeve of the clamping tong is expanded so that the treatment tool 7 can be inserted into or removed from the holding means 230 via the tool receiving opening 240 and the tool channel 250 of the head piece 20.For this purpose, the release element 210 must be actively pressed in the direction of the holding means 230 - which is achieved in particular by actuating B the lever mechanism 304 - since the interaction of the two components of the holding mechanism is self-locking, i.e. the release element 210 is pushed out by the holding means 230 itself.

[0036] Within the head part 20, the release element 210 and the holding means 230 are arranged in a recess 260 provided for this purpose. The diameter of this recess 260 is larger than the diameter of the tool receiving opening 240 or the tool channel 250, so that the components of the holding mechanism are securely mounted inside the head piece 20. In particular, it is provided that both the holding means 230 and the release element 210 are rotatably mounted together with the treatment tool 7, since they rotate at the speed of the treatment tool 7 when the hand instrument 1 is used. The components of the holding mechanism also perform a tool-centering function.

[0037] In Figure 2A first exemplary embodiment of the lid 30 is shown. The lid 30 is screwed to the head piece 20, which has a corresponding counter-thread 220, via a thread 302. The lever mechanism 304 is located in the center piece 301 of the lid 30. In this first exemplary embodiment, the center piece 301 is arranged to be freely rotatable relative to the outer piece 305, which is surrounded by a ring around the center piece 301, so that the orientation of the lever mechanism 304, and in particular of the first lever 320 operated by the user, can be changed depending on the situation. The thread 302 is arranged on the outer piece 305.

[0038] The first lever 320 (also referred to as the upper lever 320) has a handle element 322, which considerably simplifies the operation of the lever mechanism 304. On the side opposite the handle element 322, the first lever 320 is provided with lateral protrusions 323, each of which has a suspension 326, which serves to mount the lever 320 in the cover 30 and laterally overlaps the end region of the second lever 330. As a result, the two levers 320, 330 are arranged in a space-saving manner in the rest position P, as shown in the Figure 4A indicated, arranged in the cover 30. The lateral protrusions 323, with their suspensions 326, form the pivot axis X of the first lever 320, which is arranged on the first lever 320 such that it is a two-armed lever. The pivot axis X of the first lever 320 is thus spaced apart from both the handle element 322 and the end of the first lever 320 opposite the handle element 322.

[0039] The end of the first lever 320 opposite the handle element 322 forms the contact surface 329 of the first lever 320, which acts on a free end of the second lever 330 upon actuation B of the lever mechanism 304. This free end of the second lever 330 has the contact surface 339, which interacts with the contact surface 329 of the first lever 320. The handle element 322 and the contact surface 329 of the first lever 320 are connected via an elongated web 321. The contact 340 between the first lever 320 and the second lever 330 is always present via the contact surfaces 329, 339 and is not interrupted even in the rest position P of the two levers 320, 330, so that even a slight actuation B of the first lever 320 results in a movement of the second lever 330.

[0040] Furthermore, the first lever 320 is provided on its underside facing the second lever 330 with a recess 324 which, in a rest position P of the two levers 320, 330, receives at least a part of the second lever 330, so that the second lever 330 can be embedded therein in a space-saving manner.

[0041] The second lever 330 (also referred to as the lower lever 330) is designed as a single-armed lever, with its suspension 334 arranged at the end of the second lever 330 opposite the contact surface 339 of the second lever 330. This suspension 334 of the second lever 330 also forms its pivot axis Y.

[0042] Between the contact surface 339 and the suspension 334, the second lever has a deflection 331, which presses against the release element 210 to interact with it, whereby the deflection 331 limits the force acting on the release element 210. This deflection 331 gives the second lever 330 elasticity, so that above a certain lever force, the lower lever 330 no longer deflects, thus preventing excessive force from being applied to the release element 210. The deflection 331 is centered in the cover 30 so that it is always positioned on the rotation axis M regardless of the orientation of the center piece 301, and thus interacts with the release element 210 upon actuation B, ensuring optimal force transmission.

[0043] The second lever 330 is further provided in the region of its pivot axis Y with a return spring 332, in particular a leg spring, which is designed to transfer the first and second levers 320, 330 into a rest position P if the first lever 320 is not actuated B. The return spring 332 has a flat support 333 against which the return spring 332 acts, resulting in a restoring force which pushes the second lever upwards - i.e. in the direction of the first lever 320 - whereby the upper lever 320 in turn snaps back and is pushed towards the rest position P, provided the first lever 320 is not actuated.

