Hydraulic Actuator Control Reducing Valve Dead Time

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Solution Overview

Problem

Hydraulic transmission actuators in motor vehicles face inefficiencies due to dead time between valve position changes, which limits dynamics and optimal operating points, particularly in dual-clutch transmissions.

Innovation Solution

Implementing a combined path and angle control method with a negative overlap valve that cross-fades position and angle control, allowing hydraulic fluid flow from the start of valve switching, thereby reducing dead time and optimizing operating points.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If a traditional valve switching control is used, then the control structure is simple, but dead time occurs between valve position changes which reduces system dynamics

Engineering Contradiction:
Improvesystem dynamicsVSAvoiddead time
Core Design Contradiction:
SpeedVSLoss of time

Solution Approach 1:

The patent applies preliminary action by initiating hydraulic fluid flow before the valve switching is complete. The angular control starts delivering hydraulic fluid during the valve transition phase, so that when the valve reaches its final position, the hydraulic actuator is already in motion or near its target position, eliminating the dead time between valve switching and actuator response.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent ensures continuity of useful action by maintaining hydraulic fluid flow throughout the valve switching process. Instead of having discrete on/off control with gaps, the system provides continuous hydraulic pressure delivery during the entire valve transition, ensuring the actuator receives continuous useful action without interruption or delay.

Inventive Principle:
Principle #20Continuity of useful action

2Speed

If position control is used alone, then the control accuracy is good, but the response speed during valve switching is limited

Engineering Contradiction:
Improveresponse speedVSAvoidcontrol accuracy
Core Design Contradiction:
SpeedVSMeasurement precision

Solution Approach 1:

The patent merges position control and angular control into a hybrid control system. The position control ensures the actuator reaches the correct final position with high accuracy, while the angular control provides rapid response during valve switching by controlling the pump's angular position. The combination of both control modes achieves both fast response and high precision.

Inventive Principle:
Principle #5Merging (Combining)

3Measurement precision

If the valve switching is delayed to ensure position accuracy, then control precision is maintained, but the system dynamics and responsiveness are reduced

Engineering Contradiction:
Improvecontrol precisionVSAvoidsystem responsiveness
Core Design Contradiction:
Measurement precisionVSProductivity

Solution Approach 1:

The system performs preliminary action by starting the hydraulic fluid delivery before the valve switching is complete. The angular control component activates during the valve transition phase, preparing the hydraulic actuator in advance so that position accuracy is achieved without delaying the overall response, thereby maintaining both precision and responsiveness.

Inventive Principle:
Principle #10Preliminary action

4Stability of the object's composition

If the dead time between valve positions is utilized, then the valve switching can be smoother, but the system responsiveness and dynamics are reduced

Engineering Contradiction:
Improvevalve switching smoothnessVSAvoidsystem responsiveness
Core Design Contradiction:
Stability of the object's compositionVSSpeed

Solution Approach 1:

The patent eliminates unused dead time by maintaining continuous useful action during valve switching. The angular control ensures hydraulic fluid flow continues throughout the valve transition, converting what would be dead time into productive action, thus achieving both smooth switching and high responsiveness simultaneously.

Inventive Principle:
Principle #20Continuity of useful action

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This approach enhances the dynamics of hydraulic transmission actuators by reducing unused dead time and ensuring smoother transitions, leading to improved control accuracy and optimized operating points.

Implementation Method 1

a volume flow source (8) is connected to at least one hydraulic cylinder (16, 17) via a pressure line (10) filled with hydraulic fluid

Methodology Applied
Scientific EffectHydraulic fluid pressure transmission: Hydraulic Press

Data Source

PatentEP3523549B1Method for actuating a hydraulic transmission actuator assembly
Publication Date: 2020.07.29 SCHAEFFLER TECHNOLOGIES AG & CO KG
  • EP3523549B1 patent drawingFigure 1
  • EP3523549B1 patent drawingFigure 2
  • EP3523549B1 patent drawingFigure 3a~3d

AI summary

The invention relates to a method for actuating a hydraulic transmission actuator assembly, in which a volume flow source (8) is connected to at least one hydraulic cylinder (16, 17) via a pressure line (6) which is filled with a hydraulic fluid, wherein a volume of the hydraulic fluid is regulated by means of the volume flow source (8). In a method in which the dynamics of the actuation of a hydraulic transmission actuator assembly are improved, regulation is carried out as a combined travel and angle regulation process (25, 26) of the volume flow source (8), wherein the travel regulation process (24) and the angle regulation process (26) are cross-faded with another.