Single-Piece Drum Brake Linear Actuator for Faster Assembly

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Solution Overview

Problem

The existing linear actuators for drum brakes in motor vehicles are complex and time-consuming to assemble due to the large number of components involved in the assembly of the intermediate wheel flanges.

Innovation Solution

A simplified linear actuator design featuring a hollow cylindrical housing with a rotating threaded element and a sliding linear actuation element, where the intermediate wheel is mounted on a sleeve perpendicular to the main axis, and guide elements are crimped to the axial ends of the housing for secure guidance, reducing the complexity and assembly time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the intermediate wheel is mounted by means of two flanges arranged on either side of the intermediate wheel which are attached to the housing, then the intermediate wheel is securely mounted, but the number of components and assembly time increase

Engineering Contradiction:
Improvesecure mounting of intermediate wheelVSAvoidnumber of components
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the mounting function into a single integrated sleeve structure that receives the intermediate wheel, eliminating the need for separate flanges and their attachment mechanisms. This single-piece sleeve achieves secure mounting while reducing component count and assembly complexity.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If the intermediate wheel is mounted by means of two flanges arranged on either side of the intermediate wheel which are attached to the housing, then the intermediate wheel is securely mounted, but the assembly time increases

Engineering Contradiction:
Improvesecure mounting of intermediate wheelVSAvoidassembly time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent merges the mounting function into a single integrated sleeve structure that receives the intermediate wheel, eliminating the need for separate flanges and their attachment mechanisms. This single-piece sleeve achieves secure mounting while reducing component count and assembly complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Productivity

If the linear actuator comprises a simplified structure with fewer components, then the assembly time and complexity are reduced, but the reliability of component fixation may be compromised

Engineering Contradiction:
Improveassembly efficiencyVSAvoidcomponent fixation reliability
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The sleeve is segmented into functional zones: a mounting portion with external threading for secure attachment to the housing, and a wheel-receiving portion with internal geometry for secure intermediate wheel mounting. This segmentation provides reliable fixation points while maintaining overall structural simplicity.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The sleeve employs a cylindrical geometry with perpendicular axes, creating a compact three-dimensional structure that efficiently mounts the intermediate wheel in a space-optimal configuration while maintaining structural integrity and fixation reliability.

Inventive Principle:
Principle #14Spheroidality (Curvature)

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 simplified design reduces the number of components and assembly time, enhancing the efficiency and reliability of the drum brake actuator while maintaining effective operation.

Implementation Method 1

The linear actuator comprises a housing receiving a rotating threaded element and a linear actuating threaded element, which cooperate with each other to cause the linear displacement of the linear actuating threaded element

Methodology Applied
Scientific EffectThread engagement: Screw

Implementation Method 2

The casing also carries an intermediate wheel which transmits the movement from an electric motor to the rotating threaded element

Methodology Applied
Scientific EffectGear transmission: Gear

Implementation Method 3

said first axial end of the hollow body carries a guide element which guides the linear actuating threaded element in sliding along the main axis A

Methodology Applied
Scientific EffectSliding guidance: Friction

Data Source

PatentEP3752750B1Linear actuator for drum brake
Publication Date: 2023.12.27 HITACHI ASTEMO FRANCE
  • EP3752750B1 patent drawingFigure 1
  • EP3752750B1 patent drawingFigure 2
  • EP3752750B1 patent drawingFigure 3~4

AI summary

The invention proposes a linear actuator (16) for a drum brake (10) of a vehicle, in particular a motor vehicle, including: a rotary threaded element (22) that is able to rotate about a main axis (A) of the linear actuator (16), a threaded linear actuation element (18) that cooperates with the rotary threaded element (22) and that is able to slide along said main axis (A), an intermediate wheel (30) that is able to rotate about a secondary axis parallel to said main axis (A) and that is coupled with the rotary threaded element (22), a housing (40) enclosing the rotary threaded element (22), the threaded linear actuation element (18) and the intermediate wheel (30), characterised in that the housing (40) is made from a single part.