[0044] The suspension 326 of the first lever 320 and the suspension 336 of the second lever 330, or their pivot axes X, Y, are arranged parallel to each other and, moreover, are perpendicular to a plane which runs along the rotation axis M. This achieves a particularly advantageous force transmission from the lever mechanism 304 to the release element 210 positioned on the rotation axis M.

[0045] Furthermore, the suspension 326 of the first lever 320 and the suspension 336 of the second lever 330, or their pivot axes X, Y, are arranged opposite one another on the cover with respect to the rotation axis M, whereby the two-armed design of the first lever 320 and the single-armed design of the second lever 330 enable particularly efficient force transmission. Due to the superimposed arrangement of the first and second levers 320, 330, the two pivot axes X, Y are also slightly offset from one another in the direction of the rotation axis M.

[0046] In the rest position P, the second lever 330 is spaced from the release element 210, so that unintentional contact between these two elements is excluded.

[0047] Furthermore, the first lever 320 preferably has a locking element 325 on the underside of the handle element 322, which interacts and locks with the second lever 330 in the rest position P. This provides the user with haptic as well as acoustic feedback, provided the two levers 320, 330 are correctly located in the rest position P. This also increases the operational reliability of the hand instrument 1, since the locking mechanism forms an additional mechanical safeguard for the lever mechanism 304, preventing unintentional lifting of the first lever 320 and thus actuation B of the lever mechanism 304.

[0048] The two-part design of the lever mechanism 304 significantly reduces the force required by the user. While a one-part lever mechanism would also provide a noticeable reduction in load, one lever would inevitably rub against the release element 210 upon actuation, as the contact surface of one lever would then shift laterally on the release element 210, resulting in detrimental material removal on both elements. This would significantly reduce the operational reliability of the hand instrument 1. In this respect, the two-part lever mechanism 304 proves to be advantageous for the present application.

[0049] In the Figures 3A, 3B, 4A and 4B An exemplary second embodiment of a cover 30 according to the invention is shown, which can be reversibly coupled to a hand instrument 1. Essentially, the structure of this second embodiment is identical to that already shown in Figure 2known exemplary first embodiment, wherein the spatial structure of the cover 30 is more clearly visible due to the representation without the remaining components of the hand instrument 1 and thus in particular without the representation of the components of the holding mechanism. Figures 3B and 4B provide a perspective view of the lid 30 and its lever mechanism 304, which is identical to the first embodiment.

[0050] The second embodiment provides another additional feature that further increases operability and operating safety. An additional locking device 310 is provided, which allows a set orientation to be locked relative to the rotational axis M of the lever mechanism 304, such that, once locked, unintentional rotation of the center piece 301 is prevented. Of course, the locking of the locking device 310 can be released again, so that the lever mechanism 304 and, connected thereto, the center piece 301 can be reoriented and then locked again. As can be seen from the Figures 3A to 4BAs can be seen, the locking device 310 in the variant shown here is a nut device consisting of a ring element 311, which in turn has a thread and is designed to interact with an internal thread 303 arranged on the inside of the threaded piece. The ring element 311 is arranged between the middle piece 301 and the outer piece 305 and, provided the ring element 311 is screwed in accordingly, fixes the middle piece 301 by frictional engagement. The ring element 311 has corresponding tool recesses 319 for screwing in, so that a firm locking is possible. This design with the locking device 310 allows the hand instrument 1 or the cover 30 to be adapted to the individual requirements and preferences of the user, so that, for example, a left-handed person can orient the lever mechanism 304 differently, thereby significantly improving the ergonomics of the hand instrument 1.

[0051] Furthermore, the outer piece 305 can also have corresponding tool recesses 309, so that a firm screwing of the cover 30 to the head piece 20 of the hand instrument 1 is possible, in particular in such a way that a tool-free decoupling of these components is not possible, which further increases the operational reliability of the hand instrument 1.

[0052] As further evidenced by the Figures 3A and 4BAs can be seen, the outer piece 305 can also extend below the middle piece 301, thereby increasing the stability of the lid. It can further be provided that the middle piece 301 is rotatably mounted in the outer piece 305 via a ball bearing 312, so that reorientation of the middle piece 301 and thus also of the lever mechanism 304 along the rotation axis M is simplified. By means of the locking device 310, the ball bearing 312 is then also locked, so that further rotation of the middle piece 301 is prevented. These embodiments, as a whole or individually, are also applicable to the previously described Figure 2 shown first embodiment is applicable.

