Hydrostatic Axial Piston Machine Retraction Ball Pressure Chamber
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Solution Overview
Problem
Hydrostatic axial piston machines experience drive mechanism lift-ups due to eccentric loading and relief forces, leading to potential destruction and efficiency losses, especially in high-frequency oscillating drives.
Innovation Solution
A retraction ball is sealed against the cylinder drum and drive shaft, creating a pressure chamber that experiences pressure equal to the drum interior, reducing the lifting tendency of the cylinder drum and ensuring a central engagement of load forces, thereby reducing the risk of lift-up and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a customary swashplate-type axial piston machine is used with eccentric relief forces, then the machine can operate with standard control plate design, but the cylinder drum may lift off the control plate causing destruction and efficiency losses
Solution Approach 1:
The patent introduces a counterbalancing mechanism that applies an opposing force to counteract the eccentric relief force. This is achieved by creating a second pressure chamber that generates a force equal and opposite to the eccentric relief force, thereby balancing the net force on the cylinder drum and preventing lift-off without requiring complex control plate modifications
Solution Approach 2:
The patent introduces an intermediary pressure chamber between the cylinder drum and control plate. This intermediate pressure chamber acts as a mediator that transmits balanced forces, allowing the cylinder drum to remain pressed against the control plate even when eccentric relief forces are present, thus preventing direct contact between high-pressure relief forces and the control plate surface
2Reliability
If the cylinder drum is pressed against the control plate with high force, then the risk of lift-up is reduced, but the relief force acts eccentrically causing tipping moment
Solution Approach 1:
The patent creates a counterbalancing pressure chamber that generates a force equal and opposite to the eccentric relief force. This counterforce is applied centrically through the pressure chamber, creating a balancing moment that counteracts the tipping moment caused by eccentric relief forces, thereby maintaining stable centric engagement of the cylinder drum with the control plate
Solution Approach 2:
The patent equalizes the force distribution by creating a second pressure chamber that balances the eccentric relief force. This creates a state where the net force on the cylinder drum is balanced and centric, eliminating the tipping moment and ensuring stable, centered engagement between the cylinder drum and control plate throughout the rotation cycle
3Stability of the object's composition
If a 360° circumferential groove is used instead of 180° high-pressure kidney, then the relief force acts centrically, but the load force acts eccentrically producing tipping moment
Solution Approach 1:
The patent introduces a counterbalancing pressure chamber that generates a force equal and opposite to the eccentric load force. This counterforce is applied through the pressure chamber to balance the tipping moment caused by the 360° circumferential groove configuration, thereby preventing cylinder drum lift-off while maintaining the centric relief force advantage
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 solution effectively reduces the likelihood of drive mechanism lift-up and enhances the operational efficiency of hydrostatic axial piston machines by ensuring a greater load force than relief force, minimizing leakage and efficiency losses, particularly in vibration drives.
Implementation Method 1
The retraction ball pressure chamber created by the seals between the retraction ball, the cylinder drum and the drive shaft can be acted upon by a pressure above the housing pressure
Data Source
AI summary
A hydrostatic axial piston machine includes a housing, a connection plate closing the housing, working connections formed on the connection plate, a drive shaft, a swashplate, a cylinder drum coupled to the shaft in the direction of rotation, bores formed in the drum and each including a piston, a control plate against which the drum bears, a retraction plate for removing a piston from the bores, and a retraction ball arranged in front of the first end face of the drum which surrounds a drum neck of the drum and the shaft and by which the retraction plate is loaded in the direction of the swashplate. A pressure chamber is defined by seals between the retraction ball, the drum, and the shaft, and is configured to be acted upon by a pressure above a housing pressure. The retraction ball is sealed against the drum neck and against the shaft.