Variable Displacement Piston Pump With Co-Rotating Swash Plate
Solution Overview
Problem
Conventional variable displacement piston pumps experience high contact stress, friction, and efficiency losses due to side loading of pistons, especially at higher temperatures and pressures, leading to increased wear and failure risks.
Innovation Solution
An axial variable displacement piston pump design with a co-rotating swash plate and piston barrel, featuring a retention cage and rotational coupling to minimize side loading through a lubrication film and retention members, reducing friction and wear.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional variable displacement piston pumps use a rotationally fixed swash plate, then the pump structure is simpler, but piston side loading increases causing high contact stress and scuffing
Solution Approach 1:
The patent applies the dynamics principle by making the swash plate rotationally coupled to the piston barrel through a retention cage, allowing the swash plate to rotate simultaneously with the piston barrel rather than remaining rotationally fixed. This dynamic configuration enables the swash plate to follow the rotational motion of the piston barrel, reducing piston side loading and contact stress while maintaining variable displacement functionality.
2Adaptability or versatility
If piston shoes slide continuously against the swash plate, then variable displacement operation is achieved, but friction and heat generation increase
Solution Approach 1:
The patent introduces a retention cage as an intermediary component between the piston barrel and swash plate. This retention cage rotates with the piston barrel and retains the pistons, providing a mediating structure that reduces direct sliding friction between piston shoes and the swash plate while still enabling variable displacement operation through controlled piston reciprocation.
3Reliability
If ball joints are used between piston heads and retraction plate, then piston retention is achieved, but radial forces cause uneven wear and efficiency loss
Solution Approach 1:
The patent replaces the static ball joint connection with a dynamic retention cage system that rotates with the piston barrel. This dynamic retention mechanism maintains piston retention while reducing radial forces and uneven wear, thereby improving pump efficiency compared to the conventional ball joint approach.
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 design enhances robustness and efficiency by minimizing side loading, reducing heat generation, and lowering the risk of failure at higher fluid temperatures and pressures.
Implementation Method 1
minimize side loading through a lubrication film and retention members, reducing friction and wear
Data Source
AI summary
An axial variable displacement piston pump includes a drive shaft disposed on an axis, a piston barrel having a plurality of pistons disposed about and rotationally coupled to the drive shaft, a swash plate disposed about and rotationally coupled to the drive shaft, and a retention cage connected to the swash plate between the piston barrel and the swash plate. The swash plate and the piston barrel are configured to be simultaneously driven by the drive shaft and the swash plate is configured to tilt relative to the axis. The retention cage is configured to retain the plurality of pistons relative to the swash plate with rotation.