Oscillating Vane Pump Actuator Structure for Fretting Corrosion Prevention
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Solution Overview
Problem
Conventional oscillating vane type pump actuators experience fretting corrosion and abrasion issues due to the mismatch in axial and radial strength between the cylinder and side covers, leading to excessive pressure and distortion under high-pressure conditions.
Innovation Solution
The lengths of the cylinder ends are shortened, and a cylindrical part is added to the side covers to match the cylinder's shape, with a passage connecting the junction surfaces to maintain a low-pressure state through oil films, preventing excessive pressure and distortion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If the cylinder and side covers are designed with conventional structures to withstand high pressure, then the pressure resistance is improved, but the mismatch in axial and radial strength causes excessive distortion and fretting corrosion at junction surfaces
Solution Approach 1:
The invention introduces a low-pressure communication passage that creates a localized low-pressure zone at the junction surfaces between the cylinder and side covers. This local pressure differentiation allows the majority of the structure to withstand high pressure while the junction areas experience reduced pressure, preventing excessive distortion and fretting corrosion without compromising overall pressure resistance.
Solution Approach 2:
The low-pressure communication passage acts as an intermediary element that mediates between the high-pressure working environment and the sensitive junction surfaces. By providing an alternative pressure pathway, it protects the junction areas from the full impact of high pressure while maintaining the necessary pressure resistance in the main hydraulic chamber.
2Strength
If the cylinder length is increased to improve structural strength, then the axial strength is improved, but the radial strength of side covers becomes insufficient leading to distortion
Solution Approach 1:
Instead of uniformly increasing the cylinder length to improve axial strength, the invention applies local quality by creating a specific low-pressure zone at the junction surfaces. This localized pressure management compensates for the structural weakness in radial strength of side covers without requiring increased cylinder length, thereby maintaining both axial and radial structural integrity.
3Power
If high pressure is applied to the working chamber to increase power output, then the power is improved, but the pressure difference causes excessive distortion at junction surfaces
Solution Approach 1:
The invention changes the pressure parameter locally at the junction surfaces by introducing a low-pressure communication passage. While the main working chamber maintains high pressure for power output, the junction surfaces experience reduced pressure, limiting relative distortion to 20-30 μm. This parameter differentiation allows high power operation without excessive distortion at critical interfaces.
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 limits relative distortion to 20-30 μm, effectively preventing fretting corrosion and maintaining consistent pressure across contact surfaces, enhancing the durability and efficiency of the oscillating vane type pump actuator.
Implementation Method 1
a passage that always communicates with a low-pressure side working chamber is formed in the surface that is enclosed by a seal provided on a joined surface of the fixed vane that is joined to each side cover
Implementation Method 2
the side covers and the fixed vane are put into contact with each other by oil films at pressures lower than that of the conventional technology
Data Source
AI summary
Disclosed herein is an oscillating vane type pump actuator. The pump actuator of the present invention provides a method of preventing fretting corrosion from being caused on joined surfaces of elements. A cylinder (3c) has a comparatively low radial strength, and each of side covers (1c) and (2c) has a high radial strength. A cylindrical portion (1c-c), (2c-c) is provided on each side cover. Thus, when high pressure of work oil distorts the cylinder into a shape in which the cross-section of the cylinder becomes an ellipse-like shape, the cylindrical portions of the side covers act such that they are distorted in the same shape as that of the cylinder. Further, a passage that always communicates with a low-pressure side working chamber is formed in the contact surfaces between a fixed vane that is fixed to the cylinder and the side covers.