Self-Securing Coupling Sleeve for Load-Locking Instrument Joints
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Solution Overview
Problem
Conventional coupling devices for medical holding systems are difficult to release quickly and safely, especially under load, and lack the ability to rotate freely, which is crucial for precise positioning of medical instruments during minimally invasive surgery, and they often require additional securing elements that can be cumbersome to use.
Innovation Solution
A self-securing coupling device with a bolt and bushing system where the cone angles α and β are designed to create a wedge effect that locks the clamping bodies into place under tension, preventing accidental release, and includes a switching mechanism to ensure complete locking and allow for rotational freedom when needed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional securing elements like cotters or screw connections are used to secure the coupling connection, then the reliability of the coupling under load is improved, but the ease of operation deteriorates because the user must fit and remove additional elements, requiring both hands or tools for release
Solution Approach 1:
The securing function is merged into the coupling mechanism itself. The clamping bodies are integrated into the coupling bolt and bushing assembly, eliminating the need for separate securing elements like cotters or screw connections. The spring-loaded clamping bodies automatically engage with the coupling groove to provide securing under load while maintaining ease of operation through single-handed release.
Solution Approach 2:
The coupling device secures itself automatically through the spring-loaded clamping bodies that engage with the coupling groove when the coupling bolt is inserted. The mechanism self-secures under load without requiring additional elements, and the release is facilitated by the same integrated mechanism through the actuation element that moves the cage sleeve axially.
2Ease of operation
If the coupling device is designed to be easily releasable without additional securing elements, then the ease of operation is improved, but the reliability deteriorates because the coupling may come loose under withdrawal forces amounting to several kilo newtons
Solution Approach 1:
The coupling groove is designed with a curved profile that works together with the shaped clamping bodies. The geometry of the coupling groove and clamping bodies creates a self-securing mechanism where the curved surfaces guide the clamping bodies into the locked position under load while allowing easy release when the actuation element is engaged.
Solution Approach 2:
The spring force parameter is optimized to provide sufficient clamping pressure for reliable securing under several kilo newtons of withdrawal force, while the geometric parameters of the coupling groove and clamping bodies are designed to allow easy release. The spring-loaded mechanism changes the force parameters dynamically, providing high securing force under load and low release force when actuated.
3Adaptability or versatility
If the coupling device allows free rotation for positioning, then the adaptability is improved, but the reliability deteriorates because rotatability may prevent proper locking and torque absorption under load
Solution Approach 1:
The coupling device transitions from a rotatable state during positioning to a locked state under load. The clamping bodies are designed to engage with the coupling groove and prevent rotation when load is applied, while allowing free rotation during the positioning phase. This dynamic behavior provides both adaptability during setup and reliability during operation.
Solution Approach 2:
The coupling bolt and bushing are designed to allow preliminary rotation for positioning before the clamping bodies engage with the coupling groove under load. The geometry of the coupling groove and clamping bodies is arranged so that rotation is permitted during insertion and positioning, but automatic locking occurs when the operational load is applied.
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 coupling device ensures secure and reliable connection and disconnection of medical instruments under load without additional securing elements, allowing for precise positioning and safe operation, while also enabling rotational freedom for optimal instrument placement.
Implementation Method 1
a cage sleeve (329), which can be moved axially by means of a spring element (326) and which guides clamping bodies (324)
Implementation Method 2
the angle α of the front inclined coupling groove flank (304) is greater than the angle β of the cone inner face (322) such that clamping bodies (324) partially or completely latched into the coupling groove (303) can be pressed into the locking position (c) counter to the insertion direction by application of a tensile force (Fz)
Data Source
AI summary
A coupling device and coupling method for the self-securing mechanical connection of two parts of a holding system for medical instruments, including a bolt element insertable into a bushing; wherein the bushing has a main body and, connected fixedly to the latter, a cone sleeve which tapers conically at its free end, wherein a cage sleeve acted upon by a spring and guiding clamping bodies is inserted axially movably into the cone sleeve and can be moved between an uncoupled position, a release position and a locking position. The clamping bodies in the locking position can be latched into a coupling groove of the bolt element by means of the spring force. The inclined coupling groove flank, at the front in the insertion direction, of the bolt element encloses an angle α with the longitudinal axis of the bolt element, and the cone inner face of the cone sleeve encloses an angle β with the central sleeve axis. The coupling device is characterized in that, for self-securing connection, the angle α is greater than the angle β such that clamping bodies partially or completely latched into the coupling groove can be pressed into the locking position counter to the insertion direction by application of a tensile force to the bolt element.