Screwdriver with jaws that move relative to each other

Abstract

Screwing tool with a fixed jaw (13) having a first torque transmission flank (15) and fixedly connected to a head (12) pivotably attached to a handle (11) about a pivot axis (17) in a pivot plane, and a movable jaw (14) having a second torque transmission flank (16) opposite to the first torque transmission flank (15) and slidably associated with the head (12), on which an output lever arm (21) of the handle (11) engages such that a torque exerted on the handle (11) about a screw axis (A) running parallel to the pivot axis (17) and between the torque transmission flanks (15, 16) exerts a force on the two jaws (13, 14) towards each other, whereby the jaws (13, 14) at their free ends (13') pointing away from the pivot axis (17) 14') have transition areas (22, 24) where the torque transmission flanks (15, 16) each transition into an outer narrow side (23, 25),characterized in that the transition areas (22, 24) extend along a curve of curvature running in the pivot plane, wherein the curve of curvature is a circular arc or a circular arc-like line, and wherein the curve of curvature adjoins a flank (26', 27') of a corner recess (26, 27) of the torque transmission flank (15, 16).

Description

field of technology

[0001] The invention relates to a screwdriving tool with a fixed jaw having a first torque transmission flank and being fixedly connected to a head pivotably attached to a handle about a pivot axis in a pivot plane, and a movable jaw having a second torque transmission flank opposite to the first torque transmission flank and being slidably associated with the head, on which an output lever arm of the handle engages in such a way that a torque exerted on the handle about a screw axis running parallel to the pivot axis and between the torque transmission flanks exerts a force on the two jaws towards each other, wherein it is particularly provided that the jaws have transition areas at their free ends pointing away from the pivot axis, at which the torque transmission flanks each transition into an outer narrow side. State of the art

[0002] A screwdriving tool of the type described above is known from DE 10 2017 108 014 A1. Similarly functioning screwdriving tools are known from DE 931 580 C1, DE 934 099 C, DE 935 418 C, DE 94 04 031 U1, DE 200 07 561 U1 or US 8,806,988 B2. Summary of the invention

[0003] The invention is based on the objective of further developing the generic screw tool in a way that is advantageous for use.

[0004] The problem is solved by the invention specified in the independent claims, wherein the dependent claims represent advantageous further developments of the invention.

[0005] First, a screwdriving tool is proposed comprising a fixed jaw, having a first torque transmission flank and fixedly connected to a head pivotably attached to a handle about a pivot axis in a pivot plane, and a movable jaw, having a second torque transmission flank opposite to the first torque transmission flank and slidably associated with the head, on which an output lever arm of the handle engages such that a torque exerted on the handle about a screw axis running parallel to the pivot axis and between the torque transmission flanks exerts a force on the two jaws towards each other, wherein the jaws have transition areas at their free ends pointing away from the pivot axis, where the torque transmission flanks each transition into an outer narrow side, characterized in thatthat the transition areas extend along a line of curvature running in the pivot plane, wherein the line of curvature is a circular arc or a circular arc-like line, and wherein the line of curvature adjoins a flank of a corner recess of the torque transmission flank.

[0006] Furthermore, a screwdriving tool is proposed with a fixed jaw having a first torque transmission flank, which is fixedly connected to a head pivotably attached to a handle about a pivot axis in a pivot plane, and a movable jaw having a second torque transmission flank opposite to the first torque transmission flank and which is slidably associated with the head, on which an output lever arm of the handle acts in such a way that a torque exerted on the handle about a screw axis running parallel to the pivot axis and between the torque transmission flanks exerts force on the two jaws towards each other.According to the invention, the effective length of the output lever arm, determined by the distance of the pivot axis from a line extending in the displacement direction of the movable jaw and drawn through the force transmission points of an output flank of the output lever arm on an attack flank of the movable jaws, is shorter than half the minimum distance of the torque transmission flanks.

[0007] Furthermore, a screwdriving tool is proposed comprising a fixed jaw, having a first torque transmission flank and fixedly connected to a head pivotably attached to a handle about a pivot axis in a pivot plane, and a movable jaw, having a second torque transmission flank opposite to the first torque transmission flank and slidably associated with the head, on which an output lever arm of the handle engages such that a torque exerted on the handle about a screw axis running parallel to the pivot axis and between the torque transmission flanks exerts a force on the two jaws towards each other, wherein an output flank of the output lever arm engages an engagement flank of the movable jaw, characterized in that the engagement flank is formed by a rounded section of a flank, the radius of curvature of which is dimensioned to be so small,that the effective length of the output lever arm, determined by the distance of the pivot axis from a line extending in the displacement direction of the movable jaw and drawn through the force transmission point of the output flank of the output lever arm on the attack flank of the movable jaw, changes by a maximum of 10 percent during a movement of the movable jaw relative to the fixed jaw between two end positions, wherein the rounded attack flank on which the output flank engages is a corner point of an undercut flank of a recess in the movable jaw, and wherein the output flank of the output lever arm sliding along the attack flank during a pivoting movement of the handle relative to the head (12) is concavely curved.

