SAHR Brake Control Circuit Using Speed Feedback
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Solution Overview
Problem
SAHR vehicle brakes in large vehicles can apply suddenly and without warning in case of electrical system failures, leading to potential accidents, especially when the vehicle is moving, and there is a need for safe, progressive application and release of the brake, even when the ignition is off or during electrical failures.
Innovation Solution
A non-electric control circuit that uses an energy converter to manage the SAHR brake engagement based on vehicle speed or energy source output, ensuring the brake remains disengaged at higher speeds and allows controlled engagement when necessary, incorporating a hydraulic pump and fluid pressure system to oppose the spring's braking action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SAHR brake uses a spring to maintain constant engagement pressure for reliability, then the brake reliability is improved, but the brake applies very rapidly and without warning in case of electrical failure
Solution Approach 1:
The brake system transitions from a static spring-only engagement mechanism to a dynamic system where hydraulic pressure can modulate the spring force in real-time. The control circuit dynamically adjusts brake engagement based on vehicle speed signals, allowing the system to adapt between parked and moving states to prevent sudden applications
Solution Approach 2:
The system incorporates feedback from vehicle speed sensors to the hydraulic control circuit. This feedback mechanism allows the control system to monitor vehicle motion status and adjust brake engagement accordingly, preventing sudden brake applications when the vehicle is moving while maintaining reliable engagement when parked
2Ease of operation
If the brake elements are kept separated by hydraulic pressure under normal conditions, then the rotatable element can rotate freely, but the brake can be applied very rapidly without warning upon electrical failure
Solution Approach 1:
The system uses dynamic control based on vehicle speed feedback to adjust the hydraulic pressure state. When motion is detected, the control circuit maintains brake separation; when stationary, it allows spring engagement. This dynamic state change prevents sudden braking while maintaining operational freedom
Solution Approach 2:
The hydraulic control circuit acts as an intermediary between the spring force and the brake elements. It mediates the interaction by using hydraulic pressure to counterbalance the spring force when needed, providing controlled engagement rather than direct spring application
3Reliability
If the SAHR brake is designed to automatically engage when the engine is switched off, then park braking reliability is improved, but unintended brake actuation can occur during electrical failures while the vehicle is moving
Solution Approach 1:
The system dynamically determines brake engagement state based on real-time vehicle speed feedback rather than static engine-on/off status. The control circuit continuously monitors motion status and adjusts hydraulic pressure accordingly, enabling reliable park braking while preventing unintended actuation during movement
Solution Approach 2:
The control system changes the operational parameters of the brake system based on vehicle speed. When speed exceeds a threshold, the system maintains brake separation; when speed is below the threshold (parked), it allows spring engagement. This parameter-based control resolves the contradiction between park reliability and movement safety
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
Prevents unintended brake actuation during motion, ensuring safety by allowing controlled application and release of the SAHR brake, even in fault conditions, and maintaining the brake engaged when stationary on inclines, thus reducing the risk of accidents.
Implementation Method 1
A resiliently deformable spring such as a coil spring acts on the second brake element or on a member connected thereto in order to bias it into engagement with the first brake element
Implementation Method 2
The second brake element includes or is connected to a piston in a chamber having a connection to a hydraulic control circuit that is capable of applying pressure to the piston and hence indirectly to the second brake element itself
Implementation Method 3
the vehicle includes an energy convertor for generating energy in the control circuit in proportion to the speed of the vehicle and/or the energy generated by the power source
Data Source
AI summary
A powered vehicle (10) includes a power source for generating energy to power the vehicle; a spring-applied hydraulic release (SAHR) vehicle brake (11) comprising first (12) and second (13) mutually engageable brake elements. The first brake element (12) is secured to or forms part of a rotatable element of the drive train of the vehicle (10) and the second (13) is non-rotatably moveably mounted on the vehicle such that the first and second elements (12,13) are mutually engageable with and separable from one another. Mutual engagement of the brake elements (12,13) causes braking of rotation of the rotatable element, and the SAHR vehicle brake (11) includes (i) a resiliently deformable member (19) acting on the second brake element (13) so as to urge the first and second brake elements (12,13) into mutual engagement and (ii) a non-electric control circuit for applying pressure to the second brake element (13) so as to oppose the action of the resiliently deformable member (19) and thereby normally maintain the first and second brake elements separated from one another. The vehicle (10) includes an energy convertor (28) for generating energy in the control circuit in proportion to the speed of the vehicle and/or the energy generated by the power source, the energy convertor (28) energising the control circuit while the speed of the vehicle and/or the energy generated by the power source exceeds a threshold and de energising the control circuit to permit mutual engagement of the first (12) and second (13) elements under the influence of the resiliently deformable (19) member when the speed of the vehicle and/or the energy generated by the power source is less than the threshold.