[0053] The cover 30 furthermore has a receiving space 350 in which components of the head piece 20 are received when the cover 30 is coupled to the hand instrument 1. It is important here that the freedom of movement of the second lever 330 is not restricted, so that the deflection 331 can interact with the release element 210 of the head piece 20 upon actuation B of the lever mechanism 304. This is also due to the previously described Figure 2 shown version transferable.

[0054] In the Figures 3A and 3B Furthermore, actuation positions B of the lever mechanism 304 are shown, whereby in conjunction with the Figures 4A and 4B , which show the rest position P of the lever mechanism 304, the possible lever positions are illustrated. This representation of the actuation B and the rest position can be applied to all exemplary embodiments, although differently arranged two-part lever mechanisms are also conceivable.

[0055] As can be seen in particular from the Figures 4A and 4B As can be seen, the lever mechanism 304 is designed such that the first lever 320 integrates flush with the surface of the center piece 301. Only the handle element 322 protrudes slightly above the center piece 301, so that it can be operated particularly easily by a user.

[0056] In Figure 5 A further exemplary third embodiment of the lid 30 or hand instrument 1 is shown. In addition to the two-part lever mechanism 304 known from the first and second embodiments, this embodiment has a further mechanism for releasing the holding mechanism.

[0057] In this case, a spring element 40 is arranged between the cover 30 and the head piece 20. In this embodiment, the cover 30 and thus also the lever mechanism 304 are movably mounted along the rotation axis M, with the spring element 40 pushing the cover 30 away from the head piece 20. In this respect, the lever mechanism 304 is preloaded by the spring force of the spring element 40 into a position spaced apart from the release element 210.

[0058] The coupling of the cover 30 to the head piece 20 is also effected via the thread 302 and the counter-thread 220, however, this coupling is now designed such that after screwing on the cover 30 via the threads 302, 220, the cover 30 can be moved back and forth along a smooth surface, whereby the threads 302, 220 prevent an unintentional decoupling of the cover 30 from the head piece 20. In this embodiment, the lever mechanism 304 can therefore be pressed down against the spring force in order to contact the release element 210 in a rest position of the two levers 320, 330 in the pressed-down state.

[0059] In this respect, with this exemplary third embodiment, both the lever mechanism 304 and a push-button mechanism for releasing the holding mechanism are integrated in the lid 30, so that a user has the choice of which mechanism to use. In this embodiment, for example, it can be provided to use a particularly strong spring element 40, which is not compressed by light touches or force applied to the lid 30, thus preventing unintentional contact with the lever mechanism 304 during operation of the hand instrument 1. However, this would also require a great deal of force from the user of the hand instrument 1 to couple (i.e., tighten) or uncouple (i.e., release) the treatment tool 7 with the hand instrument 1.Users who cannot apply this required force can then use the lever mechanism 304 to easily release the holding mechanism of the hand instrument 1.

[0060] All of the previously described exemplary embodiments of the hand instrument 1 and the cover 30 significantly facilitate the removal of the treatment tool 7. The cover 30 is advantageously designed such that it can also be screwed onto older, already known hand instruments 1, so that the two-part lever mechanism 304 according to the invention can also be applied to older hand instruments 1. The design of a removable cover 30 allows particularly simple and advantageous maintenance, cleaning, and repair work to be carried out inside the headpiece 20 as well as on the cover 30 itself. This enables a particularly long service life of the hand instrument 1 and the cover 30.

[0061] The hand instrument 1 thus constructed, or the cover 30 for a hand instrument 1 thus constructed, thus enables particularly simple and safe operation for releasing the holding mechanism of a hand instrument 1 for a treatment tool 7. Unintentional actuation of the mechanism is thus avoided, and contact between the lever mechanism 304 and the release element 210 is also prevented, particularly during operation, so that there is no risk of burns for the patient or the attending physician.

Claims

1. Medical, in particular dental hand-held instrument (1) having a grip sleeve (10) and a headpiece (20) which is arranged at a front end (101) of the grip sleeve (10) and has a tool-receiving opening (240), wherein a holding means (230) for rotatably securing a treatment tool (7), for example a dental drill, is arranged in the interior of the headpiece (20), wherein the holding means (230) is arranged along an axis of rotation (M) for the treatment tool (7), and wherein a release element (210) is arranged in the interior of the headpiece (20) along the axis of rotation (M), said release element being designed to interact with the holding means (230), wherein the release element (210) releases the securing of the treatment tool (7) upon interaction with the holding means (230), wherein the headpiece (20) furthermore has a cover (30), wherein the cover (30) comprises a lever mechanism (304) which has a first lever (320) and a second lever (330) which cooperate in order to release the securing of the treatment tool (7), characterized in that the first lever (320), upon actuation, acts on a free end of the second lever (330).

