Surgical Instrument Steering Gear for Direct Swashplate Control

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Solution Overview

Problem

Existing surgical instruments with swashplate steering mechanisms suffer from indirect force transmission, play, and limited rotational capabilities, requiring more space due to coaxial drive arrangements.

Innovation Solution

A steering gear with at least two drives for spatial alignment of a swashplate, featuring linear slides and lever elements that allow direct pivoting and rotation of the swashplate relative to a main shaft, enabling precise control and rotation of the tool tip.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If ball-joint rods with swivel joints and gear quadrants are used to align the swashplate, then the swashplate can be positioned, but the control is indirect and subject to play with unfavorable force flow

Engineering Contradiction:
Improvecontrol precisionVSAvoidmechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent removes the intermediate swivel joints and gear quadrants from the force transmission path. Instead of using ball-joint rods with complex swivel joints, the invention directly connects the linearly movable elements to the swashplate via engagement elements, eliminating the problematic intermediate mechanisms that caused play and indirect control.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent introduces direct engagement elements (such as slots or cam profiles) as the intermediary between the linearly movable elements and the swashplate. This direct engagement mechanism eliminates the need for multiple intermediate joints while maintaining the ability to transmit force efficiently and precisely control the swashplate position.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If a differential gear with two opposing drive bevel gears is used, then direct positioning of the swashplate is achieved, but more space is required due to the coaxial arrangement

Engineering Contradiction:
Improvecontrol directnessVSAvoidspace requirement
Core Design Contradiction:
ReliabilityVSVolume of moving object

Solution Approach 1:

The patent transitions from a coaxial arrangement (differential gear with bevel gears arranged along the same axis) to a parallel arrangement where linearly movable elements move parallel to the main shaft axis. This dimensional change allows the drives to be positioned side-by-side rather than stacked coaxially, reducing the overall volume required for the steering gear mechanism.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Solution Approach 2:

The patent replaces the complex differential gear mechanism with a simpler system of linearly movable elements connected directly to the swashplate. This substitution eliminates the need for bevel gears and differential mechanisms while achieving the same direct positioning function with reduced space requirements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If the swashplate is cardanically mounted on a rotatable main shaft, then rotation around the shaft axis is enabled, but the coaxial drive arrangement requires more space

Engineering Contradiction:
Improverotational capabilityVSAvoidspace requirement
Core Design Contradiction:
Adaptability or versatilityVSVolume of moving object

Solution Approach 1:

The patent maintains the universal joint mechanism for enabling rotation around the shaft axis while simultaneously arranging the drives in a space-efficient parallel configuration. The linearly movable elements are positioned to work in conjunction with the universal joint, allowing the swashplate to both pivot for spatial alignment and rotate with the main shaft without requiring additional coaxial space.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution provides direct and sensitive control of the tool tip, allowing rotation with the main shaft while minimizing space requirements and eliminating unwanted play, enhancing the operational efficiency of surgical instruments.

Implementation Method 1

The lever element (12) has a head section (12a, 12b) at a free end of a rod section (12c) for movably receiving in the engagement opening (11, 11a, 11b, 11c)

Methodology Applied
Scientific EffectLever mechanism: Lever

Implementation Method 2

the swash plate is gimbal-mounted around a center located on the main axis A

Methodology Applied
Scientific EffectGimbal mounting: Gimbal

Data Source

PatentEP4389023B1Steering gear for surgical instrument and surgical instrument equipped with the same
Publication Date: 2025.10.15 KARL STORZ SE & CO KG
  • EP4389023B1 patent drawingFigure 1
  • EP4389023B1 patent drawingFigure 2
  • EP4389023B1 patent drawingFigure 3

AI summary

The present invention provides a steering gear (10) for a surgical instrument (1) and the surgical instrument (1) itself, wherein the steering gear (10) has at least two drives (16) for spatially aligning a swashplate (8). The swashplate (8) is rotationally coupled to a main shaft (19) that is rotatable about a main axis (A) and is gimbal-mounted about a center (Z) located on the main axis (A). The steering gear (10) has at least two linear slides (9), each of which is slidably arranged along a guide axis (Bx) parallel to the main axis (A) and is connected to the at least two drives (16).Each linear slider (9) is operatively connected to the swashplate (8) via a pair of engagement elements, which as engagement elements comprise an engagement opening (11, 11a, 11b, 11c) and a lever element (12), which has at a free end of a rod section (12c) a head section (12a, 12b) for movable reception in the engagement opening (11, 11a, 11b), wherein a pivot plane of the swashplate (8) is defined by the head sections (12a, 12b) of the lever elements (12) and the center (Z) of the swashplate (8). In this arrangement, one of the engagement elements of the engagement element pair is located on a circumference of the swashplate (8) and the other engagement element of the engagement element pair is located on a surface section (9a) of the respective linear slide (9) facing the swashplate (8), which is a surface section (9a) on a longitudinal side of the linear slide (9) parallel to the guide axis (Bx).