Screwdriver for an internal profile screw

Abstract

The invention relates to a screwdriver (2) for an internal profile screw (50). The screwdriver (2) comprises a shaft (4) and an external profile head (6) arranged at a distal end (7) of the screwdriver (2). The external profile head (6) has a longitudinal axial gap (10) that divides the external profile head (6) into a large profile head section (30) and a small profile head section (20). An area of ​​an end profile (31) of the large profile head section (30) is larger than an area of ​​an end profile (21) of the small profile head section (20). The end profile (31) of the large profile head section (30) and the end profile (21) of the small profile head section (20) each have several radially outwardly projecting teeth (22, 32). An outer radius (25) of the end profile (21) of the small profile head section (20) is larger than an outer radius (35) of the end profile (31) of the large profile head section (30).

Description

[0001] The invention relates to a screwdriver for an internal profile screw.

[0002] When surgically inserting an implant into a human body, internal profile screws are often used, which are tightened using a specially designed screwdriver. For example, when implanting a splint that is to be screwed into a bone, polygonal screws are usually used. These screws have an internal polygonal recess for the screw head drive. The external profile head of the screwdriver is specially adapted to the internal profile recess to securely screw the polygonal screw into place.

[0003] To prevent the screw from becoming detached from the screwdriver during implant insertion, it is often provided to secure the outer profile head of the screw in the screw head drive so that the screw cannot fall off accidentally. This can be achieved, for example, by clamping and / or applying magnetic force.

[0004] WO 2007 / 006282 A2 discloses a screwdriver for an internal profile screw in which the external profile head is split into two parts. Moving a sleeve relative to a screwdriver shaft causes the two parts of the external profile head to shear away from each other, causing them to become wedged in the internal profile recess of the screw.

[0005] US 2017 / 0 305 000 A1 shows a screwdriver with a holding mechanism. Using an elastic element whose free-standing end has an outward-facing projection, the tip of the screwdriver is clamped in the drive of a screw.

[0006] US 3,894,450 A discloses a tool for tightening and holding screws. A resilient tongue holds the tip of the tool in the screw head drive.

[0007] WO 00 / 20 174 A1 discloses a screw holder. The end profile of the screw holder comprises a vertical groove in which a spring is arranged, by means of which the screw holder is clamped in a screw head drive.

[0008] EP 1 502 706 B1 discloses a screwdriver with multiple wings at the distal end. Unlike other screwdrivers, one of the wings is cut out and replaced by an elastic element that secures the screwdriver in the screw head drive.

[0009] US 2011 / 0 098 715 A1 shows a self-retaining screwdriver. An elastic element clamps the screwdriver head in the screw head drive.

[0010] The object of the invention is to provide a screwdriver for an internal profile screw which simultaneously has a high holding force and high strength with low wear of the external profile head.

[0011] This object is achieved by a screwdriver for an internal profile screw, comprising a shaft and an external profile head which is arranged at a distal end of the screwdriver, wherein the external profile head has a longitudinal axial gap which splits the external profile head into a large profile head part and a small profile head part, wherein an area of ​​an end profile of the large profile head part is larger than an area of ​​an end profile of the small profile head part, wherein the end profile of the large profile head part and the end profile of the small profile head part each have a plurality of radially outwardly projecting teeth, wherein an outer radius of the end profile of the small profile head part is larger than an outer radius of the end profile of the large profile head part.

[0012] The outer profile head of the screwdriver is thus split into a large profile head section and a small profile head section, the end profiles of which each have several outwardly protruding teeth. By making the outer radius of the end profile of the small profile head section larger than the outer radius of the end profile of the large profile head section, the two profile head sections perform different functions. By making the end profile of the small profile head section protrude further outwards than the end profile of the large profile head section, the holding forces between the inner profile recess of the screw on one side and the outer profile head of the screwdriver on the other side are increased. The small profile head section therefore primarily serves to clamp the outer profile head in the inner profile recess of the screw.By having the end profile of the large profile head protrude less outward than the end profile of the small profile head, improved strength of the outer profile head is achieved because wear is reduced at high torques. This is based on the knowledge that when tightening and loosening inner profile screws, the greatest wear occurs on the radially outermost parts of the outer profile head and the inner profile recess. To better absorb the torque, the area of ​​the end profile of the large profile head is larger than the area of ​​the end profile of the small profile head. Thus, the outer profile head designed according to the invention achieves reduced wear and high torque during screw insertion.

