DENTAL TORQUE WRENCH

Description

[0001] The invention relates to a torque wrench as a ratchet instrument for medical technology, in particular dental medicine, according to the preamble of claim 1.

[0002] In dentistry, it is common practice to insert implants into the jawbone and attach connecting elements, such as abutments, to the implants. The superstructure, particularly a crown or bridge, is then placed on these abutments. To screw in the implant or connecting element, an insertion tool can be fitted onto its free end and turned using a torque wrench. The long-term stability and reliability of the screw connections depend on them being tightened to the optimal torque. Insufficient tightening can lead to loosening of the screws later, while overtightening overloads the inserted connecting elements and the implant, increasing the risk of breakage and potentially causing bone damage.

[0003] A torque wrench with a ratchet function for use in dentistry is disclosed in EP 0 704 281 A1. The torque wrench comprises a torque instrument, in particular a ratchet instrument, and a torque indicator that can be attached to it as an accessory. The torque indicator has a sleeve-shaped carrier that can be slid onto a handle of the torque instrument, to which an elastic bending rod is attached. When actuated, a force is exerted on the free end of the bending rod in the tightening direction of the torque wrench, and the generated torque is displayed on a scale. Cleaning and sterilizing this torque wrench require disassembly and are therefore relatively complex. Furthermore, its manufacture is relatively expensive due to the large number of components.

[0004] From DE 20 2004 014 195 U1, a torque wrench as a ratchet instrument for medical technology is known, comprising a head section located at the front, a neck section followed by a shaft section, and a handle section located at the rear. The head section, neck section, shaft section, and handle section extend in one plane. The torque wrench further comprises a receiving opening provided in the head section, which is surrounded by a casing and has a center point through which an axis extends perpendicular to the plane. The receiving opening serves for inserting a screw-in instrument along the extension of the axis. The torque wrench further comprises a limited-movement pawl segment arranged at the periphery of the receiving opening, the front portion of which faces the receiving opening.The front section is designed to engage with an external contour on the head of the screw-in tool when the torque wrench is operated in screw-in mode, and to release this engagement with the external contour on the head of the screw-in tool when the torque wrench is operated in reverse, i.e., in ratchet mode. The torque wrench also includes a rigid base section extending from the neck along the shaft. A pawl spring extends from the pawl segment into the neck, with the pawl segment and pawl spring forming a single, integral pawl. Long, thin slots are formed on both sides of the pawl, allowing it to deflect in the plane against the force of the pawl spring. Furthermore, the pawl is integrally formed from the neck. This one-piece design eliminates the need for disassembly during cleaning and sterilization.However, the long, thin slots on both sides of the latch make cleaning the torque wrench more difficult.

[0005] WO 2009 / 036943 A1 discloses a screwdriving tool with a ratchet head and an operating handle for use in medical technology, in particular dental prosthetics. The ratchet head has a receiving opening surrounded by a casing. The casing is ring-shaped to receive a screwdriving tool and has a circumferential break at one point. In the area of ​​this break, a pawl is arranged on one side of the casing and the operating handle on the other side. The pawl and casing are formed in one piece, with the casing providing the spring action for the pawl. The spring force is determined by the thickness of the casing and the choice of material.

[0006] In one embodiment, DE 10 2012 101050 B3 discloses a one-piece dental ratchet comprising a handle and a housing for receiving a screw-in tool. The housing is designed as a flexible spiral with two turns. US 2010 / 304330 A1 discloses a torque wrench comprising a handle and a head designed for the detachable reception of a tool. The handle is designed as an elongated body element and includes a flexible torque arm for indicating the torque applied to the torque arm. Furthermore, the handle includes a display element with a gauge and a ratchet element designed to engage with the tool.

[0007] The object of the present invention is therefore to provide a torque wrench for medical technology, in particular for dental medicine, which is inexpensive to manufacture and easy to clean.

[0008] This problem is solved according to the invention by a torque wrench according to claim 1. Preferred embodiments of the invention are described in the dependent claims.

[0009] The invention relates to a torque wrench as a ratchet instrument for medical technology, in particular dentistry. The torque wrench comprises a head section having a receiving opening, a neck section adjoining the head section, a rod-shaped actuating lever attached to the neck section and extending at least approximately in one plane, preferably in the plane, for applying torque to the head section, and a casing forming the receiving opening of the head section. The neck section forms an at least approximately cuboid, preferably solid, part. The casing defines an axis of rotation extending at least approximately perpendicularly, preferably perpendicular to the plane, and is designed to receive a screw-in tool along the extension of the axis of rotation.The plane can encompass the front of the torque wrench, and another plane running parallel to the plane can encompass the back of the torque wrench.

[0010] Furthermore, the torque wrench comprises a spring-loaded lever and a locking lug formed on this lug, which, in its rest position, projects into the receiving opening. The rest position is the position of the locking lug when no insertion tool is inserted into the receiving opening and no radial force is applied to the spring-loaded lever.

[0011] The locking lug has a drive section designed to engage with a mating surface of the screw-in tool when the screw-in tool is inserted into the receiving opening and the operating lever is rotated in the tightening direction. This engagement position can correspond to the rest position if the spring clip exerts at least approximately no force against the inserted screw-in tool. When the drive section engages with the mating surface, a torque is transmitted to the screw-in tool via a positive-locking connection.

