Movable Shaft Support for Atherectomy Torque Loss Reduction

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Solution Overview

Problem

Existing atherectomy devices experience rotational torque loss due to friction between the drive shaft and shaft support, which can occur when the rotation axis swings during use, particularly in cases of hardened or bifurcated stenosed sites in blood vessels.

Innovation Solution

The medical device incorporates an elastic body between the outer peripheral surface of the shaft support and the inner peripheral surface of the accommodation portion, allowing the shaft support to move within the accommodation portion, reducing friction and torque loss by accommodating shifts in the central axis of the drive shaft.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the shaft support is press-fitted into the housing portion to ensure liquid-tightness, then liquid-tightness is improved, but friction between the drive shaft and shaft support increases causing rotational torque loss

Engineering Contradiction:

Improveliquid-tightnessVSAvoidrotational torque loss

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

A bearing is introduced as an intermediary component between the drive shaft and the shaft support. The bearing allows the drive shaft to rotate smoothly while supporting it, reducing friction and preventing torque loss. This intermediary element solves the contradiction by enabling both liquid-tightness (through the bearing seal) and low friction rotation.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The direct mechanical contact between the drive shaft and shaft support is replaced with a bearing system. The bearing substitutes the friction-based mechanical connection with a low-friction rolling or sliding contact system, maintaining liquid-tightness while eliminating the harmful friction that caused torque loss.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Stability of the object's composition

If the shaft support is fixed to prevent movement, then structural stability is improved, but friction increases when the rotation axis swings during operation

Engineering Contradiction:

Improvestructural stabilityVSAvoidfriction during rotation axis swing

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The shaft support is designed with movable portions that allow it to dynamically adjust its position. When the rotation axis swings during operation, the shaft support can move accordingly, maintaining proper alignment and reducing friction. This dynamic capability resolves the contradiction by allowing the structure to adapt to operational changes while maintaining stability during normal operation.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The position and orientation parameters of the shaft support are made variable rather than fixed. The shaft support can change its spatial parameters (position, angle) in response to drive shaft movement, ensuring continuous proper alignment during rotation axis swing and preventing friction-induced torque loss.

Inventive Principle:

Principle #35Parameter changes

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

This design effectively reduces friction and torque loss, enabling more efficient cutting and removal of objects in body lumens, including hardened or bifurcated stenosed sites in blood vessels.

Implementation Method 1

an elastic body that is disposed between an outer peripheral surface of the shaft support and an inner peripheral surface of the accommodation portion

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS12484927B2Medical device

Publication Date: 2025.12.02 TERUMO KK

AI summary

A medical device includes: a drive shaft that is rotatable; a drive unit that is connected to a proximal portion of the drive shaft and rotates the drive shaft; a housing that accommodates the proximal portion of the drive shaft; and a handle portion that accommodates the drive unit and the housing, in which the housing includes an accommodation portion that is provided therein, a shaft support that is disposed in the accommodation portion and has a lumen through which the proximal portion of the drive shaft is inserted, and an elastic body that is disposed between an outer peripheral surface of the shaft support and an inner peripheral surface of the accommodation portion, and since an outer diameter of the shaft support is smaller than an inner diameter of the accommodation portion, the shaft support is movable in the accommodation portion.