Hydrostatic Axial Piston Machine Pressure Pulsing Reduction
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Solution Overview
Problem
Conventional hydrostatic axial piston machines experience pressure shocks and pulsing issues at high speeds, leading to cavitation, noise, and material fatigue due to inefficient pressure changeover systems, which limit their performance and durability.
Innovation Solution
The arrangement of compensating openings adjacent to kidney-shaped control ports with a compensating fluid path, where the angular spacing between these openings is greater than the control opening width, reduces dynamic loading and prevents hydraulic short circuits, ensuring smooth pressure transition and reduced pulsing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If conventional pressure changeover systems with pilot grooves are used, then the machine can operate at high pressure, but pressure shocks and pulsing occur at high speeds leading to cavitation and noise
Solution Approach 1:
The control plate is segmented into multiple control ports (first and second control ports) with associated pilot grooves, allowing the pressure changeover function to be divided across multiple pathways. This segmentation distributes the pressure transition load and prevents abrupt pressure changes that cause shocks and pulsing.
Solution Approach 2:
Pilot grooves act as intermediary channels that mediate the pressure transition between the displacement space and the control ports. These grooves provide a controlled intermediate pathway for pressure fluid, enabling gradual pressure changeover and preventing direct abrupt pressure transitions that cause cavitation and noise.
2Power
If the number of cylinder bores is increased to increase output, then higher power is achieved, but pressure pulsing and dynamic loading increase
Solution Approach 1:
Multiple control ports and their associated pilot grooves are merged into a unified control system on the control plate. This combined system coordinates the pressure changeover across all cylinder bores simultaneously, synchronizing pressure transitions and reducing overall pressure pulsing even as the number of cylinders increases for higher power output.
3Strength
If ducts are dimensioned narrowly for strength reasons, then the control lens can withstand high pressure, but pressure pulsing and volumetric flow pulsing are exacerbated
Solution Approach 1:
The pilot grooves are designed to initiate pressure changeover action before the main pressure transition occurs. By pre-establishing pressure fluid pathways through the grooves, the system prepares for pressure transition in advance, smoothing out the subsequent pressure changes and reducing volumetric flow pulsing while maintaining narrow duct dimensions for strength.
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 minimizes cavitation and noise, enhances durability by reducing dynamic load pulses, and maintains efficient pressure changeover, even at high speeds, thereby improving the overall performance and longevity of the machine.
Implementation Method 1
The two compensating openings are connected together via a compensating fluid path. In the changeover webs, the pressure changeover between high pressure and low pressure takes place in the displacement spaces.
Implementation Method 2
On account of the compressibility of the fluid, an additional amount of pressure fluid is required for compressing the pressure fluid in a closed capacity, while upon relaxation, this amount has to escape again.
Data Source
AI summary
A hydrostatic axial piston machine includes a cylinder drum that rotates during operation and has a plurality of cylinder bores in which displacement pistons are arranged, each of which opens out in a control opening in one end face of the cylinder drum, and having a control part against which the cylinder drum bears with the end face and on which two kidney-shaped control ports in the form of circular arcs are provided. Between the two kidney-shaped control ports, a first changeover web and a second changeover web are formed, wherein two sets of compensating openings that are able to be overlapped by control openings are located in the changeover webs with one compensating opening of each set located in each changeover web, and the compensating openings in the two sets of compensating openings are connected together via respective compensating fluid paths.