[0012] The locking lug is designed to move radially outwards into a release position when rotated against the tightening direction, against the force of the spring clip, in order to form a free movement between the head area and the screw-in instrument.

[0013] According to the invention, the enclosure has an opening extending across its entire cross-section and the enclosure forms the spring clip.

[0014] In a preferred embodiment, the locking lug is integral and formed in one piece with the spring clip. This simplifies cleaning because it prevents dirt from accumulating at the connection point between the locking lug and the spring clip.

[0015] In a preferred embodiment, the drive section is formed by a drive surface extending at least approximately radially to the axis of rotation, which is designed to interact with the counter surface of the inserted screwing instrument, which preferably also extends at least approximately radially to the axis of rotation. This configuration of the drive surface and the counter surface enables reliable drive of the screwing instrument.

[0016] Furthermore, the radial length of the drive surface, measured relative to the axis of rotation and the area in contact with the counter surface of the insertion tool (referred to here as the working length), can also be used as a parameter to ensure reliable insertion of the tool. The working length corresponds to the required radial outward movement of the locking lug relative to the axis of rotation, allowing the locking lug to reach its release position. A short working length can therefore be advantageous because the resulting deformation of the spring clip is correspondingly small, thus remaining within the spring clip's elastic range.However, when using a torque wrench, an excessively short working length can cause the drive section to slip radially outwards by the working length relative to the axis of rotation due to unwanted movement of the torque wrench relative to the screw-in tool onto the counter surface. Consequently, the locking lug disengages from the drive position. Preferably, the radial length of the drive surface is greater than or equal to the radial length of the counter surface to optimize force transmission. Preferably, the radial length of the drive surface is between 0.2 mm and 5 mm to optimize force transmission.

[0017] In a preferred embodiment, the locking lug is adjacent to the opening. Particularly preferably, the locking lug is directly adjacent to the opening. This maximizes the wrap angle of the spring clip around the inserted insertion tool. The wrap also generates additional static friction forces in the circumferential direction between the spring clip and the inserted insertion tool, which assist in holding the insertion tool in the receiving opening. This results in a smaller circumferential force acting on the drive section of the locking lug when rotating in the tightening direction.

[0018] In a preferred embodiment, the locking lug has an engagement surface that, viewed in the tightening direction, trails behind the drive surface and preferably adjoins the drive surface. This engagement surface allows the locking lug to move into the release position and consequently to free rotation. When the actuating lever is rotated against the tightening direction, the engagement surface forms the area over which the force of the spring clip is exerted on the screw-in tool.

[0019] Preferably, the contact surface is formed by a chamfer whose distance from the axis of rotation increases in the opposite direction of tightening, thus allowing free rotation. Preferably, the distance increases continuously to enable a constant free rotation of the contact surface against the screw-in tool. This allows the torque wrench to perform its ratchet function smoothly.

[0020] In a particularly preferred embodiment, the chamfer extends at least approximately to the free end of the spring clip. This allows for the simple manufacture of the circumferential surface of the spring clip facing the axis of rotation.

[0021] Preferably, the engagement surface has a circumferential extension surface that trails behind the engagement surface when viewed in the direction of tightening. This extension surface adjoins the engagement surface directly, and the chamfer adjoins this extension surface. The extension surface and the chamfer define a volume of the locking lug that serves to prevent shearing of the engagement section during operation. This volume may reduce wear on the insertion tool caused by the locking lug during free-running operation, because the locking lug has no sharp edge between the engagement surface and the chamfer.

[0022] In a particularly preferred embodiment, the chamfer has a length, measured radially, equal to or greater than the working length. This prevents the movement of the locking lug into the release position from being blocked by the tightening tool when rotating against the tightening direction.

[0023] In a particularly preferred embodiment, the angle, measured in the plane E, between the chamfer and a tangent to the circumferential direction, wherein the tangent runs at the intersection of the chamfer and the circumferential direction, is less than 45°, preferably between 15° and 45°, and particularly preferably between 25° and 40°. The angle is less than 45° so that the movement of the locking lug into the release position during rotation against the tightening direction requires little space in the radial direction. This is particularly important in the oral cavity, where the movement of the locking lug can be restricted. At an angle between 15° and 45°, the frictional force between the surface of the chamfer and the insertion instrument is within a range where the torque transmitted to the insertion instrument by friction during rotation against the tightening direction, e.g., the free-running torque, remains below the release torque of the implant or the connecting element.This is particularly important when implanting into bone, which can be unstable and fragile, meaning the release torque should be low. Ideally, the free-running torque should be less than 3 Ncm. Experience has shown that an angle between 25° and 40° is optimal to optimize both the free-running torque and the radial movement of the locking lug into the release position.

[0024] In a preferred embodiment, the locking lug extends, measured axially, over the entire thickness of the enclosure. The axial extension of the locking lug ensures reliable engagement, as the engagement area is correspondingly larger. However, it is also possible for the locking lug to extend only over a portion of the total thickness, preferably, viewed axially, centered with respect to the thickness of the enclosure. Due to the central position of the locking lug, there are no lateral bending moments on the spring clip.

