Pump Seal Ring Shift Mechanism for Leakage Control
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Solution Overview
Problem
Existing pumps with low sealing properties between the outer periphery of the shroud and the casing suffer from reverse fluid flow, leading to decreased performance due to the need for gaps that hinder rotor rotation and potential seal ring damage from speed differences and low rotational speed issues.
Innovation Solution
A pump design featuring a closed rotor with a seal ring and shift mechanism, where the seal ring is coaxial with the rotational axis and a shift mechanism brings the seal ring into contact with the inner wall of the pump space, reducing the need for high dimensional precision and preventing seal ring damage by ensuring contact at low speeds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If sealing units are used between the casing and shroud, then sealing property is improved, but high dimensional precision is required which increases manufacturing complexity
Solution Approach 1:
The patent changes the sealing mechanism from relying on dimensional precision to relying on pressure-driven contact. The seal ring is designed to be pressed against the shroud outer peripheral surface by pressure differential (higher pressure on the seal ring's outer surface vs. inner surface), ensuring reliable sealing without requiring high manufacturing precision of the sealing units.
2Reliability
If the end surface of the seal ring is brought into contact with the inner surface of the casing, then sealing property is improved, but speed difference between seal rings causes friction and damage
Solution Approach 1:
The patent segments the sealing interface into two distinct contact surfaces: (1) the seal ring's outer peripheral surface contacts the shroud's outer peripheral surface, and (2) the seal ring's inner peripheral surface contacts the casing's inner peripheral surface. This segmentation allows each interface to function independently, preventing speed difference issues while maintaining sealing effectiveness.
Solution Approach 2:
The shroud acts as an intermediary element between the seal ring and the casing. Instead of the seal ring contacting the casing directly (which would cause speed difference friction), the seal ring contacts the rotating shroud, which rotates at the same speed as the seal ring, eliminating relative motion and friction at the primary sealing interface.
3Reliability
If thrust action with rotation is used to bring the seal ring into contact with the casing, then sealing property is improved, but at low rotational speeds the seal ring fails to contact the casing
Solution Approach 1:
The patent employs a self-regulating pressure differential mechanism that automatically adjusts to rotational speed conditions. The seal ring's inner peripheral surface is exposed to higher pressure fluid, which automatically presses the seal ring against the shroud's outer peripheral surface. This self-service mechanism ensures reliable sealing at both high and low rotational speeds without requiring minimum speed thresholds.
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 configuration effectively suppresses fluid leakage and maintains pump efficiency by ensuring the seal ring contacts the inner wall even at low speeds, preventing reverse flow and reducing the risk of seal ring damage.
Implementation Method 1
a shift mechanism configured to exert a shift force in a direction along the rotational axis with respect to the seal ring with rotation of the pump rotor and bring the seal ring into contact with an inner wall of the pump space
Implementation Method 2
a central portion of the shroud has a low pressure and an outer peripheral portion of the pump rotor has a high pressure. Therefore, in a case where sealing property between an outer periphery of the shroud and the casing is low, fluid from the outer periphery of the pump rotor flows to the center side of the shroud
Data Source
AI summary
A pump includes a closed pump rotor being rotatably housed about a rotational axis in a pump space in a casing and including a shroud, a seal ring being shiftably provided, along the rotational axis, being coaxial with the rotational axis with respect to a cylindrical portion in a center of the shroud, and a shift mechanism configured to exert a shift force in a direction along the rotational axis with respect to the seal ring with rotation of the pump rotor and bring the seal ring into contact with an inner wall of the pump space.