WOBULENT DISC SUPPORTING ARRANGEMENT AND SURGICAL INSTRUMENT EQUIPPED WITH IT

Description

[0001] The invention relates to a bearing arrangement of a swash plate with a main shaft of a surgical instrument and to a surgical instrument having such a bearing arrangement.

[0002] Surgical instruments are known from the prior art that can be guided manually or by a robot using a handle. They have a tool at the distal end of an elongated shaft that can be pivoted relative to the shaft, which defines a main axis, by means of an angulation mechanism consisting of several interlocking pivoting members. These pivoting members are connected to a plurality of steering wires or cables to achieve sensitive control of the tool tip. For actuation, the steering wires can be attached to a swash plate that can be spatially aligned by a steering gear and can be pivoted on a main shaft of the surgical instrument about two axes that are orthogonal to one another and to the longitudinal axis of the main shaft, which corresponds to the main axis of the surgical instrument.The state of the art corresponds to GB 978 230, DE 10 2021 119533, US 1 980 846, US 2012 / 265214, DE 10 2019 121092, and DE 10 2021 119529.

[0003] From US 10,105,128 B2, it is known to operate a gimbal-mounted swashplate connected to a deflection mechanism via steering wires using two parallel rods. For this purpose, the rods have a ball socket at one end to accommodate a ball element coupled to the swashplate. At their other end, these ball-joint rods are connected via swivel joints, each with a gear quadrant, in order to move the ball-joint rods linearly back and forth to align the swashplate. While the center of the gimbal bearing for tilting the swashplate is clearly defined, swashplate control with ball-joint rods is not particularly direct, but rather subject to play and exhibits an unfavorable force flow. Furthermore, the design, which does not allow rotation of the swashplate around the shaft axis, requires precisely manufactured components, which are associated with corresponding costs.

[0004] A steering gear with a swashplate that can not only be spatially aligned but also rotate around the shaft axis is disclosed in DE 10 2019 121 092 A1. For the spatial alignment of the swashplate, a differential gear with two opposing drive bevel gears and an output bevel gear is used. The output bevel gear meshes with the drive bevel gears and is coupled to the swashplate. For this purpose, the swashplate is rotatably mounted in a steering ring, which is non-rotatably connected to the output bevel gear. In this way, the setting angles of the drives are transmitted directly to the swashplate in order to align or angle the tool tip accordingly. The swashplate is cardanically connected to a rotatable main shaft by means of a universal joint disc and two orthogonal pairs of axles and can therefore be rotated with the main shaft around the shaft axis.

[0005] Due to its design principle, the universal joint exhibits the gimbal error known from the literature: A bent universal joint results in uneven rotational transmission. This means that when the drive shaft rotates at a constant speed, the output shaft does not have a constant rotational speed. This unevenness, also known as gimbal error, increases with the angle of deflection. The transmission of the rotation angle from the shaft axis to the swashplate is therefore non-linear and exhibits a deviation of approximately ± 15% when the swashplate is angled by, for example, 30°. This deviation in the control is transmitted forward and results in an uneven, erratic movement when the instrument is rotated in the articulated state.

[0006] The alternative use of a universal joint with two pairs of pins crossed at right angles for the gimbal mounting of a swashplate on an instrument shaft, in which one pair of pins is connected to the shaft and one pair of pins is connected to the swashplate, is also associated with higher procurement, storage, and assembly costs. Furthermore, the gimbal mounting with a universal joint requires a very large installation space for large angular misalignments, which precludes miniaturization of the proximal drive of the instrument.

[0007] Based on this prior art, it is an object of the present invention to provide an improved bearing arrangement of a swash plate with a main shaft, wherein the swash plate is pivotally connected to the main shaft and rotatable about two axes which are orthogonal to each other and to the main axis.

[0008] This object is achieved by a bearing arrangement having the features of claim 1.

[0009] The further object of providing a surgical instrument with an improved storage arrangement is achieved by the surgical instrument having the features of independent claim 14.

[0010] Further developments or preferred embodiments are set out in the subclaims.

[0011] A first embodiment of the bearing arrangement according to the invention relates to the bearing of a spatially orientable swash plate of a surgical instrument having a main shaft. The swash plate, which can be connected to a plurality of steering wires for controlling a distal angulation mechanism of the surgical instrument, is pivotally connected to the main shaft, which defines a main axis. The swash plate is rotatable about two axes that are orthogonal to each other and to the main axis, with an intersection point of the two axes, which defines a pivot center of the swash plate, lying on the main axis.According to the invention, the main shaft has a spherical coupling section, and the swash plate has a hollow spherical outer bearing opening, wherein the pivot center of the swash plate corresponds to a spherical center of the hollow spherical outer bearing opening and, in the bearing arrangement, to a spherical center of the spherical coupling section. Furthermore, the bearing arrangement has rolling bearing balls with a spherical radius and a ball cage that is movably arranged in the outer bearing opening and delimits a hollow spherical inner bearing opening in which the coupling section of the main shaft is movably arranged. The ball cage has window openings, in each of which one of the rolling bearing balls is arranged.The coupling portion has first circular grooves, which run in the longitudinal direction of the main shaft, as an inner raceway for the rolling bearing balls, and the outer bearing opening has second circular grooves, which also run in the longitudinal direction of the main shaft, as an outer raceway for the rolling bearing balls.

[0012] Since the pivoting center of the swash plate is defined by the spherical center of the hollow spherical outer bearing opening of the swash plate and thus also corresponds to the spherical centers of the concentrically arranged ball cage and the spherical coupling section, the bearing arrangement according to the invention, which can transmit axial forces at least on one side, unlike known swash plate bearings by means of a universal joint, does not have a gimbal error.

[0013] The term "spherical" or "hollow spherical" also includes shapes that correspond to a part of a sphere or hollow sphere, such as a spherical segment or a spherical disc, which are a part of a spherical body that is separated by intersection with a plane or with two parallel planes.

[0014] A further embodiment of the bearing arrangement according to the invention provides that each first circular groove is formed along a first circular arc segment on the coupling section such that the circle center of the first circular arc segment is congruent with the sphere center of the coupling section and thus corresponds to the pivot center of the swash plate. Each second circular groove is formed along a second circular arc segment in the outer bearing opening such that the circle center of the second circular arc segment corresponds to the sphere center of the outer bearing opening and thus to the pivot center of the swash plate.