[0008] Furthermore, a screwdriving tool is proposed with a fixed jaw having a first torque transmission flank, fixedly connected to a head pivotably attached to a handle about a pivot axis in a pivot plane, and a movable jaw having a second torque transmission flank opposite to the first torque transmission flank and slidably associated with the head, on which an output lever arm of the handle engages in such a way that a torque exerted on the handle about a screw axis running parallel to the pivot axis and between the torque transmission flanks exerts a force on the two jaws towards each other, wherein the jaws have transition areas at their free ends pointing away from the pivot axis, where the torque transmission flanks each transition into an outer narrow side.According to the invention, it is provided that straight sections of the torque transmission flanks are joined by corner recesses that are in opposition to each other, with each corner recess having two flanks.

[0009] Another aspect of the invention, which can be implemented alone or in combination with other aspects of the invention, relates to a further development of a transition area between the opposing torque transmission flanks of the two jaws and an outer narrow side of the head. While in the prior art the torque transmission flanks transition into a side surface of the head by forming an edge, which in DE 10 2017 108 014 A1 is formed by a chamfer, the invention provides that the torque transmission flanks transition into the outer narrow sides of the head along curved surfaces. According to the invention, the transition areas extend along lines of curvature in the pivot plane. The line of curvature can be a circular arc. However, the line of curvature can also be a line similar to a circular arc, for example, a segment of an oval or a segment of an ellipse.The radius of the curve has a minimum value, preferably approximately 15 percent of the minimum distance between the two torque transmission flanks. It is particularly intended that the radius of the curve is at least 1.5 mm, preferably at least 1.6 mm. The radius can be between 1.5 and 2 mm. The two torque transmission flanks extend, at least partially, along flank lines that extend transversely to the displacement direction of the movable jaw relative to the fixed jaw. The flank lines can run parallel to each other. In a preferred embodiment of the invention, however, the flank lines converge in one direction towards the free ends of the jaws. When torque is applied to the jaws, the two jaws can deform in such a way that the flank lines run parallel to each other under load.The curved transition areas, which essentially form the end sections of the two jaws, create sliding surfaces along which the end sections of the jaws can slide on the hexagonal faces of a hexagonal profile when the screwdriver is engaged with the hexagonal profile of a nut or bolt head. When the screwdriver is engaged with a hexagonal profile, the two torque transmission flanks initially have a minimal distance between them. This is because, in a preferred embodiment, the movable jaw is subjected to force against the fixed jaw by means of a compression spring, thus limiting the movable jaw's movement to a minimum distance from the fixed jaw.The screwdriving tool according to the invention is designed to exert torque on polygonal profiles, in particular hexagonal profiles, with different wrench sizes by contacting parallel polygonal flanks of the polygonal profile with parallel sections of the torque transmission flanks. To bring the torque transmission flanks into contact with the polygonal flanks, the head is positioned against the polygonal profile with the torque transmission flanks at a minimal distance, which can be done in any rotational position. The rounded end sections of the jaws, formed by the transition areas, then come into tangential contact with the straight polygonal flanks.When the jaws are pushed onto the polygonal profile, the two jaws, or rather their torque-transmitting flanks, move apart, which is accompanied by a relative rotation of the head relative to the handle. Since the handle's rotational position remains unchanged during normal use of the tool, the rounded end sections of the jaws roll along the straight polygonal flanks until a sufficiently large distance between the torque-transmitting flanks is reached. This allows the polygonal profile to enter the space between the two jaws, forming the jaw of the open-end wrench-like tool. During this engagement phase, the curved transition areas also roll over the polygonal edges of the polygonal profile. Once the polygonal section is within the jaw of the screwdriver, the handle can be pivoted around the screw axis.The head rotates until two opposing polygonal flanks contact parallel sections of the torque transmission flanks. Alternatively, corner sections of the polygonal profile can engage in corner recesses of the torque transmission flanks. Once the two jaws have reached a position relative to each other where the distance between the straight sections of the torque transmission flanks corresponds to the wrench size of the polygonal profile, a force is exerted on the movable jaw when torque is applied to the arm from a driven flank of a driven lever arm. The driven flank of the driven lever arm preferably engages a contact flank of the movable jaw. Simultaneously, a force is applied to the diverging polygonal flanks of the polygonal profile.The design of these means for force transmission into the movable jaw is the subject of further aspects of the invention, which are described below. To optimize the curvature of the two transition areas, it is proposed that the radius of the circular arc or arc-like line may be greater than 20 percent or even greater than just 10 percent of the minimum distance between the two torque transmission flanks. The arc length of the circular arc should preferably extend over at least 45 degrees, 60 degrees, 90 degrees, or at least 120 degrees, with the circular arc having a smooth, kink-free profile overall. The circular arc, in particular, connects seamlessly to the flank line described above. However, the curvature can also originate from an angled recess. In this case, it may be provided that one flank of the angled recess transitions into the curvature by forming a kink.Preferably, this line of curvature originates without kinks from the flank line, which runs transversely to the direction of movement of the movable jaw and extends as a virtual line across the corner recess. The line of curvature can have a convex shape. Preferably, however, the line of curvature extends over a simply curved, i.e., developable, surface.

