Overhung EGR Pump Rotors for Heat and Soot Isolation
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Solution Overview
Problem
Existing EGR pumps face issues with soot deposition, high temperature demagnetization of components, and inefficient heat and lubrication, leading to performance degradation and increased emissions.
Innovation Solution
An EGR pump system with overhung rotors, insulated coupling, and a flexible lip seal to prevent soot accumulation, reduce heat transfer, and ensure efficient lubrication, using a roots device coupled to an electric motor for controlled EGR flow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the rotors are supported by bearings at both ends, then the rotor stability is improved, but the device complexity and manufacturing cost increase
Solution Approach 1:
The patent removes one set of bearings from the rotor support structure, transitioning from dual-end bearing support to single-end bearing support with overhung rotors. This extraction simplifies the bearing support structure while maintaining adequate rotor stability through proper overhung design and alignment.
Solution Approach 2:
Instead of supporting the rotor at both ends (conventional approach), the patent inverts the support configuration by supporting the rotor at only one end with overhung rotors extending beyond the bearing support. This inversion reduces structural complexity while achieving the required stability.
2Use of energy by moving object
If the electric motor is directly coupled to the rotors, then the power transmission efficiency is improved, but the heat transfer from rotors to motor increases causing demagnetization
Solution Approach 1:
The patent introduces a flexible coupling as an intermediary element between the electric motor and the overhung rotors. This flexible coupling transmits mechanical power efficiently while providing thermal isolation to prevent heat transfer from the hot rotors to the motor, thereby preventing demagnetization of the motor.
Solution Approach 2:
The direct coupling between motor and rotors is segmented into two separate functional elements: the electric motor and the flexible coupling, with the flexible coupling serving as a thermal barrier while maintaining mechanical power transmission.
3Stability of the object's composition
If conventional bearing support is used, then the rotor support is improved, but soot deposition and performance degradation occur
Solution Approach 1:
The patent extracts the rotor support from conventional enclosed bearing housings and implements open overhung rotor configuration, which reduces areas where soot can accumulate and improves airflow patterns that prevent soot deposition on critical components.
Solution Approach 2:
The overhung rotor design creates specific local flow conditions around the rotor surfaces that prevent soot accumulation, while the flexible coupling creates a thermal and contamination barrier between the hot rotor environment and the motor.
4Extent of automation
If a separate EGR pump is used, then the EGR flow control authority is improved, but the system complexity and component cost increase
Solution Approach 1:
The patent combines the EGR pump function with an electric motor and flexible coupling into an integrated assembly, providing full authority EGR flow control while reducing system complexity compared to traditional turbocharger-based EGR systems with multiple valves and complex control mechanisms.
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
Enhances engine efficiency, reduces emissions, and prolongs component life by preventing soot deposition, minimizing heat transfer, and optimizing lubrication, while maintaining precise EGR flow control.
Implementation Method 1
insulated coupling, reduce heat transfer
Implementation Method 2
bearings that support the rotors, cool and lubricate the various components
Data Source
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AI summary
An exhaust gas recirculation pump system for an internal combustion engine includes an EGR gas source and an electric motor assembly. A roots device is coupled to the electric motor. The roots device includes a housing defining an internal volume wherein the housing includes a radial inlet port receiving the EGR gas source and an outlet port expelling the EGR gas from the housing. Rotors are disposed in the internal volume and connected to the electric motor. A transmission housing is attached to the housing. The transmission housing includes journals formed therein receiving bearings that support the rotors on only a single end of the rotors.