SAHR Brake Control Modulating Power to Limit Heat
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Solution Overview
Problem
SAHR brakes in large vehicles face overheating issues due to excessive braking power, leading to potential damage and reduced service life, especially when acting on output shafts, and must also function effectively during emergency braking scenarios at various speeds.
Innovation Solution
A method that senses the output shaft speed, generates a deceleration signal, and uses a feedback control scheme to modulate braking power based on the calculated maximum braking power signal, ensuring the brake cooling system's capacity is not exceeded, and switches to open-loop control if sensor inaccuracies are detected to prevent under-braking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the SAHR brake applies high braking power to stop heavy vehicles, then the braking effectiveness is improved, but the heat generation exceeds the cooling capacity leading to brake damage
Solution Approach 1:
The patent applies dynamic control by continuously monitoring output shaft speed and dynamically adjusting braking power through modulation. The braking command is modulated based on calculated maximum braking power signals that vary with operating conditions, transforming the static brake into a dynamically controlled system that adapts braking force to real-time speed conditions, preventing overheating while maintaining stopping effectiveness
Solution Approach 2:
The patent implements feedback control by sensing output shaft speed, calculating deceleration, determining maximum braking power based on heat dissipation capacity, and using this information to modulate the braking command. This closed-loop feedback system ensures braking power remains within thermal limits while achieving required deceleration, directly resolving the contradiction between high braking power and temperature control
2Speed
If the SAHR brake acts on the output shaft to brake heavy vehicles, then the vehicle deceleration is improved, but the heat generated shortens service life or causes failure
Solution Approach 1:
The patent applies preliminary action by calculating the maximum braking power signal in advance based on the brake cooling system's heat dissipation capacity before actual braking occurs. This pre-calculated limit is used to modulate the braking command during operation, preventing excessive heat generation that would shorten service life, while still allowing effective deceleration within safe thermal boundaries
Solution Approach 2:
The feedback control scheme continuously monitors output shaft speed and modulates braking power to maintain it below the maximum braking power signal derived from heat dissipation capacity. This feedback mechanism protects the brake from thermal damage during deceleration events, extending service life while maintaining effective vehicle speed control
3Device complexity
If the brake cooling system capacity is limited, then the system complexity is reduced, but the braking power must be limited to avoid overheating
Solution Approach 1:
The patent uses feedback control to calculate maximum braking power based on the existing cooling system's heat dissipation capacity and uses this calculated limit to modulate braking commands. This allows the brake to operate at high power when needed while automatically limiting power when thermal capacity is approached, effectively managing the contradiction without requiring a more complex cooling system
Solution Approach 2:
The patent changes the operating parameters by dynamically adjusting braking power based on calculated maximum limits derived from cooling capacity. By modulating the braking command as a variable parameter rather than applying fixed high power, the system achieves effective braking while respecting thermal constraints of the existing cooling system
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 approach limits heat generation in the SAHR brake, prolongs its service life, and ensures reliable braking performance even in emergency situations by maintaining a constant braking power and avoiding overheating.
Implementation Method 1
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 2
A resiliently deformable member 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 3
SAHR brake having a pair of friction braking components that in response to a braking power request are mutually engageable to brake the output shaft
Data Source
AI summary
A method of controlling deceleration of a vehicle which includes the steps of sensing the speed of rotation of the output shaft and generating an output shaft speed signal. The method also includes deriving from the output shaft speed signal a deceleration signal indicative of deceleration of the vehicle, and generating in accordance with a selectively effective feedback control scheme a braking command. The method further includes using the output shaft speed signal to calculate a maximum braking power signal and modulating the braking command in dependence on the maximum braking power signal in order to limit the braking power applied in the SAHR brake. The maximum braking power signal is determined in dependence on the heat dissipating capacity of the SAHR brake and is such as to give rise to a constant or approximately constant value of braking power dissipated in the SAHR brake.