SURGICAL INSTRUMENT AND STEERING GEAR FOR IT

Description

[0001] The invention relates to a steering gear of a surgical instrument for angling a tool tip by means of a spatially alignable swash plate, as well as to a surgical instrument having such a steering gear.

[0002] Surgical instruments are known from the prior art that can be guided manually or by a robot, and that feature tools whose tool tips can be pivoted using several interlocking pivoting links. These pivoting links are connected to a multitude of steering wires or cables to achieve sensitive control of the tool tip. Using many thin steering wires instead of a few thicker ones allows for a more even distribution of force in all deflection directions.

[0003] From US 5,454,827 B2 it is known to couple such steering wires to a spatially adjustable disc arranged on the proximal side in an actuating unit, which is connected via a rod to a manually operable control lever, so that a movement of the spatially adjustable swash plate causes a corresponding relative movement of the distal-side pivoting members and thus a pivoting of the tool tip.

[0004] The design of the drive for the steering wires with a spatially adjustable swashplate, on which all four steering wires are mounted, has the advantage of enabling a spatially compact design and requiring only one component to be moved to control all the steering wires. This design allows for the use of only a small number of steering wires, and the spatially adjustable disc serving as the drive for the steering wires can be operated manually, both of which influence the sensitivity and reproducibility of the adjustment of the distal swivel elements.

[0005] US Pat. No. 7,699,855 B2 discloses a surgical instrument with an interface for connecting the instrument to a robotic arm. All drives controlling the instrument are located within the robotic arm. The rotation angles are transmitted from the drives to the instrument via coupling discs in a common separation plane.

[0006] Furthermore, it is known to transmit the angles of two drives directly to the swashplate in a surgical instrument with a compact steering gear, in order to align it for controlling the tool tip. Steering wires are attached to the swashplate so that the tool tip can be controlled continuously and smoothly by aligning the swashplate. For this purpose, the known steering gear has two drive bevel gears offset by 180° from each other, arranged on a common axis of rotation perpendicular to a longitudinal axis of the instrument, each with its own associated motor. The swashplate is arranged between the drive bevel gears and mounted in a steering ring, which is rotationally fixed to a third bevel gear. This third bevel gear engages with the two drive bevel gears and is rotatable about an axis of rotation perpendicular to both the longitudinal axis of the instrument and the common axis of rotation of the drive bevel gears.The toothed chain is complemented by a fourth bevel gear, which is arranged on the rotational axis of the third bevel gear, offset by 180° from the third bevel gear, and meshes with the two drive bevel gears. The steering ring is freely rotatably mounted in the fourth bevel gear. The toothed chain thus closed ensures the meshing of all bevel gears with each other and enables even power distribution throughout the entire drive.

[0007] The design of the drive for the steering wires with the spatially adjustable swash plate, on which all steering wires are mounted, has the advantage that this enables a spatially compact design and only one component has to be moved in order to be able to address all steering wires.

[0008] WO 2014 / 004242 also describes such an interface, with the drives built into the robot arm. This design involves a complex structure and indirect control. The drives are not directly located in the surgical instrument, resulting in a non-linear control of the swash plate.

[0009] US 10,105,128 B2 also discloses a control of such a tool tip; there, this is done via a mechanism that includes toothed disk segments and articulated rods to transmit the movement of the drives to the swash plate.

[0010] DE 10 2019 121 092 A1 describes a steering gear with a swashplate and two motors that move the swashplate. US 2010 / 228284 A1 describes mechanisms for controlling a joint in surgical robotics. In particular, DE 10 2019 121 092 A1 and US 2010 / 228284 A1 disclose the preamble of claim 1. Based on this prior art, the present invention seeks to provide an alternative control and guidance system for the steering ring.

[0011] This object is achieved by a steering gear having the features of claim 1. The further object of providing a surgical instrument with an alternative guide for the steering ring is achieved by the surgical instrument having the features of dependent claim 9.

[0012] Further developments of the steering gear and the surgical instrument are described in the respective subclaims.

[0013] A first embodiment of the steering gear is designed for a surgical instrument that can be arranged at the proximal end of a shaft defining a longitudinal axis B and featuring an angling mechanism at its distal end. The steering gear has two motorized drives and is configured to spatially align a swashplate via the angles of these two drives. The swashplate is further configured to control the distal angling mechanism of the surgical instrument.

[0014] According to the invention, the swash plate is arranged in a steering ring. The first of the two motorized drives has a first drive shaft driven by a first motor, which is directly operatively connected to the steering ring via a first force transmitter, in that the first force transmitter directly contacts the steering ring at a first operative section. For this purpose, the first force transmitter is arranged on the first drive shaft, which defines a first drive axis C. Furthermore, the second of the two motorized drives has a second drive shaft driven by a second motor, which is directly operatively connected to the steering ring via a second force transmitter, in that the second force transmitter directly contacts the steering ring at a second operative section. The second force transmitter is arranged on the second drive shaft, which defines a second drive axis C'.The steering ring is gimbal-mounted around a cardanic center, enabling movement in two spatial axes, which allows the tool tip to be precisely controlled. To ensure that the engagement with the force transmitters is maintained even when the steering ring is tilted, the steering ring is spherical or has a spherical segment shape at least in the first and second active sections around the cardanic center. The spherical segment-shaped active sections have a common sphere center that corresponds to the cardanic center. In this way, a first tilting axis E, which is defined by a contact point of the first force transmitter with the steering ring and the cardanic center, and a second tilting axis E', which is defined by a contact point of the second force transmitter with the steering ring and the cardanic center, intersect at right angles at the cardanic center.This means that the drives touch the steering ring with the effective sections in such a way that the normals defined as tilt axes E, E' of the surfaces touching at the respective contact points intersect perpendicularly in the gimbal center.

[0015] "Spherical segment-shaped" refers to shapes that can be defined as a part of a spherical body separated by intersection with a plane, and whose curved surface is referred to as a spherical cap. In this context, "spherical segment-shaped" also includes spherical disc shapes that arise as part of a spherical body in which two spherical segments ("polar caps") have been removed by parallel cutting planes, with the curved surface of the spherical disc being referred to as the spherical zone. For example, the steering ring can have a spherical disc shape in which the two parallel cutting planes are equidistant or symmetrical to the diameter plane, so that the steering ring surface is formed as a spherical zone symmetrical to the diameter plane.

[0016] The steering ring thus has a spherical or semi-spherical character, at least in the area of ​​the effective sections, with the center of a circle of a sphere defined by the spherical or semi-spherical effective sections being the gimbal center. In principle, it is sufficient if the surface of the steering ring is only spherical in the two effective sections that engage with the force transmitters.