[0015] The first circular grooves thus run in the spherically curved surface of the coupling section, and the second circular grooves are formed on the spherically curved surface of the outer bearing opening opposite the first circular grooves. The first and second circular arc segments lie at the respective groove base, with a difference between the radii of the first and second circular arc segments corresponding to the diameter of the rolling bearing balls. The first and second circular grooves can each have an inlet and / or outlet section that adjoins the groove region running along the circular arc segment and can have a radius and / or a different direction of curvature than the radius of the circular arc segment.

[0016] According to a further embodiment of the bearing arrangement according to the invention, the first and second circular grooves have a part-circular profile with a groove cross-sectional radius that corresponds to the ball radius of the rolling bearing balls.

[0017] Furthermore, according to a further advantageous embodiment, the bearing arrangement according to the invention can provide that the spherical shapes of the coupling section and the ball cage, as well as the hollow spherical shapes of the inner and outer bearing openings, each correspond to a spherical disk, i.e., a portion of a sphere cut out by two parallel planes. The inner bearing opening and the outer bearing opening are each designed as a through-opening, so that the main shaft extends through the swash plate and the ball cage and is rotatably mounted about the main axis on both sides of the swash plate by means of a bearing and is fixed in the axial direction.

[0018] According to an alternative embodiment of the bearing arrangement according to the invention, the spherical shapes of the coupling section and the ball cage, as well as the hollow spherical shapes of the inner and outer bearing openings, can each correspond to a spherical segment, i.e., a part of a sphere that is separated by the intersection with a plane. The inner bearing opening and the outer bearing opening are each designed as a receiving opening closed on the proximal side around the coupling section, so that the main shaft extends only distally from the swash plate and the ball cage and is mounted rotatably about the main axis distal to the swash plate and fixed in the axial direction.

[0019] Furthermore, in a bearing arrangement according to the invention according to a further embodiment, the coupling section with the first circular grooves, the ball cage with the window openings and with the inner bearing opening, the rolling element balls and the outer bearing opening of the swash plate with the second circular grooves can be dimensioned so as to be coordinated with one another that the ball cage forms an inner ball joint with the coupling section and an outer ball joint with the outer bearing opening of the swash plate, which is concentric with the inner ball joint.

[0020] In a further development of this embodiment of the bearing arrangement according to the invention, a surface of the spherical coupling section adjacent to the first circular grooves and an inner surface of the ball cage adjacent to the window openings can form an inner plain bearing. And a surface of the hollow spherical receiving opening adjacent to the second circular grooves can form an outer plain bearing with an outer surface of the ball cage adjacent to the window openings. Both concentric ball joints are supported by plain bearings.

[0021] Alternatively, the coupling section and the outer bearing opening can each have a distal and a proximal bearing section, wherein the first circular grooves, the second circular grooves, and the ball cage, which form the concentric ball joints, are located in the distal bearing section. Compared to the previous variant, a larger coupling section allows a narrower ball cage and smaller rolling bearing balls to be used while maintaining the same diameter of the outer bearing opening. In the proximal bearing section, the surface of the coupling section has an inner sliding section, and the surface of the outer bearing opening has an outer sliding section, which, together with the inner sliding section, forms a sliding bearing directly between the coupling section and the outer bearing opening.

[0022] As an alternative to the embodiments in which the bearing arrangement according to the invention provides at least one plain bearing, according to a further alternative embodiment of the bearing arrangement according to the invention, an efficient rolling bearing can be provided, wherein the bearing arrangement has secondary rolling balls that are smaller than the rolling bearing balls and that, guided by the ball cage, run internally on a surface of the coupling section adjacent to the first circular grooves and externally on a surface of the outer bearing opening adjacent to the second circular grooves. For this purpose, the ball cage can, of course, have corresponding openings for guiding the secondary rolling balls.

[0023] Accordingly, the dimensions of the bearing arrangement, i.e. dimensions of the coupling section, the ball cage and the outer bearing opening of the swash plate are matched to one another depending on the spherical radius of the rolling element balls and, if applicable, the secondary rolling balls and are designed as a clearance or transition fit.

[0024] To facilitate assembly of the bearing arrangement according to the invention, a further embodiment provides that the outer bearing opening of the swash plate has an expanded section on the distal side that is matched to the ball cage. Accordingly, the inner bearing opening of the ball cage has an opening section on the distal side that is matched to the coupling section.

[0025] Thus, the ball cage can be accommodated through the widened section in the outer bearing opening of the swash plate, and the coupling section can be accommodated through the opening section in the ball cage. The widened section of the outer bearing opening is widened with respect to the hollow spherical shape of the outer bearing opening. This means that the widened section can be cylindrical or widen in the distal direction and, for this purpose, have a radius that corresponds at least to the outer radius of the ball cage. Accordingly, the distal opening section of the inner bearing opening of the ball cage can be cylindrical or widen and have a radius that corresponds at least to the radius of the coupling section.

[0026] As an alternative to the design with the distal widening and opening sections of the outer and inner bearing openings, the swash plate and the ball cage can each be designed in two or more parts to facilitate assembly according to a further embodiment, wherein at least one joining plane of the swash plate extends through the outer receiving opening and at least one joining plane of the ball cage extends through the inner receiving opening.

[0027] Further embodiments of a bearing arrangement according to the invention can provide that the window openings, the first circular grooves and the second circular grooves are evenly distributed circumferentially, and / or that two of the window openings, which are located opposite one another on the ball cage, are designed as circular window openings, wherein the remaining window openings are each designed as an elongated hole.

[0028] The number of rolling bearing balls corresponds to the number of window openings, the first circular grooves, and the second circular grooves. The diameter of the circular window openings is adapted to the diameter of the rolling bearing balls for secure guidance. The long sides of the elongated holes run parallel to the opening section of the ball cage in the circumferential direction, with the width of each elongated hole, i.e., the distance between the long sides, adapted to the diameter of the rolling bearing balls.

[0029] According to a further embodiment of a bearing arrangement according to the invention, the outer bearing opening is formed in a distal bearing section of the swash plate. On the proximal side, this distal bearing section is connected to a spherical drive section whose spherical center is spaced from the pivot center of the swash plate.

