Rotary Vane Vacuum Pump Automatic Vacuum Breaking
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Solution Overview
Problem
Portable rotary vane vacuum pumps used in air conditioning and refrigeration systems face issues with oil being drawn back into the system when the pump is shut off, leading to contamination and component damage, and existing solutions like check valves and manual valves are inefficient or require operator intervention.
Innovation Solution
A portable rotary vane vacuum pump design with an automatic vacuum breaking arrangement that vents the pump to atmosphere when the motor stops, using a lubricating oil system with a primary and secondary container open to atmosphere, preventing significant oil backflow and allowing for easy oil replacement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a ball or check valve arrangement is installed on the input line to prevent oil backflow, then oil backflow into the system is reduced, but the flow rate from the system is significantly reduced increasing evacuation time
Solution Approach 1:
The patent removes the obstructive ball or check valve from the main evacuation path. Instead, it uses a submerged pump design where the pump intake is positioned below the oil level in the sump, allowing oil to be continuously supplied to the pump interior through dedicated oil supply passages. This extraction of the check valve eliminates flow obstruction while maintaining oil supply reliability.
Solution Approach 2:
The pump is nested within the oil sump, with the pump interior communicating with the sump through multiple passages. The oil supply passages are nested within the pump structure, allowing oil to be drawn from the sump through the pump housing to the interior chambers. This nested arrangement ensures continuous oil supply without requiring check valves.
2Reliability
If a manually operated isolation valve is provided between the system and pump to prevent oil backflow, then oil backflow can be prevented when the valve is closed, but the solution relies on operator intervention and does not prevent backflow during unintentional shutdowns
Solution Approach 1:
The pump design is self-protecting through its submerged configuration. The pump interior is continuously supplied with oil from the sump through dedicated passages, and the pump housing acts as an oil reservoir. When the pump stops operating, the oil in the pump interior and the continuous oil supply from the sump automatically prevent vacuum backflow, eliminating the need for manual valve operation.
Solution Approach 2:
The pump is pre-filled with oil from the sump before operation begins, and the oil supply passages are designed to maintain oil in the pump interior during operation. This preliminary oil filling creates a barrier that prevents vacuum backflow automatically when the pump stops, without requiring any operator action to close isolation valves.
3Reliability
If the pump is submerged in oil sump to provide continuous oil supply for lubrication and sealing, then the pump can draw deep vacuum, but oil is undesirably drawn back through the pump into the system when the pump is shut off
Solution Approach 1:
The pump structure is segmented into distinct oil supply passages and evacuation passages. The oil supply passages draw oil from the sump to the pump interior through specific routes, while the evacuation passages handle the vacuum function. This segmentation ensures that oil flow and vacuum flow are separated, preventing oil backflow into the system while maintaining deep vacuum capability.
Solution Approach 2:
The pump housing and oil supply passages act as an intermediary barrier between the sump oil and the system being evacuated. Oil is supplied through the pump housing to the interior chambers, creating a sealed interface that prevents vacuum from pulling oil back into the system. The intermediary structure maintains the benefits of submerged operation while eliminating the harmful backflow effect.
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
The automatic vacuum breaking arrangement effectively limits oil backflow into the system and pump, reducing contamination and the need for extensive cleaning, while allowing for quick oil changes and safer pump operation.
Implementation Method 1
a reed valve in the second passage that is flexed by pressure differential to open and close the second passage
Implementation Method 2
a reed valve in the second passage that is flexed by pressure differential to open and close the second passage
Data Source
AI summary
A portable, rotary vane vacuum pump with an automatic vacuum breaking arrangement that vents the pump to atmosphere whenever the drive motor ceases to rotate the pump. The arrangement prevents lubricating oil in any substantial amount from being undesirably drawn into the evacuated pump when the drive motor is shut off either intentionally or unintentionally. If the system being evacuated is also still connected to the pump, the arrangement will additionally vent it and greatly limit any amount of oil that may be undesirably sucked back into it. The pump further has a primary oil container that essentially holds all of the oil for the system. The primary container is preferably made of clear, rigid plastic and is also removable from the main body of the pump so it can be quickly and easily replaced with another container of fresh oil even while the pump is still operating.