Pneumatic Brake Isolation Valve for Anti-Compounding Control
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Solution Overview
Problem
Existing vehicle braking systems lack a reliable anti-compounding function that operates independently of electronic system power status, leading to reliability issues when electronic systems are disconnected, such as during vehicle servicing.
Innovation Solution
A pneumatic braking system with an isolation device that controls air pressure delivery to the service brake actuator based on the pressure in the parking brake chamber, ensuring service brakes can only be activated if the parking brake is released, even when electronic systems are not powered, using an isolation device like an on-off solenoid valve or electromagnetic isolation valve.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electronic anti-compounding function is used, then anti-compounding is available when electronic systems are powered-up, but anti-compounding function is not active when electrical systems are switched-off or not electrically powered
Solution Approach 1:
The braking system is divided into two independent anti-compounding mechanisms: an electronic anti-compounding function that operates when electronic systems are powered-up, and a pneumatic anti-compounding function that operates when electronic systems are not powered. The isolation device segments the control pressure delivery path, allowing the pneumatic mechanism to independently prevent compounding when electronic systems are unavailable.
Solution Approach 2:
The isolation device acts as an intermediary between the driver's braking request (control pressure) and the service brake actuator. It mediates by conditionally allowing or blocking control pressure based on parking brake status, ensuring anti-compounding protection even when electronic systems are not powered, thus bridging the gap between electronic and pneumatic operation modes.
2Ease of operation
If service brakes can be applied independently without checking parking brake status, then ease of operation is improved, but reliability issues associated with brake compounding occur
Solution Approach 1:
The isolation device implements preliminary anti-action by proactively blocking control pressure to the service brake actuator when the parking brake is applied. This preventive measure stops compounding before it can occur, maintaining reliability while allowing independent brake operation when safe (i.e., when parking brake is released).
Solution Approach 2:
The system uses feedback from the parking brake pneumatic chamber pressure to control the isolation device. The isolation device monitors parking brake status (via pressure level) and automatically adjusts control pressure delivery accordingly, creating a closed-loop safety mechanism that prevents compounding without requiring complex electronic monitoring.
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
This solution ensures anti-compounding function is maintained without relying on electronic system power, preventing excessive braking force and enhancing reliability by allowing service brakes to be applied only when the parking brake is released, even during vehicle servicing.
Implementation Method 1
an on-off solenoid valve comprising: an inlet port, an outlet port, a control port, a return spring, an electromagnet, a plunger, configured for moving under the joined action of the electromagnet, of the return spring and of a pressure in the control port
Implementation Method 2
a return spring, an electromagnet, a plunger, configured for moving under the joined action of the electromagnet, of the return spring and of a pressure in the control port
Implementation Method 3
in a second mode in which the isolation device is not electrically energized: allowing the delivery of the first air control pressure to the regulation unit so that a braking force is applied by the service brake actuator when the pressure in the parking brake chamber is higher than a first predetermined threshold
Data Source
Figure 1
Figure 2~3
Figure 4~5
AI summary
The invention relates to a pneumatic braking system (100) comprising: a. a service brake actuator (1), b. an electro-pneumatic modulator unit (2) for: i. Receiving an air control pressure (P1) representative of a driver's braking request, ii. Delivering by a regulation unit (40) a modulated air pressure (P_s) to a service brake chamber (3), c. a parking brake actuator (4), d. a parking brake unit (7), for delivering a second air pressure (P_p) to a parking brake pneumatic chamber (6), e. an isolation device (8) for: i. when the isolation device (8) is electrically energized, preventing the delivery of the air control pressure (P1) to the regulation unit (40), and ii. when the isolation device (8) is not electrically energized: 1. allowing the delivery of air control pressure (P1) to the regulation unit (40) when the second air pressure (P_p) is higher than a threshold (Th_1), and 2. preventing the delivery of air control pressure (P1) to the regulation unit (40) when the second air pressure (P_p) is lower than the threshold (Th_1).