Vacuum Pump Leaf Spring Outlet Valve Design
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Solution Overview
Problem
Vacuum pumps with leaf spring outlet valves experience significant pressure losses due to incomplete closure and backflow of compressed air when the wing passes over the air outlet opening, leading to inefficiencies.
Innovation Solution
A layered leaf spring with varying spring constant and curvature, designed to lift only the necessary area of the outlet valve, preventing excessive opening and utilizing friction to control the valve, is implemented. The leaf spring is shaped in a partial circle or kidney form and made of metal or plastic, with different thicknesses and materials for individual leaves to enhance rigidity and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a leaf spring outlet valve is used to close the air outlet opening, then the outlet opening can be sealed to prevent backflow, but the leaf spring opens excessively when the wing passes over, causing compressed air to escape into the pressure chamber behind the wing instead of being expelled into the pressure line
Solution Approach 1:
The leaf spring is designed with a non-uniform spring constant that varies along its length, with higher rigidity near the clamping point and lower rigidity toward the free end. This local variation in mechanical properties allows the valve to remain tightly sealed when closed while enabling controlled opening only to the extent necessary for air expulsion, preventing excessive opening that would cause energy loss
Solution Approach 2:
The valve system transitions from a static sealing mechanism to a dynamic one where the leaf spring's opening behavior is controlled by the interplay between the pressure differential and the position-dependent spring constant. The valve opens dynamically only when and to the extent required by the pressure conditions, optimizing both sealing and discharge functions
2Reliability
If the leaf spring is made more rigid to prevent excessive opening, then backflow is reduced, but the force required to open the valve increases, making it difficult to lift even the necessary area
Solution Approach 1:
The leaf spring features a spatially varying spring constant that is higher near the clamping point (providing control and preventing excessive opening) and lower toward the free end (allowing easy lifting). This local differentiation of mechanical properties simultaneously reduces the opening force while maintaining valve control
3Device complexity
If a constant spring rate leaf spring is used, then the design is simple, but the outlet opening is not properly controlled during wing passage, leading to compressed air loss
Solution Approach 1:
The leaf spring is designed with a non-uniform spring constant that varies along its length, creating different rigidity zones: a stiffer region near the clamping point for control and a more flexible region at the free end for easy opening. This local differentiation enables proper valve control during wing passage while maintaining reasonable design complexity
Solution Approach 2:
The spring constant parameter is changed from a constant value to a position-dependent variable, allowing the leaf spring to exhibit different mechanical behaviors at different locations. This parameter variation enables the valve to function correctly during the dynamic process of wing passage without excessive complexity
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 ensures complete expulsion of compressed air into the pressure line, reducing backflow and pressure losses, and maintaining efficient operation by adjusting the spring characteristics and shape to cover the outlet opening effectively.
Implementation Method 1
In addition, the friction between the blades can be used to control the opening of the valve.
Implementation Method 2
the leaf spring has a spring constant that changes starting from the clamping point. This means that the free end of the leaf spring can be lifted from the outlet opening with a relatively small force
Data Source
Figure 1~2
Figure 3~4
AI summary
The invention relates to a vacuum pump comprising a crucible-shaped housing, a rotor mounted eccentrically rotatably in the housing, a blade (20) supported displaceably perpendicular to the rotational axis in the rotor, the blade having the blade tips thereof resting against an internal circumferential surface delimiting a working space, thus dividing the working space into a suction space (32) and a pressure space (34), and the suction space being provided with an air inlet opening and the pressure space being provided with an air outlet opening, wherein the air outlet opening is provided with an outlet valve and the outlet valve (40) has a leaf spring (44) clamped on one side as a closing element, wherein the spring characteristic curve of the leaf spring changes from the clamped location (50) in the direction of the free end (62).