Disk Brake Wear Adjustment for Hydraulic Parking Brake Reliability

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Solution Overview

Problem

Existing hydraulically operated disc brakes with parking brakes do not have a mechanism for automatically compensating for wear of the friction linings of the brake pads, leading to reduced braking efficiency over time.

Innovation Solution

Incorporation of an automatic wear take-up unit of the screw-nut type within the brake caliper, featuring a take-up screw and nut connected to the primary piston and housing, respectively, with a spring to maintain axial length adjustment, ensuring consistent braking performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a hydraulically operated disc brake with parking brake is designed without a wear compensation mechanism, then the device complexity is reduced, but the braking efficiency deteriorates over time due to friction lining wear

Engineering Contradiction:
Improvebraking efficiencyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The wear compensation mechanism automatically adjusts the axial position of the primary piston to compensate for friction lining wear without external intervention. The screw-nut assembly with spring automatically takes up the axial play created by wear, maintaining consistent braking efficiency throughout the service life of the brake pads.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The mechanism changes the axial position parameter of the primary piston to compensate for wear. By adjusting the axial length of the piston assembly through the screw-nut mechanism, the system maintains the correct clearance and braking force despite the reduction in friction lining thickness over time.

Inventive Principle:
Principle #35Parameter changes

2Duration of action of stationary object

If an automatic wear compensation mechanism is added to the brake, then the operational life is extended, but the device complexity increases

Engineering Contradiction:
Improveoperational lifeVSAvoiddevice complexity
Core Design Contradiction:
Duration of action of stationary objectVSDevice complexity

Solution Approach 1:

The wear compensation mechanism is integrated into the existing brake caliper structure. The adjusting screw and nut are incorporated within the primary piston assembly, and the spring is housed within the same cavity, merging multiple functions into a compact unit that extends operational life without proportionally increasing overall device complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The screw-nut wear compensation mechanism is nested within the primary piston assembly. The adjusting screw is positioned inside the primary piston, the nut is threaded onto the screw, and the spring is contained within the same hydraulic cavity, creating a nested arrangement that maximizes space utilization and minimizes the increase in device complexity.

Inventive Principle:
Principle #7Nested doll (Nesting)

3Stability of the object's composition

If a spring is used to maintain axial length in the wear compensation mechanism, then the braking force consistency is improved, but the device complexity increases

Engineering Contradiction:
Improvebraking force consistencyVSAvoiddevice complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The spring is pre-loaded to constantly stress the screw and nut assembly in the direction of increasing axial length. This preliminary action ensures that the wear compensation mechanism is always ready to take up axial play as soon as wear occurs, maintaining consistent braking force without requiring active control or additional components.

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

The solution effectively compensates for brake pad wear, maintaining braking force and efficiency by automatically adjusting the axial length, thereby extending the brake's operational life and reliability.

Implementation Method 1

which includes an adjusting spring which is interposed between the adjusting screw and the adjusting nut, and which constantly stresses the two elements in the direction of increasing the total axial length of the automatic wear compensation group

Methodology Applied
Scientific EffectSpring: Spring

Implementation Method 2

at least one primary piston which is mounted to slide axially in a sealed manner within the primary hydraulic cavity of the housing in which the primary piston axially delimits a primary hydraulic chamber

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 3

a wheel, for axially locking the piston rod, which is mounted screwed, reversibly, onto the threaded section of the piston rod

Methodology Applied
Scientific EffectScrew thread: Screw

Data Source

PatentEP3087287B1Disk brake comprising a hydraulic actuation parking brake and a wear adjustment unit
Publication Date: 2021.01.27 CHASSIS BRAKES INT BV
  • EP3087287B1 patent drawingFigure 1~2
  • EP3087287B1 patent drawingFigure 3
  • EP3087287B1 patent drawingFigure 4~7

AI summary

The invention relates to a disk brake that comprises a piston, a piston rod (120), a wheel (140) for axially locking the piston rod (120), a motor for electrically rotating the locking wheel (140), and a transverse axial abutment plate (100). Said disk brake is characterized in that it comprises an automatic wear adjustment unit (44, 46), one of the two elements of which is non-rotatable. The piston rod (120) comprises a rotation lock section (126) that extends through a central hole (112) of the transverse abutment plate (100), and the non-rotatable element, either an adjustment screw or an adjustment nut, is rotatably connected to the piston rod (120).