Clutch Piston Sealed Dead Space for Fast Refill

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Solution Overview

Problem

Hydraulically actuated clutch devices in vehicles experience poor response behavior due to overpressure effects from rotation, leading to clutch slipping or delayed engagement, especially in automatic start-stop systems, where the compensating chamber is not fully filled with oil in time.

Innovation Solution

Incorporating a sealed dead space between the piston volume and the compensating chamber, allowing for independent geometry selection of the compensating chamber, and using a rigid connection between the compensating chamber and piston, along with a plate spring or helical compression springs to transmit restoring forces, optimizing the volume ratios and surface positions to reduce filling time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the compensating chamber is directly adjacent to the piston, then the pressure compensation effect is improved, but the filling time of the compensating chamber increases

Engineering Contradiction:
Improvepressure compensation effectVSAvoidfilling time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent divides the space between the piston and the compensating chamber into a sealed dead space, separating the compensating chamber from direct adjacency to the piston. This segmentation allows the compensating chamber to be filled more quickly while maintaining its pressure compensation function, as the dead space acts as an isolated volume that does not require filling.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sealed dead space acts as an intermediary element between the piston and the compensating chamber. It provides a buffer volume that is sealed off from both the piston volume and the compensating chamber, allowing the compensating chamber to be positioned away from the piston without compromising the pressure compensation effect, thus reducing filling time.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of time

If the compensating chamber volume is reduced, then the filling time is decreased, but the pressure compensation capability is weakened

Engineering Contradiction:
Improvefilling timeVSAvoidpressure compensation capability
Core Design Contradiction:
Loss of timeVSReliability

Solution Approach 1:

The plate spring or helical compression springs provide a counteracting force that compensates for the reduced volume of the compensating chamber. This mechanical restoring force ensures that the pressure compensation capability is maintained even when the compensating chamber volume is minimized, allowing rapid filling while preserving functionality.

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent changes the parameters of the system by introducing a sealed dead space and using spring elements to provide restoring force. This allows the compensating chamber volume to be optimized for rapid filling while the spring mechanism compensates for the reduced volume, maintaining the necessary pressure compensation capability.

Inventive Principle:
Principle #35Parameter changes

3Loss of time

If a sealed dead space is introduced between the piston volume and compensating chamber, then the filling time is reduced, but the device complexity increases

Engineering Contradiction:
Improvefilling timeVSAvoidstructural complexity
Core Design Contradiction:
Loss of timeVSDevice complexity

Solution Approach 1:

The sealed dead space is integrated into the existing clutch device structure, combining the pressure compensation function with the piston assembly. The dead space is sealed off from both the piston volume and compensating chamber, creating a compact arrangement that reduces filling time without adding significant structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The sealed dead space serves multiple functions: it acts as a buffer volume, provides structural support for the compensating chamber positioning, and works in conjunction with the plate spring or helical compression springs to maintain pressure compensation. This multi-functionality reduces the need for additional separate components, minimizing the increase in device complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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 configuration reduces the time required to refill the compensating chamber, improves clutch response, and maintains functionality by minimizing the influence of rotational pressures, enhancing starting performance in vehicles with automatic start-stop systems.

Implementation Method 1

using a rigid connection between the compensating chamber and piston, along with a plate spring or helical compression springs to transmit restoring forces

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

hydraulic oil or a liquid acting as hydraulic oil or hydraulic fluid is pressed into a piston, which in turn acts on the friction linings of the clutch

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 3

The actuation, ie the opening or closing of the clutch, in order to interrupt or establish a frictional connection between two components connected to the clutch, can take place automatically or through direct interaction of a user

Methodology Applied
Scientific EffectPascal's law: Pascal's Law

Implementation Method 4

compensating volumes or compensating chambers are often also provided, which serve to compensate for the overpressure generated by the rotation in the liquid located within the piston volume

Methodology Applied
Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentEP2817527B1Clutch device
Publication Date: 2015.12.30 ZF FRIEDRICHSHAFEN AG
  • EP2817527B1 patent drawingFigure 1
  • EP2817527B1 patent drawingFigure 2~3

AI summary

A clutch device (2) has a hydraulically actuatable piston (10) that can be moved in an axial direction (14) by filling a piston volume (12) with a fluid, and a disc pack (4) that can be actuated by the piston (10) comprising at least one friction lining. A closed equalisation chamber (22) is arranged on a side of the piston (10) opposite the piston volume (12) and can be filled with a fluid, wherein a sealed dead space (26) is arranged in the axial direction (14) between the piston volume (12) and the equalisation chamber (22).