CVT Torque Limit Abnormality Detection

Solution Overview

Problem

Existing continuously variable transmission systems lack effective detection mechanisms for abnormal torque limits, leading to unintended vehicle deceleration due to hardware faults or errors in control systems, which can result in adverse driving experiences.

Innovation Solution

An abnormality detection device that sets and calculates torque limits based on driver-requested acceleration, running resistance, and gear ratios, determining abnormal conditions by comparing set torque limits with determination torque, and stopping abnormal torque outputs to prevent unintended deceleration.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the upper limit of torque is set based on allowable input torque for the continuously variable transmission, then the transmission is protected from damage, but the vehicle may experience unintended deceleration when the upper limit becomes abnormal due to hardware faults or errors

Engineering Contradiction:

Improvetransmission protectionVSAvoidvehicle acceleration performance

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The system performs preliminary detection of abnormality in the upper limit of torque before it causes unintended deceleration. The determination module checks whether the upper limit is abnormal by comparing it with a calculated determination torque, and prevents adverse effects by identifying the abnormality in advance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system establishes a feedback mechanism where the abnormality detection result is used to adjust or correct the torque control. When abnormality is detected, the system can take corrective actions to prevent unintended deceleration, creating a closed-loop control system that monitors and responds to upper limit abnormalities.

Inventive Principle:

Principle #23Feedback

2Reliability

If the upper limit of torque is used to limit engine output torque, then the continuously variable transmission is protected, but it becomes difficult to determine whether the upper limit is abnormal since the same value may be normal or abnormal depending on gear ratio and driving conditions

Engineering Contradiction:

Improvetransmission protectionVSAvoidabnormality detection accuracy

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The system changes the parameter used for abnormality detection from a fixed threshold to a dynamic determination torque that is calculated based on multiple variables including gear ratio, vehicle speed, and driving conditions. This allows the detection criterion to adapt to different operating conditions, improving detection accuracy.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The determination torque acts as an intermediary value that mediates between the upper limit of torque and the abnormality determination. Instead of directly comparing the upper limit with a fixed threshold, the system introduces the calculation module that generates determination torque based on current operating conditions, making the abnormality detection more accurate.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If hardware faults or errors occur in the electrical control device, then the upper limit of torque may have abnormal values, but existing systems lack detection mechanisms to identify these abnormalities

Engineering Contradiction:

Improvefault toleranceVSAvoidcontrol system stability

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The system performs preliminary detection of abnormality in the upper limit of torque before it causes unintended deceleration. The determination module checks whether the upper limit is abnormal by comparing it with a calculated determination torque, and prevents adverse effects by identifying the abnormality in advance.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system establishes a feedback mechanism where the abnormality detection result is used to adjust or correct the torque control. When abnormality is detected, the system can take corrective actions to prevent unintended deceleration, creating a closed-loop control system that monitors and responds to upper limit abnormalities.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS9671015B2Abnormality detection device for continuously variable transmission and method of detecting abnormality of the continuously variable transmission

Publication Date: 2017.06.06 SUBARU CORP

AI summary

An abnormality detection device includes: a torque upper limit setting module that sets an upper limit of torque based on an allowable input torque for the continuously variable transmission, the upper limit of torque limiting an output torque of an engine; a determination torque calculation module that determines an acceleration requested by a driver based on an amount of operation of an accelerator, obtains a running resistance of a vehicle according to the requested acceleration, and calculates a determination torque for determining abnormality of the upper limit of torque based on the running resistance of the vehicle and a gear ratio of the continuously variable transmission; and an abnormality determination module that determines the upper limit of torque to be abnormal in the case where the upper limit of torque is less than or equal to the determination torque.