2. Medical hand-held instrument according to Claim 1, characterized in that a pivot axis (X) of the first lever (320) and a pivot axis (Y) of the second lever (330) are arranged parallel to each other and are perpendicular to a plane which extends along the axis of rotation (M).

3. Medical hand-held instrument according to Claim 2, characterized in that the pivot axis (X) of the first lever (320) and the pivot axis (Y) of the second lever (330) are arranged on the cover opposite each other in relation to the axis of rotation (M), wherein, in the direction of the axis of rotation (M), the two pivot axes (X, Y) are preferably offset from each other.

4. Medical hand-held instrument according to any one of the preceding claims, characterized in that the second lever (330) has a bend (331) which, to interact with the release element (210), presses on the latter, wherein a force acting on the release element (210) is limited by the bend (331).

5. Medical hand-held instrument according to any one of the preceding claims, characterized in that the second lever (330) is provided, in the region of its pivot axis (Y), with a return spring (332), in particular a leg spring, which is designed, in the absence of actuation (B) of the first lever (320), to transfer the first and second levers (320, 330) into a rest position (P), wherein, in the rest position (P), the second lever (330) is spaced apart from the release element (210).

6. Medical hand-held instrument according to any one of the preceding claims, characterized in that the first lever (320) is provided, at its end region facing the pivot axis (X), with lateral protrusions (323) which serve for mounting the lever (320) in the cover (30) and each engage laterally over the end region of the second lever (330).

7. Medical hand-held instrument according to any one of the preceding claims, characterized in that the first lever (320) is provided, at its end region remote from the pivot axis (X), with a grip element (322).

8. Medical hand-held instrument according to any one of the preceding claims, characterized in that the first lever (320) is provided, on its underside facing the second lever (330), with a recess (324) which, in a rest position (P) of the two levers (320, 330), receives at least a part of the second lever (330).

9. Medical hand-held instrument according to any one of the preceding claims, characterized in that the cover (30) is able to be coupled reversibly to the headpiece (20) of the hand-held instrument (1), wherein preferably, for this purpose, the cover (30) has a thread (302) and the headpiece (20) has a corresponding mating thread (220).

10. Medical hand-held instrument according to any one of the preceding claims, characterized in that the cover (30) has a fixing device (310), wherein the lever mechanism (304) is able to be locked selectively in a desired orientation with respect to the axis of rotation (M) by means of the fixing device (310).

11. Medical hand-held instrument according to any one of the preceding Claims 1 to 9, characterized in that the lever mechanism (304) is mounted movably along the axis of rotation (M), and in that the lever mechanism (304) is preloaded by means of spring force into a position spaced apart from the release element (210), wherein the lever mechanism (304) is able to be depressed counter to the spring force in order, in the depressed state, to contact the release element (210) in a rest position of the two levers (320, 330).

12. Medical hand-held instrument according to any one of the preceding Claims 1 to 11, characterized in that the holding means (230) is a collet, and / or the release element (210) is a wedge element having a wedge-shaped head region (211) and a planar bottom region (212).

13. Cover (30) for a headpiece (20) of a medical, in particular dental hand-held instrument (1) having a grip sleeve (10) and a headpiece (20) which is arranged at a front end (101) of the grip sleeve (10) and has a tool-receiving opening (240), wherein a holding means (230) for rotatably securing a treatment tool (7), for example a dental drill, is arranged in the interior of the headpiece (20), wherein the holding means (230) is arranged along an axis of rotation (M) for the treatment tool (7), and wherein a release element (210) is arranged in the interior of the headpiece (20) along the axis of rotation (M), said release element being designed to interact with the holding means (230), wherein the release element (210) releases the securing of the treatment tool (7) upon interaction with the holding means (230), wherein the cover (30) comprises a lever mechanism (304) which has a first lever (320) and a second lever (330) which cooperate in order to release the securing of the treatment tool (7), characterized in that the first lever (320), upon actuation, acts on a free end of the second lever (330).

14. Cover for a headpiece according to Claim 13, characterized in that the first lever (320) is in the form of a two-armed lever and the second lever (320) is in the form of a one-armed lever.