Driveline Retarder Torque Modulation via Speed Feedback
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Solution Overview
Problem
Existing driveline retarder systems face challenges in precisely controlling braking torque, especially when vehicle weight and road grade are difficult to determine, leading to inefficiencies in speed control, particularly on steep grades.
Innovation Solution
A method and system that utilize electronic control units to compare set speed values with current rotational speeds, calculate driveline retarder cruise modulation torque requests based on acceleration, time, and engine load, and adjust the driveline retarder operation accordingly, ensuring precise torque control and adaptive speed management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional driveline retarder systems are used without precise weight and road grade data, then the system structure remains simple, but speed control precision deteriorates on steep grades
Solution Approach 1:
The patent implements a closed-loop control system where the electronic control unit continuously monitors actual vehicle speed via sensors and compares it with the set speed value. Based on this feedback, the ECU dynamically adjusts the driveline retarder torque to maintain precise speed control, resolving the contradiction by using information feedback rather than complex mechanical structures.
Solution Approach 2:
The system uses readily available data from existing vehicle sensors (speed, engine load, transmission state) and combines it with driver inputs (cruise control setpoint) to automatically calculate and adjust retarder torque. This self-service approach achieves precise control without requiring additional complex measurement systems for weight and road grade.
2Stability of the object's composition
If driveline retarder torque is increased to improve speed control on steep grades, then speed stability improves, but energy consumption increases
Solution Approach 1:
The patent implements dynamic torque adjustment where the driveline retarder torque is continuously modified based on real-time conditions including actual speed deviations, engine load state, and transmission gear position. The ECU calculates optimal torque values that provide sufficient braking force for speed stability while minimizing energy consumption by adapting to changing operating conditions rather than applying constant high torque.
Solution Approach 2:
The system changes the operational parameters of the driveline retarder dynamically by adjusting torque magnitude based on speed deviation from setpoint, engine load availability, and transmission state. This parameter adaptation allows the system to use minimal torque when speed is stable and increase torque only when needed, resolving the contradiction between stability and energy consumption.
3Measurement precision
If electronic control algorithms are added to improve torque modulation precision, then control precision improves, but device complexity increases
Solution Approach 1:
The patent integrates the driveline retarder control functionality into the existing electronic control unit that already manages cruise control and transmission operations. By making the ECU multi-functional and reusing existing sensors and communication protocols, the system achieves precise torque modulation without adding separate dedicated control hardware, thus minimizing the increase in device complexity.
Solution Approach 2:
The control algorithms for driveline retarder torque modulation are merged with the existing cruise control and transmission management systems. The ECU combines multiple control functions (cruise control, transmission shifting, retarder modulation) into a unified control architecture that shares computational resources and data pathways, achieving precise control while avoiding the complexity of separate dedicated control systems.
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 enables precise and adaptive control of driveline retarder torque, improving speed management and stability, especially on steep grades, by using closed-loop algorithms and customer-modifiable constants to account for varying conditions.
Implementation Method 1
The driveline retarder employs a rotary member connected to the hub of a transmission output shaft that is operative to circulate fluid between vane members on a stationary housing. The fluid circulation results in power absorption and retardation of the rotational speed of the transmission output shaft.
Implementation Method 2
The duty cycle at which the solenoid valve is actuated or modulated regulates the driveline retarder capacity or the load applied to the output shaft of the transmission and, accordingly, controls the braking activity of the driveline retarder.
Data Source
AI summary
A method of controlling a driveline retarder of a powertrain including a transmission having a rotatable input shaft connected to an engine and an output shaft connected to the driveline retarder is provided. The method includes determining a set speed value and comparing the set speed value plus a customer modifiable constant value to a current rotational speed value of the output shaft. A driveline retarder cruise modulation torque request value is then calculated when the current rotational speed value of the output shaft is greater than or equal to the set speed value plus the customer modifiable constant value. The driveline retarder is controlled as a function of the driveline retarder cruise modulation torque request value. A powertrain configured to implement the aforementioned method is also disclosed.