[0030] The spherical drive section of the swash plate can be accommodated in a cylindrical sleeve element which can be spatially aligned with a drive device.

[0031] The spherical drive section, which is rotatably and slidably mounted in the sleeve element, follows the movement of the sleeve element, causing the swashplate to pivot in space around its pivot center. A swashplate axis orthogonal to the swashplate plane runs through the pivot center and the center of the spherical section. The swashplate plane is defined by the attachment points of the steering wires on the swashplate. This means that in the neutral position of the swashplate, in which the main axis is orthogonal to the swashplate plane, the center of the spherical section lies on the main axis, meaning that the swashplate axis corresponds to the main axis in the neutral position of the swashplate.A proximal opening extending from the outer bearing opening through the spherical drive section widens in the proximal direction to allow the swashplate to pivot while the main shaft is continuous. The opening angle of the proximal opening section depends on the length of the spherical drive section along the swashplate axis and the desired pivot angle of the swashplate.

[0032] According to a first embodiment, a surgical instrument according to the invention comprises a shaft, a tool at a distal shaft end, and a handle at a proximal shaft end. The handle has a bearing arrangement with a swash plate that is pivotally connected to a main shaft that defines a main axis. The swash plate is pivotable about a pivot center located on the main axis in two directions orthogonal to the main axis. Furthermore, the swash plate is connected to a plurality of steering wires that extend along the main axis through the shaft to a bending mechanism of the tool. According to the invention, the bearing arrangement of the swash plate on the main shaft is a bearing arrangement according to the invention.

[0033] According to a further embodiment of the surgical instrument according to the invention, in which the swash plate has a spherical drive section on the proximal side, the spherical center of which is spaced from the pivot center of the swash plate, the handle of the surgical instrument has a drive device for spatially aligning a cylindrical sleeve element in which the spherical drive section of the swash plate is movably received. In this way, the swash plate can be pivoted via the spherical drive section by the spatially alignable sleeve element, and thus the tool at the distal shaft end can be angled accordingly by the angling mechanism.

[0034] Further embodiments as well as some of the advantages associated with these and other embodiments will become clear and easier to understand from the following detailed description with reference to the accompanying figures. Objects or parts thereof that are substantially the same or similar may be provided with the same reference numerals. The figures are merely a schematic representation of an embodiment of the invention. The drawings, the description and the claims contain numerous features in combination. It is to be understood that the features mentioned above and those to be explained below can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the present invention.

[0035] Showing: Fig. 1 a perspective view of a surgical instrument according to the invention with a schematically illustrated handle and storage arrangement, Fig. 2 a perspective exploded view of a bearing arrangement according to the invention, Fig. 3 a longitudinal sectional view through the bearing arrangement according to the invention Fig. 2 with the swashplate in neutral position, Fig. 4 a longitudinal sectional view through the bearing arrangement according to the invention Fig. 2 with the swashplate in a position pivoted around the X-axis, Fig. 5 a detailed view Fig. 3 , Fig. 6 a longitudinal sectional detail view of the coupling section of the main shaft, Fig. 7 a cross-sectional view through the coupling section of the main shaft along section line BB in Fig. 6 , Fig. 8 a longitudinal sectional view of the ball cage, Fig. 9 a longitudinal sectional view of the swashplate.

[0036] In Fig. 1 A surgical instrument 1 with a hollow shaft 2 is shown, wherein a handle 5 arranged at the proximal end 2b of the shaft 2 is shown only schematically. At the distal end 2a of the shaft 2, a tool 3 is arranged, which is, for example, a tool 3 provided with jaw parts, as in Fig. 1 shown, or it can be an endoscope, an applicator or the like. The tool 3 of the surgical instrument 1 is, as shown in Fig. 1 can be seen, pivotable relative to the main axis A of the shaft 2 via a deflection mechanism 4 at the distal shaft end 2a. The deflection mechanism 4 consists of pivoting members which are connected via steering wires 6 extending through the shaft 2 to the swash plate 8 of the bearing arrangement 10 in the handle 5 at the proximal end 2b of the shaft 2. In the bearing arrangement 10, an example of which is shown in Fig. 2 bis 9 As shown, the swash plate 8 is pivotally connected to the main shaft 7 and rotatable about two axes X, Y, which are orthogonal to one another and to the main axis A. The main shaft 7 extends through the swash plate 8 and is mounted on both sides of the swash plate 8 by means of a bearing 9 each, rotatable about the main axis A and fixed in the axial direction. The distal end 7.4 of the main shaft 7 is connected to the proximal end 2b of the shaft 2 and has longitudinal slots through which the steering wires 6 are guided from the interior of the shaft 2 to the outside for attachment to the swash plate 8.

[0037] An axially displaceable actuating element (not shown) can extend through the shaft 2 and the connected main shaft 7 to actuate the tool 3, e.g., to open and close the jaws. This actuating element is operatively connected on the proximal side to an actuating unit of the handle 5. For this purpose, the main shaft 7 has an axial bore 7.5 coaxial with the main axis A. The actuating element can be designed, for example, as a push / pull rod that can be moved back and forth to actuate the tool 3.

[0038] A movement of the swash plate 8, which is connected to the main shaft 7 in an articulated manner, causes a corresponding relative movement of the distal pivoting members of the angling mechanism 4 via the steering wires 6 and thus a pivoting of the tool 3. Even if the term steering wires 6 is used here, steering cables can also be used functionally, which is why the term steering wires 6 used should also be read and understood as a synonym for steering cable.

[0039] At the Fig. 2 bis 9 In the bearing arrangement 10 shown, the swash plate 8 is pivotally connected to the main shaft 7 and rotatable about two axes X, Y, which are orthogonal to each other and to the main axis A. An intersection point of the two axes X, Y, which defines a pivot center C of the swash plate 8, lies on the main axis A. The main shaft 7 has a spherical coupling section 7.1, and a hollow spherical outer bearing opening 8.1 is formed in the swash plate 8, in which the spherical coupling section 7.1 is arranged. First circular grooves 7.2 are formed in the spherical coupling section 7.1, and second circular grooves 8.2 are formed in the outer bearing opening 8.1, which each run in the spherically curved surfaces of the coupling section 7.1 and the outer bearing opening 8.1 in the longitudinal direction of the main shaft 7. Every first round groove 7.2 forms an inner raceway and every second round groove 8.2 an outer raceway for each rolling bearing ball 12, wherein the part-circular profiles of the first circular grooves 7.2 and the second circular grooves 8.2 have a groove cross-sectional radius R' which, with a corresponding tolerance, corresponds to the ball radius R of the rolling bearing balls 12, as in . Fig. 7 can be seen.