[0025] A conventional insertion instrument comprises a cylindrical ratchet head, defining an axis of rotation for the insertion instrument, which can be inserted into the receiving opening of the torque wrench, and a shaft extending from the ratchet head in the direction of the axis of rotation. The free end of the shaft has a preferably standardized profile, for example, a Torx® profile or a hexagonal head, for interacting with the implant or connecting element, so that the insertion instrument can transmit the torque applied to the ratchet head to the implant or connecting element. The ratchet head has a circumferential surface that includes a contour forming the mating surface to enable the transmission of the torque applied to the torque wrench to the insertion instrument.The contouring can be formed by a groove that preferably runs parallel to the axis of rotation of the insertion instrument.

[0026] Preferably the groove has a cross-section that is at least approximately rectangular, the wall of which, in the direction of tightening, extends at least approximately radially towards the axis of rotation and forms the opposite surface.

[0027] Preferably, the contouring comprises a plurality of grooves which are identical in design and, viewed in the circumferential direction, are arranged at the same distance from each other.

[0028] In a preferred embodiment of the torque wrench, the locking lug is designed such that, measured in the circumferential direction of the encirclement, the total length of the chamfer, possibly including the extension surface, is longer than the width of the groove. This allows the insertion of the entire locking lug into the groove and the resulting potential blockage of the locking lug's movement into the release position during rotation against the tightening direction to be at least almost completely avoided.

[0029] In a preferred embodiment, the spring-loaded lever has, on its side facing the axis of rotation, a recess that, viewed in the tightening direction, projects forward of the drive surface and adjoins it. Preferably, the recess is at least approximately semicircular. Furthermore, it is designed such that a portion of the ratchet head projecting forward of the opposing surface can extend into the recess during rotation in the tightening direction. This ensures reliable engagement of the screwing tool.

[0030] In a preferred embodiment, the opening borders the neck area. Preferably, the opening is formed by a slot extending at least approximately radially to the axis of rotation. This maximizes the circumferential length of the spring clip. Consequently, the wrap angle of the spring clip around the inserted screw-in tool is maximized in the tightening direction. The opening is designed such that the locking lug can move radially outward with respect to the axis of rotation by at least its working length, allowing it to reach its release position.

[0031] In a preferred embodiment, the opening is formed by a cut extending at least approximately radially. This allows the opening to be formed simply, particularly in the case of an enclosure with a thin wall.

[0032] In a preferred embodiment, the opening is formed by a cut extending at least approximately axially. With a thicker wall than in the previous embodiment, the opening can also be formed simply.

[0033] In a preferred embodiment, the opening can be designed such that the movement of the spring clip in the circumferential direction is limited.

[0034] The spring clip has at its free end a front surface defined by the opening, extending at least approximately radially to the axis of rotation, which faces a counter-front surface of the neck area defined by the opening, extending at least approximately radially to the axis of rotation.

[0035] In a preferred embodiment, the width of the opening, measured circumferentially, is dimensioned such that, when deformed by compression, the end face of the spring clip can at least partially come into contact with the opposite end face of the neck region, once the deformation of the spring clip has reached a predetermined degree. The width of the opening is determined such that the deformation of the spring clip remains within its elastic range. This prevents further deformation of the spring clip and consequently damage to the torque wrench.

[0036] According to the invention, the opening forms a first hook projecting from the neck area and a second hook projecting from the spring clip. The first and second hooks have a first and a second projection, respectively, which extend transversely, preferably at right angles to the tightening direction, and overlap. In the rest state and during normal operation of the torque wrench, the first and second projections are spaced apart from each other. That is, the first and second projections are designed such that a gap exists between them in the rest state and during normal operation.

[0037] To prevent overextension of the spring clip, the first and second projections engage when the spring clip's deformation reaches a predetermined limit. This prevents further deformation of the spring clip and consequently damage to the torque wrench. Overextension can occur, for example, when gripping and removing the torque wrench from a surgical case, if the torque wrench and other tools become entangled and the wrench is tightened too much.

[0038] The gap is determined such that the deformation of the spring clip remains within its elastic range. This means that the deformation is reversible and the spring clip returns to its original shape when no further deformation force is applied. This ensures that the spring clip retains its properties, particularly the force required to engage the locking lug in the release position.

[0039] If the outer diameter of the ratchet head of the inserted insertion tool is smaller than the inner diameter of the receiving opening, the gap may be smaller during normal operation than in the resting state.

[0040] The opening formed by the at least approximately radial cut can, viewed in longitudinal section of the enclosure, be at least approximately S-shaped and run from the front to the back of the torque wrench, with a first half of the S-shape facing the front forming the first hook and a second half of the S-shape facing the back forming the second hook.

[0041] It is also possible that the opening formed by the at least approximately axially extending cut, viewed in cross-section of the enclosure, is at least approximately S-shaped and extends from an inner side of the enclosure facing the axis of rotation to an outer side of the enclosure facing away from the axis of rotation. In this embodiment, the first half of the S-shape facing the inner side forms the first hook, and the first half of the S-shape facing the outer side forms the second hook.

