Drum Brake Actuator Elastic Stop for Release Shock Protection

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Solution Overview

Problem

Existing electromechanical drum brake actuators face issues with premature damage due to sudden contact between the nut and housing during brake release, leading to increased current consumption and risk of motor overload, which can result in actuator damage after numerous cycles.

Innovation Solution

Incorporating an elastic stop mechanism between the drive system and the actuator housing to absorb the force progressively, allowing the control unit to detect the increase in current consumption and stop the motor before contact, thus preventing damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the nut is rotated by the electric motor during brake release, then the pistons are brought together and the brake is released, but the nut comes into sudden contact with the housing bottom causing damage and increased current consumption

Engineering Contradiction:
Improveactuator service lifeVSAvoidsudden contact damage
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

An elastic element is introduced between the nut and the housing bottom to provide cushioning before contact occurs. This elastic element absorbs the impact energy during brake release, preventing sudden contact damage to the actuator components and extending service life.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The elastic element acts as an intermediary between the nut and the housing bottom. Instead of direct contact between the rigid nut and housing, the elastic element mediates the interaction, distributing forces and preventing damage while still allowing the brake release function to occur.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Reliability

If the control unit continues motor activation after brake release, then the brake remains released, but current consumption increases sharply and motor damage risk increases

Engineering Contradiction:
Improvemotor protectionVSAvoidcurrent consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

The control unit monitors current consumption as feedback during brake release. When the elastic element is compressed and current consumption increases, the control unit detects this signal and stops motor activation, preventing both energy waste and potential motor damage from excessive current.

Inventive Principle:
Principle #23Feedback

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 elastic stop mechanism extends the lifespan of the actuator by preventing sudden shocks and allowing sufficient time for the control unit to stop the motor, reducing wear and tear, and ensuring the actuator can operate for approximately 250,000 cycles without significant damage.

Implementation Method 1

the elastic stop means configured to interpose between the drive system and the housing of the actuator at the end of the brake release phase

Methodology Applied
Scientific EffectElastic deformation: Elasticity

Data Source

PatentEP3674577B1Actuator for electromechanical brake drum with increased sturdiness
Publication Date: 2021.11.17 HITACHI ASTEMO FRANCE
  • EP3674577B1 patent drawingFigure 1~3
  • EP3674577B1 patent drawingFigure 4A~6
  • EP3674577B1 patent drawingFigure 7~8B

AI summary

An electromechanical actuator for a drum brake, comprising a housing (12), two pistons (28, 30) for applying force to a friction element against a drum, and a drive system mounted in the housing for separating the pistons (28, 30) from each other during braking. The drive system comprises a screw-nut assembly and a preloaded elastically deformable element (40), said system having a first longitudinal end face (42) facing a first longitudinal bottom (44) of the housing. The drive system includes interposing means (11) positioned between the first end face (42) of the drive system and the first longitudinal bottom (44) of the housing, configured so that at the end of the release phase, they come into contact with the first longitudinal bottom (44) of the housing and form an elastic stop with the first longitudinal bottom (44) of the housing.