Coaxial CPR Compression Assembly for Compact Direct Drive

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Solution Overview

Problem

Existing cardiopulmonary resuscitation devices are bulky, require significant space, and suffer from low transmission efficiency and poor heat dissipation due to the use of motors with intermediate elements like synchronous pulleys, which complicates handling and operation.

Innovation Solution

A cardiopulmonary resuscitation device design featuring a coaxial arrangement of a motor assembly, screw rod, and push-rod assembly, with a direct drive mechanism using a screw nut and guide sleeve, eliminating intermediate transmission elements to enhance compactness and efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a motor is arranged on a lateral side of a push-rod assembly and driven by a synchronous pulley assembly, then the device can perform chest compression operations, but the device becomes large in volume, heavy, and difficult to handle

Engineering Contradiction:
Improvehandling and carryingVSAvoiddevice volume
Core Design Contradiction:
Ease of operationVSVolume of moving object

Solution Approach 1:

The motor assembly and push-rod assembly are merged into a coaxial integrated structure, where the motor's rotational output directly drives the screw rod along the same axis. This eliminates the need for lateral arrangement and synchronous pulley assemblies, significantly reducing device volume and improving portability while maintaining compression functionality

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The synchronous pulley assembly and intermediate transmission elements are extracted and removed from the system. The motor is repositioned to eliminate the lateral offset, and only the essential screw rod and screw nut transmission mechanism are retained, simplifying the overall structure

Inventive Principle:
Principle #2Taking out (Extraction)

2Productivity

If a synchronous pulley assembly is used to transmit motor power, then the device can operate, but transmission efficiency becomes low

Engineering Contradiction:
Improvetransmission efficiencyVSAvoidenergy loss in transmission
Core Design Contradiction:
ProductivityVSLoss of energy

Solution Approach 1:

The synchronous pulley assembly and all intermediate transmission elements are removed from the power transmission path. The motor's rotational output is directly coupled to the screw rod through a coaxial connection, eliminating energy losses associated with belt slippage, pulley friction, and multiple transmission stages

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The complex mechanical transmission system involving pulleys and belts is replaced with a direct mechanical coupling between the motor shaft and screw rod. This substitution eliminates intermediate conversion steps and maintains higher mechanical efficiency throughout the power transmission process

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

3Temperature

If a motor with synchronous pulley is used, then the device can function, but heat dissipation performance becomes poor due to motor heating

Engineering Contradiction:
Improveheat dissipation performanceVSAvoidmotor heating
Core Design Contradiction:
TemperatureVSObject-generated harmful factors

Solution Approach 1:

The motor assembly is merged with the push-rod assembly in a coaxial configuration, creating integrated heat dissipation pathways. The compact integrated structure allows for better thermal coupling between components and improved heat transfer to surrounding environments, reducing motor heating issues

Inventive Principle:
Principle #5Merging (Combining)

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 design achieves miniaturization, improved transmission efficiency, and better heat dissipation, facilitating easier handling and operation in various environments.

Implementation Method 1

the screw rod is configured to drive the screw nut to move linearly along an axial direction while rotating

Methodology Applied
Scientific EffectScrew mechanism: Screw

Implementation Method 2

a first bearing, which is configured to simultaneously support a rotation of the rotor and a linear movement of the push-rod assembly

Methodology Applied
Scientific EffectBearing: Ball Bearing

Data Source

PatentEP4686464A1Cardiopulmonary resuscitation device
Publication Date: 2026.02.04 SHENZHEN MINDRAY BIO MEDICAL ELECTRONICS CO LTD
  • EP4686464A1 patent drawingFigure 1~2
  • EP4686464A1 patent drawingFigure 3
  • EP4686464A1 patent drawingFigure 4

AI summary

An embodiment provides a cardiopulmonary resuscitation device, including a motor assembly, a screw rod, a screw nut, a push-rod assembly, a first bearing, a guide sleeve, and a connection structure. The push-rod assembly includes a push-rod body and a compression structure The push-rod assembly has an initial retraction position, at which position, orthographic projections of the screw nut and the stator on a plane, which plane is parallel to an axial direction, at least partially overlaps with each other, and orthographic projections of the first bearing and the guide sleeve on a plane, which plane is parallel to the axial direction, at least partially overlaps with each other. Tis disclosure enables the cardiopulmonary resuscitation device to have a reduced dimension in the axial direction perpendicular to the screw rod, and a reduced dimension in the axial direction, which is conducive to an overall miniaturization of the cardiopulmonary resuscitation device.