Hydraulic Quick Coupler Locking Mechanism

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Solution Overview

Problem

Existing quick couplers rely solely on spring force for locking, which is insufficient under extreme stress conditions, limiting the holding force and dimensioning of the spring.

Innovation Solution

Integration of a hydraulic system that uses a directional valve to apply hydraulic force in conjunction with spring force to secure the locking element in the locked position, allowing for secure locking and easy unlocking by controlling the hydraulic valve.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If spring force alone is used to hold the locking element in the locked position, then the device complexity is reduced, but the holding force becomes insufficient under extreme stress conditions

Engineering Contradiction:
Improveholding forceVSAvoiddevice complexity
Core Design Contradiction:
ForceVSDevice complexity

Solution Approach 1:

The patent applies hydraulic force through a hydraulic piston to the locking element in addition to spring force. The hydraulic system includes a hydraulic cylinder with opening and locking chambers, controlled by a directional valve, to provide supplementary holding force that ensures secure locking under extreme stress conditions while maintaining reasonable device complexity.

Inventive Principle:
Principle #29Pneumatics and hydraulics

2Force

If a larger spring is used to increase holding force, then the holding force improves, but the device dimensions and weight increase

Engineering Contradiction:
Improveholding forceVSAvoidspring weight
Core Design Contradiction:
ForceVSWeight of moving object

Solution Approach 1:

The patent uses a hydraulic system to provide additional holding force, allowing the use of a smaller, lighter spring compared to a purely mechanical spring-based system. The hydraulic piston transmits force efficiently, reducing the mechanical load on the spring and thus reducing its weight and dimensions.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent combines spring force and hydraulic force to act on the locking element simultaneously. This combination allows the spring to be smaller and lighter since it only needs to provide part of the total holding force, with the hydraulic system contributing the remainder.

Inventive Principle:
Principle #5Merging (Combining)

3Force

If a larger spring is used to increase holding force, then the holding force improves, but the device dimensions increase

Engineering Contradiction:
Improveholding forceVSAvoidspring length
Core Design Contradiction:
ForceVSLength of moving object

Solution Approach 1:

The hydraulic piston provides force transmission with mechanical advantage, allowing a more compact spring configuration. The hydraulic system's compact cylinder and piston arrangement enable sufficient holding force without requiring a large-dimensioned spring.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

By merging spring force and hydraulic force, the patent achieves high holding force with a compact overall design. The spring can be smaller in length and the hydraulic components are compact, resulting in a more space-efficient locking mechanism.

Inventive Principle:
Principle #5Merging (Combining)

4Productivity

If purely mechanical locking is used, then the device complexity is reduced, but the reaction speed during locking and unlocking is limited

Engineering Contradiction:
Improvereaction speedVSAvoiddevice complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The hydraulic system enables rapid locking and unlocking through fast fluid pressure changes. The directional valve controls hydraulic oil flow to quickly build pressure in the locking chamber for locking, and to quickly drain pressure for unlocking, achieving high reaction speed.

Inventive Principle:
Principle #29Pneumatics and hydraulics

Solution Approach 2:

The patent replaces purely mechanical spring-based actuation with a hydraulic actuation system controlled by a directional valve. This substitution allows for faster response times due to the rapid compressibility and flow characteristics of hydraulic fluid, while the valve provides precise control.

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

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

Enhances the holding force in the locked position, ensuring secure engagement even under extreme stress while reducing installation costs and increasing reaction speed during locking and unlocking.

Implementation Method 1

the locking device has at least one locking element, which is acted upon by a spring force in the direction of a locking position

Methodology Applied
Scientific EffectSpring force: Spring

Implementation Method 2

hydraulic pressure is applied to the opening chamber and thus to the hydraulic piston as required, so that the hydraulic piston and the locking element connected to the hydraulic piston are moved from the locked position to an open position against the spring force

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 3

the holding force in the locking position can be easily improved by additionally applying a hydraulic force to the locking element, so that the hydraulic piston and thus also the locking element is held and fixed in the locking position not only by the spring force, but also by a hydraulic force

Methodology Applied
Scientific EffectHydraulic force: Pressure Increase

Data Source

PatentEP2698477B1Quick coupling, method for operating a quick coupling and quick coupling device
Publication Date: 2020.09.23 LEHNHOFF HARTSTAHL GMBH & CO KG
  • EP2698477B1 patent drawingFigure 1
  • EP2698477B1 patent drawingFigure 2

AI summary

The quick coupler has a locking device (32) for connecting working machine and tool. The locking device has locking elements (22,24) that are connected with hydraulic piston (28) which is moved in cylinder (30). An opening chamber (44) is connected with hydraulic valve over hydraulic passage (50) so that the locking elements are moved to opening position hydraulic pressure of hydraulic piston. The locking chamber (42) is connected with hydraulic valve (56) over hydraulic passage (46) so that locking elements are moved to locking position by hydraulic pressure of piston. An independent claim is included for a method for operating quick coupler.