[0040] The bearing arrangement 10 also includes a ball cage 11 for guiding the rolling bearing balls 12, which is arranged in the outer bearing opening 8.1. The ball cage 11 defines a hollow spherical inner bearing opening 11.3, in which the coupling section 7.1 of the main shaft 7 is arranged. The ball cage 11 has window openings 11.1, 11.2 distributed over the circumference, the number of which corresponds to the number of the first and second circular grooves 7.2, 8.2, so that one of the rolling bearing balls 12 is arranged in each window opening 11.1, 11.2. Unlike the previous swash plate bearing using a universal joint, the bearing arrangement 10, which can also transmit axial forces, does not exhibit any gimbal error.

[0041] The first circular grooves 7.2 of the spherical coupling section 7.1 are formed along a first circular arc segment b 1. The circle center of each first circular arc segment b 1 is congruent with the sphere center of the spherical coupling section 7.1, which in the bearing arrangement 10 corresponds to the pivot center C of the swash plate 8. In Fig. 6 und 7 it can be seen that the circular arc segment b 1 of the first circular groove 7.2 lies at the groove base. The central angle α 1 of the circular arc segment b 1 with the circular arc radius r 1 is spanned by the lines that connect the center of the circle or sphere, which corresponds to the pivot center C, with the end points of the circular arc segment b 1. The circular arc radius r 1 is smaller than the radius r 0 of the coupling section 7.1, but larger than the shaft radius rw of the main shaft 7. The circular arc segment b 1 of the first circular grooves 7.2 is each followed by an inlet and outlet section a 1. In the example shown, these have a direction of curvature that deviates from the convex curvature of the circular arc segment b 1, with the radius of curvature of the concavely curved inlet and outlet section a 1 roughly corresponding to the circular arc radius r 1.

[0042] Fig. 9 shows the swash plate 8, in which the second circular grooves 8.2 of the hollow spherical outer bearing opening 8.1 are formed along a second circular arc segment b 2. The circle center of every second circular arc segment b 2 is congruent with the hollow sphere center of the hollow spherical outer bearing opening 8.1, which corresponds to the pivot center C of the swash plate 8. At the groove base of the second circular groove 8.2 lies the circular arc segment b 2 with the circular arc radius r 2, whereby the central angle α 2 is spanned by the lines that connect the end points of the circular arc segment b 2 with the pivot center C. The circular arc radius r 2 is greater than the radius r 3 of the outer bearing opening 8.1. An inlet or outlet section a 2 of the second circular groove 8.2 adjoins the proximal end of the circular arc segment b 2.In the example shown, this has the same direction of curvature as the circular arc segment b 2 , but a different radius of curvature, which is significantly smaller than the circular arc radius r 2 and corresponds to approximately one third of the circular arc radius r 2 . On the distal side, the second circular groove 8.2 ends at a distal opening section 8.4 of the swash plate 8, which widens conically in the distal direction.

[0043] The circular arc radius r 1 of the first circular grooves 7.2 and the circular arc radius r 2 of the second circular grooves 8.2 are selected such that the difference between the circular arc radius r 2 of the second circular grooves 8.2 and the circular arc radius r 1 of the first circular grooves 7.2 corresponds, with corresponding tolerances, to the ball radius R of the rolling bearing balls 12.

[0044] The ball cage 11, which is Fig. 8 is shown, has an outer radius r 4 on the spherical outer surface 11.6, which is coordinated with the radius r 3 of the outer bearing opening 8.1 in order to form a plain bearing. The inner bearing opening 11.3 delimited by the ball cage 11 is designed with an inner radius r 5 for the plain bearing accommodation of the spherical coupling section 7.1, so that the inner radius r 5 of the ball cage 11 corresponds to the radius r 0 of the coupling section 7.1 with the corresponding tolerances. The surface 7.3 of the spherical coupling section 7.1 adjacent to the first circular grooves 7.2 thus forms an inner plain bearing with the inner surface 11.6' of the ball cage 11 adjacent to the window openings 11.1, 11.2. The surface 8.3 of the hollow spherical bearing opening 8.1 adjacent to the second circular grooves 8.2 forms an outer plain bearing with the outer surface 11.6 of the ball cage 11 adjacent to the window openings 11.1, 11.2.In order to prevent excessive frictional forces from occurring when tilting under load, the ball cage 11 can be made of a material that forms a low-friction material pairing with the materials of the spherical section 7.1 and the outer bearing opening 8.1. Examples of suitable materials for the ball cage include brass, Teflon, or self-lubricating high-performance polymers, etc. Alternatively, the ball cage 11 can have a corresponding coating on the outer and / or inner surface 11.6, 11.6' to provide a low-friction material pairing with the materials of the spherical section 7.1 and the outer bearing opening 8.1. Depending on the material of the spherical section 7.1 or the outer bearing opening 8.1, the outer and inner surfaces 11.6, 11.6' of the ball cage 11 can optionally have different materials / coatings to form a low-friction material pairing.

[0045] In any case, the ball cage 11 forms an inner ball joint with the coupling section 7.1 and an outer ball joint with the outer bearing opening 8.1 of the swash plate 8, which is concentric with the inner ball joint. The rolling bearing balls 12 are guided by the ball cage 11 in the respective circular grooves 7.2, 8.2 along the circular arc segments b 1 , b 2 .

[0046] The window openings 11.1, 11.2 are evenly distributed around the circumference of the ball cage 11. The window openings 11.1, 11.2 are located along an equatorial plane of the ball cage 11, which in the neutral position, as shown in Fig. 8 shown, extends orthogonally to the main axis A through the ball center of the ball cage 11. The circumferential arrangement of the window openings 11.1, 11.2 thus corresponds to the circumferential arrangement of the first circular grooves 7.2 on the coupling section 7.1 and the circumferential arrangement of the second circular grooves 8.2 in the outer bearing opening 8.1.