[0017] All the power transmission variants described below share this basic principle: At the contact points between the power transmission and the steering ring, the movement of the power transmission, when considered infinitesimal, is always parallel to the main axis B of the surgical instrument and directed forward or backward with respect to the main axis B, depending on the direction of movement of the power transmission. This movement is transmitted to the steering ring. Due to its gimbal mounting, this results in a tilting of the steering ring about one or both tilting axes E, E'.

[0018] "Power transmitter" refers to any component that directly absorbs the movement initiated by motors, whether rotary or linear, and can transmit it to the active section of the steering ring.

[0019] The "effective section" here refers to the area of ​​the steering ring that can enter into a force-transmitting operative connection with the force transmitter, i.e., is in direct contact with the force transmitter, e.g., through a frictional operative connection using friction elements, or is engaged, e.g., through a toothing or other suitable force-transmitting operative connections.

[0020] Advantageously, the steering ring, which surrounds the swashplate, can be directly controlled by the drive motors via the power transmitters. No additional deflection mechanisms or gear ratios are required, enabling the shortest possible transmission chain. Such a direct, short power transmission is advantageously associated with low backlash and a reduction in transmission and friction losses. Furthermore, due to the linear transmission behavior, it enables simple software control for precise control of the component to be controlled.

[0021] A further embodiment of the steering gear according to the invention provides that the cardanic mounting of the steering ring is provided by a) the steering ring being cardanically suspended from a first fastening device. The fastening device is a bracket that is arranged on a section of the steering ring that faces away from the active sections. Furthermore, the bracket is pivotally mounted on the housing at both ends about a pivot axis A that runs perpendicular to the longitudinal axis B and perpendicular to the drive axes C, C'. The bracket has a receiving opening in the center, wherein the steering ring is rotatably mounted in the receiving opening about a rotation axis D that runs perpendicular to the pivot axis A.The swash plate can preferably be rotatably mounted in the steering ring in order to also allow a rotational movement of the swash plate in the steering ring, but can also be firmly connected to the steering ring or even formed in one piece with the steering ring, so that a combined component of steering ring and swash plate is created.

[0022] The swivel mounting of the bracket to the housing includes bearing pins by means of which the bracket is rotatably mounted in the housing on both sides about the pivot axis A, thus defining the spatial position of the steering ring, which can only rotate about its transverse and vertical axes, including any superimposed axes, and preventing rotation about the main axis B. This gimbal suspension of the steering ring by means of the bracket is structurally simple and allows for precise control. Furthermore, the steering ring is additionally enclosed and protected by the bracket spanning it.

[0023] As an alternative to the gimbal suspension using a bracket, the steering ring can be gimbal-mounted by b) mounting the steering ring via the swashplate, which is rotatably mounted in the steering ring about the longitudinal axis B or fixed to the steering ring, on a main shaft running coaxially to the longitudinal axis B of the shaft. For this purpose, the swashplate is pivotably mounted on a universal joint disc via two bearing pins arranged diametrically and coaxially offset from each other by 180°. The universal joint disc, in turn, is pivotally mounted on the main shaft via two bearing pins arranged diametrically and coaxially offset from each other by 180°, with the bearing pin pairs of the swashplate and the universal joint disc being arranged 90° apart from each other.

[0024] To ensure that the steering ring can rotate exclusively around the transverse and vertical axes, including superimpositions, and that its position in space is fixed and rotation around the main axis B is prevented, the steering ring can optionally be coupled to a housing in a rotationally fixed manner with respect to the longitudinal axis B, for example by guiding a pin extending radially outwards from the steering ring, for example on the underside of the steering ring between the working sections, in a groove in the housing that extends parallel to the longitudinal axis B along the radius of movement of the pin.

[0025] If the first motor moves the first drive shaft and rotates the first power transmission around the drive axis C, this movement is transmitted to the steering ring at the first working section due to the operative connection between the steering ring and the first power transmission. If the second power transmission remains stationary during this process, the steering ring moves at its contact point with the first power transmission and stops at the contact point of the second working section with the second power transmission, causing the steering ring to tilt about the second tilting axis E', which passes through the fixed contact point of the second working section with the second power transmission and lies at an angle of 45° to both the axis of rotation D and the axis of rotation A.Conversely, a rotation of the second force transmitter about the drive axis C' causes a rotation of the steering ring about the first tilting axis E, which, analogous to the second tilting axis E', lies at an angle of 45° to both the rotation axis D and the rotation axis A and this time passes through the fixed contact point of the first force transmitter and the first effective section of the steering ring. If both force transmitters rotate, the tilts are superimposed, and the steering ring, and thus the swashplate, can tilt in space about both tilting axes E and E', i.e., two-dimensionally.

[0026] A further embodiment of the steering gear according to the invention provides that the operative connection forms an engagement in that the first and second force transmitters are rotationally mounted drive cones with a conical head that has a plurality of drive studs around its circumference, forming a stud ring. In this case, the steering ring has recesses at the operative sections that mesh with the drive studs of the two stud rings. The conical head preferably has a partially or fully toroidal shape to achieve a good contact point with the steering ring.

[0027] Preferably, it can be provided that the knobs in a further embodiment of the steering gear according to the invention have a hemispherical or a semi-ellipsoidal shape.

[0028] These shapes enable secure meshing with the active section of the steering ring and good power transmission from the respective force transmitter to the steering ring. The recesses correspond to the shape of the drive studs, either concentrically arranged ring grooves or arcuate grooves, which essentially form a hypoid-like toothing. The rings are best meshed with hemispherical studs, and the arcuate grooves are best meshed with semi-ellipsoidal studs. In both cases, power transmission occurs smoothly and with low friction. The engagement of the studs in the recesses allows for precise transmission of large drive forces without slippage.

[0029] In an alternative embodiment of the steering gear according to the invention, the first and second force transmitters can be worm shafts that run parallel to the longitudinal axis B. For this purpose, the steering ring has concentrically arranged recesses / annular grooves on its active sections that mesh with the respective worm shaft.

[0030] The two aforementioned designs offer positive-locking connections in which the two components, the steering ring and the force transmitter, mesh with each other in a kind of toothed arrangement. This enables good and precise power transmission, which then enables precise control of the swashplate.

[0031] Yet another alternative embodiment of the steering gear according to the invention provides that the operative connection is provided by friction. This is achieved in that the first and second force transmitters are rotationally mounted drive cones with a conical head that has a friction element around its circumference. The friction element is preferably a material applied around the conical head that provides higher friction with the active portion of the steering ring than the material from which the conical head is made. Such a friction-increasing material can also be introduced into a groove surrounding the conical head for improved grip on the conical head. Alternatively, the friction element can be a friction band applied circumferentially around the conical head, which can be a rubber band or a band with a roughened surface or a band with teeth, micro-teeth, or nubs.

