CVT Powertrain Rotation Detector Logic for Fail-Safe Shift Control

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Solution Overview

Problem

Existing continuously variable powertrain devices for work vehicles face challenges in accurately and promptly determining the abnormality of duplicated rotation detectors, which are crucial for stepless shift control. Additionally, there is a need to efficiently detect the rotation speed of each transmission element to ensure proper shift control and achieve fail-safe conditions.

Innovation Solution

The proposed solution involves a continuously variable powertrain device that includes a rotation detector group with multiple detectors for engine, continuously variable, composite, and travel rotation speeds. A powertrain controller is programmed to generate control signals for the transmission components and function as a determiner to assess the abnormality of the rotation detector group using predefined rules based on the operation conditions of the planetary clutch mechanism and the forward-reverse direction switcher.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple rotation detectors are duplicated for fail-safe control, then reliability is improved, but device complexity increases

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies the copying principle by duplicating rotation detectors to create redundant detection systems. Multiple rotation detectors are installed to detect the same rotational parameters, and when one detector fails, the system can switch to or reference the other detectors to maintain continuous operation. This redundancy directly improves reliability while the complexity increase is managed through systematic evaluation methods.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent implements feedback mechanisms by continuously monitoring the outputs of multiple rotation detectors and comparing their readings. The system evaluates detection signals from all detectors in real-time, and when discrepancies or failures are detected, the feedback loop triggers abnormality determination processes and switches to backup detectors or alternative evaluation methods, ensuring continuous reliable operation.

Inventive Principle:
Principle #23Feedback

2Reliability

If multiple rotation detectors are used for abnormality determination, then reliability is improved, but the difficulty of detecting and measuring increases

Engineering Contradiction:
ImprovereliabilityVSAvoiddifficulty of detecting and measuring
Core Design Contradiction:
ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent applies segmentation by dividing the abnormality determination process into distinct stages: signal acquisition from multiple detectors, preliminary consistency checking, abnormality evaluation based on predetermined criteria, and final determination. This segmented approach breaks down the complex task of evaluating multiple detectors into manageable steps, reducing the overall difficulty while maintaining high reliability through systematic analysis.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent implements preliminary action by establishing predetermined abnormality determination rules and evaluation criteria before actual operation. The system pre-configures threshold values, comparison methods, and decision logic for evaluating detector outputs. When detectors are deployed, these pre-established rules are immediately applied, eliminating the need for complex real-time analysis and simplifying the detection and measurement process while ensuring reliable abnormality identification.

Inventive Principle:
Principle #10Preliminary action

3Reliability

If rotation detectors are duplicated for fail-safe operation, then reliability is improved, but loss of time increases due to examination required

Engineering Contradiction:
ImprovereliabilityVSAvoidloss of time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent maintains continuity of useful action by implementing real-time continuous monitoring of all rotation detectors throughout system operation. Instead of periodically checking detector status, the system continuously evaluates detection signals from all detectors simultaneously, ensuring that abnormality determination occurs without interruption. This continuous evaluation eliminates downtime and ensures immediate detection and response to detector failures, maintaining reliable operation without time loss.

Inventive Principle:
Principle #20Continuity of useful action

Solution Approach 2:

The patent applies the skipping principle by implementing streamlined abnormality determination processes that rapidly evaluate detector outputs against predetermined criteria. When a potential abnormality is detected, the system immediately rushes through the evaluation steps using pre-configured rules and thresholds, bypassing lengthy analysis procedures. This allows quick determination of detector status and rapid switching to backup systems if needed, minimizing time loss while maintaining high reliability through thorough yet efficient evaluation.

Inventive Principle:
Principle #21Skipping (Rushing through)

Data Source

PatentEP4372249B1Continuously variable powertrain device for work vehicle and work vehicle including the same
Publication Date: 2025.05.14 KUBOTA CORP
  • EP4372249B1 patent drawingFigure 1
  • EP4372249B1 patent drawingFigure 2
  • EP4372249B1 patent drawingFigure 3

AI summary

A continuously variable powertrain device for a work vehicle includes a continuously variable transmission (28) configured to output a continuously shifted motive power while continuously varying a speed of the motive power received from an engine (4), a planetary transmission (31) configured to receive the motive power from the engine (4) and the continuously shifted motive power and to output a compound motive power, a planetary clutch mechanism (37) configured to switch a shift level of the planetary transmission (31), a forward-reverse direction switcher (23) configured to receive the compound motive power and to output either a forward motive power or a reverse motive power, a rotation detector group (70) including a plurality of rotation detectors, and a powertrain controller (50).