[0047] In Fig. 2 It can also be seen that two opposite window openings 11.1 are circular, so that they can be made by simple bores, while the remaining window openings 11.2 are designed as elongated holes, since when the swash plate 8 tilts, the distances between the rolling bearing balls 12 along their path in the circular grooves 7.2, 8.2 change slightly. The long sides of the window opening 11.2 designed as an elongated hole run in the circumferential direction parallel to the equatorial plane. The width or the distance between the long sides of the window opening 11.2 designed as an elongated hole is dimensioned as the diameter of the two circular window openings 11.1 for receiving the rolling bearing balls 12, whereby the length of the elongated holes 11.2 in Fig. 2 , 8exaggerated for illustrative purposes. Each window axis that runs radially through a (window) center point and the sphere center point of the ball cage 11, which corresponds to the pivot center C in the bearing arrangement 10, lies in the equatorial plane of the ball cage 11.

[0048] As in Fig. 2 bis 9 As can be seen, the (hollow) spherical shapes of the coupling section 7.1, the ball cage 11 and the outer bearing opening 8.1 each correspond to a (hollow) spherical disk, i.e. a part of a sphere that is cut out by two parallel planes which, in the case of the main shaft 7, extend orthogonally to the main axis A. The spherical disk shape results from the fact that shaft sections of the main shaft 7 adjoin both sides of the spherical coupling section 7.1, so that the main shaft 7 can be easily rotatably mounted and axially fixed on both sides of the swash plate 8 in the housing of the handle 5. Accordingly, the ball cage 11 also has a spherical disk shape, and the outer bearing opening 8.1 in the swash plate 8 and the inner bearing opening 11.3 of the ball cage 11 are hollow spherical disk-shaped and designed as through-openings.

[0049] The inner bearing opening 11.3 of the ball cage 11 is, as shown in Fig. 8 can be seen, connected to a distal opening section 11.4 and a proximal opening section 11.5. The cross-section of the distal opening section 11.4 is widened with respect to the hollow spherical shape of the inner bearing opening 11.3 and is cylindrically shaped to allow the mounting of the ball cage 11 on the coupling section 7.1. Therefore, the cross-sectional radius of the distal opening section 11.4 in this example corresponds to the inner radius r 5 of the hollow ball cage 11, which is dimensioned to movably receive the coupling section 7.1 and therefore corresponds to or is slightly larger than the radius r 0 of the coupling section 7.1. The cross-sectional radius of the proximal opening section 11.5 in the example shown is slightly smaller than the circular arc radius r 1 , but also depends on a maximum tilt angle provided for the swash plate 8, at which, as in Fig. 4 As can be seen, the ball cage 11 and the swash plate 8 abut the proximal shaft section of the main shaft 7.

[0050] Similarly, the outer bearing opening 8.1 is designed as a through-opening, wherein the swash plate 8 in the illustrated example has, in addition to a distal bearing section 8.6, in which the hollow spherical outer bearing opening 8.1 is formed, a spherical drive section 8.9 for coupling to a drive device. The hollow spherical outer bearing opening 8.1 lies between a distal opening section 8.4 and a proximal opening section 8.5, which extends through the spherical drive section 8.9 and widens in the proximal direction (see Fig. 9 ).

[0051] At a transition to the distal opening section 8.4, the outer bearing opening 8.1 has a distal widened section 8.1', the opening cross-section of which is widened with respect to the hollow spherical disc shape of the outer bearing opening 8.1 with the radius r 3 to allow mounting on the ball cage 11 arranged on the coupling section 7.1 of the main shaft 7. The distal widened section 8.1' is considered part of the hollow spherical outer bearing opening 8.1, since the second circular grooves 8.2 extend not only through the hollow spherical part of the outer bearing opening 8.1, but also through the distal widened section 8.1'.

[0052] The length h 1 of the spherical disk-shaped coupling section 7.1 ( Fig. 6 ) in the direction of the main axis A corresponds to the distance between the two parallel planes orthogonal to the main axis A at the transitions to the shaft sections of the main shaft 7. In the present case, the two cutting planes are equidistant from an equatorial plane of the coupling section 7.1, which extends orthogonal to the main axis A through the center of the spherical coupling section 7.1, which in the bearing arrangement 10 corresponds to the pivot center C of the swash plate 8. In the neutral position of the ball cage 11, in which the equatorial plane is orthogonal to the main axis A, the length h 2 of the ball cage 11 ( Fig. 8 ) in the direction of the main axis A is the distance between the parallel planes that delimit the distal and proximal opening sections 11.4, 11.5 to the outside and determine the spherical disk shape of the ball cage 11. The length h 3 of the outer bearing opening 8.1 ( Fig. 9 ), in the neutral position of the swash plate 8 in the direction of the main axis A, is composed of the length h 4 of the widening section 8.1' and the length h 5 of the (unmarked) hollow spherical disc-shaped section of the outer bearing opening 8.1.

[0053] Unlike the spherical disk-shaped coupling section 7.1, the (hollow) spherical disk shapes of the ball cage 11 and the outer bearing opening 8.1 in the example shown are not symmetrical to the respective equatorial plane due to the distal opening or widening section 11.4, 8.1', which passes through the center of the respective (hollow) spherical shape, which in the bearing arrangement 10 corresponds to the pivot center C of the swash plate 8. As in Fig. 5 As can be seen, the lengths h 1 , h 2 , h 3 of the coupling section 7.1, the ball cage 11 and the outer bearing opening 8.1 in the direction of the main axis A differ from one another in this embodiment.

[0054] In the case of other bearing arrangements not shown, which for example provide for multi-part swash plates and ball cages or a modified plain or rolling bearing concept, the dimensions (lengths h 1 to h 5 and radii r 0 , r 3 , r 4 , r 5 of coupling section 7.1, ball cage 11 and outer bearing opening 8.1, rolling bearing ball radius R as well as circular arc segments b 1 , b 2 and circular arc radius r 1 , r 2 of the circular grooves 7.2, 8.2 etc.) can deviate from the example shown, as long as the sphere center point of the respective (hollow) spherical disk shape in the bearing arrangement 10 corresponds to the pivot center C of the swash plate 8.

