Vacuum Pump Conical Lid Geometry for Solid Backflow Prevention
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Solution Overview
Problem
Conventional vacuum pumps face issues with solids accumulating in the rotor recess and bouncing back into the pumping target device due to lid members with planar or hemispherical shapes that inadequately direct solids away from the rotor.
Innovation Solution
A vacuum pump design featuring a lid member with a cone shape and specific curved surfaces that guide solids away from the suction port and utilize centrifugal force to prevent solids from exiting the pump, incorporating a generatrix with increasing angles from the vertex to the bottom.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a lid member with planar or hemispherical shape is used to cover the rotor recess, then the solid is prevented from entering the rotor recess, but the solid bounces back into the pumping target device
Solution Approach 1:
The lid member employs a conical shape with a curved generatrix instead of planar or hemispherical surfaces. The specific curvature profile (first curved portion) creates a surface that guides solids away from the suction port while preventing accumulation in the rotor recess, resolving the contradiction between preventing solid entry and avoiding solid bounce-back
Solution Approach 2:
The invention changes the geometric parameters of the lid member surface by defining a generatrix with specific curvature characteristics. The angle between the tangent to the generatrix and the gas flow direction increases from the vertex to the bottom, creating optimal solid guidance that prevents both accumulation and bounce-back
2Reliability
If the lid member has a large surface perpendicular to gas flow direction, then it effectively covers the rotor recess, but it bounces back most solids in the direction opposite to gas flow
Solution Approach 1:
The conical shape with curved generatrix replaces the planar or hemispherical surface. This curvature design maintains adequate coverage of the rotor recess while the specific angle progression along the generatrix directs solids away from the suction port, improving solid direction control without sacrificing coverage
3Device complexity
If the lid member has a linear inclined surface, then it provides structural simplicity, but the insufficient inclination causes solid bounce-back to the pumping target device
Solution Approach 1:
The curved generatrix with increasing angle from vertex to bottom provides the necessary inclination to prevent solid bounce-back while maintaining relative structural simplicity. The continuous curvature profile is more effective than linear inclination but can be manufactured using standard forming processes
Solution Approach 2:
The invention optimizes the lid member structure by defining a generatrix where the angle between tangent and gas flow direction increases from vertex to bottom. This parameter variation achieves effective solid containment without excessive structural 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
Effectively prevents solids from accumulating in the rotor recess and bouncing back into the pumping target device by guiding them away from the suction port and utilizing centrifugal force to redirect solids perpendicular to the gas flow.
Implementation Method 1
Great centrifugal force acts on the surface of the lid member due to rotation of the rotor. With this centrifugal force, the solid existing on the side close to the bottom of the lid member is blown in a direction close to a direction perpendicular to the gas flow direction.
Data Source
AI summary
A vacuum pump includes a housing having a suction port, a rotor housed in the housing and rotationally driven to suck gas through the suction port and pump the gas, and a lid member that covers a recess of the rotor. The lid member has a cone shape having a vertex on a side close to the suction port and having a bottom on a side close to the rotor. The generatrix of the cone shape includes a first curved portion having such a curve that an angle between a tangent to the generatrix and a gas flow direction increases from a vicinity of the vertex to a vicinity of the bottom.