[0032] "Friction" here refers to an active connection that forms by friction, where the frictional force between two components that touch (here, the steering ring and the drive cone) is so great that when the drive cone is set in rotation, it essentially rolls on the steering ring, thereby setting it in motion. "Friction element" in this context refers to any component that exhibits a required material property, such as increased frictional resistance (e.g., sliding friction force). This can be achieved through a specific choice of material or surface finish, such as the aforementioned roughening or toothing. The risk of slippage, which inevitably cannot be completely eliminated with a frictional connection, can be reduced by increased contact pressure, which is determined by the positioning of the force transmitters in relation to the steering ring.

[0033] The advantage of this variant is that the frictional connection allows for a nearly continuous, i.e., stepless, tilt of the steering ring. This also allows for precise control of the swashplate. Further advantages of this variant are absolute freedom from play and inexpensive components and manufacturing.

[0034] In order to combine the respective advantages of the positive and frictional operative connection, or to minimize the respective disadvantages, mixed forms are also conceivable: In a further embodiment, it is therefore provided that the operative connection of the first force transmitter provides a positive engagement and the operative connection of the second force transmitter is provided by friction. The first force transmitter can be a rotatably mounted drive cone with a conical head, which has a plurality of drive knobs around its circumference forming a knob ring, or a worm shaft that runs parallel to the longitudinal axis B. The steering ring accordingly has recesses on the first operative section, which mesh with the drive knobs of the two knob rings or the worm shaft.The second force transmitter, which is also a rotationally mounted drive cone with a cone head, has a friction element around the circumference of the cone head, preferably a material applied around the cone head, which provides a higher level of friction with the second active portion of the steering ring than the material from which the cone head is made. Alternatively, the friction element can be a friction band applied around the circumference of the cone head, which can be a rubber band or a band with a roughened surface or a band with teeth or knobs. By designing one drive cone with positive toothing and the other with frictional engagement, slippage and play are minimized. As a variant of this embodiment, a combined positive and frictional engagement connection can also be implemented together on one drive cone, for example byThis has a dimpled ring that, in addition to the positive engagement provided by the teeth with the recesses on the active section, also provides a frictional engagement. The surface of the drive cone with the dimpled ring or the surface of the active section with the recesses is additionally provided with a rubber coating, thus preventing play. However, the underlying toothing contour still ensures positive engagement throughout the entire service life and prevents slippage while simultaneously ensuring high power transmission.

[0035] Furthermore, in a further embodiment of the steering gear according to the invention, the rotationally mounted drive cones each have a conical shaft around which a bearing ring is arranged adjacent to the conical head, which bearing ring houses, for example, a roller or ball bearing. For this purpose, the housing has a base, each with a through-opening with two opening sections for each drive axle. The two opening sections of the through-openings are axially adjacent to one another, such that they merge into one another and form a shoulder, wherein above the shoulder they widen towards the steering ring to a diameter corresponding to the diameter of the bearing rings. I.e.that each passage opening has a first opening section with a diameter that corresponds to a diameter of the bearing ring, and a second opening section coaxial with the first opening section and with a diameter that is smaller than the diameter of the first opening section, so that the housing forms a shoulder in each passage opening. Each of the bearing rings then rests on the respective shoulder and is securely held. The drive shaft, which penetrates through the bearing ring and thus also both passage opening sections, is guided laterally in its rotation and held. This allows the power generated by the motors to be transmitted directly to the drive bevel gears via the drive shafts.

[0036] An alternative embodiment of the steering gear according to the invention provides that the working connection forms a linear drive, in that the first and second force transmitters are racks with a toothed section. The steering ring has concentrically arranged recesses on its working section that mesh with the toothed sections of the two racks. In yet another alternative embodiment of the steering gear according to the invention, a bonded working connection could also be achieved. For this purpose, tension elements such as ropes or straps could be attached at both ends to the respective working sections of the steering ring and looped once around the respective force transmitter. These variants offer direct control of the swashplate in the case of narrow housings or differently arranged motors required for other design reasons.

[0037] A first embodiment of a surgical instrument according to the invention, which has a shaft, an actuating unit arranged at the proximal end of the shaft and a tool arranged at the distal end of the shaft with a tool tip that can be bent by means of a distal bending mechanism and which can be controlled by a swash plate that can be spatially aligned by means of two drives, relates to the fact that the surgical instrument has a steering gear according to the invention for the spatial alignment of the swash plate.

[0038] The steering gear according to the invention allows for a simple and space-saving design of the surgical instrument, thus enabling easy connection to a robot arm, where the movement of the drives can be directly transmitted to the tool tip. The result is precisely controllable use of the surgical instrument.

[0039] To enable adjustment of the spatially adjustable swashplate, a preferred embodiment of the surgical instrument provides that the swashplate is gimbal-mounted on a main shaft running coaxially to a longitudinal axis B of the shaft. The steering ring is then gimbal-mounted via the swashplate, which can also be described as an internal gimbal mounting. This is an alternative embodiment compared to an external gimbal mounting of the steering ring via the yoke. This mounting can be advantageous depending on the design and available installation space of the surgical instrument.

[0040] In a further embodiment of the surgical instrument according to the invention, the actuating element is mounted axially displaceably in the shaft and is operatively connected to the actuating unit on the proximal side. The distal deflection mechanism of the deflectable tool tip consists of pivoting members arranged at the distal end of the shaft, which are connected to the steering gear via the steering wires running in the longitudinal direction of the shaft. The steering wires are attached to the swash plate, for example by means of a clamp connection, so that the steering wires can be easily replaced in the event of damage. This clamp connection can be provided, for example, by grub screws inserted into radially inserted bores in the swash plate.However, the steering wires can also be permanently attached to the swashplate, for example, by welding or gluing, which is less complex and therefore more cost-effective. This may be preferred for single-use surgical instruments. The advantage of this design over known designs is that not only does it allow the use of a small number of steering wires—namely, only four—and that the spatially adjustable disc serving as the drive for the steering wires can be operated exclusively manually, but also that a large number of steering wires can be freely selected, thus enabling sensitive and reproducible adjustment of the distal pivoting elements.

[0041] The surgical instrument according to the invention has the advantage that many thin steering wires can be used to control the pivotable tool tip and that this control is sensitive, precise and reproducible due to the motorized drive for the spatially adjustable disc on which the steering wires are mounted on the proximal side.