[0010] Another aspect of the invention, which can be implemented on its own or in combination with the other aspects of the invention, relates to the design of the output lever arm. The handle is, with respect to the pivot axis, a two-armed lever. The user grips the longer lever arm with their hand, and the shorter lever arm is the output lever arm, which applies a clamping force to the hexagonal profile via the two torque transmission flanks. The magnitude of the applied force depends significantly on the effective length of the output lever arm. The effective length of the output lever arm is defined as the distance from the pivot axis to a line extending in the displacement direction of the movable jaw, passing through the force transmission point of an output flank of the output lever arm to an engagement flank of the movable jaw.In the prior art, the effective length of the output lever arm engaging the engagement flank changes with the distance between the two torque transmission flanks or jaws. According to the invention, it is proposed that the effective length of the output lever arm be shorter than half the minimum distance between the torque transmission flanks. This minimum distance between the torque transmission flanks is preferably achieved when the two jaws are spring-loaded in a first stop position. In this position, a polygonal profile of a minimum wrench size is received in the jaw of the screwdriver, the wrench size corresponding to the minimum distance between the torque transmission flanks. The force transmitted to the movable jaw by the output lever arm must be greater than the counterforce on the torque transmission flanks resulting from the torque applied to the polygonal profile.This is particularly the case when the effective length of the output lever arm is sufficiently short, i.e., shorter than half the minimum distance between the torque transmission flanks, or preferably shorter than one-third of the minimum distance, or more preferably shorter than one-quarter of the minimum distance, furthermore provided that the effective length of the output lever arm is at most one-tenth the length of the long lever arm of the handle. The torque with which the screwdriver acts on the screw axis corresponds, for example, to the product of the force applied at the free end of the handle arm in a tangential direction and the sum of the distance of the free end of the handle to the pivot axis and the distance of the pivot axis to the screw axis.When torque is applied, the two jaws are spread apart by a force equal to the quotient of the torque and the flank length of the hexagonal profile. For a hexagon with the smallest wrench size, this flank length is related to the wrench size by a square root of three. This force is the minimum force that must be transmitted from the output lever arm to the movable jaw. The force acting on the movable jaw is the product of the quotient of the length of the long lever arm, the length of the short lever arm, and the force acting at the free end of the lever. The condition for the maximum length of the short lever arm resulting from this moment equilibrium, given a sufficiently small distance between the screw axis and the pivot axis, is the value described above.A further condition according to the invention for optimizing the leverage ratios can be the ratio of the two distances from the screw center to the force transmission point between the output flank and the engagement flank, and the distance of this force transmission point to the pivot axis. The quotient of these two distances should be greater than two.

[0011] According to a further aspect of the invention, which is particularly advantageous in combination with one of the aforementioned aspects, the effective length of the output lever arm changes only insignificantly when the movable jaw is moved relative to the fixed jaw. For this purpose, it is proposed that the engagement flank be formed by a rounded section of a flank of the movable jaw. The rounded section has a radius of curvature that is sufficiently small that the effective length of the output lever arm changes only insignificantly, preferably by a maximum of 10 percent, when the movable jaw is moved relative to the fixed jaw between two stop-limited end positions. The rounded section can adjoin an undercut flank of a recess. The recess forms, in effect, a tooth gap into which the output lever arm, designed as a single tooth, can engage.The attack flank, which runs along a circular arc or arc-like line extending in the pivot plane, forms a convex curvature. According to the invention, this convex curved section slides along a concavely curved output flank of the output lever arm, wherein the radius of curvature of the concavely curved output flank is significantly larger than the radius of curvature of the attack flank. While the radius of curvature of the attack flank can be between 0.5 and 2 mm, the radius of curvature of the output flank is preferably at least 6 mm and preferably lies in a range between 5 mm and 20 mm, and the attack flank can also be composed of several sections with different curvatures. Brief description of the drawings