[0013] Viewed longitudinally from the front, the end profile of the outer profile head is split into the end profile of the large profile head section and the end profile of the small profile head section. The split in the outer profile head allows the screwdriver to be locked in the screw drive of an inner profile screw. The outer profile head is adapted to the screw head drive of the inner profile screw that is to be screwed in with the screwdriver. For example, the outer head profile is a lobe (5-lobe, 6-lobe, 7-lobe, etc.), e.g. a Torx or Torx Plus geometry, a spline or SIT profile or another profile that is typically used for inner profile screws. The SIT profile is a trademark of Adolf Würth GmbH + Co. KG. Torx and Torx Plus are registered trademarks of Acument Intellectual Properties, LLC.

[0014] The term "longitudinal axis" refers to the screwdriver's longitudinal axis, from the proximal end of the screwdriver to the distal end, or vice versa. The outer radius of the end profiles refers to the radius of a circular arc that is applied to the outer edges of the respective end profiles. These circular arcs intersect, in particular, the tips of the teeth of the profile head parts.

[0015] Preferably, the teeth of the end profile of the large profile head section protrude radially outward to a lesser extent than the teeth of the end profile of the small profile head section. The radial direction refers in particular to a central axis through the outer profile head in the longitudinal direction. In particular, a radius of a profile base, from which the teeth of the end profiles protrude, is identical for the small profile head section and the large profile head section. Thus, in particular, only the shape of the outwardly protruding teeth of the profile head sections differs. In particular, the teeth of the end profile of the large profile head section are flattened.

[0016] Preferably, the teeth of the end profile of the small profile head section have rounded tips. Rounded tips are advantageous because they enable high holding forces while reducing tooth wear. In particular, the teeth of the end profile of the small profile head section are completely rounded. In particular, the teeth of the end profile of the small profile head section do not transmit any torque when screwing in or unscrewing a screw. Instead, the torque is transmitted entirely by the teeth of the end profile of the large profile head section.

[0017] Preferably, the end profile of the large profile head section comprises more teeth than the end profile of the small profile head section. A larger number of teeth on the large profile head section is advantageous, as the large profile head section is primarily responsible for transmitting torque. The exact number of teeth on the two end profiles depends on the internal profile recess of the internal profile screw for which the screwdriver is intended. For internal profile screws with six recesses, for example, the small profile head section has two teeth and the large profile head section has four teeth.

[0018] According to one embodiment, the end profile of the small profile head and / or the end profile of the large profile head is a star-shaped wave profile. Such a star-shaped wave profile is, for example, the profile known under the brand name "Torx" or "Torx Plus." For example, the end profile of the small profile head is a Torx profile, and the end profile of the large profile head is a Torx Plus profile.

[0019] Preferably, the end profile of the small profile head section and / or the end profile of the large profile head section each have outer profile edges between the teeth, which have the shape of a recess or an outwardly curved circular arc. In particular, the teeth do not directly adjoin one another, but are separated from one another by the outer profile edges.

[0020] Preferably, a circular arc passing through the points located centrally between two teeth on the outer profile edge of the small profile head section has the same radius as a circular arc passing through the points located centrally between two teeth on the outer profile edge of the large profile head section. In other words, the base parts of the large profile head section and the small profile head section, from which the teeth protrude, have the same outer radius. This is advantageous because the two profile head sections make it easier to hold and turn the inner profile screw.

[0021] Preferably, the end profile of the small profile head and the end profile of the large profile head have the same wrench size, so they are designed for screwing screws with the same screw head drive size. This ensures that both profile head sections engage well with the screw head drive. In particular, the end profile of the profile head section has a geometric flattening. This geometric flattening makes the outer profile head universally applicable. A cleavage plane of the gap preferably extends along a longitudinal direction of the shaft and a direction parallel to the end profile of the profile head parts. Thus, the gap separates the end profile of the outer profile head into the two profile head parts and extends from the end profile in the longitudinal direction toward a screwdriver holder of the screwdriver.

[0022] Preferably, the gap splits the end profile of the outer profile head asymmetrically. In particular, the gap in the end profile of the outer profile head runs along a cutting line that extends parallel to a center line through the end profile of the outer profile head.

[0023] According to one embodiment, the screwdriver comprises a clamping mechanism designed to shear the small profile head part and the large profile head part against each other, with a shearing direction extending, in particular, along the gap parallel to the end profiles of the profile head parts. By shearing the profile head parts against each other, they are clamped in the screw head drive of the internal profile screw. The small profile head part ensures a secure hold in the screw head drive, while the large profile head part primarily absorbs the torque.

