Hierarchical Control for Tandem Axle Mode Switching
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Solution Overview
Problem
Current tandem axle assemblies in vehicles require manual shifting between 6×4 and 6×2 modes, which increases complexity and costs, and result in lower fuel economy compared to vehicles without these assemblies.
Innovation Solution
A hierarchical control system for tandem axle assemblies that includes a vehicle level controller, actuator, and sensor, allowing automatic shifting between 6×4 and 6×2 modes based on parameters like rotational speed and power source conditions, using a dual range axle disconnect system with a planetary inter-axle differential and axle disconnect device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a tandem axle assembly is configured to switch between 6×4 and 6×2 modes automatically using a control system, then fuel economy is improved and operational versatility is enhanced, but device complexity and cost increase
Solution Approach 1:
The control system is divided into multiple hierarchical levels: vehicle level controller, axle level controllers, and actuator controllers. Each level handles specific control functions independently, allowing the system to achieve complex automatic mode switching while distributing complexity across manageable segments rather than requiring a monolithic control system.
Solution Approach 2:
The vehicle level controller serves multiple functions: it monitors overall vehicle operating conditions, coordinates axle disconnect operations, manages power distribution, and interfaces with the transmission system. This multi-functionality reduces the need for separate dedicated controllers for each function, thereby controlling overall system complexity while achieving versatile automatic mode switching.
2Extent of automation
If a tandem axle assembly uses a control system with multiple controllers and sensors to enable automatic shifting, then operational automation is improved, but device complexity and cost increase
Solution Approach 1:
The vehicle level controller is merged with the transmission control system, allowing a single integrated controller to perform both transmission gear management and axle disconnect coordination. This merging reduces the total number of separate controllers needed while maintaining automatic shifting capability.
Solution Approach 2:
The axle level controllers are equipped with onboard sensors that automatically monitor local operating conditions and make real-time control decisions without requiring constant external intervention. The system uses self-service diagnostics and automatic fault detection, reducing the need for additional monitoring sensors and centralized control complexity.
Data Source
AI summary
A hierarchical control system for a tandem axle assembly for a vehicle is provided. The hierarchical control system includes a vehicle level controller, an actuator, a shift controller, and a sensor. The shift controller is capable of placing the tandem axle assembly in at least a first operating condition and a second operating condition using the actuator. In response to the sensor and an operating condition of at least one of the power source and the transmission of the vehicle, the shift controller adjusts a manner of placing the tandem axle assembly in at least one of the first operating condition and the second operating condition. The hierarchical control system facilitates performing a shifting procedure in an automatic manner or as desired by an operator of the vehicle without excessively increasing a cost and a complexity of the tandem axle assembly.