Hydraulic Actuator Transmission with Bellows-Sealed Piston Chambers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional hydraulic translation units face challenges with fluid leakage and contamination, low rigidity, and high energy losses, particularly in piston systems, while bellows systems suffer from reduced fluid rigidity and mechanical losses.
Innovation Solution
A hydraulic translation unit with a design featuring a first and second chamber, where each chamber is separated by a piston into a working and back chamber, with the back chamber partially limited by a ball with variable axial length, ensuring tightness and compensating for volume changes to maintain constant volume and reduce leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a piston system is used for hydraulic transmission, then a desired transmission ratio can be achieved through area ratio of pistons, but sealing the working volume is difficult and hydraulic fluid can leak through the gap between piston and cylinder wall
Solution Approach 1:
The piston is divided into two distinct parts: a first piston part that divides the first chamber into working and rear chambers, and a second piston part that acts as a sealing element. This segmentation allows the sealing function to be separated from the area-ratio transmission function, enabling effective sealing while maintaining the desired transmission ratio through proper design of the piston parts.
2Reliability
If a bellows system is used for hydraulic transmission, then fluid-tight sealing is achieved, but the area between bellows corrugations reduces fluidic stiffness and dynamics
Solution Approach 1:
The sealing function is extracted from the bellows structure and implemented through a dedicated second piston part that provides fluid-tight sealing. This removes the detrimental corrugated structure from the fluid volume, eliminating the reduction in fluidic stiffness and dynamics while maintaining the fluid-tight sealing benefit.
3Strength
If bellows with thick walls are used to withstand high pressure peaks, then structural integrity is maintained, but mechanical losses in the transmission unit increase
Solution Approach 1:
The piston structure employs local quality differentiation: the first piston part is designed with sufficient strength to withstand high pressure peaks, while the second piston part provides sealing. This localized functional assignment allows optimal material distribution, maintaining structural integrity where needed without adding unnecessary mass and mechanical losses throughout the entire transmission unit.
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 achieves high tightness for hydraulic fluid, high dynamic performance, and low energy losses, enhancing the rigidity and dynamics of the translation unit compared to conventional systems.
Implementation Method 1
a first piston (13a) which is arranged to be movable along a piston axis, so that this first piston (13a) divides the first chamber (11a) into a first working chamber (15a) of variable volume and a first rear chamber (17a)
Implementation Method 2
a first bellows element (19a) of variable axial length, wherein said first bellows element (19a) compensates for a change in volume of said first rear chamber (17a)
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a hydraulic transmission unit (5) for an actuator (1), which hydraulic transmission unit can be filled with a hydraulic fluid (7) and has a first and a second chamber (11a, 11b) which are hydraulically interconnected and of which one is designed as a drive chamber (11a) and the other one is designed as an output chamber (11b). At least in the first chamber (11a), a piston (13a) is arranged movably along a piston axis (A), such that this piston (13a) subdivides the first chamber (11a) into a variable-volume working chamber (15a) and a rear-side chamber (17a), the rear-side chamber (17a) being delimited at least partially by a bellows element (19a) having a variable axial length. The invention further relates to an actuator (1) having such a hydraulic transmission unit (5).