Separating Clutch Control via Differential Speed Feedback

Solution Overview

Problem

Hybrid vehicles experience discomfort due to inaccuracies in power transmission factors caused by component tolerances and wear, leading to unintended disengagement of the separating clutch during slip decoupling.

Innovation Solution

A method that determines a corrected power transmission factor and actuating pressure based on the deviation between target and actual differential speeds, using a controller to adjust the clutch control, ensuring the desired slip differential speed is maintained, and adaptively updating the characteristic map to compensate for component changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a power transmission factor is determined based on a previously empirically ascertained characteristic map, then the clutch can be controlled with a defined actuating pressure to achieve a target differential speed, but component tolerances and wear cause the power transmission factor to become inaccurate, leading to unintended disengagement and reduced comfort

Engineering Contradiction:

Improveclutch engagement stabilityVSAvoidpower transmission factor accuracy

Core Design Contradiction:

ReliabilityVSMeasurement precision

Solution Approach 1:

The control unit continuously monitors the actual differential speed at the separating clutch and compares it to the target differential speed. Based on this feedback, the controller dynamically adjusts the actuating pressure to compensate for deviations caused by component tolerances and wear, thereby maintaining reliable clutch engagement and preventing unintended disengagement.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system dynamically changes the actuating pressure parameter based on real-time operating conditions and deviations from target differential speed. By adjusting this critical parameter, the control unit compensates for inaccuracies in the power transmission factor caused by component variations and wear, ensuring accurate clutch control throughout the component lifecycle.

Inventive Principle:

Principle #35Parameter changes

2Ease of operation

If the separating clutch is controlled with a defined actuating pressure to achieve slip decoupling, then the desired target differential speed can be set, but inaccuracies in the power transmission factor cause the clutch to break loose, adversely affecting comfort

Engineering Contradiction:

Improveslip decoupling controlVSAvoidcomfort during operation

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The control unit continuously monitors the actual differential speed at the separating clutch and compares it to the target differential speed. Based on this feedback, the controller dynamically adjusts the actuating pressure to compensate for deviations caused by component tolerances and wear, thereby maintaining reliable clutch engagement and preventing unintended disengagement.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from a static, pre-determined actuating pressure based on empirical characteristic maps to a dynamic control approach where the actuating pressure is continuously adjusted in real-time. This dynamic adaptation ensures smooth and reliable slip decoupling control throughout the component lifecycle, maintaining comfort even as components wear.

Inventive Principle:

Principle #15Dynamics

3Adaptability or versatility

If a characteristic map with power transmission factors is stored on the control side for multiple support points, then the clutch can be controlled for various torques and differential speeds, but the map becomes inaccurate due to component tolerances and wear, requiring frequent recalibration

Engineering Contradiction:

Improveclutch control for various conditionsVSAvoidcharacteristic map accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The control unit continuously monitors the actual differential speed at the separating clutch and compares it to the target differential speed. Based on this feedback, the controller dynamically adjusts the actuating pressure to compensate for deviations caused by component tolerances and wear, thereby maintaining reliable clutch engagement and preventing unintended disengagement.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system transitions from a static, pre-determined actuating pressure based on empirical characteristic maps to a dynamic control approach where the actuating pressure is continuously adjusted in real-time. This dynamic adaptation ensures smooth and reliable slip decoupling control throughout the component lifecycle, maintaining comfort even as components wear.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentUS10781870B2Control unit for a motor vehicle, and method to control the motor vehicle

Publication Date: 2020.09.22 ZF FRIEDRICHSHAFEN AG

AI summary

A method for operating a motor vehicle includes, when a target differential speed is set for a separating clutch (4), determining a power transmission factor depending on the target differential speed and an internal combustion engine-driven torque to be transmitted by the separating clutch (4). The method also includes determining an actuating pressure for the separating clutch (4) depending on the power transmission factor, controlling the separating clutch (4) with the actuating pressure, ascertaining an actual differential speed forming at the separating clutch (4) depending on the actuating pressure, determining a corrected power transmission factor with a controller (10) depending on a deviation between the target differential speed and the actual differential speed, determining a corrected actuating pressure for the separating clutch (4) depending on the corrected power transmission factor and the internal combustion engine-driven torque to be transmitted, and controlling the separating clutch (4) with the corrected actuating pressure.