[0042] Further embodiments of the steering gear and the surgical instrument, as well as some of the advantages associated with these and other embodiments, will become clear and more easily understood from the following detailed description with reference to the accompanying figures. Items 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 and the description contain numerous features in combination. Those skilled in the art will expediently consider the features individually and combine them into meaningful further combinations while adhering to the scope of the claims.

[0043] Showing: Fig. 1 is a perspective view of the surgical instrument with a schematically illustrated actuating unit, Fig. 2 is a perspective detailed view of a first embodiment of the steering gear according to the invention without a force transmitter with part of a housing, Fig. 3 is a perspective detailed view of the first embodiment of the steering gear according to the invention with a force transmitter without a housing, Fig. 4 is a sectional view of the steering gear according to the invention according to the first embodiment with a force transmitter and housing, Fig. 5 is a perspective detailed view of yet another embodiment of the steering gear according to the invention with a rubber ring, Fig. 6 is a perspective detailed view of yet another embodiment of the steering gear according to the invention with drive heads with knobs, Fig. 7 is a perspective detailed view of yet another embodiment of the steering gear according to the invention with worm shafts, Fig.8 a perspective detailed view of yet another embodiment of the steering gear according to the invention for a linear drive with a rack, Fig. 9 a detailed view according to . Fig. 8 the rack, Fig. 10 a perspective view of the actuating unit with a further embodiment of the steering gear according to the invention, Fig. 11 a partial sectional view of the steering gear according to Fig. 10 , Fig. 12 a detailed view of a steering ring and a force transmitter according to Fig. 10 and 11 , and Fig. 13 a sequence of steps in the production of the force transmitter according to Fig. 12 .

[0044] Fig. 1shows a schematic diagram of a surgical instrument 1 with a hollow shaft 2, an actuating unit 4 arranged at the proximal end 3 of the shaft 2, shown only schematically, and a tool tip 6 with a tool 7 arranged at the distal end 5 of the shaft 2. The tool 7 can be actuated via an actuating element 8 mounted axially displaceably in the shaft 2, which is operatively connected to the actuating unit 4 on the proximal side. The actuating unit 4 can be a manually actuated handle or a unit designed for robotic use, i.e., one that can also be actuated without manual intervention - which is advantageous for the reproducibility of the actuation. The tool 7 of the tool tip 6 can, for example, be a tool provided with jaw parts, as in Fig. 1The tool tip 6 is depicted, or it may be an endoscope, an applicator, or the like. The tool tip 6 is pivotable relative to the longitudinal axis B of the shaft 2 via a joint mechanism 9. The joint mechanism 9 consists of pivot links 11 arranged at the distal end of the shaft 5, which are connected via guide wires 12 running longitudinally along the shaft 2 to a steering gear 13 arranged at the proximal end 3 of the shaft 2, such that a movement of the proximal-side drive 13 causes a corresponding relative movement of the distal-side pivot links 11 and thus a pivoting of the tool tip 6. Although only the term "guide wires 12" is used above and below, the term "steering cables" can also be used functionally, which is why the term "guide wires 12" should also be read and understood synonymously as "steering cable".

[0045] The actuating element 8, which is axially displaceable in the shaft 2 and is used to actuate the tool 7, which consists, for example, of two jaw parts, is designed as a pull / push rod in the illustrated embodiment.

[0046] The steering gear 13 for the steering wires 12 is designed as a motorized steering gear 13 in the surgical instrument 1.

[0047] In Fig. 10 and 11 An embodiment of the steering gear 13 with a spatially adjustable swash plate 14 is shown, in which the swash plate 14 is cardanically mounted on a main shaft 38 running coaxially to the shaft 2 in order to displace it relative to the longitudinal axis B of the shaft 2. The steering wires 12 are mounted or fastened to the swash plate 14 in such a way that when the swash plate 14 is displaced via the steering wires 12, the tool tip 6 is pivoted.

[0048] The number of steering wires 12 to be used for the motorized steering gear 13 is ten, although the steering gear 13 according to the invention is not limited to this number. The steering wires 12 of the swashplate 14, which run distally parallel to the longitudinal axis B of the shaft 2, exit the shaft 2 via a guide element 44 and are fed to the swashplate 14, increasing the diameter of the steering wire bundle. To secure the steering wires 12 to the swashplate 14, through-holes 50 are formed in the swashplate 14 for each steering wire 12, which are fixed by means of set screws 41 inserted radially into the swashplate 14. A radial arrangement of the set screws 41 necessitates mounting the steering wires 12 to the swashplate 14 before the swashplate 14 is arranged in the steering ring 19.Therefore, the grub screws can be arranged slightly inclined or shifted from the radial direction as shown, so that they remain accessible despite the swashplate being arranged in the steering ring.

[0049] Alternative methods of fastening the steering wires to the swashplate are conceivable; for example, the steering wires can be connected to the swashplate via a clamping disc arranged proximally behind the swashplate, or simply inseparably by welding or gluing; not shown figuratively.

[0050] In Fig. 2 are the central components of the steering gear 13, which also form the basis for the further components, especially those in Fig. 3 to 8shown embodiments are shown in simplified form: The housing 20 has a base 20a and two opposite lateral housing parts 20b and enables the mounting of the bracket 15, which is rotatably mounted via bearing pins 18, 18' in corresponding bearings or through holes 18a, as in Fig. 4 visible. Thus, the bracket 15 is pivotable about a pivot axis A, which runs perpendicular to the longitudinal axis B. Between the lateral housing parts 20b, the swash plate 14 is arranged, which is surrounded by a steering ring 19 along its circumference. The swash plate 14 is preferably rotatably mounted in the steering ring 19, for example as shown in Fig. 11 as can be seen, by means of a rolling or ball bearing, so that the swashplate 14 can be rotated with the main shaft 38, while the steering ring 19 does not rotate around the longitudinal axis B.

[0051] The steering ring 19 is spanned by the bracket 15 and is held in a through-opening 22 of the bracket 15 by means of a bearing ring 21, rotatable about a rotation axis D running perpendicular to the pivot axis A. For this purpose, the steering ring 19 has an axle stub 33.

[0052] Below the base 20a are Fig. 2 to 6 two motors 17, 17' are arranged, the drive axes C, C' of which are parallel to each other and perpendicular to both the pivot axis A and the longitudinal axis B, without intersecting the longitudinal axis B. Furthermore, the drive axes C, C' in the illustrated representation of the steering gear 13 in the neutral starting position are parallel to the rotational axis D of the steering ring 19, although this can change depending on the displacement of the swash plate 14. In the example of Fig. 7 and 8the drive axes C, C' also run parallel to each other, but also parallel to the longitudinal axis B and perpendicular to the pivot axis A, but without intersecting the pivot axis A. The motors 17, 17' have drive shafts 17a, 17b, which are Fig. 3 to 7 The drive shafts 17a, 17b of the motors 17, 17' protrude through through openings each having two opening sections 30, 31 in the housing base 20a, as shown particularly in Fig. 4 can be seen.