[0042] In a preferred embodiment, the opening leads into a recess formed in the neck region, which contains the first hook. Furthermore, the second hook, projecting from the spring clip, extends into the recess to engage with the first hook when the deformation of the spring clip due to compression or expansion reaches a predetermined limit. Because the engagement of the first and second hooks prevents further movement of the spring clip with respect to the neck region, further deformation of the spring clip and consequently damage to the torque wrench can be prevented.

[0043] In a preferred embodiment of the torque wrench, the spring clip is designed to protrude from the side of the neck area facing away from the operating lever. This arrangement allows for easy handling of the torque wrench when used in the patient's mouth.

[0044] Preferably, the spring clip is integral and formed in one piece with the neck area. This simplifies cleaning, as the absence of a connection point between the neck area and the spring clip prevents dirt from accumulating at the joint.

[0045] In a preferred embodiment of the torque wrench, a section of the spring clip has a reduced cross-section to dimension the force exerted at least approximately in the radial direction by the spring clip on the inserted insertion tool. This design is easy to implement in the manufacture of the torque wrench and represents a cost-effective way to achieve the desired spring clip force. The reduction in the cross-section of the spring clip aims to reduce the force exerted by the spring clip, so that the torque transmitted to the insertion tool by friction in the release position of the locking lug is minimal. This prevents the implant or connecting element from unintentionally unscrewing into the release position.

[0046] The section of the spring clip with the reduced cross-section can be formed by a recess in the spring clip. For example, this recess can be formed by a cut extending radially to the axis of rotation. However, using the same material for the spring clip, it is also possible to choose a thinner cross-section that remains constant along its entire length to achieve the same force. Determining the force of the spring clip is straightforward in this case, but the thin cross-section can represent a weak point for certain materials. Furthermore, it is also possible to dimension the force exerted by the spring clip by selecting a suitable material. Depending on the requirements for dimensioning the force of the spring clip, a person skilled in the art can choose one of the solutions mentioned above or combine them.

[0047] In a preferred embodiment of the torque wrench, the housing is at least approximately annular in shape. This housing shape fits a majority of the torque wrench's insertion tools, allowing for a wide range of applications. Furthermore, this shape is simple and inexpensive to manufacture.

[0048] In a particularly preferred embodiment of the torque wrench with an approximately annular enclosure, a tangent to the circumferential surface of the spring clip facing the axis of rotation extends at a point on the section where, measured radially, the spring clip has its approximately smallest cross-section. This tangent extends at least approximately parallel to a radius extending from the axis of rotation to the drive section. However, it is also possible to make the tangent at least approximately parallel to a normal with respect to the contact surface, which is preferably a plane. These arrangements provide an optimal distribution of stresses in the enclosure, thus reducing the risk of breakage or non-elastic deformation of the spring clip.

[0049] When dimensioning the force exerted by the spring-loaded lever on the insertion tool during rotation against the tightening direction, it must be ensured that the transmitted torque, i.e., the torque transmitted in the release position of the locking lug, does not exceed a predetermined torque limit that could lead to the implant or connecting element unscrewing. This allows the torque wrench to perform its ratchet function when rotating against the tightening direction.

[0050] In a preferred embodiment, the torque wrench comprises a shaft section projecting from the neck section on the side of the neck section facing away from the head section, extending in a plane at least approximately parallel to the plane, and an indicator section projecting from the free end section of the shaft section, wherein the actuating lever extends at least to the indicator section. Preferably, the actuating lever extends into the indicator section.

[0051] Preferably, the actuating lever is formed in one piece and integrally with the neck area to simplify cleaning.

[0052] Preferably, the actuating lever extends beyond the indicator area to allow for easy operation of the actuating lever beyond its section extending beyond the indicator area.

[0053] A rest position or a deflection position of the actuating lever defines its position when no force or a force is exerted on the actuating lever, i.e., when the actuating lever has no or a bend.

[0054] Preferably, the shaft section, viewed in the tightening direction, is attached to the neck section below the operating lever and runs parallel to the operating lever in its rest position. This arrangement provides a compact form for the torque wrench, so that the torque wrench takes up little space in the surgical case. Furthermore, the torque wrench and other tools do not interfere with each other in the surgical case.

[0055] Preferably, there is a gap between the shaft area and the operating lever to allow for easy cleaning.

[0056] Preferably, the indicator area also extends at least approximately parallel to the plane, for example in the form of a plate. Particularly preferably, the indicator area is formed integrally with the shaft area. This embodiment is particularly simple in design and inexpensive to manufacture.

[0057] It is also possible to design the shaft area with a first and a second arm, which extend at least approximately parallel to the plane and from the neck area on the side facing away from the head area, wherein the free ends of the first and second arms are connected via the indicator area and the operating lever is arranged on the neck area between the first and second arms. The first and second arms, together with the indicator area, form a handle, preferably in the form of an acute-angled triangle, which allows for easy handling of the torque wrench, particularly when placing it on the screw-in tool.

[0058] Preferably, the shaft area is rigid to bending, so that the relative movement of the actuating lever with respect to the shaft area can be reliably and easily reproduced.

[0059] In a particularly preferred embodiment of the torque wrench, the operating lever is bendable, preferably elastically bendable, and most preferably linearly elastically bendable. An elastically bendable operating lever ensures that the bending remains reversible and that the lever returns to its original shape when no force is applied. This guarantees the accuracy of the applied torque reading throughout the service life of the torque wrench. A linearly elastically bendable operating lever exhibits a bend proportional to the applied force, enabling reliable and practical operation of the torque wrench.

