Two-Phase Stepper Axle Generator for Railway Brake Speed Sensing
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Solution Overview
Problem
Existing wheel slide protection systems for freight trains are hindered by the need for high flow valves due to large brake cylinders and lack of autonomous electrical power, making them unreliable and costly, limiting their adoption and causing slower travel speeds to prevent track damage.
Innovation Solution
A two-phase stepper motor axle generator assembly that uses both phases for power generation and speed sensing, eliminating the need for opto-isolators and pulse rejection circuitry, allowing for efficient and reliable speed determination and direction detection without internal spurious signals, and enabling instantaneous speed evaluation at 1/50 of a revolution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a generator is coupled to the axle with permanent magnets and induction coils, then electrical energy can be generated from rotary motion, but the arrangement requires careful alignment of parts and is difficult to implement
Solution Approach 1:
The patent replaces the mechanical alignment-dependent generator system with a stepper motor that has integral frequency detection circuitry. The stepper motor's electronic commutation eliminates the need for mechanical alignment of permanent magnets and induction coils, while the integral encoder provides speed sensing without additional mechanical components.
Solution Approach 2:
The patent combines the power generation function and speed sensing function into a single integrated stepper motor assembly. The stepper motor generates electrical energy while its integral encoder simultaneously provides frequency and direction signals, eliminating the need for separate alignment-critical components.
2Reliability
If optical couplers are used to handle half-waves and protect against spurious signals, then signal protection is improved, but the circuitry becomes more complex and galvanic isolation is required
Solution Approach 1:
The patent extracts the frequency detection function from the power generation circuitry by using the stepper motor's integral encoder. This separates the speed sensing function from the power conversion function, eliminating the need for optical couplers and complex signal protection circuitry in the power generation path.
Solution Approach 2:
The stepper motor's integral encoder provides self-contained frequency and direction signals without requiring external protection circuitry. The encoder generates clean digital signals that are inherently protected against spurious signals, eliminating the need for optical isolators and complex filtering arrangements.
3Ease of manufacture
If a two-phase stepper motor is used for both power generation and speed sensing, then manufacturing is simplified and cost is reduced, but the system must handle both power and signal functions
Solution Approach 1:
The patent uses a two-phase stepper motor that serves multiple functions: it generates electrical power from the axle's rotary motion and simultaneously provides speed and direction sensing through its integral encoder. This multi-functional approach simplifies manufacturing by using a single standardized component rather than multiple specialized parts.
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 provides a reliable, cost-effective, and efficient means for both power generation and speed sensing in railway braking systems, reducing wheel and track damage by enabling faster and more precise wheel slide protection, suitable for both passenger and freight trains.
Implementation Method 1
a two-phase stepper motor which is adapted to be driven by the axle and which has two phases, both of which are adapted for power generation
Implementation Method 2
the frequency detection circuitry is filtered to limit the expected frequency resulting from the speed of the axle
Implementation Method 3
both phases are used for frequency detection. As the two phases are out of phase with one another, it is also possible to determine direction with the solution of the invention
Data Source
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AI summary
Axle generator assembly for a brake system for a railway vehicle comprises a two phase motor adapted to be driven from an axle end of a freight wagon. Both phases can be rectified to generate power for the brake system and the assembly further comprising frequency detection circuitry to detect the frequency of the phases. The frequency of one or both of said phases is then used to generate a speed signal.