Variable Flux Starter Motor Relay Control
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Solution Overview
Problem
Conventional electric starter motors lack the ability to adjust torque-speed response effectively for varying cranking conditions, such as cold and warm starts, leading to inefficient engine initiation and potential over-speed issues.
Innovation Solution
A variable flux electric starter motor design incorporating a primary field with windings of differing turns and a supplemental field, where the relay selectively shorts windings and directs current through the supplemental field to adjust flux and torque-speed characteristics, ensuring optimal performance across different cranking scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional electric starter motors use fixed flux, then the structure is simple, but the torque-speed response cannot be adjusted for varying cranking conditions
Solution Approach 1:
The field winding is segmented into primary windings and supplemental windings that can be independently controlled. The relay selectively shorts portions of the primary windings based on cranking conditions, allowing the system to adjust flux levels without requiring a completely separate winding system for each operating mode.
Solution Approach 2:
The system transitions from a static fixed-flux design to a dynamic variable-flux design. The relay dynamically reconfigures the winding connections based on real-time cranking conditions (cold vs. warm start), enabling the flux to be adjusted during operation to optimize torque-speed response for different scenarios.
2Force
If the starter motor provides high torque for cold cranking, then cold start performance is improved, but the motor may over-speed during warm cranking
Solution Approach 1:
The system changes the flux parameter based on operating conditions. During cold cranking, full flux is applied to maximize torque. During warm cranking, the relay shorts portions of the primary windings to reduce flux, which limits the maximum speed the motor can achieve, preventing over-speed conditions while still providing adequate torque for starting.
Solution Approach 2:
The relay acts as an intermediary device that mediates between the fixed winding structure and the variable operational requirements. By selectively shorting windings, the relay provides intermediate flux levels that allow the motor to adapt its torque-speed characteristics without requiring multiple complete winding sets.
3Speed
If the starter motor is designed for fast warm cranking, then warm start speed is improved, but torque availability for cold cranking is reduced
Solution Approach 1:
Rather than designing for a fixed operating point, the system dynamically adapts its characteristics. The same motor structure can provide high torque at low speeds when needed for cold cranking, or allow higher speeds when appropriate for warm cranking, by dynamically reconfiguring the field winding connections through the relay.
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
The solution enables a balanced torque-speed response, maintaining high torque for cold cranking and achieving faster starts during warm cranking while limiting high-speed performance to prevent over-speed conditions, thus ensuring efficient and reliable engine starting within design specifications.
Implementation Method 1
passing an electrical current through a primary field having a plurality of primary windings electrically connected one to another to generate a first flux, rotating an armature at a first speed in response to the first flux
Implementation Method 2
limiting the second speed by directing electrical current through a supplemental winding of a supplemental field electrically coupled in parallel to the primary field
Data Source
AI summary
A variable flux electric starter motor includes a frame, an armature rotatably mounted within the frame, and a primary field mounted to the frame. The primary field includes a plurality of primary windings electrically connected one to another. A relay is electrically coupled to at least one of the plurality of poles. A supplemental field is mounted to the frame. The supplemental field includes a supplemental winding electrically connected in parallel to the plurality of primary windings.