Geared-Neutral Transmission Slip Control

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Solution Overview

Problem

Existing methods for slip control in tractor vehicles at low speeds often result in reduced available power for work processes due to changes in drive torque, leading to uncontrolled wheel spin and increased tire wear or damage to road surfaces.

Innovation Solution

A method utilizing a geared-neutral transmission to control drive wheel slip by regulating the transmission ratio independently of engine power, allowing precise control of drive wheel speed and preventing uncontrolled slip, even at low speeds, by decoupling wheel speed from engine power and using sensors for accurate slip determination.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If drive torque is changed by adjusting engine speed to control slip, then slip is optimized, but the power available for work processes is reduced

Engineering Contradiction:
Improveslip controlVSAvoidpower availability
Core Design Contradiction:
ReliabilityVSPower

Solution Approach 1:

The transmission system is segmented into multiple independent control elements: a controllable transmission for ratio adjustment and a torque limiter for torque management. This segmentation allows slip control to be achieved through transmission ratio adjustment rather than engine speed reduction, preserving power availability while maintaining reliable slip control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the control parameter from engine speed to transmission ratio. By adjusting the transmission ratio in the controllable transmission, slip is optimized without reducing engine speed, thereby maintaining power availability for work processes while achieving reliable slip control.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If transmission ratio is controlled using conventional transmissions, then slip can be regulated, but the transmission cannot independently control output speed from input power

Engineering Contradiction:
Improvespeed controlVSAvoidtransmission control capability
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The transmission system is divided into a controllable transmission with independent ratio control and a torque limiter. This segmentation enables the controllable transmission to independently regulate output speed through ratio adjustment without being constrained by input power changes, achieving reliable speed control while maintaining manageable device complexity through functional separation.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The controllable transmission is designed to perform multiple functions: it controls transmission ratio for slip optimization, independently regulates output speed, and works in conjunction with the torque limiter for comprehensive drive control. This multi-functionality enables independent speed control without proportionally increasing device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP2279363B1Method for controlling slip in a tractor vehicle or the like
Publication Date: 2012.08.01 ZF FRIEDRICHSHAFEN AG
  • EP2279363B1 patent drawingFigure 1~2

AI summary

The invention relates to a method and a device for controlling slip in a tractor vehicle or the like. In said method, the slip of the drive wheels is determined, and the gear ratio of a controllable transmission arranged in the drive train is controlled such that the slip is optimized if the actual slip deviates from a predefined target slip (2, 4, 6).  According to the invention, the transmission is a geared-neutral transmission in which the output speed at the full driving power can be adjusted to extremely small values close to a speed of zero.