EGR Pump Locking Mechanism for Zero-Speed Engine Braking
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Solution Overview
Problem
Conventional diesel engines face challenges in achieving zero EGR flow during engine braking due to insufficient torque from the electric motor, necessitating a mechanism to lock the EGR pump at zero speed.
Innovation Solution
An EGR pump system with an EGR locking mechanism and control method, utilizing an electromechanical solenoid actuator to lock the transmission assembly and prevent rotor rotation during high pressure ratio events, managed by an EGR control unit and sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the electric motor is used to control EGR flow during engine braking, then the EGR valve can be eliminated, but the motor does not have enough torque to achieve zero speed due to extremely high pressure ratio
Solution Approach 1:
A locking mechanism acts as an intermediary between the electric motor and the rotor assembly. The locking mechanism includes a locking member that can engage with a locking surface on the rotor shaft, providing the additional holding force needed to maintain zero speed during high pressure ratio conditions when motor torque alone is insufficient.
Solution Approach 2:
The system dynamically transitions between two states: a locked state where the locking mechanism engages to prevent rotor rotation during high pressure ratio events, and an unlocked state where the electric motor independently controls rotor speed during normal operation. This dynamic switching allows the system to adapt to varying torque requirements.
2Productivity
If the EGR pump is locked at zero speed during engine braking, then zero EGR flow is achieved, but additional locking mechanism components are required
Solution Approach 1:
The locking mechanism is designed to serve multiple functions: it provides mechanical locking during high pressure ratio events, acts as a safety backup for the electric motor, and can be integrated with existing pump housing structures. The locking member and locking surface are designed to be compact and compatible with the existing pump geometry.
Solution Approach 2:
The locking mechanism components are nested within the existing pump housing structure. The locking member is positioned within the housing and engages with the rotor shaft without requiring external additions, effectively nesting the locking function within the existing pump assembly boundaries.
3Reliability
If a locking mechanism is added to prevent rotor rotation, then rotor damage is prevented during high pressure ratio events, but the device complexity increases
Solution Approach 1:
The locking mechanism serves as a protective intermediary that engages during high pressure ratio events to prevent excessive forces from damaging the rotor assembly. The locking member distributes the high pressure loads across the locking surface on the rotor shaft, preventing concentrated stress points that could cause damage.
Solution Approach 2:
The locking mechanism provides beforehand protection by being pre-positioned and ready to engage before damage can occur. During high pressure ratio events, the locking mechanism activates to cushion the rotor assembly from damaging forces, preventing damage before it happens rather than reacting after damage occurs.
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
Effectively locks the EGR pump at zero speed during engine braking, preventing rotor damage and maintaining system control, even under high pressure ratios.
Implementation Method 1
An EGR locking mechanism is attached to the EGR pump assembly... utilizing an electromechanical solenoid actuator to lock the transmission assembly
Data Source
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AI summary
An EGR pump system includes an EGR pump assembly including an electric motor assembly coupled to a transmission assembly. A roots device is coupled to the electric motor through the transmission assembly. The roots device includes a housing defining an internal volume and rotors are disposed in the internal volume and connected to the transmission assembly. An EGR locking mechanism is attached to the EGR pump assembly. The EGR locking mechanism is selectively connected to the transmission assembly locking the transmission assembly and preventing rotation of the rotors.