Shift Drum Calibration Using Single End-Stop Verification

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Solution Overview

Problem

Existing methods for calibrating shift drums in motor vehicle transmissions require the vehicle to be stationary, which is inefficient and causes noise and vibrations, and do not allow for reliable and quick calibration under dynamic conditions.

Innovation Solution

A method that calibrates a rotatable shift drum by rotating it to one end stop position, verifying it, and then rotating it again to confirm the position, allowing calibration to occur under various vehicle conditions without jamming or incorrect measurement, using a single end stop position and torque application to clear locked conditions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the shift drum is calibrated by rotating it to both upper and lower stops while the vehicle is stationary, then the calibration can be performed safely with the combustion engine idling, but the process takes 4-5 seconds per shift drum and causes noise and vibrations in the transmission

Engineering Contradiction:

Improvecalibration reliabilityVSAvoidcalibration speed

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The calibration process is segmented into two distinct phases: a quick initial calibration phase that rotates the shift drum only to the upper stop, and a verification phase that checks the calibrated position. This segmentation allows the system to achieve faster calibration while maintaining reliability through the separate verification step.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of rotating the shift drum to both upper and lower stops as in traditional calibration, the invention uses partial action by rotating the shift drum only to the upper stop for initial calibration. The verification phase then ensures accuracy without requiring full rotation to both limits, reducing calibration time and transmission noise.

Inventive Principle:

Principle #16Partial or excessive action

2Measurement precision

If the shift drum is calibrated by rotating it to both upper and lower stops, then the position can be verified, but the calibration causes noise and vibrations and requires the vehicle to be stationary

Engineering Contradiction:

Improveposition verification accuracyVSAvoidnoise and vibrations

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The invention uses partial rotation to the upper stop only for calibration, avoiding the need to rotate to both upper and lower stops. The verification is performed by checking the position at the upper stop, which provides sufficient accuracy without causing the noise and vibrations associated with rotating through all gear positions to both limits.

Inventive Principle:

Principle #16Partial or excessive action

Solution Approach 2:

The system performs preliminary calibration by rotating the shift drum to the upper stop and storing this position. The verification is then performed as a separate preliminary check before normal operation begins, ensuring accuracy without requiring the vehicle to remain stationary for extended periods.

Inventive Principle:

Principle #10Preliminary action

3Reliability

If the shift drum position is lost and recalibration is performed, then the transmission control can be reset, but the process requires the vehicle to be stationary and the combustion engine to be idling

Engineering Contradiction:

Improvetransmission control reliabilityVSAvoidcalibration condition flexibility

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The calibration method transitions from a static process (requiring the vehicle to be stationary) to a dynamic process that can be performed during vehicle operation. The simplified upper-stop-only calibration can be executed while the vehicle is moving, making the system adaptable to various driving conditions and eliminating the need for the vehicle to be stationary.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system performs preliminary calibration actions by rotating the shift drum to the upper stop and storing the position, which can be done quickly under various vehicle conditions. This preliminary calibration maintains transmission control reliability without requiring the vehicle to be stationary or the engine to be idling.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentEP3770467B1Method for calibrating at least one shift drum and transmission control

Publication Date: 2021.12.15 MAGNA PT B V & CO KG

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AI summary

Method for calibrating at least one rotatable shift drum in a powertrain of a motor vehicle, wherein the powertrain comprises an internal combustion engine and a transmission and at least one control unit, and the shift drum is limited against rotation in at least one of the two directions of rotation, wherein, in a first method step, the shift drum is rotated in one of the two directions of rotation up to the limit for the purpose of calibrating the rotational position, wherein this rotational position is stored in the control unit as an end stop position, and the stored end stop position is subjected to verification.