[0012] An embodiment of the invention is explained below with reference to the accompanying drawings. These show: Fig. 1 a sectional view of a head 12 of a screwdriver, wherein the plane of the paper is the plane of rotation in which a handle 11, only partially shown, can be pivoted about a pivot axis 17 to displace a movable jaw 14 relative to a fixed jaw 13 of the head 12, wherein two torque transmission flanks 15, 16 assume their minimum distance S1, Fig. 2 a follow-up presentation to Fig. 1 after an increase in the swivel angle α and an increase in the distance between the torque transmission flanks 15, 16 to the distance S2, Fig. 3 a further subsequent representation with a further increased swivel angle α and a further increased distance S3 of the two torque transmission flanks 15, 16, Fig. 4 another subsequent representation in which the head 12 has pivoted to a stop position by a maximum swivel angle α, whereby the distance S4 between the torque transmission flanks 15, 16 has reached the maximum value, Fig. 5 another subsequent representation, in which the swivel angle α has decreased slightly, Fig. 6 another subsequent representation, in which the swivel angle α has again decreased slightly, Fig. 7 another subsequent representation in which the swivel angle α has been reduced in such a way that the distance S7 between the two torque transmission flanks 15, 16 corresponds to the wrench size of a polygonal profile 28, whose hexagonal flanks 29 are in contact with the torque transmission flanks 15, 16, Fig. 8 enlarged, section VIII in Fig. 7, Fig. 9 enlarged, section IX in Fig. 1, Fig. 10 a perspective view of a screw tool according to the invention with jaw arrangement arranged at each of its two ends and Fig. 11 an exploded view of the screw tool. Description of the embodiments

[0013] The in the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. The screwdriver 11 shown in cross-section in Figure 9 has an elongated handle 11. The handle 11 is a two-armed lever with a long lever arm approximately the width of a hand, i.e., 10 to 15 cm long, extending from a free end of the handle 11 to a pivot axis 17. A short lever arm of the handle 11 forms a drive lever arm 21, which engages with a concavely curved drive flank 20 on an engagement flank 18 of a movable jaw 14 of the head 12 in order to displace the movable jaw 14 linearly along a line b relative to a fixed jaw 13 of the head 12.

[0014] The head 12 is articulated to the handle 11 by means of a pivot pin defining the pivot axis 17. The handle 11, the movable jaw 14, and the fixed jaw 13 formed by the head 12 are preferably made of steel. The fixed jaw 13 forms a torque transmission flank 15, which is opposite a torque transmission flank 16 formed by the movable jaw 14. During a pivoting movement of the head 12 about the pivot axis 17, the distances S1 to S7 between the torque transmission flanks 15 and 16 change. The movable jaw 14 is guided linearly relative to the fixed jaw 13 by means of a linear guide.

[0015] The torque transmission flanks 15, 16 extend from the base of a mouth flanked by the torque transmission flanks 15, 16, initially in a straight line along flank lines running transversely to the displacement line b, with the flank lines converging slightly in the direction of mouth opening. Corner recesses 26, 27, positioned in opposition to each other, adjoin the straight sections of the torque transmission flanks 15, 16. Each of the corner recesses 26, 27 has two flanks 26', 26''; 27', 27''. The straight sections of the torque transmission flanks 15, 16 serve to contact the parallel hexagonal profile flanks 29 of a hexagonal profile 28. The corner recesses 26, 27 can accommodate the hexagonal corners of the hexagonal profile 28, so that the flanks 26', 26''; 27', 27'' bear against the hexagonal flanks 29 in the corner area, each in order to transmit a torque around a screw axis A to the hexagonal profile 28.

[0016] According to a first aspect of the invention, the torque transmission flanks 15, 16 terminate on the jaw opening side in rounded jaw end sections 22, 24. These rounded sections 22, 24 form transition areas in which the inner jaw surface, i.e., the torque transmission flanks 15, 16, transition into the outer narrow sides 23, 25 of the two jaws 13, 14. The transition areas 22, 24 extend along lines of curvature that are located in the pivot plane about the pivot axis 17, i.e., in the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6, Fig. 7, Fig. 8 to Fig. 9 extend in the plane of the paper. The surfaces of the transition areas 22, 24 are preferably cylindrical surfaces, wherein the lines of curvature can extend along a circular arc or a line similar to a circular arc. The diameters or radii of the two lines of curvature characterizing the transition areas 22, 24 are preferably equal to each other and preferably amount to at least 10 percent, 15 percent, or at least 20 percent of the minimum distance S1 between the two torque transmission flanks 15, 16, which is limited by a stop 30 against a counter-stop 31. The effective radii of curvature of the transition areas 22, 24 can be 1.6 or 1.7 mm, respectively. The stop 30 is formed here by a section of the fixed jaw 13, and the stop 31 by a section of the handle 11.A compression spring 34 is provided, which is supported on one side by the movable jaw 14 and on the other side by a plug 35 which is inserted into an opening in the fixed jaw 13.

