Wet Brake Disc Stack Radial Coolant Flow

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Solution Overview

Problem

Existing wet brake assemblies face issues with elevated coolant pressure causing seal leaks due to restricted coolant flow through the disc stack, which can lead to system failures and reduced longevity of the final drive.

Innovation Solution

The brake assembly design includes a coolant inlet and outlet with axial and radial passages in the disc stack, directing coolant from the outer periphery radially inward and then axially out, reducing pressure at the seal interface and minimizing restrictions to maintain low pressures and prevent seal leakage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If coolant is supplied to the inner periphery of the disc stack, then cooling of the brake is achieved, but coolant pressure increases upstream of the disc stack causing seal leaks

Engineering Contradiction:

Improvebrake coolingVSAvoidseal leakage

Core Design Contradiction:

TemperatureVSReliability

Solution Approach 1:

The patent inverts the conventional coolant flow direction by supplying coolant to the outer periphery of the disc stack instead of the inner periphery. This reversal allows coolant to flow radially inward through the disc stack, cooling the brake components while directing high-velocity flow away from the seal interface, thereby preventing seal leakage caused by elevated upstream pressure.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent implements different flow characteristics in different regions of the disc stack. By supplying coolant to the outer periphery, the system creates a localized high-velocity flow path through the friction and separator plates that does not directly impinge on the seal interface. This local differentiation allows effective cooling while maintaining low pressure at the seal location.

Inventive Principle:

Principle #3Local quality

2Strength

If coolant flow restrictions are present in the disc stack, then structural integrity is maintained, but coolant pressure increases causing seal failures

Engineering Contradiction:

Improvedisc stack structural integrityVSAvoidseal reliability

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the flow path from axial (through the thickness of the disc stack) to radial (from outer periphery to inner periphery). This dimensional change in flow direction allows the coolant to pass through the disc stack structure without creating high upstream pressure at the seal interface, as the radial flow path naturally directs high-velocity coolant away from the axial seal location.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Temperature

If coolant is directed axially through the disc stack, then cooling efficiency is improved, but pressure buildup occurs upstream causing seal leaks

Engineering Contradiction:

Improvecooling efficiencyVSAvoidcoolant pressure upstream

Core Design Contradiction:

TemperatureVSStress or pressure

Solution Approach 1:

The patent inverts the conventional axial flow direction by implementing radial flow from the outer periphery inward. This inversion allows coolant to cool the disc stack effectively while the flow direction naturally prevents pressure buildup upstream of the seal, as the high-velocity radial flow moves away from the seal interface rather than toward it.

Inventive Principle:

Principle #13The other way round (Inversion)

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 design effectively reduces coolant pressure at the seal interface, enhancing the longevity of the final drive by preventing seal leaks and ensuring efficient cooling of the brake components.

Implementation Method 1

directing coolant from the outer periphery radially inward through the disc stack

Methodology Applied

Scientific EffectHeat transfer: Convection

Implementation Method 2

a seal located at an axial interface between the stationary housing and the rotatable member and downstream of the disc stack relative a flow of coolant

Methodology Applied

Scientific EffectSealing:

Data Source

PatentUS9169884B2Wet brake assembly

Publication Date: 2015.10.27 CATERPILLAR INC

AI summary

A brake assembly for a mobile machine is disclosed. The brake assembly may have a stationary housing forming a coolant inlet and a coolant outlet, a rotatable member, and a disc stack disposed within a cavity at least partially formed by the stationary housing and the rotatable member. The disc stack may have a plurality of friction plates operatively coupled to the rotatable member and a plurality of separator plates interleaved with the plurality of friction plates and operatively coupled to the stationary housing. The brake assembly may also have a piston disposed within the cavity and configured to compress the disc stack, and a seal located at an axial interface between the stationary housing and the rotatable member and downstream of the disc stack relative a flow of coolant from the coolant inlet to the coolant outlet.