[0053] In Fig. 3 to 7Force transmitters 16a, 16b are arranged on the drive shafts 17a, 17b, which transmit the rotational movement of the drive shafts 17a, 17b to the steering ring 19 for performing a turning / tilting movement. Each force transmitter 16a, 16b is coupled to the steering ring 19, preferably in a lower region of the steering ring 19 shown in the figures, which forms a respective active section W1, W2. In the active section W1, W2, the direct force transmission between the force transmitter 16a, 16b and the steering ring 19 takes place. The outer surface of the steering ring 19, the shape of which corresponds to a spherical layer or spherical disk, forms a spherical zone, wherein the two imaginary parallel sectional planes on a corresponding sphere run equidistant or symmetrically to the diameter plane.The steering ring 19 thus has a partially spherical shape in the active section W1, W2 to coordinate its movements and, when tilted, to maintain contact with the force transmitters 16a, 16b, which initiate the movements. The center of the sphere, on which the spherical zone is based, which represents the outer surface of the steering ring 19, is identical to an intersection point of the rotation axis D of the steering ring 19 and the pivot axis A of the bracket 15. This intersection point defines the gimbal center Z of the gimbal suspension.

[0054] In contrast to the examples shown, the steering ring can also have an outer surface shaped as a spherical cap only in the effective sections W1, W2, the associated spherical segment of which is based on the same spherical center point, which is also the cardanic center Z.

[0055] Below, various embodiments for force transmitters 16a, 16b and effective sections W1, W2 of the steering ring 19 are described, as in the Fig. 3 to 9 shown, wherein the force transmitters 16a, 16b are rotatably mounted drive cones, shown in Fig. 3 to 6 and 10 to 13 , or rotary driven worm shafts, shown in Fig. 7 , or linearly driven drive rods, shown in Figs. 8 and 9 , can be.

[0056] In Fig. 3 and 4The force transmitters 16a, 16b are shown with a functional shape to clarify the basic geometric principle. The force transmitters 16a, 16b are rotationally mounted drive cones with a conical head 23 and a conical shaft 42. In the present case, the term "conical head 23" refers not only to conical heads with a conical or truncated cone shape, but also to heads 23 with a spherical segment or spherical disk shape or a semi-ellipsoidal shape, which offers a good relationship between the surfaces of the conical head 23 and the steering ring 19, wherein the respective contact planes on the surfaces of the conical head 23 and the steering ring 19 at their respective contact point K1, K2 are each perpendicular to the axis E, E' between this contact point K1, K2 and the gimbal center Z. The shape of the conical head 23 can depend on the type of operative connection (frictional, positive) between the steering ring 19 and the conical head 23.A conical head 23 with a spherical segment or spherical disc shape with a small radius compared to the radius of the steering ring 19 may, for example, be preferred for a friction-fit connection, as already mentioned in connection with . Fig. 5 described.

[0057] For example, the embodiment in Fig. 3 The motion transmission and swash plate movement is explained: In the contact points K1, K2 between force transmitter 16a, 16b and steering ring 19, where Fig. 3Only contact point K1 of the first force transmitter 16a with the steering ring 19 is visible. The rotational movement of the force transmitter 16a, 16b, when viewed infinitesimal, is always parallel to the main axis B of the surgical instrument 1 at this point and, with respect to the main axis B, is directed forwards (distal) or backwards (proximal), depending on the direction of rotation. This movement is transmitted to the steering ring 19. Due to its cardanic suspension around the cardanic center Z, this results in a tilting of the steering ring 19 around a tilting axis E, E', which is assigned to the respective drive (motor 17, 17').

[0058] If the first drive shaft 17a is rotated by the first motor 17, and with it the first force transmitter 16a, the rotary movement of the first force transmitter 16a is transmitted to the first active section W1 due to the operative connection between the steering ring 19 and the first force transmitter 16a. Meanwhile, the second force transmitter 16b remains stationary, so that the steering ring 19, which is moved in the active section W1 by the first force transmitter 16a, remains stationary at the contact point K2 of the active section W2 with the second force transmitter 16b. The steering ring 19 is thus tilted about the second tilting axis E', which runs through the contact point K2 in the active section W2 and the gimbal center Z and is at an angle of 45° to both the rotational axis D and the rotational axis A. In this case, when the first force transmitter 16a rotates counterclockwise when viewed from above and the second force transmitter 16b is stationary, tilts in Fig. 3a left upper area of ​​the steering ring 19 rotates backwards around the second tilting axis E', and simultaneously a right lower area of ​​the steering ring 19 rotates forwards around the second tilting axis E'. Conversely, a rotation of the second force transmitter 16b while the first force transmitter 16b is stationary causes the steering ring 19 to tilt about the first tilting axis E, which, analogous to the second tilting axis E', lies at an angle of 45° to both the rotational axis D and the rotational axis A and accordingly passes through the contact point K1 of the first force transmitter 16a and the effective section W1 of the steering ring 19 and through the gimbal center Z, where the two tilting axes E, E' intersect perpendicularly. If both force transmitters 16a, 16b rotate, all rotations or tilts of the steering ring 19 and thus of the swashplate 14 in space can be effected together.

[0059] This principle is also the basis for all other embodiments of power transmitters 16a, 16b shown here.

[0060] Around the cone shaft 42 of each drive cone, adjacent to the cone head 23, is a bearing ring 25 (see figure). Fig. 2 to 6 ), which preferably houses a rolling bearing, for example a roller or ball bearing. The bearing ring 25 ensures a guided rotation of the drive cone and thus a good transmission of the rotational movement to the steering ring 19. In order to hold the respective bearing ring 25, the housing 20 has in its base 20a two through openings for the drive shafts 17a, 17b, each with two opening sections 30, 31, as shown in particular in Fig. 4The opening sections 30, 31 are connected to each other and have different diameters, with the opening sections 31 facing their respective motors 17, 17' having a smaller diameter than the opening sections 30 above them facing the steering ring 19. This forms a shoulder 32 at the junction of the two opening sections 30, 31, with each of the bearing rings 25 resting on the respective shoulder 32, as shown in Fig. 4 shown.

