Elastically Driven Vacuum Mixer for PMMA Bone Cement
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current vacuum mixing systems for PMMA bone cements suffer from reproducibility issues due to user-dependent energy input, leading to inconsistent cement properties and potential bond deterioration between bones and prostheses, and require manual operation which is cumbersome and prone to errors.
Innovation Solution
A closed vacuum mixing system with an integrated mixing device that uses an elastically deformable energy storage element to drive a mixing element with a cam-driven periodic axial movement, eliminating the need for external energy sources and ensuring consistent mixing without manual intervention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual mixing is used, then ease of operation is improved, but mixing precision and reproducibility deteriorate due to variable user energy input
Solution Approach 1:
The mixing device is designed to be self-operating through elastic energy storage elements that automatically drive the mixing elements without requiring external power sources or complex control systems. The system loads elastic energy during assembly and releases it during mixing, making the device self-sufficient and eliminating dependence on external energy infrastructure in operating theaters.
Solution Approach 2:
The mixing process employs periodic axial movement of mixing elements through cam mechanisms that convert rotational motion into reciprocating motion. This periodic action ensures thorough mixing by repeatedly moving material through different zones of the mixing chamber, improving homogeneity and reproducibility compared to continuous manual stirring.
2Power
If external energy sources are used, then mixing power is improved, but device complexity increases due to requirements for electrical drives and motors
Solution Approach 1:
Elastic energy is stored in advance during the assembly or preparation phase by deforming elastic energy storage elements (springs). This pre-stored energy is then released during the mixing operation, providing the necessary power without requiring external energy sources during the actual mixing process. This approach separates the energy storage phase from the energy consumption phase.
Solution Approach 2:
The patent replaces electrical drives and motors with a purely mechanical energy storage and transmission system based on elastic elements. This substitution eliminates the need for complex electrical components, control electronics, and power supply infrastructure, significantly reducing device complexity while maintaining adequate mixing power for bone cement application.
3Manufacturing precision
If vacuum mixing is used, then cement quality is improved by reducing porosity, but device complexity increases due to vacuum system requirements
Solution Approach 1:
The mixing chamber is designed as a sealed, vacuum-tight environment that can be evacuated to remove air and other gases before and during mixing. This creates an inert atmosphere that prevents air entrapment in the cement dough, eliminating porosity and improving cement quality. The sealed design also allows the elastic energy storage elements to operate without contamination from the external environment.
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 system provides reproducible mixing of PMMA bone cement components, reducing porosity and improving mechanical properties, simplifying the application process, and ensuring consistent product quality without the need for electrical drives or motors, making it suitable for use in operating theaters.
Implementation Method 1
at least one elastically deformable energy storage element which is connected to the transmission so that the transmission can be driven with elastic energy from the energy storage element
Implementation Method 2
The movement of the at least one mixing element is influenced by a cam during the rotary movement in such a way that the at least one mixing element also performs a periodic axial stroke movement during the rotary movement
Implementation Method 3
the mixing of bone cement powder with the monomer liquid in vacuum mixing systems is preferred because air inclusions are largely removed from the cement dough by mixing in a vacuum
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a mixing device for polymethyl methacrylate bone cements (PMMA bone cements) comprising a mixing chamber (2) for mixing the PMMA bone cement, at least one mixing element (4) rotatably mounted in the mixing chamber (2), a gearbox for driving the rotation of the at least one mixing element (4), and at least one elastically deformable energy storage element (16) connected to the gearbox such that elastic energy from the energy storage element (16) drives the gearbox and, upon release of elastic energy from the energy storage element (16), the at least one mixing element (4) is rotatable in the mixing chamber (2) via the gearbox. The invention further relates to a vacuum mixing system with such a mixing device and a method for mixing a cement, in particular a PMMA bone cement.