[0017] A second aspect of the invention relates to the effective length a of the output lever arm 21. Fig. Figure 8 shows an enlarged view of the output lever arm 21 of the handle 11, which engages in a recess 10 of the movable jaw 14. The recess 19 forms two opposing walls 19', 19'', with wall 19' being an undercut wall and forming a rounded corner. This rounded corner forms an engagement flank 18, against which a similarly rounded output flank 20 of the output lever arm 21 engages. While the engagement flank is convexly rounded, the output flank 20 is concavely rounded. The radius of curvature of the engagement flank 18 is significantly smaller than the effective length a of the drive lever arm 21.

[0018] The effective length a of the output lever arm 21 is the perpendicular distance of the pivot axis 17 from a line b extending in the displacement direction of the movable jaw 14 and drawn through the engagement flank 18 or through force transmission points 1 to 7 located on the engagement flank 18. The force transmission points 1 to 7 are the positions on the engagement flank 18 at which the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. In the seven depicted rotational positions, force transmission points 1' to 7' are located on the output flank 20 and engage the attack flank 18. It is evident that the first force transmission points 1 to 7 are significantly closer together than the second force transmission points 1' to 7', which extend along the output flank 20. All first force transmission points 1 to 7 on the attack flank 18 lie on the rounded corner section of the wall 19' of the recess 19 and are spaced apart from each other by a maximum of 10 percent of the effective length a, so that the leverage ratios with which the handle 11 engages the movable jaw 14 are essentially the same in all operating positions of the two jaws 13, 14.It is particularly important that the effective length a in the area of ​​the force transmission points 1, 1', which are in contact with each other when the torque transmission flanks 15, 16 have their minimum distance S1, is minimal.

[0019] During a pivoting movement of the head 12 relative to the handle 11, as described in the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. As shown in Figure 7, the rounded attack flank 18 slides along the rounded output flank 20 in such a way that the power transmission points 1, 1' to 7, 7' move along the attack flank 18 and output flank 20, respectively. In the Fig. In the position shown in Figure 1, in which the torque transmission flanks 15, 16 have the minimum distance S1, the power transmission point 1, 1', i.e. the effective length a of the drive lever arm 21, has a length that is shorter than half the distance S1, i.e. the distance between the torque transmission flanks 15, 16.

[0020] The screw tool shown in the embodiment can be used to apply torques to hexagonal profiles 28 whose wrench size lies in the range between the minimum distance S1 and the maximum distance S4.

[0021] The function of the rounded transition areas 22, 24 is explained below using the Fig. 1, Fig. 2, Fig. 3, Fig. 4, Fig. 5, Fig. 6 to Fig. 7 explained:

[0022] In one in the Fig. In the initial position shown in Figure 1, the two torque transmission flanks 15, 16 have their minimum distance S1 from each other. The pivot angle α of the head 12 relative to the handle 11 is minimal. The head 12 is held in a first stop position by the spring 34, in which the stop 30 rests against the counter-stop 31. When the two rounded free ends 13', 14' of the jaws 13, 14 are brought against a hexagonal profile 28, the rounded transition areas 22, 24 come into contact with the hexagonal flanks 29. The handle 11 is in a horizontal position in the illustrations.

[0023] The Fig. Figure 2 shows a subsequent representation in which the head 12 is pivoted relative to both the handle 11 and the hexagonal profile 28 by shifting the handle 11 in the pivot plane, while maintaining the angular position of the handle 11 relative to the hexagonal profile 28. This increases the distance between the torque transmission flanks 15, 16 to the value S2. The rounded transition areas 22, 24 roll smoothly on the hexagonal profile flanks 29. The force transmission points 2, 2' are in contact with each other.

[0024] A further linear displacement of the handle 11 without changing the pivot position relative to the hexagonal profile 28 shows the Fig. 3. The head 12 has rotated further relative to the handle 11 and the hexagonal profile 28. The power transmission points 3, 3' are now in contact. The distance S3 between the two torque transmission flanks 15, 16 is now sufficiently large to allow the hexagonal profile 28 to enter the jaw extending between the torque transmission flanks 15, 16. Here, too, the rounded transition areas 22, 24 slide over the hexagonal flanks 29 and the hexagonal corner sections of the hexagonal profile 28, respectively.

