Hydraulic Unit Manual Control Neutral Setting With Lateral Shaft Adjustment
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Solution Overview
Problem
Hydrostatic units with manual displacement control devices often suffer from asymmetrical behavior due to manufacturing and assembly tolerances, leading to non-centered starting positions and rotational angle asymmetries, which negatively affect control behavior.
Innovation Solution
A manual displacement control device with an input shaft that is laterally adjustable to compensate for manufacturing and assembly tolerances, featuring a feedback transmitting element and positioning means to ensure symmetrical rotational behavior, and a servo spring bracket to set the neutral position of the displacement element accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If manual displacement control device is assembled after hydraulic unit assembly, then installation flexibility is improved, but zero position coincidence with neutral position deteriorates due to manufacturing tolerances
Solution Approach 1:
The input shaft is made laterally adjustable through positioning means that allow dynamic repositioning. The input shaft block can be shifted laterally relative to the control housing to compensate for manufacturing tolerances and achieve proper zero position alignment with the neutral position of the hydraulic unit.
Solution Approach 2:
The lateral position of the input shaft is changed as a parameter to compensate for manufacturing tolerances. By adjusting the lateral position through the positioning means (wedge-shaped parts and fixation bolts), the system adapts to tolerance variations and achieves accurate zero position coincidence.
2Manufacturing precision
If input shaft is made laterally adjustable, then zero position alignment precision is improved, but device structural complexity increases
Solution Approach 1:
The control device is segmented into separable components: the input shaft block, control housing, and positioning means with wedge-shaped parts. This segmentation allows the input shaft to be independently positioned and adjusted without redesigning the entire control system.
Solution Approach 2:
The positioning means with wedge-shaped parts act as an intermediary mechanism between the input shaft block and control housing. This intermediary structure enables lateral adjustment of the input shaft while maintaining a relatively simple overall device structure.
3Adaptability or versatility
If positioning means with wedge-shaped parts are used, then lateral adjustment capability is improved, but manufacturing complexity of positioning mechanism increases
Solution Approach 1:
The positioning mechanism uses asymmetric wedge-shaped parts with inclined surfaces. This asymmetric geometry provides effective lateral adjustment capability through simple mechanical means, where the wedge shape converts vertical bolt movement into horizontal positioning of the input shaft block.
Data Source
AI summary
Manual displacement control device (MDC) for hydraulic units has an input shaft mounted rotatably about an input shaft axis in an input shaft block. The input shaft protrudes from the input shaft block with a first end, onto which a rotating torque can be applied. The MDC further includes a control spool housed in a control housing, which is moveable by rotating the input shaft for controlling a servo pressure. The control device is configured for adjusting and fixing the lateral position of the input shaft with respect to the control housing in a direction perpendicular to the input shaft axis and perpendicular to the direction of a restoring force exerted on the input shaft.