Hydrostatic Machine Coupled Control Discs
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Solution Overview
Problem
Existing hydrostatic machines face inefficiencies due to high dead volume and increased load on control discs at lower inclinations, limiting their compactness, lightness, and versatility as hydraulic pumps or motors.
Innovation Solution
The use of two coupled control discs with pivot axes positioned to increase the distance between them as inclination decreases, allowing for reduced dead volume and improved load distribution, along with a torque-proof connection and a coupling mechanism like a curved track or toothed gear to compensate axial forces, enabling efficient operation across varying angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single control disc is used to control axial piston units, then the structure is simple, but the dead volume of cylinders increases at lower inclinations and load on the control disc increases
Solution Approach 1:
The single control disc is divided into two separate control discs, each controlling one axial piston unit. This segmentation allows independent optimization of each control disc's inclination angle, enabling the distance between control discs to increase as inclination decreases, thereby reducing dead volume loss while maintaining structural manageability
Solution Approach 2:
The solution moves from a single-plane control architecture to a multi-dimensional arrangement where two control discs are positioned at different axial locations. By controlling the distance between control discs as a variable dimension that changes with inclination angle, the system reduces dead volume without significantly increasing overall complexity
2Productivity
If control disc inclination decreases to improve flow distribution, then flow control improves, but the distance between control discs decreases increasing dead volume
Solution Approach 1:
The distance between the two control discs is made dynamic rather than fixed. As the inclination angle decreases, the axial distance between control discs automatically increases, compensating for the reduced inclination and maintaining adequate clearance to minimize dead volume while preserving flow control capability
Solution Approach 2:
The system changes the parameter of inter-disc distance as a function of inclination angle. By making this parameter variable and dependent on the operating condition (inclination angle), the system optimizes both flow control and dead volume minimization across different operating ranges
3Volume of moving object
If control discs are mounted at a common location to compact the structure, then compactness improves, but axial forces on the mounting increase
Solution Approach 1:
The two control discs are positioned and oriented such that the axial forces exerted by each piston unit on its respective control disc are equal and opposite. This creates a counterbalancing effect where the forces compensate each other at the common mounting location, reducing the net load on the suspension while maintaining compact architecture
4Device complexity
If control discs are fixed in position to simplify mounting, then mounting simplicity improves, but the harmful volume cannot be minimized at varying inclinations
Solution Approach 1:
Rather than fixing the control discs at a rigid mounting, the system allows the distance between control discs to dynamically adjust with inclination angle. This dynamic arrangement enables the harmful volume to be minimized at each inclination position while using a relatively simple common mounting structure that accommodates the varying distance
Data Source
Figure 1~2
Figure 3~4
Figure 5~7
AI summary
A hydrostatic machine comprises a first and a second axial piston unit (5, 6) arranged coaxially and featuring pistons (9) interacting with an adjustable control disk (13, 14). A first control disk (13) is associated with the first axial piston unit (5), and a second control disk (14) is associated with the second axial piston unit (6). The first and second control disks (13, 14) are jointly adjustable parallel to each other by a coupling mechanism (17-25; 26-28; 30-33).