[0060] When a force is applied in the tightening direction to a free end region of the actuating lever, the deflection of the actuating lever from its rest position is a measure of the generated torque. Preferably, the actuating lever includes a cam on its section overlapping the indicator region, and the indicator region includes an elongated slot designed to receive the cam. When the actuating lever is bent from its rest position at least to a maximum predetermined bend, the cam moves along the elongated slot. Particularly preferably, the elongated slot is designed such that it forms an end stop for the cam when the bend of the actuating lever corresponds to the maximum torque to be applied. This almost completely prevents overextension and thus deformation outside the elastic range of the actuating lever.

[0061] In a more preferred embodiment of the torque wrench, measuring marks are provided on the indicator area, from which the deflection of the actuating lever can be read as the generated torque. Preferably, the measuring marks are arranged along the elongated hole, so that the applied torque can be read from the position of the cam in the elongated hole relative to the measuring marks. Preferably, the cam is aligned with the surface of the indicator area, so that a parallax error when evaluating the alignment of the cam with a measuring mark can be avoided.

[0062] Materials suitable for manufacturing the torque wrench include those already used in medical technology that are biocompatible, cleanable, and sterilizable. Examples of suitable materials include metals and metal alloys such as steel, stainless steel, titanium, titanium alloys, and plastics.

[0063] The torque wrench can also be used to loosen the implant or the connecting element by rotating the torque wrench 180° around the operating lever and placing it back onto the screwing instrument.

[0064] Further advantages and features of the invention will become apparent from the following description of an exemplary embodiment, which is explained with reference to the accompanying figures.

[0065] These show purely schematically: Fig. 1 a perspective view of a non-inventive torque wrench; Fig. 2 a top view of the torque wrench according to Fig. 1 Fig. 3 shows a view of the back of the torque wrench according to Fig. 1 ; Fig. 4 a side view of a conventional screw-in instrument; Fig. 5 a top view of the head area with the inserted screw-in instrument shown in cross-section Fig. 4Fig. 6 is a perspective view of the head and neck area of ​​an embodiment of the torque wrench according to the invention; Fig. 7 is a top view of the head and neck area of ​​another embodiment of the torque wrench according to the invention; and Fig. 8 is a top view of the head and neck area of ​​another embodiment of the torque wrench according to the invention.

[0066] The torque wrench 10 depicted in Figures 1, 2, and 3 comprises a head section 30 having a receiving opening 20, a neck section 40 adjoining the head section 30, and a rod-shaped, rectangular-section, flexible operating lever 50 attached to the neck section 40 for applying torque to the head section 30. The receiving opening 20 of the head section 30 is formed by an annular enclosure 60, which defines an axis of rotation R. The enclosure 60 is designed to receive a screw-in tool 62 along the axis of rotation R, which is inserted into the head section 30. Fig. 4 is described in more detail. A plane E extends perpendicular to the axis of rotation R and encompasses a front face 64 of the torque wrench 10, which front face 64 in Fig. 2 is shown. A reverse side 66 of the torque wrench 10 is in Fig. 3 shown.

[0067] A front face 68 of the actuating lever 50 extends in the plane E. Furthermore, the extent of the cross-section of the actuating lever 50 is larger in the direction perpendicular to the plane E than in the direction parallel to the plane E.

[0068] The neck area 40 forms an at least approximately cuboid-shaped, solid part and includes a notch 70 extending perpendicular to the plane E for receiving an end area of ​​the actuating lever 50 and its fastening.

[0069] Furthermore, the enclosure 60 has an opening 72 extending across its entire cross-section, and the enclosure 60 forms a spring clip 80. The spring clip 80 projects from the side of the neck region 40 facing away from the actuating lever 50, is integral and integral with the neck region 40. The opening 72 adjoins the neck region 40 and is formed by a slot 72 extending at least approximately radially to the axis of rotation R.

[0070] Section 82 of the spring clip 80 has a reduced cross-section, which is located in the Fig. 5 will be described in more detail.

[0071] A locking lug 90 is formed integrally and integrally with the spring clip 80, adjacent to the opening. In its rest position, the locking lug 90 projects into the receiving opening 20. The rest position is the position of the locking lug 90 when no screw-in tool is inserted into the receiving opening 20 and no radial force is exerted on the spring clip 80.

[0072] Furthermore, the locking lug 90 has a drive section 92 which is designed to engage a counter surface 94 of the locking instrument 62 when the screw-in tool 62 is inserted into the receiving opening 20 and the actuating lever 50 is rotated in the tightening direction A. Fig. 4 and 5It is evident that they interact. When the drive section 92 interacts with the counter surface 62, a torque is transmitted to the screwing instrument 62 by means of a positive locking engagement.

[0073] The locking lug 90 is designed to move radially outwards into a release position when rotated against the tightening direction A, against the force of the spring clip 80, in order to form a free movement between the head area 30 and the screw-in instrument 62.

[0074] In addition, the spring clip 80 has on its side facing the axis of rotation R a semicircular recess 96, which, viewed in the direction of tightening A, extends forward with respect to the drive surface 92 and adjoins the drive surface 92.