[0055] In the neutral position, the swash plate 8, or the equatorial plane of the outer bearing opening 8.1 or a swash plate plane, which is defined, for example, by the attachment points of the steering wires 6 on the swash plate 8, is orthogonal to the main axis A. For the attachment of the steering wires 6, the swash plate 8 of the Fig. 9 In the example shown, the bearing section 8.6 has steering wire bores 8.7 that extend from openings on the distal side of the swashplate 8 through the bearing section 8.6. Furthermore, a fastening bore 8.8 extends from the circumference of the swashplate 8 to each steering wire bore 8.7 orthogonally thereto, in order to fasten a steering wire 6 that extends through the steering wire bore 8.7, e.g., by means of a grub screw. Of course, the steering wires 6 can also be fastened to the swashplate in a different manner.

[0056] To assemble the bearing arrangement 10, the ball cage 11 is inserted through the distal widened section 8.1' into the outer bearing opening 8.1 of the swash plate 8, and the rolling bearing balls 12 are inserted from the inside into the window openings 11.1, 11.2 and the second circular grooves 8.2. The outer ball joint thus obtained is pushed onto the main shaft 7 from the proximal side until the spherical section 7.1 is received in the ball cage 11 through the distal opening section 11.4 to form the inner ball joint. The ball cage 11 thus forms an intermediate plane in the ball joint between the main shaft 7 and the swash plate 8 and ensures their one-sided axial fixation to one another. The tensile forces acting in the distal direction of the steering wires 6 attached to the swash plate 8 can thus be diverted into the main shaft 7.

[0057] With the bearing arrangement 10, the position of the pivot center C of the swash plate 8 on the main axis A is clearly defined in any case. The pivoting of the swash plate 8 is achieved by movement of the spherical drive section 8.9, whose spherical center K is spaced from the pivot center C of the swash plate 8, as in Fig. 9 can be seen. Any movement of the spherical drive section 8.9 upwards, downwards, forwards or backwards (with respect to the plane of the drawing) directly causes a pivoting of the swashplate 8 about its pivot center C. In this case, the spherical center K moves on a spherical path in space due to the fixed distance from the pivot center C of the swashplate 8 and therefore cannot be directly actuated by a Cartesian drive.

[0058] Therefore, the surgical instrument 1 has a drive device in the handle 5 and a connected, spatially alignable cylindrical sleeve element (not shown), in whose cylindrical receptacle the spherical drive section 8.9 is movably received. A fit between the inner diameter of the sleeve element and the outer diameter of the spherical drive section 8.9 is selected depending on the application and the respective material pairing such that the spherical drive section 8.9 can rotate and / or tilt within the sleeve element and can also move within the sleeve element along the sleeve axis.

[0059] Depending on the type of drive device, the sleeve element can be moved either in a plane orthogonal to the main axis A in two spatial directions X, Y by a drive device (not shown) with a Cartesian control mechanism. The sleeve axis always remains parallel to the main axis A. Drive devices with a Cartesian control mechanism with two single-axis, preferably orthogonally arranged linear guide devices are known. These include, for example, cross or coordinate tables.

[0060] A parallel kinematic articulated arm chain is advantageous as the drive device, which moves the sleeve element in a plane perpendicular to the main axis A in order to pivot the swash plate 8 about its center C via the spherical drive section 8.9. For this purpose, a parallel kinematic articulated arm chain has four arm segments that are articulated together in a closed chain via a housing component. The drive device has two motors arranged axially parallel to the main axis A, with a first arm segment attached to each motor shaft, which is pivotally connected to a second arm segment. The two second arm segments are each rotatably mounted on the sleeve element, forming a central joint, and thus also rotatable relative to each other by means of rolling bearings. The sleeve element acts as the pivot pin of the central joint.

[0061] Since the sleeve element and the spherical drive section 8.9 can be oriented relative to one another in any desired manner, within certain limits, without fear of jammed or blocked components, the sleeve element can be shifted to a certain extent along or parallel to the main axis A, or tilted relative to the main axis A, so that the sleeve axis is not parallel to the main axis A, but rather at an angle to it. Therefore, as an alternative to the Cartesian control mechanism, other drive devices can also be used to move the sleeve element, such as a drive device with a differential gear that rotates the sleeve element about a (virtual) pivot center, which can be offset from the pivot center C of the swash plate 8. The coupling of the spherical drive section 8.9 to the sleeve element enables movement without blockage, and all angles can be easily reached.In a differential gear as a drive device, which has two opposing input bevel gears and an output bevel gear that meshes with the two input bevel gears, the output bevel gear is non-rotatably connected to a steering ring in which the spherical drive section 8.9 of the swash plate 8 is mounted via a rolling bearing, so that the swash plate 8 is rotatable relative to the steering ring for rotation with the main shaft 7. The sleeve element in which the spherical drive section 8.9 is received is provided by the inner ring of the rolling bearing, which is pivotable with the steering ring about the pivot center of the differential gear.

[0062] Modifications and further embodiments of the bearing arrangement according to the invention, which are not shown, relate to the fact that - as an alternative to the design with the distal expansion and opening sections 8.1', 11.4 of the swash plate 8 and the ball cage 11 that are widened with respect to the spherical shape - the swash plate 8 and the ball cage 11 can each be formed in two or more parts to enable the assembly of the bearing arrangement 10. For this purpose, at least one joining plane runs through the outer receiving opening 8.1 of the swash plate 8 and the inner receiving opening 11.3 of the ball cage 11. For example, a joining plane can run along the respective equatorial plane or orthogonal thereto. In such a bearing arrangement, in contrast to the variant with the widened distal expansion and opening sections 8.1', 11.4, with which only forces can be transmitted one-sidedly in the axial direction, forces can be transmitted in both axial directions.

[0063] Furthermore, it is possible for the main shaft, contrary to the illustration, not to extend through the swash plate but to end in the spherical coupling section, which is then correspondingly designed as a spherical segment that is separated from the shaft section of the main shaft by a sectional plane orthogonal to the main axis. In such an embodiment, the main shaft is rotatable distally to the swash plate, preferably mounted by means of two bearings in the housing of the handle and likewise axially fixed. Corresponding to such a coupling section, the ball cage and the outer bearing opening are also designed as (hollow) spherical segments, so that the inner and outer bearing openings are each designed as a receiving opening closed on the proximal side. The surfaces available for the plain bearing between the coupling section, ball cage and outer bearing opening would be larger and thus more advantageous.Alternatively or additionally, the larger contact surfaces can be used to introduce additional rolling balls in order to achieve a more efficient rolling bearing arrangement.

