Pneumatic Emergency Brake Release Timer for Wheel Protection
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Solution Overview
Problem
Existing pneumatic brake systems for rail vehicles face issues with wheel slides and lockups during emergency braking due to inhibited brake pressure modulation, leading to increased stopping distances and a need for enhanced wheel protection and safety.
Innovation Solution
A pneumatic emergency brake release timer is introduced, featuring a high capacity transfer valve and a timing reservoir with a check valve and choke circuit, which delays the application of emergency braking pressure by at least seven seconds, allowing for controlled wheel slip and protection during emergency conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If emergency braking pressure is applied immediately, then stopping distance is reduced, but wheel slides and lockups occur
Solution Approach 1:
The timer circuit performs preliminary action by delaying the connection of emergency brake pressure for a predetermined time period (e.g., 7 seconds) before full emergency braking is applied. This preliminary delay allows wheel protection mechanisms to remain active during the initial phase, preventing wheel slides and lockups while still achieving effective stopping.
Solution Approach 2:
The system uses periodic action through the timer circuit that creates a time-based sequence: first allowing wheel protection during the delay period, then transitioning to full emergency braking after the predetermined time expires. This periodic control structure manages the transition between protection mode and stopping mode.
2Speed
If brake pressure modulation is inhibited during emergency braking, then emergency stopping is achieved, but wheel slip control is lost
Solution Approach 1:
The timer circuit performs preliminary action by maintaining the ability for brake pressure modulation during the initial delay period. This allows wheel slip control to remain functional while still preparing for emergency stopping, and only after the predetermined time expires does the system fully inhibit modulation to achieve maximum stopping force.
3Reliability
If a timer delay is introduced before emergency braking, then wheel protection is improved, but stopping time is extended
Solution Approach 1:
The timer circuit applies partial action by providing wheel protection during only the initial phase of braking (the delay period), rather than throughout the entire braking process. After the predetermined time expires, full emergency braking is applied without protection, optimizing the balance between wheel protection and stopping time by applying protection only when most beneficial.
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 effectively reduces emergency brake pressure for a limited time, provides non-electronic wheel protection, and enables software-controlled wheel slip control, enhancing safety and reliability in emergency braking scenarios.
Implementation Method 1
a dissipating choke 62. The dissipating choke 62 is in one path
Implementation Method 2
The check valve and choke circuit 60 are provided with two parallel paths. The dissipating choke 62 is in one path. In the other path is a check valve 64
Implementation Method 3
The high capacity transfer valve is forced to the first position by pressure exceeding a preset pilot pressure at the pilot port of the high capacity transfer valve
Data Source
AI summary
A pneumatic emergency brake release timer comprises a high capacity transfer valve, a timing reservoir in communication with the pilot port of the high capacity transfer valve, the check valve and choke circuit providing parallel connections between the main source of pressure and the reservoir through a check valve and opposite flow through a dissipating choke.