[0024] The screwdriver preferably comprises a sleeve that accommodates the outer profile head and can be screwed to the outer profile head. According to one embodiment, the outer profile head tapers towards the distal end to form at least one run-on bevel, wherein the sleeve comprises an inwardly projecting run-on body that is designed to run along the at least one run-on bevel in order to shear the small profile head part and the large profile head part against each other. The run-on body is designed in particular as a circumferential run-on ring. Thus, the sleeve with the run-on body and the run-on bevel in particular form the clamping mechanism. This method of clamping the outer profile head in the screw head drive represents a safe, reproducible, and easy-to-use option for securing the outer profile head in the screw head drive.

[0025] Further features of the invention will become apparent from the description of embodiments of the invention together with the claims and the accompanying drawings. Embodiments of the invention may incorporate individual features or a combination of several features.

[0026] Within the scope of the invention, features marked with “in particular” or “preferably” are to be understood as optional features.

[0027] The invention is described below, without limiting the general inventive concept, using exemplary embodiments with reference to the drawings, whereby express reference is made to the drawings for all details of the invention not explained in more detail in the text. They show: Fig. 1 a schematically simplified perspective view of a screwdriver for internal profile screws for surgical applications, Fig. 2 a schematically simplified perspective view of an outer profile head of the screwdriver in a relaxed state, Fig. 3 a schematically simplified perspective view of the outer profile head from Fig. 2 in a tense state, Fig. 4 a schematically simplified cross-sectional view through the outer profile head in the relaxed state, while the outer profile head is arranged in a screw head drive of an inner profile screw, Fig. 5 a schematically simplified cross-sectional view through the outer profile head of Fig. 4 in the tense state, Fig. 6 a schematically simplified perspective view of the outer profile head in the relaxed state, with part of the sleeve omitted for better visibility of the internal components, Fig. 7 a schematically simplified perspective view of the outer profile head from Fig. 6 in the tense state, Fig. 8 a schematically simplified cross-sectional view of the outer profile head from Fig. 6 in a relaxed state and Fig. 9 a schematically simplified cross-sectional view of the outer profile head from Fig. 7 in the tense state.

[0028] In the drawings, identical or similar elements and / or parts are provided with the same reference numbers, so that a repeated presentation is omitted.

[0029] Fig. Figure 1 shows a simplified schematic perspective view of a screwdriver 2. The screwdriver 2 comprises a rotatable handle 8, from which a shaft extends and ends in an outer profile head 6 at the distal end 7 of the screwdriver 2. The shaft is enclosed by a sleeve 5, which Fig. 1. Such screwdrivers 2 are used during the surgical insertion of implants into a human body to tighten or loosen internal profile screws in the implant. It is of great importance that the internal profile screws do not detach from the external profile head 6 during screwing or loosening, as otherwise the screws could enter the human body and cause significant damage.

[0030] Fig. 2 shows a schematically simplified enlarged perspective view of the outer profile head 6 at the distal end of the screwdriver 2 or the shaft. In a longitudinal direction 14 of the screwdriver 2 or the sleeve 5, the outer profile head 6 protrudes from the sleeve 5. The outer profile head 6 comprises an end profile 12 with a plurality of teeth 22, 32 for engaging the screw head drive of the screw. In the exemplary embodiment shown, the end profile 12 comprises six teeth 22, 32 and is intended for screwing screws with a star-shaped wave profile, for example the profile known under the brand name "Torx". In order to clamp the outer profile head 6 in the screw head drive, the outer profile head 6 comprises a gap 10 that extends along the longitudinal direction 14 through the outer profile head 6.The gap 10 is arranged asymmetrically in the end profile 12, so that it splits the outer profile head 6 into a small profile head portion 20 and a large profile head portion 30. The small profile head portion 20 comprises two teeth 22, while the large profile head portion 30 has four teeth 32. For reasons of clarity, only one tooth 22, 32 is provided with a reference symbol.

[0031] Fig. 3 shows a simplified schematic view of the outer profile head 6 from Fig. 2 in a clamped state. In this clamped state, the small profile head portion 20 is sheared relative to the large profile head portion 30 along a shear direction 44. This results in the outer profile head 6 being able to clamp into the screw head drive of the screw and remain securely held there. The shear direction 44 runs in a plane of the gap 10 parallel to the end profile 12.