[0061] In Fig. 5 the force transmitters 16a, 16b are as in Fig. 3 and 4A rotaryally mounted drive cone with a conical head 23, which is designed for a friction-fit connection with a friction element. The friction element shown is a toroidal friction band 26, such as a rubber band or rubber ring, circumferentially applied to the conical head 23, so that the operative connection between force transmitters 16a, 16b and steering ring 19 is established by means of frictional force. Alternatively, the friction element can be a friction-enhancing material applied circumferentially to the conical head 23. For this purpose, but also for improved retention of a circumferentially applied friction band 26 by means of positive locking, a groove circumferentially around the conical head 23 can be provided, into which the friction-enhancing material penetrates during application or into which a correspondingly shaped inner circumferential section of the friction band 26 is received.The material used for the friction element preferably provides a frictional force with the steering ring that is higher than the frictional force existing between the material of the conical head 23 and the steering ring 19. Due to the high frictional force between the components of the conical head 23 and the active section W1, W2 of the steering ring 19, the active connection is provided by friction.

[0062] In Fig. 6 The functional connection between force transmitters 16a, 16b and the steering ring 19 is formed by a positive engagement. Again, the first and second force transmitters 16a, 16b are rotatably mounted drive cones with a conical head 23. In this embodiment, a plurality of drive studs 27 are arranged circumferentially on the respective conical head 23, forming a circumferential ring of studs 28. To enable the studs 27 to engage with the steering ring 19, the steering ring 19 has a corresponding feature on its functional section W1 and, accordingly, also on its second functional section, which is located in Fig. 6 not visible, has recesses 29 which mesh with the drive studs 27 of the two stud rings 28. In order to achieve movement transmission, the recesses 29 are designed as concentric rings with a diameter adapted to the size and tooth spacing of the studs 27 and with a corresponding width in the active section W1.

[0063] In Fig. 7 The operative connection between the force transmitters 16a, 16b and the steering ring 19 is also formed by a positive engagement, wherein the first and the second force transmitter 16a, 16b are worm shafts 34. These worm shafts 34 run parallel to the longitudinal axis B, so that the drive axes C, C' of the motors 17, 17' also run parallel to the main axis B. As already in the embodiment in Fig. 6 the case, the steering ring 19 has at its effective section W1 and accordingly also the second effective section, which in Fig. 7not visible, has concentrically arranged recesses 29 that mesh with the worm shaft 34 when the worm shaft 34 rotates. The motion transmission is also direct and corresponds to the motion transmission process already explained for the rotationally driven drive cones.

[0064] Figs. 8 and 9 show an alternative drive type: Instead of a rotary drive element, the first and second force transmitters 16a, 16b are toothed racks 35. These are equipped with a toothed section 36. The steering ring 19 has here, analogously to the previous embodiments, on its effective section W1 and accordingly also on the second effective section, which in Fig. 8Not visible, concentrically arranged recesses 29 are provided, which can mesh with the toothed sections 36 of the two racks 35. The operative connection formed here is designed for a linear drive, the drive element of which (not shown in the figure), which in a steering gear according to the invention corresponds to the drive shaft that defines the drive axis C, C', does not rotate, but is moved back and forth parallel to the main axis B. The toothed section consists of an elongated recess 36a and machined teeth 36b arranged in this recess, which are linearly and equidistantly spaced from one another.

[0065] In Fig. 10 and 11An alternative cardanic bearing of the steering ring 19 is shown: The steering ring 19 comprises the swash plate 14, which is arranged on a universal joint disc 37, which is mounted on the main shaft 38. The swash plate 14 is pivotally mounted on a universal joint disc 37 via two bearing pins 40 offset by 180° to each other, ie coaxially and diametrically arranged, which in turn is pivotally mounted on the main shaft 38 via two bearing pins 39 offset by 180° to each other, ie coaxially and diametrically arranged. For reasons of better clarity, Fig. 11Only one bearing pin 39 and one bearing pin 40 are shown in each case. The bearing pins 40 of the swash plate 14 and the bearing pins 39 of the universal joint disc 37 are arranged offset by 90° to one another, with the pin axes defining the cardanic center Z. This bearing enables the swash plate 14 to be pivoted about two axes at right angles to one another relative to the longitudinal axis B of the shaft 2, whereby the tool tip 6 (cf. Fig. 1 ) can be pivoted in all spatial directions relative to the longitudinal axis B of the shaft 2. A bracket, as shown in the Fig. 2 to 8was intended, is not necessary with this inner cardanic bearing of the swash plate 14. In order that the steering ring 19 can also rotate with this inner cardanic bearing exclusively about the transverse and vertical axes including overlays and to fix its position in space and prevent rotation about the main axis B, the steering ring 19 is here coupled to the housing 20 in a rotationally fixed manner with respect to the longitudinal axis B by a pin (not visible) extending radially outwards from the underside of the steering ring 19 in a groove 24 of the housing 20 (see Fig. 11 ) which extends parallel to the longitudinal axis B along the radius of movement of the pin.

[0066] The main shaft 38 is surrounded at its distal end 3, which corresponds to the proximal end 3 of the shaft 2, by a protective cap 45. This cap protects the entry of the shaft 2, and thus the main shaft 38, into the housing 20. The protective cap 45 is screwed into a housing opening with a corresponding thread 48 via an external thread 47. Distally, the protective cap 45 also encloses a ball bearing 49 in which the main shaft 38 is rotatably mounted. Adjacent to this ball bearing 49, the guide element 44 is arranged around the main shaft 38 to allow the steering wires 12 to exit the shaft 2 and feed to the swashplate 14, thereby widening the diameter of the steering wire bundle accordingly.

[0067] On the proximal side behind the guide element 44, the steering wires 12, which extend continuously widening toward the longitudinal axis B of the shaft 2, are fed to the swash plate 14. To secure the steering wires 12 to the swash plate 14, through-holes 50 are formed in the swash plate 14 for each steering wire 12. In the example shown, the steering wires 12 are non-positively connected and fixed to the swash plate 14 within the through-holes 50 via grub screws 41.

[0068] The main shaft 38 is rotatably mounted at its proximal end 46 in a further housing part 51 in a through-opening 52, for example by means of a plain bearing or a roller bearing. Further proximal to the housing part 51, the actuating unit 4 can have a drive (not shown) for moving the actuating element 8.

[0069] The steering ring 19, which is arranged in the steering gear 13 Fig. 10 and 11is used, does not require a separate suspension by a bracket, since the cardanic suspension and bearing is carried out on the main shaft 38. In order for the swash plate 14 to rotate with the main shaft 38 about the longitudinal axis B, the swash plate 14 is rotatably mounted in the steering ring 19 by a rolling bearing. Fig. 11 A ball is shown as the rolling element 54, and the rolling bearing is preferably designed as a full-complement bearing. In the example shown, the bearing raceways are not formed in separate bearing shells, but directly on the outer surface of the swashplate 14 and on the inner surface of the steering ring 19. Therefore, the steering ring 19 has a filling port 53 for filling the rolling element balls 54. Eliminating bearing shells allows for a more compact design of the swashplate-steering ring combination. After the rolling bearing has been filled, the filling port 53 is closed, for example, with a screw as a plug.

