Spring Brake Actuator Release Mechanism Reducing Axial Space

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Solution Overview

Problem

Existing spring brake actuators for commercial vehicles require high torque and suffer from wear and increased space requirements due to the use of release bolts with helical threads for releasing the brake, making them inefficient and bulky.

Innovation Solution

A spring brake actuator with a rotational coupling mechanism that allows for minimal axial space usage, featuring a cam disc and radially movable locking elements to interrupt force transmission between the piston pipe and spring brake piston, enabling easy operation and compact design.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If release bolts with helical threads are used for releasing the brake, then the brake can be released mechanically, but high torque is required and wear increases

Engineering Contradiction:
Improveease of operationVSAvoidtorque
Core Design Contradiction:
Ease of operationVSForce

Solution Approach 1:

The patent replaces the traditional helical thread mechanical system with a cam mechanism. The cam profile converts rotational motion into linear motion to move the piston, eliminating the need for high torque helical threads. This substitution reduces the operating force from high torque requirements to a simpler rotational action on the release rod.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The cam mechanism introduces dynamic motion characteristics where the cam profile is designed to provide mechanical advantage during the release stroke. The varying radius of the cam creates changing leverage throughout the rotation, optimizing the force application and reducing the peak torque required compared to a static helical thread system.

Inventive Principle:
Principle #15Dynamics

2Ease of operation

If release bolts with helical threads are used for releasing the brake, then the brake can be released mechanically, but wear increases

Engineering Contradiction:
Improveease of operationVSAvoidwear
Core Design Contradiction:
Ease of operationVSObject-generated harmful factors

Solution Approach 1:

The patent replaces the helical thread mechanism with a cam-based release mechanism. The cam profile and corresponding follower eliminate the sliding friction and wear associated with threaded bolts. The release rod rotates the cam, which then pushes the piston through a follower, creating rolling or point contact instead of the continuous sliding wear of threaded fasteners.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

3Ease of operation

If traditional release mechanisms are used, then the brake can be released, but axial space requirements increase

Engineering Contradiction:
Improveease of operationVSAvoidaxial space
Core Design Contradiction:
Ease of operationVSLength of moving object

Solution Approach 1:

The cam mechanism is positioned within the existing actuator housing, with the release rod extending through the housing wall. The cam profile is arranged concentrically around the piston rod, and the follower is positioned axially adjacent to the piston. This nested arrangement allows the release mechanism to occupy minimal axial space while still providing full release functionality.

Inventive Principle:
Principle #7Nested doll (Nesting)

Solution Approach 2:

The invention moves the release mechanism from an axial extension (helical threads requiring longitudinal space) to a radial arrangement. The cam rotates in a plane perpendicular to the axial direction, utilizing the radial dimension for the release mechanism's operation. This dimensional change allows the same release function to be achieved with significantly reduced axial length.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

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 reduces the axial space required for the release mechanism, allowing for easier operation and a more compact design while minimizing wear, enabling independent movement of the piston pipe without overcoming the compression spring's resistance, thus improving ease of use and reducing space consumption.

Implementation Method 1

a compression spring that is operatively coupled to the spring brake piston and effective to push the spring brake piston towards the braking position, generating a braking force

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 2

A spring brake actuator with a rotational coupling mechanism that allows for minimal axial space usage, featuring a cam disc and radially movable locking elements to interrupt force transmission between the piston pipe and spring brake piston

Methodology Applied
Scientific EffectCam mechanism: Cam

Data Source

PatentEP3498550B1Spring portion of a spring brake actuator, spring brake actuator and vehicle having the same
Publication Date: 2021.02.17 ZF CV SYST EURO BV
  • EP3498550B1 patent drawingFigure 1
  • EP3498550B1 patent drawingFigure 2a~2b
  • EP3498550B1 patent drawingFigure 3a

AI summary

The invention relates to a spring portion (1) of a spring brake actuator, in particular parking or emergency spring brake actuator, for use in a commercial vehicle. In particular, it is suggested that the spring portion (1) is configured to be coupled to a service brake portion of the spring brake actuator, and comprises a spring brake piston (11) configured to move between a release position and a braking position; a compression spring (6) that is operatively coupled to the spring brake piston (11) and effective to push the spring brake piston (11) towards the braking position, generating a braking force; the spring brake piston (11) comprising a piston pipe (15) that is configured to transfer the braking force to the service brake portion; a coupling (17) that is interposed between the piston pipe (15) and the spring brake piston (11) and configured to move between a locking state and a release state, couple the piston pipe (15) to the spring brake piston (11) when in the locking state, and uncouple the piston pipe (15) and the spring brake piston (11) when in the release state and wherein a rotatable release rod (23) that is operatively coupled to the coupling (17) such that a rotation of the release rod (23) causes the coupling (17) to move between the locking state and the release state.