Tank Steer Drivetrain Assembly With Differential Case Grounding
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Solution Overview
Problem
Existing vehicles are limited by the turning circle of their steering systems, particularly in off-road conditions, and existing tank steer systems are expensive due to the need for multiple electric machines and components.
Innovation Solution
A drivetrain assembly with a gearbox, planetary gear set, and differential that allows for independent wheel rotation on opposite sides of the vehicle, utilizing selectable connectors and a pawl to achieve a tank steer mode, reducing the need for multiple electric machines.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If a tank steer system uses four electric machines and four power inverters to rotate wheels independently, then the vehicle achieves tighter turning radius, but the system cost increases significantly
Solution Approach 1:
The patent combines multiple functions into a single drivetrain assembly that integrates a differential, planetary gear set, and selectable connectors. This single assembly can operate in both conventional differential mode and tank steer mode, eliminating the need for separate electric machines and power inverters at each wheel, thereby significantly reducing system cost while maintaining tight turning capability
Solution Approach 2:
The drivetrain assembly is designed with multi-functionality to perform both conventional driving and tank steer operations. The differential case can be selectively grounded to enable the same assembly to provide either normal differential action or tank steer mode, making the system versatile and eliminating the need for separate dedicated tank steer components
2Device complexity
If a vehicle uses a conventional steering system while rolling, then the system structure is simple, but the vehicle cannot achieve tight turns when obstacles block the forward path
Solution Approach 1:
The system dynamically switches between conventional steering mode and tank steer mode based on driving conditions. The selectable connectors allow the drivetrain to transition from normal differential operation to tank steer operation, enabling the vehicle to adapt its turning capability dynamically without requiring a completely different steering system structure
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
Enables tighter vehicle turns without the high cost of existing systems, by rotating wheels on opposite sides to achieve a tighter turning radius with a single drivetrain assembly.
Implementation Method 1
a planetary gear set selectively coupled to an output of the gearbox assembly
Implementation Method 2
a pawl configured to ground the differential case in the tank steer mode
Implementation Method 3
the pawl is hinged to a ground and is spring-loaded to engage the differential case
Data Source
AI summary
A drivetrain assembly for a vehicle having a propulsion system configured to drive first and second half shafts is provided. In one example, the drivetrain assembly includes a gearbox assembly configured to couple to the propulsion system, a planetary gear set selectively coupled to an output of the gearbox assembly, and a differential having a differential case, the differential configured to operably couple to the first and second half shafts. The drivetrain assembly operates in a tank steer mode by selectively grounding the differential case and connecting the output of the gearbox assembly to the first half shaft via the planetary gear set, such that the propulsion system rotates the first half shaft in the first direction and, via the differential, rotates the second half shaft in the opposite second direction.