Multi-Head Hydraulic Actuator for Force-Speed Switching

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Solution Overview

Problem

Conventional hydraulic actuators face challenges in balancing slew rate and load capabilities, often resulting in high leakages, stability issues, and increased envelope size due to the need for larger piston diameters to meet load and slew rate requirements, which do not coincide in maximum load conditions.

Innovation Solution

The design incorporates three piston heads with a large head and two smaller heads, allowing for fast slew rates at lower force outputs and greater force outputs at reduced slew rates, utilizing a mode selection device to operate in high speed and high power output modes by selectively connecting fluid volumes and pressure sources.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If a larger piston diameter is used to meet load requirements, then force output capability is improved, but slew rate decreases and envelope size increases

Engineering Contradiction:

Improveforce output capabilityVSAvoidslew rate

Core Design Contradiction:

ForceVSSpeed

Solution Approach 1:

The piston is segmented into multiple piston heads with different diameters (first piston head, second piston head, third piston head) arranged in series within the housing. Each piston head can be selectively connected to different fluid volumes, allowing the system to achieve different force and speed characteristics by engaging different piston heads based on operational requirements.

Inventive Principle:

Principle #1Segmentation

2Force

If a larger piston diameter is used to meet load requirements, then force output capability is improved, but envelope size increases

Engineering Contradiction:

Improveforce output capabilityVSAvoidenvelope size

Core Design Contradiction:

ForceVSVolume of stationary object

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

3Force

If the actuator is designed for maximum load conditions, then force output is improved, but stability and leakage performance worsen

Engineering Contradiction:

Improveforce outputVSAvoidstability

Core Design Contradiction:

ForceVSReliability

Solution Approach 1:

The actuator system dynamically switches between different operational modes by using a mode selection device to connect different fluid volumes to different piston heads. The system can operate in a first mode using the first and second piston heads, and in a second mode using the second and third piston heads, allowing optimization of stability and leakage performance for different operating conditions rather than being fixed for maximum load.

Inventive Principle:

Principle #15Dynamics

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

This configuration enables the actuator to achieve efficient force output and slew rate capabilities, allowing for faster movements at lower forces with low flow and greater forces at reduced speeds, effectively addressing the limitations of conventional designs.

Implementation Method 1

A hydraulic actuator comprises a cylindrical housing in which is mounted an axially moveable piston rod. A head of the rod, inside the housing, divides the housing into two chambers each having a fluid port via which pressurized fluid can be injected into the chamber or low-pressure fluid exits the chamber, so as to change the relative pressure in the two chambers either side of the piston head, thus causing movement of the piston relative to the housing.

Methodology Applied

Scientific EffectHydraulic fluid pressure: Pressure Increase

Implementation Method 2

The system also includes First, second, and third piston heads connected to piston shaft with the first piston head being tween the second and third piston, wherein the first position head is within the first region and divides the first region into two volumes, the second piston head is in the second region and defines a first volume and the third piston head is in the third region and defines a fourth volume and a mode selection device operably connected to the first, second, third and fourth volume.

Methodology Applied

Scientific EffectFluid flow control: Valve

Data Source

PatentUS12145719B2Hydraulic actuator including a multi-head piston for hydraulic gearing

Publication Date: 2024.11.19 HAMILTON SUNDSTRAND CORP

AI summary

A hydraulic actuator system includes a hydraulic actuator having a housing with a piston having a piston shaft arranged within the housing. The housing is formed to have first, second and third regions, wherein the first region is between the second and third regions and has a larger major dimension than the second and third regions. The system also includes first, second, and third piston heads connected to the piston shaft with the first piston head being tween the second and third piston, wherein the first position head is within the first region and divides the first region into two volumes, the second piston head is in the second region and defines a first volume and the third piston head is in the third region and defines a fourth volume. The system also includes a mode selection device operably connected to the first, second, third and fourth volume.