[0025] In the Fig. In the pivot position shown in Figure 4, where the force transmission points 4 and 4' are adjacent, a second pivot end position is reached in which the stop 32 rests against the counter stop 33. The pivot angle α and the distance S4 are at their maximum here.

[0026] Starting from the in Fig. 4 depicted position of the head 12 further over the in the Fig. The intermediate position shown in section 5 is pushed further onto the hexagonal profile 28 and, consequently, until the position shown in the Fig. 6 shows the functional position of the handle 11 in the direction of the Fig. Rotating the handle 11 in the direction of the arrow shown in point 6 reduces the distance S6 between the torque transmission flanks 15 and 16. Further rotation of the handle 11 in the screw direction (arrow in the direction shown) Fig. 6 and Fig. 7) leads to a further reduction in the distance between the two torque transmission flanks 15, 16, until they reach the value specified in the Fig. The distance S7 shown in Figure 7 corresponds to the wrench size of the hexagonal profile 28, in which the hexagonal flanks 29 bear against the straight sections of the torque transmission flanks 15, 16. In this position, the force transmission points 7, 7' are adjacent to each other.

[0027] Starting from the in Fig.In the position shown in Figure 7, a torque is exerted on the handle 11 in the direction of the arrow, and this torque is transmitted to the hexagonal profile 28. Due to the small effective length a, the forces with which the torque transmission flanks 15, 16 act on the hexagonal flanks 29 are greater than the counterforces generated by the applied torque.

[0028] If the distance of the screw axis A from the pivot axis 17 is denoted by e, the effective length of the output lever arm 21 by a, and the length of the long lever arm, i.e., the distance of the free end of the handle 11 from the pivot axis 17, by c, then a force F acting tangentially at the free end of the handle 11 causes a torque (e + c) F to be exerted on the hexagonal profile. This torque is transmitted via the torque transmission flanks 15, 16 to the two hexagonal flanks 29, whose length f = (wrench size) / √(3). The forces with which the jaws 13, 14 act on the hexagonal flanks 29 must therefore be at least equal to (torque applied to the hexagonal profile 28) / (length of the hexagonal flank 29). This force is the same force that is transmitted from the short lever arm to the movable jaw 14, i.e. (the force F acting at the free end of the handle 11) * c / a.This results in the following minimum condition for the effective length of the output lever arm 21: a < f / (1 + e / c). For a sufficiently small ratio of e / c, the dimensioning rule given above applies.

[0029] If the distance of the force transmission point 1 to 7 to the screw axis A is denoted by g and the distance of the force transmission point 1 to 7 to the pivot axis 17 is denoted by a, then a further specification for optimizing the lever ratios can be: a < g / 2.

[0030] The foregoing statements serve to explain the inventions covered by the application as a whole, which each independently further develop the prior art at least through the following combinations of features, whereby two, several or all of these combinations of features may also be combined, namely:

[0031] A screw tool characterized in that the transition areas 22, 24 extend along a line of curvature running in the pivot plane.

[0032] A screw tool characterized by the fact that the curve line is a circular arc or a circular arc-like line.

[0033] A screwdriving tool characterized in that the radius of curvature of the curve line is greater than 15 percent of a minimum distance S1 between the two torque transmission flanks 15, 16, in particular at least 1.6 mm.

[0034] A screw tool characterized by the fact that the line of curvature extends over an arc length of at least 45 degrees, 90 degrees or 120 degrees.

[0035] A screwdriving tool characterized in that the line of curvature originates essentially without kinks from a flank line running transversely to the direction of displacement of the movable jaw 14, along which flank line at least a section of a torque transmission flank 15, 16 extends.

[0036] A screw tool characterized in that the arc line of the circular arc connects to a flank 26', 27' of a corner recess 26, 27 of the torque transmission flank 15, 16.

[0037] A screwdriving tool characterized in that the narrow side of the jaw 13, 14 extending along the line of curvature is a simply curved surface.

[0038] A screwdriving tool characterized in that the effective length a of the output lever arm 21, given by the distance a of the pivot axis 17 from a line b extending in the displacement direction of the movable jaw 14 and drawn by the force transmission points 1 to 7 of an output flank 20 of the output lever arm 21 on an attack flank 18 of the movable jaw 14, is shorter than half the minimum distance S1 of the torque transmission flanks 15, 16.

[0039] A screwdriving tool characterized in that the effective length a of the lever arm 21 is shorter than one third or one quarter of the minimum distance S1 of the torque transmission flanks 15, 16.

