Axial Piston Cavity Segmentation for Hydraulic Efficiency
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Solution Overview
Problem
Existing axial piston machines face challenges with solid pistons at higher speeds due to strength and thermal issues, while hollow pistons suffer from efficiency losses due to dead spaces and complex manufacturing processes.
Innovation Solution
A piston design featuring a pressure-tightly sealed cavity with multiple chambers, stabilized by webs, allowing for separate or partial connection of chambers, and manufactured using material-removing or forming processes, such as extrusion or DMLS, to enhance stability and reduce production costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If hollow pistons with open cavities are used to reduce mass for higher speeds, then weight is reduced, but dead space is created causing efficiency deterioration
Solution Approach 1:
The cavity is divided into multiple separate chambers instead of forming a single continuous dead space. This segmentation allows the hydraulic fluid to flow through the chambers without creating compression/expansion dead zones, maintaining efficiency while still reducing overall piston mass compared to solid design
Solution Approach 2:
The cavity chambers are arranged in a specific spatial configuration (e.g., radially distributed around the piston axis) rather than along the axial direction. This dimensional arrangement eliminates dead space compression while preserving weight reduction benefits
2Productivity
If the cavity is sealed pressure-tight to eliminate dead space, then hydraulic efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The piston body structure serves multiple functions simultaneously: it provides the structural framework, contains the sealed chambers, and guides the hydraulic flow paths. This multi-functionality reduces the need for additional separate components, simplifying manufacturing while maintaining pressure-tight sealing
Solution Approach 2:
The chambers are nested within the piston body structure in a compact arrangement, with chamber walls formed as integral parts of the piston. This nesting eliminates the need for separate sealing components and simplifies the manufacturing process while ensuring pressure-tight containment
3Ease of manufacture
If material-removing methods are used to create chambers, then manufacturing simplicity is improved, but piston stability deteriorates
Solution Approach 1:
Material is removed selectively from specific regions of the piston to create chambers, while maintaining full material density in critical structural areas. This localized material distribution ensures ease of chamber manufacturing while preserving piston stability in load-bearing regions
Solution Approach 2:
The piston employs a composite structural approach where solid material regions provide structural stability and chamber regions provide weight reduction. The transition between these regions is designed to maintain overall structural integrity while enabling straightforward chamber fabrication
4Productivity
If chambers are arranged to minimize dead space, then hydraulic efficiency is improved, but piston structural stability deteriorates
Solution Approach 1:
Chambers are arranged in a radial or circumferential pattern around the piston axis rather than in axial alignment. This dimensional reconfiguration eliminates dead space for hydraulic efficiency while the radial distribution maintains structural balance and stability
Solution Approach 2:
The piston structure is segmented into multiple discrete chamber units distributed throughout the body. This segmentation allows each chamber to be optimally positioned for hydraulic efficiency while the distributed arrangement maintains overall structural stability through balanced material distribution
Data Source
Figure 1
Figure 2a~2c
Figure 3a~3b
AI summary
The piston has a cavity that closed in a pressure-tight way in the interior of a piston portion (4). The webs are left between several chambers into which the cavity is divided. The hollow and cylindrical chambers are arranged beside the other in cross-section of the piston portion and/or extended axially in the piston portion. The piston portion is provided with an integral base element in which the chambers are incorporated, and wherein the chambers are closed towards a working surface of the piston by one or more closure elements. An independent claim is included for the method for manufacturing piston for axial piston machine.