Electric Machine Shutter for Arcing Containment
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Solution Overview
Problem
Track-bound vehicle electric machines experience arcing issues in the stator winding, leading to high temperatures and potential damage, with existing solutions like directing molten materials away from critical components still posing safety risks and inefficiencies.
Innovation Solution
Incorporating a temperature-dependent shutter mechanism in the outlet opening of the casing that closes upon arcing detection, using materials or substances that lose mechanical strength or react at elevated temperatures to irreversibly transition to a closed position, preventing air and molten material exit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the outlet opening is directed downward towards the rail track to blow molten copper and steel away from the gearbox and other components, then the safety of internal components is improved, but the risk to safety-related equipment on or near the rail track increases
Solution Approach 1:
Instead of directing the outlet opening downward to blow harmful materials away, the patent inverts the approach by using a shutter mechanism to block the outlet opening during arcing events, preventing molten copper and steel from being expelled towards the rail track while still allowing cooling air flow during normal operation
Solution Approach 2:
The patent converts the harmful effect of air flow during arcing (which transports molten materials) into a beneficial protective action. The same air flow path that would normally carry harmful materials is instead used to trigger the shutter closure, transforming the dangerous situation into a protective response that contains the arcing within the motor housing
2Duration of action of moving object
If the vehicle is braked to lower speed as soon as an arc is detected to remove the voltage sustaining the arc, then the arc duration is reduced, but the response time is delayed and substantial damage may occur before braking takes effect
Solution Approach 1:
The shutter mechanism is pre-positioned in the outlet opening and can be rapidly actuated upon arc detection. This preliminary positioning allows the shutter to immediately block the outlet opening when arcing occurs, preventing the expulsion of molten materials without requiring any mechanical movement or complex response time
Solution Approach 2:
The patent replaces the mechanical braking system (which requires time to reduce vehicle speed and remove voltage) with a rapid shutter closure mechanism that can instantly block the outlet opening. This substitution of a fast-acting mechanical shutter for a slower vehicle braking system eliminates the response time delay while still achieving arc suppression
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 contains arcing-related heat and molten materials within the electric machine, reducing the risk of damage and ensuring safety by maintaining the outlet opening closed during arcing events, thus enhancing the reliability and safety of the track-bound vehicle electric machine.
Implementation Method 1
a temperature dependent member in the air flow through the outlet opening and configured to transfer said at least one shutter to a second closed position upon an increase of the temperature of the air flow through the outlet opening above a predetermined level
Implementation Method 2
an impeller with blades fixed to an axle of the rotor at one end of the stator body so as to generate a flow of air substantially axially with respect to an axis of rotation of the rotor towards the other end of the stator body for cooling end turns of the stator windings
Implementation Method 3
a rotor rotatably disposed within said stator and having a rotor body with a plurality of permanent magnets received therein
Implementation Method 4
By using a plurality of permanent magnets to produce the magnetic flux of the rotor a synchronous motor called permanent magnet synchronous motor is achieved
Data Source
AI summary
An electric machine with a rotor (4) rotatably disposed within a stator (1) with a stator winding (3) has a plurality of permanent magnets (8) received therein. A casing (17) encloses the stator and the rotor, and an impeller (13) with blades is fixed to an axle (7) of the rotor so as to generate a flow of air through the casing for cooling end-turns (25) of the stator winding by drawing air through an inlet opening (18) at one end of the casing and blowing it out of the casing through an outlet opening (19) at the other end of the casing. At least one shutter is arranged to close the outlet opening (19) when the temperature of the cooling air through the outlet opening reaches a predetermined level well above a maximum level of the temperature possible to be reached under normal operation of the electric machine so as to close the outlet opening upon occurrence of arcing in the end-turns. A temperature dependent member is arranged in the air flow through the outlet opening to obtain such closing.