[0075] The torque wrench 10 also comprises a rigid shaft section 100 extending from the neck section 40 on the side of the neck section 40 facing away from the head section 30, extending in a direction at least approximately parallel to the plane E, and an indicator section 110 extending from the free end section of the shaft section 100, wherein the actuating lever 50 extends beyond the indicator section 110.

[0076] The shaft section 100, viewed in the direction of pull-up A, is attached to the neck section 40 downwards of the actuating lever 50, is formed in one piece and integrally with the neck section 40 and runs parallel to the actuating lever 50 in its rest position, with a gap between the shaft section 100 and the actuating lever 50.

[0077] The indicator area 110 extends in the form of a plate 112, which has a front surface 113 extending in the plane E, and is formed in one piece and integrally with the shaft area 100.

[0078] The actuating lever 50 includes a recess 116 on its section overlapping the indicator area 110, which forms a clearance 116 for the indicator area 110. The clearance 116 is designed such that it allows the front surface 68 of the actuating lever 50 to move in the plane E, i.e., in the same plane as the front surface 113 of the plate 112, when the actuating lever 50 is actuated. The recess 116 is formed by two rectangular incisions whose height, measured perpendicular to the plane E, corresponds at least approximately to the thickness of the plate 112, and which are separated by a section of the actuating lever 50 extending in the plane E. The section of the actuating lever 50 forms a cam 117, which serves as a pointer 117 and moves into an elongated hole 114 formed in the plate 112 when the actuating lever 50 is actuated.The cam 117 is thus aligned with the front surface 113 of the indicator area 110. The elongated hole 114 extends in the form of a circular arc, the center of which is defined by the center of curvature of the actuated actuating lever 50.

[0079] When the actuating lever is bent from its rest position at least to a maximum predetermined bend, the pointer 117 moves along the elongated hole 114. The elongated hole 114 is designed such that it forms an end stop 118 for the cam 117 when the bend of the actuating lever 50 corresponds to the maximum torque to be applied.

[0080] Measuring marks 119 are provided along the elongated hole 114 on the indicator area 110, from which the deflection of the actuating lever 50 can be read as the generated torque. When a force is applied in the tightening direction A to a free end region of the actuating lever 50, the deflection of the actuating lever 50 from its rest position is a measure of the generated torque.

[0081] Depending on the dental implant system, torques in the range of 10 Ncm to 100 Ncm are typically required.

[0082] Fig. 4Figure 1 shows a conventional insertion instrument 62 comprising a cylindrical ratchet head 120, defining an axis of rotation D of the insertion instrument, which can be inserted into the receiving opening 20 of the torque wrench 10, and a shaft 130 extending from the ratchet head 120 in the direction of the axis of rotation D. The free end 140 of the shaft has a standardized profile for interaction with an implant or a connecting element, so that the insertion instrument 62 can transmit the torque applied to the ratchet head 120 to the implant or the connecting element. The ratchet head 120 has a circumferential surface 150, which includes a contour forming the counter surface 94 to enable the transmission of the torque applied to the torque wrench 10 to the insertion instrument 62.The contour comprises a plurality of grooves 160 running parallel to the axis of rotation D of the screwing instrument 62, which are identical in shape and arranged at the same distance from each other in the circumferential direction. The grooves 160 have a cross-section that is at least approximately rectangular, the wall 94 of which, in the tightening direction with respect to the drive surface, preferably extends at least approximately radially in the direction of the axis of rotation D and forms the counter surface 94.

[0083] In Fig. 5 The interaction of the drive section 92 of the locking lug 90 with the counter surface 94 of the inserted screwing tool 62 in the tightening direction A is shown. The drive section 92 is formed by the drive surface 92 extending at least approximately radially to the axis of rotation R, which is designed to interact with the counter surface 94 of the inserted screwing tool 62, which also extends at least approximately radially to the axis of rotation R.

[0084] The length of the drive surface 92, measured radially to the axis of rotation R and coming into contact with the counter surface 94 of the turning instrument 62, forms the working length L. The working length L corresponds to the minimum length of the required movement of the locking lug 90 radially outwards with respect to the axis of rotation R, so that the locking lug 90 can reach its release position.

[0085] Furthermore, the locking lug 90 has an attack surface 170, which, viewed in the direction of pull-in A, follows the drive surface 92 and adjoins the drive surface 92, and which allows the locking lug 90 to move into the release position.

[0086] The contact surface 170 is formed by a chamfer 172, the distance of which to the axis of rotation R increases continuously in the opposite direction of tightening A and which allows free movement. The chamfer 172 extends at least approximately to the free end 174 of the spring clip 80.

[0087] In addition, the attack surface 170 includes a circumferential extension surface 176, which directly adjoins the drive surface 92 and to which the chamfer 172 directly adjoins.

[0088] The locking lug 90 is designed such that, measured in the circumferential direction of the enclosure 60, the total length of the chamfer 172 together with the extension surface 176 is longer than the width of the grooves 160.

[0089] In the embodiment shown, an angle W measured in the plane E between the chamfer 172 and a tangent T1 running to the circumferential direction at the trailing endpoint of the chamfer (as seen in the direction of pull-in) is approximately 30°.