[0040] A screw tool characterized by a spring 34 which acts on the jaws 13, 14 in a first stop position in which the distance S1 of the torque transmission flanks 15, 16 is minimal.

[0041] A screw tool characterized in that the attack flank 18 is formed by a rounded section of a flank 19', the radius of curvature of which is dimensioned so small that the effective length of the output lever arm 21, given by the distance a of the pivot axis 17 from a line b extending in the displacement direction of the movable jaw 14 and drawn through the force transmission point 1 to 7 of the output flank 20 of the output lever arm 21 on the attack flank 18 of the movable jaw 14, changes by a maximum of 10 percent when the movable jaw 14 is moved relative to the fixed jaw 13 between two end positions.

[0042] A screw tool characterized in that the rounded attack flank 18, on which the output flank 20 engages, is a corner point of an undercut flank 19' of a recess 19 of the movable jaw 14.

[0043] A screwdriving tool characterized in that the output flank 20 of the output lever arm 21, which slides along the attack flank 18 during a pivoting movement of the handle 11 relative to the head 12, is concavely curved.

[0044] All disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of this application hereby incorporates in full the disclosure content of the associated / attached priority documents (copy of the earlier application), also for the purpose of including features of these documents in the claims of the present application. The dependent claims, even without the features of a referenced claim, characterize independent inventive developments of the prior art, in particular for the purpose of filing divisional applications based on these claims. The invention specified in each claim may additionally comprise one or more of the features described above, in particular those identified by reference numerals and / or listed in the reference numeral list.The invention also relates to design forms in which individual features mentioned in the preceding description are not realized, in particular insofar as they are recognizably unnecessary for the respective purpose or can be replaced by other technically equivalent means. List of reference symbols 1 Power transmission point 1' Power transmission point 2 Power transmission point 2' Power transmission point 3 Power transmission point 3' Power transmission point 4 Power transmission point 4' Power transmission point 5 Power transmission point 5' Power transmission point 6 Power transmission point 6' Power transmission point 7 Power transmission point 7' Power transmission point 11 Handle 12 heads 13 firm cheek 13' free end 14 movable jaws 14' free end 15 Torque transmission flank 16 Torque transmission flank 17 Swivel axis 18 Attacking flank 19 Exclusion 19' wall 19" wall 20 Drive flank 21 Output lever arm 22 Transition area / Jaw end section 23 Outer narrow side 24 Transition area / Jaw end section 25 Outer narrow side 26 Corner recess 26' Flank 26'' flank 27 Corner recess 27' Flank 27'' flank 28 Hexagonal profile 29 Hexagonal profile flank 30 first attack 31 Counterattack 32 second attack 33 Counterattack 34 spring 35 plugs a output arm length b line (cheek) c distance e distance f Length (wrench size) g distance A screw axle F force S1 distance S2 distance S3 distance S4 distance S5 distance S6 distance S7 distance α Swivel angle QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2017 108 014 A1 [0002, 0009] DE 931 580 C1

[0002] DE 934 099 C

[0002] DE 935 418 C

[0002] DE 94 04 031 U1

[0002] DE 200 07 561 U1

[0002] US 8,806,988 B2

[0002]

