Stepped Servo Piston Damping for Hydraulic Motor Shift
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Two-position hydraulic motors experience abrupt changes in displacement due to fluctuating system pressures, leading to unsteady behavior and difficulty in controlling shifting performance, which results in a 'digital' stop-and-go operation and requires robust, heavy-weight designs.
Innovation Solution
A hydraulic unit with a stepped servo piston and ring-shaped damping surface, allowing for individual pressurization of opposing front faces and a damping volume that slows down servo piston motion, enabling smooth shifting between operational states and reducing the risk of sudden changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-position hydraulic motor is designed for low cost and small package size, then the device complexity and weight are reduced, but the shifting performance becomes unsteady and difficult to control due to abrupt changes in displacement
Solution Approach 1:
A damping volume is introduced as an intermediary element between the high-pressure chamber and the servo piston. This damping volume, filled with hydraulic fluid, acts as a buffer that mediates the interaction between pressure changes and piston movement, converting abrupt pressure fluctuations into controlled, gradual piston displacement and eliminating the digital stop-and-go behavior
Solution Approach 2:
The damping volume is pre-filled with hydraulic fluid before operation, creating a cushioning effect that anticipates and absorbs sudden pressure changes. This beforehand cushioning prevents abrupt piston movements by providing a compliant buffer that gradually transmits pressure changes to the servo piston, ensuring smooth shifting performance from the outset
2Speed
If the servo piston changes position abruptly between end positions, then the reaction time is reduced, but the displacement changes become unsteady and difficult to control
Solution Approach 1:
The damping volume is pre-filled with hydraulic fluid to create a cushioning effect that anticipates sudden pressure changes. This beforehand cushioning prevents abrupt piston movements by providing a compliant buffer that gradually transmits pressure changes to the servo piston, ensuring smooth and predictable shifting while maintaining quick response
3Reliability
If robust design of support and mounting elements is implemented to bear high alternating forces, then the reliability is improved, but the weight and package size increase
Solution Approach 1:
The damping volume converts the harmful effect of high alternating forces into a beneficial cushioning effect. By introducing this fluid-filled buffer, the system absorbs and dampens pressure fluctuations that would otherwise require robust structural support, allowing for lighter mounting elements and support structures while maintaining reliability
Solution Approach 2:
The pre-filled damping volume provides beforehand cushioning that protects structural components from high alternating forces. This cushioning effect reduces the peak loads experienced by support and mounting elements, enabling their design with reduced mass while maintaining sufficient strength and reliability
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
The damping volume allows for controlled and predictable shifting, reducing the risk of unsafe operational states and enabling lighter, cost-effective designs while maintaining quick reaction times and avoiding clogging issues in hydraulic lines.
Implementation Method 1
a damping volume is formed in the servo cylinder by the damping surface, the shoulder surface and the servo cylinder... The damping volume allows for controlled and predictable shifting
Data Source
Figure 1
Figure 2
Figure 3~4
AI summary
A hydraulic unit includes a driving mechanism whose displacement volume is adjustable to two operational states by means of a positionable adjustment element. The adjustment element can be positioned by a servo piston of a servo unit into a first, initial position and a second, operative position. A first front face and a second front face of the servo piston, which are opposing each other, can be pressurized individually with pressurized hydraulic fluid in order to position the servo piston at either end position of a servo cylinder of the servo unit. The servo piston is of a stepped design thereby forming a ring-shaped damping surface opposing the first front face. In the servo cylinder a ring-shaped shoulder surface is formed opposing the damping surface such that a damping volume is formed in the servo cylinder by the damping surface, the shoulder surface and the servo cylinder.