Tank Steer Gear Set Assembly for Tighter Vehicle Turns

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Solution Overview

Problem

Existing vehicles are limited by the turning circle of their steering systems, particularly in off-road maneuvers where tighter turns are desired, and current electric tank steer systems are expensive due to the need for multiple electric machines and components.

Innovation Solution

A tank steer gear set assembly using a compound planetary gear set with clutches, allowing selective operation in direct drive and tank steer modes, which reverses the rotation of one axle shaft to enable tighter turns without the need for multiple electric machines.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a tank steer system uses four electric machines and four power inverters to enable tighter turns, then the turning radius is improved, but the system cost and complexity increase significantly

Engineering Contradiction:

Improveturning speedVSAvoidsystem complexity

Core Design Contradiction:

SpeedVSDevice complexity

Solution Approach 1:

The patent divides the tank steer function into two separate axles: the front axle uses a planetary gear set with clutch to enable independent wheel rotation, while the rear axle uses a differential. This segmentation allows the complex tank steer function to be achieved through distributed mechanical components rather than a centralized complex electric system, reducing overall system complexity while maintaining the tight turning capability

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent replaces the proposed electric machine system with a mechanical solution using a planetary gear set, clutch, and differential. The planetary gear set provides the mechanical means to rotate wheels in opposite directions on the front axle, substituting the need for four electric machines and four power inverters, thereby achieving tank steer through pure mechanical means

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Speed

If a tank steer system uses four electric machines and four power inverters to enable tighter turns, then the turning radius is improved, but the manufacturing cost increases

Engineering Contradiction:

Improveturning speedVSAvoidmanufacturing cost

Core Design Contradiction:

SpeedVSEase of manufacture

Solution Approach 1:

The patent employs a planetary gear set and differential assembly that uses conventional, readily available mechanical components rather than expensive electric machines and power inverters. These mechanical components are mature technologies with established manufacturing processes, making the system more cost-effective to manufacture while achieving the same tank steer function

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The planetary gear set serves multiple functions: it enables tank steer mode for tight turns, provides normal driving mode through the differential, and can potentially provide other gear ratios. This multi-functionality eliminates the need for separate electric machines for each function, reducing the overall component count and manufacturing cost

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS12448042B2Tank steer system for vehicle

Publication Date: 2025.10.21 FCA US LLC

AI summary

A tank steer gear set assembly for a vehicle having at least one set of first and second axle shafts. The gear set assembly is configured to be operably coupled between a first portion and a second portion of the second axle shaft, and includes a compound planetary gear set having a carrier, a first clutch, and a second clutch. The gear set assembly operates in a tank steer mode by selectively grounding the carrier via the second clutch such that the second portion of the second axle shaft is rotated in a direction opposite the first axle shaft.