Dual-Piston Hydraulic Clutch Actuation for Hysteresis-Free Torque Transfer

Solution Overview

Problem

Existing torque distribution devices in motor vehicles experience hysteresis during transitions between release and sensing positions due to delays in bridging the release clearance, affecting control precision and efficiency.

Innovation Solution

Incorporation of a preloaded spring element that moves the primary piston against the disc pack without delay by using a secondary pressure chamber pressure relief, coupled with a secondary piston and a transmission component, allowing for immediate bridging of the release clearance and hysteresis-free control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If pressure medium is pressed into the primary pressure chamber to compress the disc packs, then the clutch device can be actuated, but the release clearance cannot be bridged immediately causing time delay

Engineering Contradiction:

ImproveResponse speed of clutch actuationVSAvoidTime delay in bridging release clearance

Core Design Contradiction:

SpeedVSLoss of time

Solution Approach 1:

The secondary piston is pre-loaded by the spring element in the opposite direction to the primary piston's actuating movement. When pressure relief occurs in the secondary pressure chamber, the pre-loaded spring element immediately presses the primary piston against the disc pack, bridging the release clearance without delay. This preliminary positioning of the spring element enables instantaneous response when needed.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The spring element is pre-loaded in the direction opposite to the primary piston's actuating movement by the secondary piston. This creates a counter-balancing force that is ready to act immediately when the secondary pressure chamber is relieved, preventing the time delay that would otherwise occur while waiting for primary pressure chamber pressurization to bridge the release clearance.

Inventive Principle:

Principle #9Preliminary anti-action

2Adaptability or versatility

If a tandem arrangement with two pressure pistons is used, then torque distribution control is achieved, but hysteresis occurs during transitions between release and sensing positions

Engineering Contradiction:

ImproveTorque distribution control capabilityVSAvoidControl precision due to hysteresis

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The spring element is pre-loaded in the direction opposite to the primary piston's actuating movement by the secondary piston. This creates a counter-balancing force that is ready to act immediately when the secondary pressure chamber is relieved, preventing the time delay that would otherwise occur while waiting for primary pressure chamber pressurization to bridge the release clearance.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The secondary piston is pre-loaded by the spring element in the opposite direction to the primary piston's actuating movement. When pressure relief occurs in the secondary pressure chamber, the pre-loaded spring element immediately presses the primary piston against the disc pack, bridging the release clearance without delay. This preliminary positioning of the spring element enables instantaneous response when needed.

Inventive Principle:

Principle #10Preliminary 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

Enables rapid and hysteresis-free transitions between clutch positions, enhancing control precision and efficiency by eliminating delays in the torque distribution process.

Implementation Method 1

a spring element is movable, and the spring element is coupled to the primary piston in such a way that it moves the primary piston against the external disc pack when the pressure in the secondary pressure chamber is reduced

Methodology Applied

Scientific EffectSpring element restoring force: Spring

Implementation Method 2

when the pressure medium or a pressure medium located in the secondary chamber is pressurized

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Increase

Data Source

PatentUS12352320B2Torque distribution device for a motor vehicle having two dual piston hydraulic clutches, and method for operating the torque distribution device

Publication Date: 2025.07.08 SCHAEFFLER TECHNOLOGIES AG & CO KG

AI summary

A torque distribution device includes a rotor support, an internal disc carrier, a clutch device including a disc pack and an actuation device for actuating the clutch device. The actuation device includes a stationary holding element, a spring element, and primary and secondary pistons axially displaceably mounted on the holding element. The primary piston delimits a primary pressure chamber and is arranged to be moved in a first axial direction against the disc pack the primary pressure chamber is pressurized. The secondary piston delimits a secondary pressure chamber and is movable counter to a restoring force of the spring element in a direction opposite the first axial direction the secondary pressure chamber is pressurized. The spring element is coupled to the primary piston to move the primary piston in the direction opposite the first axial direction when the secondary pressure chamber is depressurized.