[0064] A further alternative according to the invention to the illustrated example can provide for the ball cage to be designed narrower and for smaller rolling bearing balls to be inserted into circular grooves along a circular arc segment with a relatively larger circular arc radius, by dividing the coupling section and the outer bearing opening into a distal and a proximal bearing section. The first and second circular grooves and the ball cage are then arranged in the distal bearing section, while in the proximal bearing section, the surface of the coupling section forms a sliding bearing directly with the surface of the outer bearing opening.

[0065] Furthermore, a bearing arrangement according to the invention can be designed as a pure rolling bearing, for which purpose the bearing arrangement has secondary rolling balls which are smaller than the rolling bearing balls running in the first and second circular grooves, so that the secondary rolling balls run guided by the ball cage on the inside on the surface of the coupling section adjacent to the first circular grooves and on the outside on a surface at the outer bearing opening adjacent to the second circular grooves.

[0066] The drawings, the description, and the claims contain numerous features in combination. It is understood that the aforementioned features can be used not only in the respective combination specified, but also in other combinations or alone, without departing from the scope of the present invention. The present invention provides a surgical instrument 1 and a bearing assembly 10 comprising a swash plate 8 with a main shaft 7. The swash plate 8 is connectable to a plurality of steering wires 6 and pivotally connected to the main shaft 7, which defines a main axis A. The swash plate 8 is rotatable about two axes X, Y that are orthogonal to each other and to the main axis A. An intersection point of the two axes X, Y defines a pivot center C of the swash plate 8 and lies on the main axis A. The main shaft 7 has a spherical coupling portion 7.1, and the swash plate 8 has a hollow spherical outer bearing opening 8.1, wherein the pivot center C of the swash plate 8 corresponds to a sphere center of the outer bearing opening 8.1 and, in the bearing arrangement 10, to a sphere center of the spherical coupling section 7.1. Furthermore, the bearing arrangement 10 comprises rolling bearing balls 12 with a spherical radius R and a ball cage 11, which is movably arranged in the outer bearing opening 8.1 and delimits a hollow spherical inner bearing opening 11.3, in which the coupling section 7.1 of the main shaft 7 is movably arranged. The ball cage 11 has window openings 11.1, 11.2, in each of which one of the rolling bearing balls 12 is arranged. The coupling section 7.1 has, in the longitudinal direction of the main shaft 7, first circular grooves 7.2 as an inner raceway for the rolling bearing balls 12 and the outer bearing opening 8.1 has, in the longitudinal direction of the main shaft 7, second circular grooves 8.2 as an outer raceway for the rolling bearing balls 12. BEZUGSZEICHENLISTE

[0067] 1 Surgical instrument 2 Shaft 2a, 2b Distal, proximal shaft end 3 Tool 4 Articulation mechanism 5 Handle 6 Steering wire 7 Main shaft 7.1 Spherical coupling section 7.2 First circular groove 7.3 First surface 7.4 Distal main shaft end 7.5 Axial bore 8 Swash plate 8.1, 8.1 Outer bearing / through opening, distal expansion section 8.2 Second circular groove 8.3 Second surface 8.4, 8.5 Distal, proximal opening section 8.6 Bearing section 8.7, 8.8 Steering wire bore, mounting bore 8.9 Spherical drive section 9 Bearing 10 Bearing assembly 11 Ball cage 11.1 Round window opening 11.2 Elongated window opening 11.3Internal storage / through-opening 11.4, 11.5Distal, proximal opening section 11.6, 11.6'outer, inner surface 12Rolling ball AMain axis α 1 , α 2 Center angle of circular arc segment a 1 , a 2 Inlet / outlet section b 1 , b 2 first, second circular arc segment h 1 , h 2 Length of coupling section, spherical disk h 3 , h 4 Length of outer bearing opening, distal expansion section KCenter of spherical drive section R, R'Radius of rolling ball / cross-sectional radius of first / second circular groove r 0 Radius of the spherical coupling section r 1 , r 2 Radius of the first, second circular arc segment r 3 Radius of the receiving / through opening r 4 Outer radius of the hollow ball cage r 5 Inner radius of the hollow ball cage rw Radius of main shaft X, Y Spatial axes CSwivel center of swash plate.

Claims

1. A bearing arrangement (10) with a spatially alignable swash plate (8) of a surgical instrument (1) having a main shaft (7), wherein the swash plate (8) can be connected to a plurality of steering wires (6) for activating a distal bending mechanism (4) of the surgical instrument (1) and is connected in an articulated manner to the main shaft (7), which defines a main axis (A), wherein the swash plate (8) is rotatable about two axes (X, Y) which are orthogonal to each other and to the main axis (A), and wherein a point of intersection of the two axes (X, Y), which defines a pivot centre (C) of the swash plate (8), lies on the main axis (A), wherein the main shaft (7) has a spherical coupling section (7.1), and the swash plate (8) has a hollow spherical outer bearing opening (8.1), wherein the pivot centre (C) of the swash plate (8) corresponds to a ball centre of the hollow spherical outer bearing opening (8.1) and in the bearing arrangement (10) corresponds to a ball centre of the spherical coupling section (7.1), and the bearing arrangement (10) has rolling bearing balls (12) with a ball radius (R) and a ball cage (11), which is movably arranged in the outer bearing opening (8.1) and delimits a hollow spherical inner bearing opening (11.3), in which the coupling section (7.1) of the main shaft (7) is movably arranged, wherein the ball cage (11) has window openings (11.1, 11.2), in each of which one of the rolling bearing balls (12) is arranged, and the coupling section (7.1) has first round grooves (7.2) in the longitudinal direction of the main shaft (7) as the inner raceway for the rolling bearing balls (12) and the outer bearing opening (8.1) has second round grooves (8.2) in the longitudinal direction of the main shaft (7) as the outer raceway for the rolling bearing balls (12).

2. The bearing arrangement (10) according to claim 1, characterised in that each first round groove (7.2) is formed along a first circular arc segment (b1) the circle centre of which is congruent with the spherical centre of the spherical coupling section (7.1), and each second round groove (8.2) is formed along a second arc segment (b2), the circle centre of which corresponds to the pivot centre (C) of the swash plate (8).