[0090] The spring clip 80 has its smallest cross-section at least approximately at a point P1, measured radially. Point P1 is located at least approximately 90° away from the contact surface 170 in the direction of pull-in. The section 82 of the spring clip 80 with the reduced cross-section extends on both sides of point P1 in the illustrated embodiment.

[0091] In Fig. 6 Another embodiment of the opening 72 is shown, which is formed by a radially extending cut. The enclosure 60 has a thin wall, i.e., a longitudinal section that is significantly larger in the axial direction than in the radial direction.

[0092] The opening 72 is designed in such a way that it limits the movement of the spring clip 80 relative to the neck area 40 in the circumferential direction in the direction of tightening A and against the direction of tightening A.

[0093] The spring clip 80 has on its free end 174 a front surface 175 defined by the opening 72, extending at least approximately radially to the axis of rotation R, which faces a counter-front surface 177 of the neck region 40 defined by the opening 72, extending at least approximately radially to the axis of rotation.

[0094] The opening 72, and thus the front surface 175 and the opposite front surface 177, run, seen in the longitudinal section of the enclosure 60, at least approximately in an S-shape and from the front 64 to the rear 66 of the torque wrench 10, wherein a first half of the S-shape facing the front 64 forms a first hook 178 projecting from the neck area 40 and a second half of the S-shape facing the rear 66 forms the second hook 180 projecting from the spring clip 80.

[0095] A gap 182 between the first and second hooks 178 and 180, respectively, is present in the rest state and during normal operation of the torque wrench. The first and second hooks 178 and 180, respectively, have a first and second projection 179 and 181, respectively, which engage when the deformation of the spring clip 80 reaches a predetermined dimension, thus preventing further deformation of the spring clip 80. It should also be noted that deformation can be prevented both in the tightening direction and against the tightening direction.

[0096] In Fig. 7 Another embodiment of the opening 72 is shown, which is formed by an axially extending cut. In contrast to the embodiment of the Fig. 6 Enclosure 60 has a thick wall.

[0097] The opening 72, viewed in cross-section of the enclosure 60, i.e., in a plane parallel to the plane E, runs at least approximately in an S-shape and from an inner side 184 of the enclosure 60 facing the axis of rotation to an outer side 186 of the enclosure 60 facing away from the axis of rotation. The first half of the S-shape facing the inner side 184 forms the first hook 178 projecting from the neck region 40, and the second half of the S-shape facing the outer side 186 forms the second hook 180 projecting from the spring clip 80.

[0098] In the event of deformation of the spring clip 80, the interaction of the first and second hooks 178 and 180 respectively and their first and second projections 179 and 181 respectively is the same as in the embodiment of the Fig. 6 .

[0099] In Fig. 8A further embodiment of the opening 72 is shown, in which the opening 72 opens into a rectangular recess 188 formed in the neck region 40 and connected to the receiving opening 20. The recess 188 has a wall 190, directed at least approximately radially to the axis of rotation R and trailing behind the opening 72 in the direction of pull-up A, from which the second and a further projection 179 and 193 respectively project towards the interior of the recess 188.

[0100] The second hook 180 comprises an arm 194 projecting radially outwards from the spring clip 80 with respect to the axis of rotation R. This arm extends into the recess 188 and lies between the second and the further projection 179 and 193, respectively. The free end of the arm 194 has the first projection 181, which is directed towards the wall 190. The first projection 181 engages with the second projection 179 to limit the movement of the spring clip 80 by expansion when the deformation of the spring clip 80 reaches a predetermined dimension. This prevents overextension of the spring clip 80. Conversely, the first projection 181 engages with the further projection 193 to limit the movement of the spring clip 80 by compression.

[0101] For the sake of completeness, it should also be mentioned that in a similar embodiment to the embodiment of the Fig. 8The first hook 178 can have one projection and the second hook 180 can have two projections. Mutatis mutandis, the interaction of the first and second hooks 178 and 180, respectively, and their respective projections, when the spring clip 80 is deformed, is the same as in the embodiment of the Fig. 8 . Reference sign level E axis of rotation R Working length L Direction of pull A Direction of rotation D tangent T1 Point P1 angle W torque wrench 10 opening 20 Head area 30 neck area 40 Actuating lever 50 Enclosure 60 Screw-in instrument 62 front 64 back 66 front 68 (of the operating lever) incision 70 Perforation, slit 72 Spring clip 80 Section of the spring clip 82 Rastnose 90 Carrying section, carrying surface of the locking nose 92 Counter surface of the screw-in instrument 94 Exclusion 96 shaft area 100 Indicator range 110 Plates 112 front surface 113 Slotted hole 114 Recess, free space 116 Cams, pointers 117 End stop 118 Measuring marks 119 ratchet head 120 shaft 130 free end of the shaft 140 Perimeter area 150 grooves 160 Attack surface 170 bevel 172 free end of the spring clip 174 Front surface 175 Extension area 176 Opposite face 177 First hook 178 first lead 179 second hook 180 second lead 181 gap 182 Inside of the enclosure 184 Outside of the enclosure 186 recess 188 Wall 190 arm 194 further advantage 193

