Roots Pump Rotor Independent Stop Positioning

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Solution Overview

Problem

Existing Roots type pumps face issues with rotor adhesion to the casing due to freezing of condensed water when stopped, especially when the rotors are positioned in a way that moisture is retained by surface tension, leading to difficulties in restarting the pump in low temperature environments.

Innovation Solution

The Roots type pump is designed with a mechanism where the rotors can be stopped at independent positions to prevent adhesion, using a synchronous and asynchronous rotation system with gear engagement and disengagement, and positioning the rotors to allow condensed water to fall and be discharged, ensuring they do not adhere to the casing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If the pump is stopped with rotors in synchronous rotation position, then the pump structure is simple and easy to control, but the condensed water remains in the clearance between rotor and casing causing rotor adhesion

Engineering Contradiction:

Improvepump control structureVSAvoidrotor adhesion prevention

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The pump control system dynamically switches between synchronous rotation mode during operation and independent stop position mode during shutdown. The drive mechanism can independently control each rotor's stop position, allowing the rotors to be positioned where condensed water does not accumulate in clearances, thereby preventing adhesion while maintaining operational simplicity.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Before the pump is fully stopped, the control system preliminarily positions the rotors at specific stop positions where condensed water will not remain in the clearances. This preliminary positioning action prevents water accumulation that would cause adhesion, ensuring the pump can be restarted without delay even in low temperature environments.

Inventive Principle:

Principle #10Preliminary action

2Stability of the object's composition

If the rotors are stopped at fixed synchronous positions, then the pump operation is stable, but the condensed water cannot be discharged and freezing occurs in low temperature

Engineering Contradiction:

Improverotor positional stabilityVSAvoidcondensed water freezing

Core Design Contradiction:

Stability of the object's compositionVSObject-affected harmful factors

Solution Approach 1:

The pump design implements different functional qualities for different rotor positions. During operation, rotors maintain stable synchronous rotation. During shutdown, the control system positions rotors at specific locations where the local geometry prevents condensed water accumulation in clearances, allowing water to be discharged and preventing freezing at these specific stop positions.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The rotor stop positions are made dynamically adjustable rather than fixed. The control system can independently set each rotor's stop position to optimize water discharge. This dynamic positioning capability allows the pump to adapt to different operational states, ensuring stable operation during pumping and effective water discharge during shutdown.

Inventive Principle:

Principle #15Dynamics

3Reliability

If forward/reverse rotation is used to remove frozen water, then the pump can be restarted, but the operation time is extended and productivity is reduced

Engineering Contradiction:

Improvepump restart capabilityVSAvoidpump restart time

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The control system performs preliminary positioning of rotors at optimal stop positions before shutdown is complete. This preliminary action ensures that condensed water is already in a discharged state before the pump stops rotating, eliminating the need for time-consuming forward/reverse rotation operations to remove frozen water, thus enabling immediate restart.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The invention skips the time-consuming process of using forward/reverse rotation to remove frozen water by pre-positioning the rotors during shutdown. The control system rushes through the water discharge process by independently controlling rotor positions to optimal stop locations where water naturally discharges, allowing the pump to be restarted immediately without productivity loss.

Inventive Principle:

Principle #21Skipping (Rushing through)

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 prevents rotor adhesion and allows for prompt starting of the pump even in low temperature environments by ensuring that condensed water is discharged and does not freeze, facilitating quick system operation.

Implementation Method 1

moisture is retained by surface tension

Methodology Applied

Scientific EffectSurface tension: Surface Tension

Implementation Method 2

condensed water

Methodology Applied

Scientific EffectCondensation: Condensation

Implementation Method 3

freezing of condensed water

Methodology Applied

Scientific EffectFreezing: Freezing

Data Source

PatentUS7794218B2Roots type pump and fuel cell system

Publication Date: 2010.09.14 TOYOTA JIDOSHA KK

AI summary

There is disclosed a Roots type pump in which two rotors are rotated synchronously in a pump chamber to compress fluid therein, wherein respective stop positions of the rotors in the pump chamber at a time of stopping the pump are determined independently of each other.