Variable Displacement Pump Rotor Galling Prevention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing variable displacement vane pumps experience galling between the rotor and the rear body due to uneven rigidity in the suction and discharge regions, leading to misalignment and contact issues under high discharge pressure.
Innovation Solution
The design incorporates a thin wall portion in the rear body with a recessed shape and specific thickness distribution to equalize the rigidity between the suction and discharge regions, featuring a radially outer portion overlapping with the discharge opening and a radially inner portion overlapping with the back pressure groove, ensuring balanced rigidity and preventing galling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the discharge region side of the rear body is formed into a solid state (tight state) to increase rigidity, then the rigidity in the discharge region is improved, but the rigidity in the suction region remains low causing uneven shape change under high discharge pressure
Solution Approach 1:
The patent applies local quality by forming a thin wall portion (local area) on the discharge region side of the rear body with a specific thickness (smaller than other portions). This creates a localized reduction in rigidity that balances the overall shape change between suction and discharge regions under high discharge pressure, preventing galling while maintaining structural integrity in other areas.
2Reliability
If discharge pressure is acted to all circumferences of base ends of slots to maintain vane positioning, then vane support is improved, but uneven rigidity distribution causes the rotor surface to become non-flat leading to galling
Solution Approach 1:
The patent changes the geometric parameter (thickness) of the rear body in the discharge region by forming a thin wall portion. This parameter change adjusts the rigidity distribution to ensure uniform shape change under discharge pressure, maintaining the rotor surface flatness and preventing galling while preserving reliable vane positioning through the back pressure chambers.
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 effectively suppresses partial contact between the rotor and the rear body, preventing galling and ensuring stable operation by maintaining equal shape changes in both regions, thus enhancing the pump's performance and longevity.
Implementation Method 1
a pressure plate provided within the cylindrical portion of the first housing between the bottom portion of the first housing and the cam ring, and pressed toward the cam ring by a discharge pressure discharged from the pump chambers
Implementation Method 2
a back pressure introduction groove which is formed in the second housing, which has an arc shape to confront base end portions of the slits that are radially innermost ends of the slits, which is formed at least on the suction region side, and which is arranged to protrude the vanes in the radially outside direction by receiving a part of the discharge hydraulic fluid
Data Source
AI summary
A variable displacement pump includes: a discharge opening formed at a position to confront a discharge region; a back pressure introduction groove formed on the suction region side; and a discharge side thin wall portion which is formed in the second housing, which has a recessed shape opened to the outside, which is disposed on the discharge region side, which is overlapped with the rotor in the radial direction, and which includes a smallest thickness portion having a smallest wall thickness of thicknesses each of which is an axial length between a bottom surface of the recessed shape and an axially inner side surface of the second housing, the smallest wall thickness being a smallest wall thickness of axial thicknesses of the second housing.