Claims

1. A torque wrench (10) as a ratchet instrument for medical technology, in particular dentistry, having a head region (30) which has a receptacle opening (20), a neck region (40) which adjoins the head region (30), a bar-shaped activation lever (50) which, for applying a torque to the head region (30), is fastened to the neck region (40) and extends at least approximately in one plane (E), a bezel (60) which forms the receptacle opening (20) of the head region (30) and defines a rotation axis (R) that runs so as to be at least approximately orthogonal to the plane (E) and is specified for receiving a driver instrument (62) in the extent of the rotation axis (R), a spring bracket (80) and a latching cam (90) which is configured on said spring bracket (80) and in the resting position of said latching cam (90) protrudes into the receptacle opening (20), the entrainment portion (92) of said latching cam (20), when the driver instrument (62) is inserted in the receptacle opening (20), and when the activation lever (50) is rotated in the tightening direction (D) in an entraining position of the latching cam (90), being specified for interacting with a mating face (94) of the driver instrument (62) so as to by way of entrainment transmit a torque to the driver instrument (62), said latching cam (90), when rotating counter to the tightening direction, being specified for moving counter to the force of the spring bracket (80) to a releasing position, so as to form a freewheeling mechanism between the head region (30) and the driver instrument (62), wherein the bezel (60) has a cutout (72) running across the entire cross section of the latter and forms the spring bracket (80), wherein the bezel (60) is configured so as to be at least approximately annular, wherein the cutout (72) forms a first hook (178), which projects from the neck region (40), and a second hook (180), which projects from the spring bracket (80), and the first hook (178) and the second hook (180) have a first protrusion (179) and a second protrusion (181), respectively, which mutually overlap and are configured in such a manner that the first protrusion (179) and the second protrusion (181) come to bear on one another once the deformation of the spring bracket (80) as a result of expansion has reached a predetermined measure.

2. The torque wrench (10) as claimed in claim 1, characterized in that the latching cam (90) is configured so as to be integral to and in one piece with the spring bracket (80).

3. The torque wrench (10) as claimed in claim 1 or 2, characterized in that the latching cam (90) is adjacent to the cutout (72).

4. The torque wrench (10) as claimed in one of claims 1 to 3, characterized in that the entrainment portion (92) is formed by an entrainment face (92) which runs so as to be at least approximately radial to the rotation axis (R) and is specified for interacting with the mating face (94) of the inserted driver instrument (62) that preferably runs so as to be at least approximately radial to the rotation axis (R).

5. The torque wrench (10) as claimed in one of claims 1 to 4, characterized in that the latching cam (90) has a taper (172) which, when viewed in the tightening direction (D), trails the entrainment face (92) and adjoins the entrainment face (92), the spacing of said taper (172) from the rotation axis (R) increasing counter to the tightening direction (D) and permitting the freewheeling mechanism.

6. The torque wrench (10) as claimed in one of claims 1 to 5, characterized in that the spring bracket (80) on the side thereof that faces the rotation axis (R) has a clearance (96) which, when viewed in the tightening direction (D), leads the entrainment face (92) and adjoins the entrainment face (96).

7. The torque wrench (10) as claimed in one of claims 1 to 6, characterized in that the cutout (72) which is preferably formed by a slot (72) that extends so as to be at least approximately radial to the rotation axis (R) is adjacent to the neck region (30).

8. The torque wrench (10) as claimed in one of claims 1 to 7, characterized in that the spring bracket (80) on that side of the neck region (30) that faces away from the activation lever (50) projects from the latter and is preferably configured so as to be integral to and in one piece with the neck region (30).

9. The torque wrench (10) as claimed in one of claims 1 to 8, characterized in that a portion (82) of the spring bracket (80) has a reduced cross section so as to dimension the force which, by the spring bracket (80), is exerted at least approximately in the radial direction on the inserted driver instrument (62).

10. The torque wrench (10) as claimed in one of claims 1 to 9, characterized in that the bezel (60) is designed at least approximatively in the shape of a circular ring.

11. The torque wrench (10) as claimed in claim 9, characterized in that a tangent to that circumferential face of the spring bracket (80) that faces the rotation axis (R), at a point (P1) of the portion (82) where the spring bracket (80), when measured in the radial direction, has the at least approximately smallest cross section, extends so as to be at least approximately parallel to a radius, which radius runs from the rotation axis (R) to the entrainment portion (92).

12. The torque wrench (10) as claimed in one of claims 1 to 11, characterized by an indicator region (110) which, from the neck region (40), projects on that side of said neck region (40) that faces away from the head region (30), projects in a shaft region (100) that extends so as to be at least approximately parallel to the plane (E), and projects from the free end region of the shaft region (100), wherein the activation lever (50) extends at least up to the indicator region (110), preferably into the indicator region (110), particularly preferably beyond the latter.

13. The torque wrench (10) as claimed in claim 12, characterized in that the activation lever (50) is flexural, preferably flexural in a linear-elastic manner, and in that, when a force in the tightening direction (D) is applied to a free end region of the activation lever (50), a deflection of the activation lever (50), proceeding from the resting position of the latter, is a measure for the torque generated.

14. The torque wrench (10) as claimed in claim 13, characterized in that measurement marks (119) on which the deflection of the activation lever (50) can be read as the torque generated are attached to the indicator region (110).