[0032] In the Fig. 4 and Fig. 5 shows a schematically simplified cross-sectional view along the end profile 12 of the outer profile head 6, while the outer profile head 6 is made of Fig. 2 is arranged in a screw head drive 52 of an internal profile screw 50. In Fig. 4 is the outer profile head 6 made of Fig. 2 in a relaxed state. This illustration clearly shows that the teeth 22 of the small profile head part 20 have a different shape than the teeth 32 of the large profile head part 30. Specifically, the teeth 22 protrude radially further outwards than the teeth 32, so that an end profile 21 of the small profile head part 20 has a larger outer radius 25 than the outer radius 35 of an end profile 31 of the large profile head part 30. These outer radii 25, 35 each extend from a center of the end profile 12 to a tip or a point of the teeth 22, 32 that projects furthest outwards. In the present case, the teeth 22 of the small profile head part 20 are rounded, while the teeth 32 of the large profile head part 30 are flattened. For example, teeth 22 have a profile known under the brand name “Torx”, while teeth 32 have a profile known under the brand name “Torx Plus”.This different design of the teeth 22, 32 has the effect that an end profile 21 of the small profile head part 20 performs a different function than an end profile 31 of the large profile head part 30. Specifically, the larger outer radius 25 of the teeth 22 ensures that the teeth 22 can engage well in the screw head drive 52 of the inner profile screw 50 and thus exert large holding forces during clamping, which hold the outer profile head 6 out. Fig. 3 on the inner profile screw 50. In contrast, the teeth 32 of the large profile head part 30 primarily have the function of absorbing the torques that occur during tightening of the inner profile screw 50. The flattened tips of the teeth 32 significantly reduce wear on the teeth 32. For this reason, it is advantageous to provide more teeth 32 than teeth 22, since in this way the teeth 32 absorb the majority of the torques that occur. Outer profile edges 24, 34 extend between the teeth 32 and the teeth 22, which in the embodiment shown have the shape of a recess. In another embodiment, not shown, the outer profile edges can also have the shape of an outwardly curved circular arc, so that the end profile 12 as a whole has the shape of a circle from which the teeth 22, 32 protrude outwards.

[0033] In Fig. 5 shows the end profile 12 and the inner profile screw 50 in the clamped state. It can be seen that the small profile head part 20 and the large profile head part 30 are sheared against each other along the shear direction 44. As a result, the teeth 22 and 32 are more firmly fixed in the recesses of the screw head drive 52, so that the outer profile head 6 from Fig. 3 is clamped in the internal profile head screw 50. In the embodiment shown, the small profile head portion 20 is pressed toward the large profile head portion 30 in addition to the movement along the shearing direction 44, so that the gap 10 becomes smaller. According to other embodiments, however, the gap 10 can retain the same width in the clamped state as in the relaxed state, without the profile head portions 20, 30 being moved toward each other.

[0034] Fig. 6 and Fig. 7 show the outer profile head 6 from the Fig. 2 and Fig. 3 in another perspective view, in which a part of the sleeve 5 is cut out for better visibility of the internal components. This view shows the shaft 4, which extends within the sleeve 5. It can be seen that an outer surface of the shaft 4, which is located inside the sleeve 5, is designed as a run-on bevel 42. This run-on bevel 42 is an inclined plane that drops down in the longitudinal direction 14. At the same time, the sleeve 5 comprises a run-on body 41, which in the illustrated embodiment is designed radially as a run-on ring or run-on ring segment. The run-on body 41 projects inward from the sleeve 5 and runs on the run-on bevel 42. Due to the inclination of the run-on bevel 42, this causes the run-on body 41 to press the run-on bevel 42 and the small profile head part 20 connected thereto in the direction of the shearing direction 44 when the sleeve 5 is displaced against the longitudinal direction 14, as in Fig. 7. In this way, a clamping mechanism 40 is formed, which comprises the starting bevel 42 and the starting body 41.

[0035] In the Fig. 8 and Fig. 9, the sleeve 5 and the outer profile head 6 are made of the Fig. 6 and Fig. 7 each shown in a cross-sectional view, where Fig. 8 the relaxed and Fig. 9 shows the clamped state. In this view, it can be clearly seen how the starting body 41 runs on the starting bevel 42 and thus moves the small profile head part 20 in the shearing direction 44 when the sleeve 5 is moved relative to the outer profile head 6 opposite to the longitudinal direction 14. Such a movement of the sleeve 5 relative to the outer profile head 6 is effected, for example, by a rotation of a component of the handle 8, as shown in Fig.1. In this way, screws on the outer profile head 6 can be easily clamped or loosened using the handle 8.

