Hybrid Clamp Force Circuit for Fast Lift Truck Clamp Closure

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Hydraulic control systems for lift truck clamp attachments face limitations in achieving high-speed closure without damaging loads, as low initial pressure requirements restrict productivity and the use of flow dividers can inhibit speed and efficiency due to pressure and flow rate constraints.

Innovation Solution

A hydraulic control circuit that alternates between hydraulically linked and unlinked modes for hydraulic actuators, allowing high-speed coordinated movement during clamp positioning and adjusting clamp force efficiently upon contact, without relying on flow dividers, by using a sequence valve to manage fluid pressure and linkage between actuators.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If high initial pressure is used to achieve high-speed closure of clamps, then closing speed is improved, but load damage risk increases

Engineering Contradiction:

Improveclosing speedVSAvoidload damage

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The system uses two distinct pressure phases: a first relief valve setting during initial closure to allow high-speed movement, and a second relief valve setting after load contact to limit maximum force. This periodic switching of pressure thresholds enables both high closing speed and load protection.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system changes the pressure parameter dynamically by providing two different relief valve settings. The first setting allows higher pressure for rapid closure, while the second setting limits pressure to prevent load damage. This parameter switching resolves the contradiction between speed and safety.

Inventive Principle:

Principle #35Parameter changes

2Object-affected harmful factors

If low initial pressure is used to prevent load damage, then load safety is improved, but closing speed decreases

Engineering Contradiction:

Improveload damageVSAvoidclosing speed

Core Design Contradiction:

Object-affected harmful factorsVSSpeed

Solution Approach 1:

The system implements periodic pressure control with two phases: initial high-pressure closure for speed, followed by pressure limitation after load contact. This temporal separation of pressure levels achieves both fast closure and load protection.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The system performs preliminary high-speed closure at higher pressure before load contact, then switches to pressure-limited mode. This preliminary action allows the clamps to reach the load quickly, after which safety constraints are applied.

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If flow dividers are used to coordinate clamp movement, then synchronization is improved, but closing speed is limited due to pressure constraints

Engineering Contradiction:

Improveclamp synchronizationVSAvoidclosing speed

Core Design Contradiction:

Stability of the object's compositionVSSpeed

Solution Approach 1:

The patent removes flow dividers from the hydraulic circuit entirely, replacing them with a direct dual-relief-valve control system. This extraction eliminates the speed-limiting effect of flow dividers while maintaining synchronization through shared hydraulic pressure control.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The hydraulic fluid acts as an intermediary that simultaneously controls both clamps through the relief valve settings. The fluid pressure serves as the mediating mechanism for synchronization without requiring flow dividers, enabling faster operation.

Inventive Principle:

Principle #24Intermediary (Mediator)

4Productivity

If high closing pressure is used to achieve fast closure, then productivity is improved, but the pressure becomes trapped by check valves exceeding desired threshold

Engineering Contradiction:

Improveclosure speedVSAvoidtrapped pressure

Core Design Contradiction:

ProductivityVSStress or pressure

Solution Approach 1:

The relief valves provide continuous pressure feedback control. When pressure exceeds the first relief valve setting during closure, the valve opens to prevent pressure trapping. This feedback mechanism allows high-speed closure while automatically preventing excessive pressure accumulation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The system uses periodic pressure relief through the first relief valve during the closure phase, allowing pressure to build for speed but release when thresholds are exceeded. This periodic action prevents trapped pressure while maintaining high closing speed.

Inventive Principle:

Principle #19Periodic 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

Enables high-speed closure of clamps while minimizing load damage, improving productivity and efficiency by optimizing clamp force application and reducing the risk of premature contact and fluid pressure issues.

Implementation Method 1

Methodology Applied

Scientific EffectHydraulic pressure control: Pressure Increase

Implementation Method 2

A hydraulic control circuit that alternates between hydraulically linked and unlinked modes for hydraulic actuators

Methodology Applied

Scientific EffectHydraulic linkage: Pascal's Law

Data Source

PatentUS12145828B2Synchronized hybrid clamp force controller for lift truck attachment

Publication Date: 2024.11.19 CASCADE CORPORATION

AI summary

A hydraulic control circuit operable to selectively hydraulically link first and second hydraulic actuators and to bypass that hydraulic link.