Fluid Actuator Rod Engagement for Long Stroke in Compact Cylinders

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Solution Overview

Problem

Current fluid actuator arrangements with multiple piston rods require large cylinder chamber volumes for long strokes, leading to bulkiness, high energy consumption, and inefficiencies, particularly when used in applications requiring precise and high-force movements.

Innovation Solution

A compact fluid actuator arrangement with a first and second cylinder housing, each having a piston body with through-bores for piston rods, featuring engagement and disengagement devices that allow independent control of piston rods, reducing the need for large volume variations and enabling efficient energy use.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If large cylinder chamber volumes are used to provide long strokes for multiple piston rods, then the actuator can achieve long stroke movements, but the actuator becomes bulky and heavy

Engineering Contradiction:
Improvestroke lengthVSAvoidcylinder chamber volume
Core Design Contradiction:
Length of moving objectVSVolume of moving object

Solution Approach 1:

The invention divides the actuator system into multiple independent piston rod assemblies, each with its own piston body and cylinder chamber. This segmentation allows each piston rod to achieve long stroke independently without requiring the entire actuator to have a proportionally large volume, as each segment operates autonomously within its own chamber.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention arranges multiple piston rods in a spatial configuration where they extend in different directions or planes from a common mounting structure. This dimensional arrangement allows long stroke lengths to be achieved in multiple directions without proportionally increasing the overall actuator volume, as the strokes occur in different spatial dimensions rather than requiring a single large chamber.

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

2Adaptability or versatility

If multiple piston rods are actuated simultaneously in current arrangements, then multiple movements can be achieved, but energy consumption increases significantly

Engineering Contradiction:
Improvemultiple simultaneous movementsVSAvoidenergy consumption
Core Design Contradiction:
Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The invention employs dynamic control of each piston rod's actuation, allowing the system to selectively engage only the piston rods that are currently needed for the task. This dynamic engagement/disengagement mechanism enables multiple movements to be achieved sequentially or selectively rather than continuously powering all piston rods, significantly reducing energy consumption while maintaining versatility.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The invention implements periodic or intermittent actuation of piston rods based on task requirements, rather than continuous operation. Each piston rod can be activated only when its movement is needed, creating a periodic action pattern that reduces overall energy consumption while still achieving multiple simultaneous or sequential movements when required.

Inventive Principle:
Principle #19Periodic action

3Measurement precision

If electrical actuators are used to hold piston rods in position for long periods, then precise positioning can be maintained, but the actuators generate excessive heat and consume high electricity

Engineering Contradiction:
Improvepositioning precisionVSAvoidheat generation and electricity consumption
Core Design Contradiction:
Measurement precisionVSLoss of energy

Solution Approach 1:

The invention employs passive mechanical retention mechanisms, such as friction holds or mechanical locks, that maintain piston rod positions without requiring continuous active power input. The system uses the inherent mechanical properties of the piston rod and cylinder assembly to self-maintain position, eliminating the need for continuous electrical power and associated heat generation while preserving positioning precision.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The invention extracts the continuous power consumption function from the positioning system by separating the holding function from the actuation function. Mechanical retention features are integrated into the piston rod assembly to maintain position passively, removing the need for continuous electrical actuator engagement and thereby eliminating the associated energy loss and heat generation.

Inventive Principle:
Principle #2Taking out (Extraction)

4Force

If conventional fluid actuators are used for high-force applications, then sufficient force can be generated, but the actuators become bulky and less compact

Engineering Contradiction:
Improveoutput forceVSAvoidactuator volume
Core Design Contradiction:
ForceVSVolume of moving object

Solution Approach 1:

The invention segments the force-generating function across multiple independent piston rod assemblies, each contributing to the total output force. This allows high total force to be achieved through the combined action of multiple smaller, more compact piston chambers rather than requiring a single large-volume chamber, thereby maintaining high force output while reducing overall actuator volume.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention merges multiple piston rod assemblies into a single integrated actuator unit, combining their force outputs to achieve high total force. By consolidating multiple compact force-generating elements into one unified structure, the system achieves high force capability without the bulkiness of a single large chamber, as the combined volume of multiple smaller chambers is less than one large chamber of equivalent force capacity.

Inventive Principle:
Principle #5Merging (Combining)

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 achieves a compact, lightweight, and cost-effective actuator capable of high-force, precise movements with reduced energy consumption and heat generation, suitable for various industrial applications, including those requiring simultaneous rod movements in both directions.

Implementation Method 1

at least the first cylinder chamber is coupled to the fluid supply; the first piston body divides the first cylinder housing interior into a first cylinder chamber and a second cylinder chamber

Methodology Applied
Scientific EffectHydraulic pressure: Hydraulic Press

Implementation Method 2

the first through-bore comprises a first engagement and disengagement device and the second through-bore comprises a second engagement and disengagement device, each of the first engagement and disengagement device and the second engagement and disengagement device being arranged for providing individual engagement or disengagement to or from the respective first and second piston rod

Methodology Applied
Scientific EffectFriction: Friction

Data Source

PatentEP3405683B1A fluid actuator arrangement
Publication Date: 2022.08.10 SAAB AB
  • EP3405683B1 patent drawingFigure 1a~1e
  • EP3405683B1 patent drawingFigure 1f~2
  • EP3405683B1 patent drawingFigure 3~5

AI summary

The present invention regards a fluid actuator arrangement (101) comprising a first cylinder housing (103) including a first head member (105) and a second head member (107); a first piston body (109) is slidable arranged in said first cylinder housing; the first piston body (109) divides the first cylinder housing interior into a first cylinder chamber (111) and a second cylinder chamber (113), at least the first cylinder chamber (111) is coupled to a fluid supply (126). The first piston body (109) exhibits a first through-bore (115) and a second through-bore (117) that extend through the first piston body in an axial direction (X); a first piston rod (119) is arranged slidable in the first through-bore (115) and a second piston rod (121) is arranged slidable in the second through-bore (117); and the first through-bore (115) comprises a first engagement and disengagement device (123) and the second through-bore (117) comprises a second engagement and disengagement device (125), which are arranged for providing individual engagement or disengagement to or from the respective first and second piston rod. The invention also regards a method for controlling the motion of at least the first piston rod (119) and the second piston rod (121).