Hydrostatic Servo Piston Spring Arrangement for Tilting Force Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing hydrostatic variable displacement units with swash plates face challenges in manufacturing and installation due to the complexity of servo systems, including tilting forces and precise manufacturing requirements, especially when trying to minimize construction space and maintain accurate spring force distribution.
Innovation Solution
The solution involves arranging springs around the servo piston parallel to its axis of movement, with spring plates bearing against servo-piston rear surfaces and servo cylinder stops, allowing for a single-part servo piston design and eliminating tilting moments, and enabling independent displacement of servo cylinders for adjustment, which can rotate within the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If springs are placed on one side of the servo piston to avoid tilting forces, then tilting forces are avoided, but construction space increases
Solution Approach 1:
The spring arrangement is positioned asymmetrically on one side of the servo piston rather than symmetrically on both sides. This asymmetric placement eliminates tilting forces on the servo piston while occupying less construction space compared to a symmetric dual-sided arrangement.
Solution Approach 2:
The spring force is applied at an offset position from the servo piston centerline, utilizing the lateral dimension to create a moment arm that counteracts tilting forces. This dimensional approach allows force application that prevents tilting without requiring symmetric space on both sides of the piston.
2Length of stationary object
If springs are placed into the servo-cylinder pressure space to reduce construction width, then construction width is reduced, but manufacturing precision requirements increase and spring force selection is restricted
Solution Approach 1:
The spring arrangement is extracted from the constrained servo-cylinder pressure space and repositioned in the spring arrangement space. This extraction removes the spring forces from the high-precision manufacturing zone, thereby reducing manufacturing precision requirements while still achieving compact construction width through proper spatial organization.
Solution Approach 2:
A dedicated spring arrangement space is introduced as an intermediary zone between the servo piston and the external environment. This intermediary space accommodates the springs and their mounting structures, allowing them to be positioned away from the precision-critical servo cylinder while maintaining overall compactness through integrated design.
3Adaptability or versatility
If servo piston is designed in multiple parts to accommodate springs on both sides, then springs can be fitted, but manufacturing costs and assembly complexity increase
Solution Approach 1:
The spring arrangement is segmented into modular components including spring plates, mounting structures, and positioning elements that can be independently manufactured and then assembled. This segmentation allows the springs to be accommodated in a single-part servo piston design through modular assembly, reducing overall device complexity while maintaining spring accommodation capability.
4Measurement precision
If neutral position is adjusted by displacement of entire servo system, then neutral position can be set, but a dedicated variable displacement housing is required
Solution Approach 1:
The servo system and the variable displacement housing are merged into a single integrated structure. The housing simultaneously serves as both the structural enclosure and the adjustment mechanism for the neutral position, eliminating the need for a separate dedicated housing while maintaining precise neutral position adjustment capability through integrated design features.
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 configuration simplifies manufacturing and installation, reduces construction space, and allows for precise adjustment of the servo system without the need for a separate housing, maintaining high spring forces with relaxed manufacturing tolerances and lower production costs.
Implementation Method 1
The spring forces of the spring arrangement for the resetting are dimensioned in such a manner that they return the pivoting angle of the swash plate into the neutral position
Implementation Method 2
The force required to change the pivoting angle of the swash plate is generally produced hydraulically by the servo system. For this purpose, the swash plate is connected to one or more servo pistons which are guided in corresponding servo cylinders and can be acted upon by pressure
Data Source
AI summary
A hydrostatic variable displacement unit is provided having a swash plate which serves to adjust the stroke of displacement pistons in a cylinder block and can be pivoted in its angular position by means of a servo system, the servo system having at least one servo piston with two servo-piston end surfaces which are in each case assigned a servo cylinder and a servo-piston rear surface, and the servo cylinders, by means of the assigned servo-piston end surfaces, in each case bounding a servo-cylinder pressure space. The servo piston is acted upon by a spring arrangement having at least one spring arranged outside the servo-cylinder pressure space and clamped between two spring plates. The two spring plates are acted upon by the springs in the direction of a stop of the particular servo cylinder that is situated on its side such that in the neutral position, the spring plates bear against the servo-piston rear surfaces and against the stop of the particular servo cylinder.