Vacuum Pump Stator Fastening with Counterbore Screw
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Solution Overview
Problem
Existing vacuum pumps face resistance issues due to protruding headed bolts in the screw groove exhaust portion, leading to product accumulation and interference with gas flow, which affects the pump's efficiency and maintenance.
Innovation Solution
The use of a hexagon socket head cap screw with a reduced head height, arranged in a counterbore on the stator's upper surface, ensures that the screw stator is flush with the stator's surface, reducing interference with the gas flow and eliminating product accumulation, while maintaining sufficient clamping force through standardized dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If headed bolts are used to fix the screw stator, then the stator is securely fastened to the base, but the protruding head portions create resistance to gas flow and cause product accumulation
Solution Approach 1:
The head portion of the hexagon socket head cap screw is nested within the counterbore of the stator, creating a flush surface that eliminates protruding elements into the gas flow path while maintaining secure fastening through the threaded engagement with the base
2Ease of manufacture
If headed bolts protrude from the stator surface, then the fastening structure is simple and easy to manufacture, but product accumulates on the aside surface of the head portions
Solution Approach 1:
The counterbore provides a recessed space that accommodates the head portion of the fastening screw, nesting it within the stator surface to eliminate the protruding geometry that causes product accumulation while maintaining the simplicity of screw fastening
3Strength
If standard height hexagon socket head cap screws are used, then the fastening strength is sufficient, but the head height interferes with the gas flow in the screw groove exhaust portion
Solution Approach 1:
The height of the head portion is changed from the standard dimension to a reduced dimension that fits within the counterbore depth, altering the geometric parameter to eliminate gas flow interference while maintaining adequate clamping force through the threaded engagement portion
Data Source
AI summary
A vacuum pump comprises: a base; a rotor shaft rotatably provided at the base; a rotor including rotor blades arranged in multiple stages and a rotor cylindrical portion, and attached to the rotor shaft; stationary blades each arranged between adjacent ones of the rotor blades, the stationary blades and the rotor blades forming a turbo exhaust portion; a stator forming, together with the rotor cylindrical portion, a screw groove exhaust portion; and a hexagon socket head cap screw configured to fix the stator to an upper surface of the base in a guiding path of the screw groove exhaust portion to which gas is guided from the turbo exhaust portion. The hexagon socket head cap screw is a bolt having a smaller height of a head portion than that of a hexagon socket head cap screw according to a provision of a country of use or an international organization.