Vane Pump Thermal Expansion Control
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Solution Overview
Problem
Vane pumps face a challenge in maintaining discharge pressure stability as temperature increases, due to increased clearance between the casing, rotor, and vanes when they are made of materials with similar linear expansion coefficients, leading to decreased discharge pressure.
Innovation Solution
The vane pump design ensures that the linear expansion coefficients of the casing, rotor, and vanes satisfy specific ratios, such as l≤(b/a)×k and m≤(c/a)×j, to restrict the increase in clearance and maintain discharge pressure stability during temperature rises.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the casing, rotor, and vanes are made of materials with substantially the same linear expansion coefficients, then manufacturing and assembly are simplified, but the discharge pressure decreases when temperature increases due to increased clearance
Solution Approach 1:
The patent changes the material parameters (linear expansion coefficients) of the components. Specifically, it selects materials where the rotor and vanes have a linear expansion coefficient of 10×10^-6/℃ to 20×10^-6/℃, while the casing has a linear expansion coefficient of 5×10^-6/℃ to 15×10^-6/℃. This parameter differentiation allows the components to expand at different rates during operation, maintaining optimal clearance and discharge pressure stability across temperature variations.
2Stability of the object's composition
If the linear expansion coefficients of all components are made similar, then thermal expansion behavior is uniform and assembly is easier, but clearance increases during temperature rise leading to discharge pressure fluctuation
Solution Approach 1:
The patent deliberately utilizes differential thermal expansion by selecting materials with different linear expansion coefficients for different components. The rotor and vanes use materials with higher expansion coefficients (10×10^-6/℃ to 20×10^-6/℃) compared to the casing (5×10^-6/℃ to 15×10^-6/℃). This controlled differential expansion ensures that as temperature increases, the components expand at different rates, maintaining the optimal clearance between moving parts and preventing discharge pressure fluctuations.
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 design effectively suppresses the decrease in discharge pressure when the temperature increases, ensuring consistent performance and preventing fluctuations in fluid pressure discharge.
Implementation Method 1
a rotor arranged inside the casing to rotate eccentrically with respect to the casing
Implementation Method 2
a plurality of vanes configured to rotate with the rotor and slide on an inner side surface of the casing
Implementation Method 3
l≤(b/a)×k, wherein 'a' represents a height of the pump chamber in a rotation axis direction of the rotor, 'b' represents a height of the rotor in the rotation axis direction, 'l' represents a linear expansion coefficient of the casing in the rotation axis direction, and 'k' represents a linear expansion coefficient of the rotor in the rotation axis direction
Data Source
AI summary
A vane pump includes: a casing forming a pump chamber therein; a rotor arranged inside the casing to rotate eccentrically with respect to the casing; and a plurality of vanes configured to rotate with the rotor and slide on an inner side surface of the casing. At least one of Formula (1): l≤(b/a)×k and Formula (2): l≤(c/a)×j is satisfied, where “a” represents a height of the pump chamber, “b” represents a height of the rotor, “c” represents a height of the vane in a rotation axis direction of the rotor, and where “l” represents a linear expansion coefficient of the casing in the rotation axis direction, “k” represents a linear expansion coefficient of the rotor in the rotation axis direction, and “j” represents a linear expansion coefficient of the vane in the rotation axis direction.