[0036] All mentioned features, including those revealed solely in the drawings as well as individual features disclosed in combination with other features, are considered essential to the invention, both individually and in combination. Embodiments according to the invention may be fulfilled by individual features or a combination of several features. List of reference symbols 2 screwdrivers 4 shaft 5 sleeve 6 External profile head 7 distal end 8 Handle 10 gap 11 Cleavage level 12 End profile 14 Longitudinal direction 20 small profile headboard 21 End profile 22 tooth 24 Outer profile edge 25 outer radius 30 large profile headboard 31 End profile 32 teeth 34 Outer profile edge 35 outer radius 40 jamming mechanism 41 Starting body 42 run-on slope 44 Shear direction 50 internal profile screw 52 screw head drive

Claims

[1] Screwdriver (2) for an internal profile screw (50), comprising a shaft (4) and an external profile head (6) arranged at a distal end (7) of the screwdriver (2), wherein the external profile head (6) has a longitudinal axial gap (10) which splits the external profile head (6) into a large profile head part (30) and a small profile head part (20), wherein an area of ​​an end profile (31) of the large profile head part (30) is larger than an area of ​​an end profile (21) of the small profile head part (20), wherein the end profile (31) of the large profile head part (30) and the end profile (21) of the small profile head part (20) each have a plurality of radially outwardly projecting teeth (22, 32), wherein an outer radius (25) of the end profile (21) of the small profile head part (20) is larger than an outer radius (35) of the end profile (31) of the large profile head part (30). [2] Screwdriver (2) according to claim 1, characterized bythat the teeth (32) of the end profile (31) of the large profile head part (30) protrude less radially outwards than the teeth (22) of the end profile (21) of the small profile head part (20). [3] Screwdriver (2) according to claim 1 or 2, characterized by that the teeth (22) of the end profile (21) of the small profile head part (20) have rounded tips. [4] Screwdriver (2) according to one of claims 1 to 3, characterized by that the end profile (31) of the large profile head part (30) comprises more teeth (22, 32) than the end profile (21) of the small profile head part (20). [5] Screwdriver (2) according to one of claims 1 to 4, characterized by that the end profile (21) of the small profile head part (20) and / or the end profile (31) of the large profile head part (30) is a star-shaped wave profile. [6] Screwdriver (2) according to one of claims 1 to 5, characterized bythat the end profile (21) of the small profile head part (20) and / or the end profile (31) of the large profile head part (30) between the teeth (22, 32) each have outer profile edges (24, 34) which have the shape of a depression or an outwardly curved circular arc. [7] Screwdriver (2) according to claim 6, characterized by that a circular arc through the points on the outer profile edge (24) of the small profile head part (20) lying centrally between two teeth (22) has the same circular radius as a circular arc through the points on the outer profile edge (34) of the large profile head part (30) lying centrally between two teeth (32). [8] Screwdriver (2) according to one of claims 1 to 7, characterized bythat the end profile (21) of the small profile head part (20) and the end profile (31) of the large profile head part (30) have the same key size, so that they are designed to screw screws with the same size of the screw head drive (52). [9] Screwdriver (2) according to one of claims 1 to 8, characterized by that a cleavage plane (11) of the gap (10) extends along a longitudinal direction (14) of the shaft (4) and a direction parallel to the end profile (12) of the profile head parts (20, 30). [10] Screwdriver (2) according to one of claims 1 to 9, characterized by that the gap (10) splits the end profile (12) of the outer profile head (6) asymmetrically. [11] Screwdriver (2) according to one of claims 1 to 10, comprising a clamping mechanism (40) which is designed to shear the small profile head part (20) and the large profile head part (30) against each other, wherein in particular a shearing direction (44) extends along the gap (10) parallel to the end profiles (21, 31) of the profile head parts (20, 30). [12] Screwdriver (2) according to one of claims 1 to 11, characterized by that the screwdriver (2) comprises a sleeve (5) which receives the outer profile head (6) and can be screwed to the outer profile head (6). [13] Screwdriver (2) according to claim 12, characterized byin that the outer profile head (6) tapers towards the distal end (7) to form at least one run-on bevel (42), wherein the sleeve (5) comprises an inwardly projecting run-on body (41) which is designed to run on the at least one run-on bevel (42) in order to shear the small profile head part (20) and the large profile head part (30) against each other.

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