Wet Clutch Diffusor Pressure Control for Smooth Gear Shifts

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Solution Overview

Problem

The tilting of the piston in wet clutches during gear shifts leads to non-uniform hydraulic pressure, causing shocks and torque oscillations in the driveline, resulting in jerky and unpleasant gear shifts for vehicle drivers and passengers.

Innovation Solution

A pressure control system for the clutch, comprising a piston housing with a piston cavity and a diffusor positioned within the cavity, where the diffusor has tangential channels to direct fluid flow, ensuring smooth gear shifts by maintaining perpendicular alignment of the piston and distributing hydraulic pressure uniformly.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If hydraulic fluid is delivered directly to the piston cavity without a diffusor, then the clutch can engage quickly, but the piston tilts and causes non-uniform pressure leading to shocks and torque oscillations

Engineering Contradiction:

Improveclutch engagement speedVSAvoidpiston tilting and non-uniform pressure

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

A diffusor is introduced as an intermediary component between the hydraulic fluid delivery system and the piston cavity. The diffusor receives hydraulic fluid and distributes it uniformly to the piston cavity, preventing direct impact on the piston that would cause tilting. This intermediary structure enables both quick engagement and uniform pressure distribution.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The diffusor creates local quality differences in the hydraulic fluid distribution within the piston cavity. By providing tangential flow paths, the diffusor ensures that fluid pressure is applied uniformly across different regions of the piston cavity, preventing localized pressure imbalances that would cause piston tilting.

Inventive Principle:

Principle #3Local quality

2Speed

If the piston cavity volume is small, then the clutch responds faster, but the piston alignment is harder to maintain perpendicular to the axial direction

Engineering Contradiction:

Improveclutch response speedVSAvoidpiston alignment stability

Core Design Contradiction:

SpeedVSStability of the object's composition

Solution Approach 1:

The patent utilizes hydraulic principles by designing the diffusor to create tangential fluid flow patterns within the piston cavity. This hydraulic approach uses fluid dynamics to generate forces that maintain piston alignment, allowing for a smaller piston cavity volume while preserving stability through controlled fluid pressure distribution.

Inventive Principle:

Principle #29Pneumatics and hydraulics

3Power

If hydraulic pressure is applied directly to the piston, then torque transfer is faster, but shocks and torque oscillations occur in the driveline

Engineering Contradiction:

Improvetorque transfer speedVSAvoidshocks and torque oscillations

Core Design Contradiction:

PowerVSObject-generated harmful factors

Solution Approach 1:

The diffusor serves as a mediator between the hydraulic pressure source and the piston. It transforms direct pressure application into a controlled tangential flow pattern that gradually builds pressure on the piston, enabling fast torque transfer while preventing sudden pressure spikes that cause shocks and oscillations.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The diffusor structure provides beforehand cushioning by distributing hydraulic pressure through tangential channels before it reaches the piston. This pre-distribution of pressure prevents sudden impacts and cushions the transition, eliminating shocks and torque oscillations during clutch engagement.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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

The pressure control system prevents piston tilting during gear shifts, ensuring smooth torque transfer and eliminating shocks and torque oscillations, thereby enhancing the smoothness and quality of gear shifts.

Implementation Method 1

an inflow of hydraulic fluid into a cavity of a wet clutch piston may apply a non-uniform hydraulic pressure on the piston during engagement of the wet clutch

Methodology Applied

Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 2

The diffusor may have tangential channels for directing flow of a fluid into the piston cavity

Methodology Applied

Scientific EffectFluid flow direction:

Implementation Method 3

a combination of a volume of the piston cavity and a return force exerted by at least one return spring may maintain a perpendicular alignment of the piston with an axial direction

Methodology Applied

Scientific EffectElastic force: Spring

Data Source

PatentUS12292088B2Wet clutch pressure control

Publication Date: 2025.05.06 DANA BELGIUM

AI summary

Methods and systems are provided for a transmission clutch. In one example, the clutch has a pressure control system that includes a piston housing enclosing a piston cavity and a piston, as well as a diffusor positioned in the piston cavity. The diffusor may have tangential channels for directing flow of a fluid into the piston cavity.