[0070] The steering ring 19 is moved by a rotationally driven drive cone as a force transmitter 16a, the cone head 23 of which, as also particularly in Fig. 11 and 12 shown, protrudes through the through-opening in the housing base 20a and is guided and supported in its rotation by the bearing ring 25. The conical head 23 here has a stud ring 28, which carries semi-ellipsoidal studs 27. In Fig. 11 and 12 the conical head 23, which rests on the conical shaft 42, is in engagement with the effective section W1 of the steering ring 19 and meshes with its stud ring 28 the effective section W1 of the steering ring 19. The effective section W1 of the steering ring 19 has arcuate recesses 29, which follow the ellipsoidal shape of the studs 27 of the conical head 23.

[0071] In Fig. 13 a) to e) is the machining of the Fig. 11 and 12 shown conical head 23 is shown step by step. In a first step, Fig. 13 a)from a mushroom-shaped drive cone with a semi-ellipsoidal conical head 23 on the shaft 42. A recess 43 is made in the shell of the conical head 23 and an ellipsoidal nub 27 is left ( Fig. 13 b) ). In two further steps after Fig. 13 c) and d) The nubs 27 are formed into their semi-ellipsoidal shape and faceted. The remaining nubs 27 are then created in the same way. Fig. 13 e) shows the final state when all studs 27 are formed in the semi-ellipsoidal shape and the stud ring 28 is fully formed. Alternatively, and preferably for larger quantities, a drive cone shaped in this way can be manufactured by injection molding.

[0072] A surgical instrument 1 designed as described above is characterized in that many thin steering wires 12 can be used to control the pivotable tool tip 6, and this control is carried out sensitively, precisely and reproducibly due to the motor-driven steering gear 13 for the swash plate 14 on which the steering wires 12 are mounted.

[0073] The drawings, the description, and the claims contain numerous features in combination. Those skilled in the art will expediently consider the features individually and combine them into further useful combinations. The present invention provides a steering gear 13 for a surgical instrument 1, wherein the steering gear 13 can be arranged at the proximal end 3 of a shaft 2, with a longitudinal axis B and an angling mechanism 9 at the distal end 5. The steering gear 13 has two motorized drives and, via the setting angles of the two drives, spatially aligns a swash plate 14 in order to control the angling mechanism 9 of the surgical instrument 1. The swash plate 14 is arranged in a steering ring 19, wherein the two motorized drives each have a drive shaft 17a, 17b driven by a motor 17, 17', which is directly operatively connected to the steering ring 19 via a respective force transmitter 16a, 16b.The first force transmitter 16a contacts the steering ring 19 at a first working section W1, and the second force transmitter 16b contacts the steering ring 19 at a second working section W2, wherein the steering ring 19 is gimbal-mounted about a gimbal center Z and is spherically segmented at least at the first and second working sections W1, W2, the working sections W1, W2 having a common spherical center at which a first tilting axis E, defined by a contact point K1 of the first force transmitter 16a with the steering ring 19 and the gimbal center Z, and a second tilting axis E', defined by a contact point K2 of the second force transmitter 16b with the steering ring 19 and the gimbal center Z, intersect at right angles. Furthermore, a surgical instrument 1 is disclosed which has such a steering mechanism 13. LIST OF REFERENCE SYMBOLS

[0074] 1Surgical instrument 2Shaft 3Proximal end (shaft) 4Actuating unit 5Distal end (shaft) 6Tool tip 7Tool 8Actuating element 9Joint mechanism 11Pivoting link 12Steering wire 13Steering gear 14Swash plate (spatially adjustable) 15Brace 16a, 16bPower transmitter 17, 17'Motor 17a, 17bDrive shaft 18,18'Bearing pins 18aThrough hole 19Steering ring 20Housing 20aBase 20bSide housing parts 21Ball bearing for steering ring 22Receiving opening 23Drive cone head 24Guide groove 25Bearing ring 26Friction band 27Nubs 28Nub ring 29Recesses 30First section through opening 31Second section through opening 32Shoulder 33Shaft stub 34Worm shaft 35Tooth rack 36Tooth section 36aRecess 36bTeeth 37Universal joint disc 38Main shaft 39Bearing pin 40Bearing pin 41Set screw 42Tapered shaft 43Recess 44Guide element 45Protective cap 46Proximal end of main shaft 38 47External thread 48Thread in housing opening 49Ball bearing 50Through openings swash plate 14 51Housing part 52Through opening 53Filling nozzle 54Rolling elements, A Swivel axis fastening device bracket 15 BLongitudinal axis of the instrument or shaft C, CDrive axis of the first drive 17', of the second drive DRotation axis of the steering ring E, E'First, second tilt axis of the steering ring K1, K2Contact point of the first, second force transmitter steering ring W1, W2First, second effective section ZCardanic center

Claims

1. A steering gear (13) for a surgical instrument (1), wherein the steering gear (13) has a swash plate (14), wherein the steering gear (13) can be arranged at the proximal end (3) of a shaft (2) which defines a longitudinal axis (B) and has a bending mechanism (9) at the distal end (5), wherein the steering gear (13) has two motorised drives and is designed to spatially align the swash plate (14) via the adjustment angles of the two drives, which swash plate is designed to control the distal bending mechanism (9) of the surgical instrument (1), wherein the swash plate (14) is arranged in a steering ring (19), characterised in that the first of the two motorised drives has a first drive shaft (17a) which is driven by a first motor (17) and is directly operatively connected to the steering ring (19) via a first force transmitter (16a), by the first force transmitter (16a) directly contacting the steering ring (19) at a first operative section (W1), wherein the first force transmitter (16) is arranged on the first drive shaft (17a), which defines a first drive axis (C), and the second of the two motorised drives has a second drive shaft (17b) which is driven by a second motor (17') and is directly operatively connected to the steering ring (19) via a second force transmitter (16b), by the second force transmitter (16b) directly contacting the steering ring (19) at a second operative section (W2), wherein the second force transmitter (16b) is arranged on the second drive shaft (17b), which defines a second drive axis (C'), wherein the steering ring (19) is cardanically mounted about a cardanic centre (Z) and is formed in the shape of a spherical segment at least on the first and the second operative section (W1, W2), wherein the spherical segmentshaped operative sections (W1, W2) have a common spherical centre point which corresponds to the cardanic centre (Z), in which a first tilt axis (E), which is defined by a contact point (K1) of the first force transmitter (16a) with the steering ring (19) and the cardanic centre (Z), and a second tilt axis (E'), which is defined by a contact point (K2) of the second force transmitter (16b) with the steering ring (19) and the cardanic centre (Z), intersect at right angles.