3. The bearing arrangement (10) according to claim 1 or 2, characterised in that the first round grooves (7.2) and the second round grooves (8.2) each have a part-circular profile with a groove cross-sectional radius (R') that corresponds to the ball radius (R) of the rolling bearing balls (12).

4. The bearing arrangement (10) according to at least one of claims 1 to 3, characterised in that a spherical shape of the coupling section (7.1), a spherical shape of the ball cage (11), a hollow spherical shape of the inner bearing opening (11.3) and a hollow spherical shape of the outer bearing opening (8.1) each correspond to a spherical disc, wherein the inner bearing opening (11.3) and the outer bearing opening (8.1) are each designed as a through-opening (8.1, 11.3), such that the main shaft (7) extends through the swash plate (8) and the ball cage (11) and is supported on both sides of the swash plate (8) by means of a bearing (9) in each case so as to be rotatable about the main axis (A) and is fixed in the axial direction.

5. The bearing arrangement (10) according to at least one of claims 1 to 3, characterised in that a spherical shape of the coupling section (7.1), a spherical shape of the ball cage (11), a hollow spherical shape of the inner bearing opening (11.3) and a hollow spherical shape of the outer bearing opening (8.1) each correspond to a spherical segment, wherein the inner bearing opening (11.3) and the outer bearing opening (8.1) are each designed as a receiving opening (8.1, 11.3) closed on the proximal side around the coupling section (7.1), such that the main shaft (7) extends on the distal side out of the swash plate (8) and the ball cage (11) and is supported distally to the swash plate (8) so as to be rotatable about the main axis (A) and is fixed in the axial direction.

6. The bearing arrangement (10) according to at least one of claims 1 to 5, characterised in that the coupling section (7.1) with the first round grooves (7.2), the ball cage (11) with the window openings (11.1, 11.2) and with the inner bearing opening (11.3), the rolling element balls (12) and the outer bearing opening (8.1) of the swash plate (8) with the second round grooves (8.2) are dimensioned such that the ball cage (11) forms, with the coupling section (7.1), an inner ball joint and, with the outer bearing opening (8.1) of the swash plate (8), an outer ball joint which is concentric with the inner ball joint.

7. The bearing arrangement (10) according to claim 6, characterised in that a surface (7.3) of the spherical coupling section (7.1) adjacent to the first round grooves (7.2) and an inner surface (11.6') of the ball cage (11) adjacent to the window openings (11.1, 11.2) form an inner sliding bearing, and a surface (8.3) of the hollow spherical receiving opening (8.1) adjacent to the second round grooves (8.2) and an outer surface (11.6) of the ball cage (11) adjacent to the window openings (11.1, 11.2) form an outer sliding bearing.

8. The bearing arrangement (10) according to claim 6, characterised in that the coupling section (7.1) and the outer bearing opening (8.1) each have a distal and a proximal bearing section, wherein the first round grooves (7.2), the second round grooves (8.2) and the ball cage (11) are present in the distal bearing section, and wherein in the proximal bearing section a surface (7.3) of the coupling section (7.1) has an inner sliding section and a surface (8.3) of the outer bearing opening (8.1) has an outer sliding section, which forms a sliding bearing with the inner sliding section.

9. The bearing arrangement (10) according to claim 6, characterised in that the bearing arrangement (10) has secondary rolling balls which are smaller than the rolling bearing balls (12) and which, guided by the ball cage (11), run internally on a surface (7.3) of the coupling section (7.1) adjacent to the first round grooves (7.2) and externally on a surface (8.3) of the outer bearing opening (8.1) adjacent to the second round grooves (8.2).

10. The bearing arrangement (10) according to at least one of claims 1 to 9, characterised in that the outer bearing opening (8.1) of the swash plate (8) has an expansion section (8.1') on the distal side that is matched to the ball cage (11.3), and the inner bearing opening (11.3) of the ball cage (11) has an opening section (11.4) on the distal side that is matched to the coupling section (7.1).

11. The bearing arrangement (10) according to at least one of claims 1 to 9, characterised in that the swash plate (8) and the ball cage (11) are each formed in two or more parts, wherein at least one joining plane extends through the outer receiving opening (8.1) of the swash plate (8) and the inner receiving opening (11.3) of the ball cage (11).

12. The bearing arrangement (10) according to at least one of claims 1 to 11, characterised in that - the window openings (11.1, 11.2), the first round grooves (7.2) and the second round grooves (8.2) are circumferentially evenly distributed, and / or, - two of the window openings (11.1, 11.2), which are located opposite one another on the ball cage (11), are designed as circular window openings (11.1), wherein the remaining window openings (11.2) are each designed as an elongated hole.

13. The bearing arrangement (40) according to at least one of claims 1 to 12, characterised in that the outer bearing opening (8.1) is formed in a distal bearing section (8.6) of the swash plate (8), which is connected on the proximal side to a spherical drive section (8.9), the spherical centre (K) of which is spaced from the pivot centre (C) of the swash plate (8), wherein the spherical drive section (8.9) can be accommodated in a cylindrical sleeve element (9), which can be spatially aligned with a drive device.

14. A surgical instrument (1) having a shaft (2), a tool (3) at a distal shaft end (2a) and a handle (5) at a proximal shaft end (2b), wherein the handle (5) has a bearing arrangement (10) with a swash plate (8) which is connected in an articulated manner to a main shaft (19), which defines a main axis (A), and is pivotable about a pivot centre (C), which lies on the main axis (A), in two directions orthogonal to the main axis (A), wherein the swash plate (8) is connected to a plurality of steering wires (6), which extend along the main axis (A) through the shaft (2) to a bending mechanism (4) of the tool (3), characterised in that the bearing arrangement is a bearing arrangement (10) according to at least one of claims 1 to 13.

15. The surgical instrument (1) according to claim 14, characterised in that the swash plate (8) has a spherical drive section (8.9) on the proximal side, the spherical centre (K) of which is spaced from the pivot centre (C) of the swash plate (8), wherein the handle has a drive device for the spatial alignment of a cylindrical sleeve element (9), in which the spherical drive section (8.9) is accommodated.