Claims

Screwing tool with a fixed jaw (13) having a first torque transmission flank (15) and fixedly connected to a head (12) pivotably attached to a handle (11) about a pivot axis (17) in a pivot plane, and a movable jaw (14) having a second torque transmission flank (16) opposite to the first torque transmission flank (15) and slidably associated with the head (12), on which an output lever arm (21) of the handle (11) engages such that a torque exerted on the handle (11) about a screw axis (A) running parallel to the pivot axis (17) and between the torque transmission flanks (15, 16) exerts a force on the two jaws (13, 14) towards each other, whereby the jaws (13, 14) at their free ends (13') pointing away from the pivot axis (17) 14') have transition areas (22, 24) where the torque transmission flanks (15, 16) each transition into an outer narrow side (23, 25),characterized in that the transition areas (22, 24) extend along a curve of curvature running in the pivot plane, wherein the curve of curvature is a circular arc or a circular arc-like line, and wherein the curve of curvature adjoins a flank (26', 27') of a corner recess (26, 27) of the torque transmission flank (15, 16). Screwing tool according to one of the preceding claims, characterized in that the radius of curvature of the curve line is greater than 15 percent of a minimum distance (S1) between the two torque transmission flanks (15, 16), in particular at least 1.6 mm. Screw tool according to one of the preceding claims, characterized in that the line of curvature extends over an arc length of at least 45 degrees, 90 degrees or 120 degrees. Screwing tool according to one of the preceding claims, characterized in that the line of curvature originates essentially without kinks from a flank line extending transversely to the direction of displacement of the movable jaw (14), along which flank line at least a section of a torque transmission flank (15, 16) extends. Screwing tool according to one of the preceding claims, characterized in that the narrow side of the jaw (13, 14) extending along the line of curvature is a simply curved surface. A screwdriving tool comprising a fixed jaw (13) having a first torque transmission flank (15) and fixedly connected to a head (2) pivotably mounted about a pivot axis (17) in a pivot plane on a handle (1), and a movable jaw (14) having a second torque transmission flank (16) opposite to the first torque transmission flank (15) and slidably associated with the head (2), on which an output lever arm (21) of the handle (1) engages such that a torque exerted on the handle (1) about a screw axis (A) extending parallel to the pivot axis (17) and between the torque transmission flanks (15, 16) exerts a force on the two jaws (13, 14) towards each other, characterized in that the distance (a) of the pivot axis (17) from a point extending in the displacement direction of the movable jaw (14) extending,the effective length (a) of the output lever arm (21) given by the force transmission points (1 to 7) of an output flank (20) of the output lever arm (21) on an attack flank (18) of the movable jaw (14) drawn by the line (b) is shorter than half the minimum distance (S1) of the torque transmission flanks (15, 16). Screwing tool according to claim 6, characterized in that a radius of curvature of the attack flank (18) is significantly smaller than the effective length (a) of the drive lever arm (21). Screwing tool according to claim 6 or 7, characterized in that the effective length (a) of the lever arm (21) is shorter than one third or one quarter of the minimum distance (S1) of the torque transmission flanks (15, 16). Screwing tool according to one of claims 6 to 8, characterized by a spring (34) which acts the jaws (13, 14) in a first stop position in which the distance (S1) of the torque transmission flanks (15, 16) is minimal. Screwing tool with a fixed jaw (13) having a first torque transmission flank (15) and fixedly connected to a head (12) pivotably attached to a handle (11) about a pivot axis (17) in a pivot plane, and a movable jaw (14) having a second torque transmission flank (16) opposite to the first torque transmission flank (15) and slidably associated with the head (12), on which an output lever arm (21) of the handle (11) engages such that a torque exerted on the handle (11) about a screw axis (A) running parallel to the pivot axis (17) and between the torque transmission flanks (15, 16) exerts a force on the two jaws (13, 14) towards each other, wherein an output flank (20) of the output lever arm (21) engages an attack flank (18) of the attacking movable jaw (14), characterized in that the attack flank (18) is formed by a rounded section of a flank (19'),whose radius of curvature is dimensioned so small that the effective length of the output lever arm (21) given by the distance (a) of the pivot axis (17) from a line (b) drawn in the displacement direction of the movable jaw (14) through the force transmission point (1 to 7) of the output flank (20) of the output lever arm (21) on the attack flank (18) of the movable jaw (14) changes by a maximum of 10 percent when the movable jaw (14) moves relative to the fixed jaw (13) between two end positions, wherein the rounded attack flank (18) on which the output flank (20) engages is a corner point of an undercut flank (19') of a recess (19) of the movable jaw (14), and wherein the force transmission point (1 to 7) on the attack flank (18) during a pivoting movement of the The output flank (20) of the output lever arm (21) sliding along the handle (11) opposite the head (12) is concavely curved. Screwing tool according to one of the preceding claims, characterized in that oppositely opposed corner recesses (26, 27) are connected to straight sections of the torque transmission flanks (15, 16). Screwing tool according to claim 11, characterized in that the two corner recesses (26, 27) each have two flanks (26' , 26" ; 27' , 27"). Screwing tool with a fixed jaw (13) having a first torque transmission flank (15) and fixedly connected to a head (12) pivotably attached to a handle (11) about a pivot axis (17) in a pivot plane, and a movable jaw (14) having a second torque transmission flank (16) opposite to the first torque transmission flank (15) and slidably associated with the head (12), on which an output lever arm (21) of the handle (11) engages such that a torque exerted on the handle (11) about a screw axis (A) running parallel to the pivot axis (17) and between the torque transmission flanks (15, 16) exerts a force on the two jaws (13, 14) towards each other, whereby the jaws (13, 14) at their free ends (13') pointing away from the pivot axis (17) 14') have transition areas (22, 24) where the torque transmission flanks (15, 16) each transition into an outer narrow side (23, 25),characterized in that straight sections of the torque transmission flanks (15, 16) are adjoined by oppositely opposed corner recesses (26, 27), each having two flanks (26' , 26" ; 27' , 27").

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