Hydraulic Pallet Truck with Dual-Pump Electric Assist

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Solution Overview

Problem

Existing pallet trucks are inefficient for operators, lacking power-assisted lifting capabilities while maintaining simplicity, and often require excessive manual effort, especially when handling heavy loads on rough surfaces.

Innovation Solution

A pallet truck with a hydraulic lifting system powered by a manual tiller arm and an electric motor, featuring a common hydraulic reservoir, a bypass valve for load limitation, and sensors for controlled lift height and weight management, allowing for efficient operation with optional electric assistance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If an electric motor and second hydraulic pump are added to provide powered lift capability, then operational efficiency is improved, but device complexity increases

Engineering Contradiction:
Improveoperational efficiencyVSAvoidsystem complexity
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent combines two hydraulic pumps (manual first hydraulic pump and electric second hydraulic pump) into a single integrated hydraulic system that shares a common hydraulic reservoir and controls a single hydraulic cylinder. This merging approach allows the system to leverage both manual and electric power sources without requiring separate hydraulic circuits, thereby improving operational efficiency while minimizing the increase in system complexity.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The hydraulic system is designed to be multi-functional, capable of operating in both manual mode (using the first hydraulic pump) and electrically assisted mode (using the second hydraulic pump). The system can adaptively switch between power sources based on operational needs, providing versatility without requiring entirely separate systems for each function.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Use of energy by moving object

If lift height and weight are limited to conserve energy, then energy consumption is reduced, but lifting capability is restricted

Engineering Contradiction:
Improveenergy consumptionVSAvoidlifting capability
Core Design Contradiction:
Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The system implements partial action by providing electric motor assistance only for a portion of the lifting operation - specifically for lighter loads or for the initial phase of lifting. For heavier loads or complete lifting operations, the manual first hydraulic pump remains fully capable of performing the entire lifting function. This approach conserves energy by using the electric motor only when necessary while preserving full lifting capability through the manual system.

Inventive Principle:
Principle #16Partial or excessive action

3Device complexity

If a common hydraulic reservoir is used for both pumps, then system simplicity is improved, but fluid management complexity increases

Engineering Contradiction:
Improvesystem simplicityVSAvoidfluid management
Core Design Contradiction:
Device complexityVSEase of manufacture

Solution Approach 1:

The common hydraulic reservoir is designed to be self-regulating, where the hydraulic system automatically manages fluid distribution between the two pumps based on operational demands. The system utilizes the natural properties of hydraulic fluid and pressure differential to direct flow to the appropriate pump without requiring complex electronic fluid management systems, thereby maintaining simplicity while ensuring proper fluid management.

Inventive Principle:
Principle #25Self-service

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 enhances operational efficiency by allowing powered lift capabilities within the original manual pallet truck framework, conserving energy by limiting lift height and weight, and enabling adaptable lifting restrictions, while maintaining simplicity and reliability.

Implementation Method 1

The pallet truck has a hydraulic lifting system comprising a first hydraulic pump and a hydraulic cylinder

Methodology Applied
Scientific EffectHydraulic pressurization: Hydraulic Press

Implementation Method 2

The pallet truck comprises an electric motor and a second hydraulic pump powered by said electric motor

Methodology Applied
Scientific EffectElectromagnetic conversion: Electromagnetic Induction

Data Source

PatentEP3421321B1Pallet truck
Publication Date: 2022.05.11 TOYOTA MATERIAL HANDLING MFG SWEDEN
  • EP3421321B1 patent drawingFigure 1~2
  • EP3421321B1 patent drawingFigure 3~4
  • EP3421321B1 patent drawingFigure 4a

AI summary

Pallet truck (1) comprising two forks (2) for lifting and transporting a pallet, a hydraulic lifting system comprising a first hydraulic pump (4) and a hydraulic cylinder (5) a tiller arm (3) that is operable for powering the first hydraulic pump (4) by a manual lifting an lowering movement of the tiller arm (3), such that a load is lifted by actuating of the hydraulic cylinder (5) on the forks (2) to a maximal height H and at a maximal weight M, further comprised are a main wheel (6) that are hinged in a vertical axle (13) to which they are attached, the tiller arm (3) is connected to said wheels (6) for steering them by rotating in the vertical axle (13), wherein the pallet truck (1) comprises an electric motor (8) and a second hydraulic pump (9) powered by said motor (8), wherein said electric motor (8) and the second hydraulic pump (9) are operable to lift the forks (2) to the maximal height h, wherein h < H, and/or wherein the electric motor (8) and second hydraulic pump (9) has a capacity to lift a maximal load of mass m, wherein m < M. There is also disclosed a method of modifying a pallet truck a first method of operating a pallet truck and a second method of operating a pallet truck. Further disclosed is a computer readable software for executing any of the methods.