2. The steering gear (13) according to claim 1, characterised in that the cardanic mounting of the steering ring (19) is provided by a) the steering ring (19) being cardanically suspended on a first fastening device, wherein the first fastening device is a bracket (15) which - is arranged on a section of the steering ring (19) which faces away from the operative sections (W1, W2), and - at both ends is mounted on a housing (20) so as to be rotatable about a pivot axis (A) which runs perpendicular to the longitudinal axis (B) and perpendicular to the drive axes (C, C'), and - has a receiving opening (22) in the centre, wherein the steering ring (19) is mounted in the receiving opening (22) so as to be rotatable about an axis of rotation (D) which runs perpendicular to the pivot axis (A); or by b) the steering ring (19) being cardanically mounted on a main shaft (38) running coaxially to the longitudinal axis (B) of the shaft (2) via the swash plate (14), which is mounted in the steering ring (30) so as to be rotatable about the longitudinal axis (B) or is fixedly connected to the steering ring (19), wherein the swash plate (14) is pivotably mounted on a universal joint disc (37) via two bearing pins (39) arranged offset by 180° relative to one another, and the universal joint disc (28) is pivotably mounted on the main shaft (38) via two bearing pins (40) arranged offset by 180° relative to one another, and wherein the bearing pins (39, 40) of the swash plate (14) and the universal joint disc (37) are arranged offset by 90° relative to one another.

3. The steering gear (13) according to claim 1 or 2, characterised in that the operative connection provides a form-fitting engagement by - the first and second force transmitters (16a, 16b) being rotatably mounted drive cones with a cone head (23) which has circumferentially a plurality of drive knobs (27) forming a knob ring (28), and wherein the steering ring (19) has, on each operative section (W1, W2), recesses (29) which mesh with the drive knobs (27) of the two knob rings (28), or - the first and second force transmitters (16a, 16b) are worm shafts (34) which run parallel to the longitudinal axis (B), and wherein the steering ring (19) has, on each operative section (W1, W2), concentrically arranged recesses (29) which mesh with the worm shaft (34).

4. The steering gear (13) according to claim 3, characterised in that the drive knobs (27) have a hemispherical or semi-ellipsoidal shape, and / or the recesses (29) are rings arranged concentrically one inside another or are arc-shaped grooves.

5. The steering gear (13) according to claim 1 or 2, characterised in that the operative connection is provided by friction by - the first and second force transmitters (16a, 16b) being rotatably mounted drive cones with a cone head (23) which has circumferentially a friction element, preferably a material which is applied around the cone head (23) and which provides a higher friction than the material of which the cone head (23) consists, or a friction band (26) which is applied circumferentially around the cone head (23) and which is a rubber band or a band with a roughened surface or a band with a toothing or knobs.

6. The steering gear (13) according to claim 1 or 2, characterised in that the operative connection of the first force transmitter (16a) with the steering ring (19) provides a form-fitting engagement and the operative connection of the second force transmitter (16b) with the steering ring (19) is provided by frictional engagement, wherein the form-fitting engagement of the first force transmitter (16a) with the steering ring (19) is provided by the first force transmitter (16a) - being a rotatably mounted drive cone with a cone head (23) which has circumferentially a plurality of drive knobs (27) forming a knob ring (28), wherein the steering ring (19) has, on the first operative section (W1), recesses (29) which mesh with the drive knobs (27) of the two knob rings (28), or - being a worm shaft (34) which runs parallel to the longitudinal axis (B), and wherein the steering ring (19) has, on the first operative section (W1), concentrically arranged recesses (29) which mesh with the worm shaft (34), and wherein the frictional engagement of the second force transmitter (16b) with the steering ring (19) is provided by the second force transmitter (16b) being a rotatably mounted drive cone with a cone head (23), which has circumferentially a friction element which preferably - is a material which is applied around the cone head (23) and which provides a higher friction than the material of which the cone head (23) consists, or - is a friction band (26) which is applied circumferentially around the cone head (23) and which is a rubber band or a band with a roughened surface or a band with a toothing or knobs.

7. The steering gear (13) according to at least one of claims 3 to 6, characterised in that the rotatably mounted drive cones each have a cone shaft (42) around which a bearing ring (25) is arranged adjacent to the cone head (23), and in that the housing (20) has a base (20a) with a respective through-opening for each drive axle (17a, 17b), wherein each through-opening has a first opening section (30) with a diameter which corresponds to a diameter of the bearing ring (25), and a second opening section (31) which is coaxial with the first opening section (30) and has a diameter which is smaller than the diameter of the first opening section (30) such that the housing (20) forms, in each through-opening, a shoulder (32), on which the respective bearing ring (25) rests.

8. The steering gear (13) according to claim 1 or 2, characterised in that the operative connection - forms a linear drive, by the first and second force transmitters (16a, 16b) being toothed racks (35) with a toothing section (36) and wherein the steering ring (19) has, on its operative section (W), concentrically arranged recesses (29) which mesh with the toothing sections (36) of the two toothed racks (35), or - has a materially-bonded operative connection, wherein a first traction means is fastened at both ends to the first operative section (W1) and the first force transmitter (16a) is wrapped around by the first traction means, and a second traction means is fastened at both ends to the second operative section (W2) and the second force transmitter (16b) is wrapped around by the second traction means.

9. A surgical instrument (1) having a shaft (2), an actuation unit (4) arranged at the proximal end (3) of the shaft (2) and a tool (7) arranged at the distal end (5) of the shaft (2) with a tool tip (6) which can be angled by means of a distal bending mechanism (9) and which can be controlled by a swash plate (14) which can be spatially aligned by means of two drives, characterised in that the surgical instrument (1) has a steering gear (13) according to at least one of claims 1 to 8 for the spatial orientation of the swash plate (14).

10. The surgical instrument (1) according to claim 9, characterised in that an actuating element (8) is mounted so as to be axially displaceable in the shaft (2) and is operatively connected to the actuation unit (4) on the proximal side, and / or the distal bending mechanism (9) of the bendable tool tip (6) consists of swivel members (11) which are arranged at the distal end (5) of the shaft (2) and which are connected to the steering gear (13) via steering wires (12) which run in the longitudinal direction of the shaft (2) and which are fastened to the swash plate (14).