Actuator Device with Opposing Biasing Elements for Constant Force

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Solution Overview

Problem

Existing actuator devices face limitations due to varying preload of hydraulic fluid, leading to pressure differences that restrict maximum deflection and result in inconsistent force development, especially when requiring both forward and backward movements.

Innovation Solution

The actuator device incorporates a drive unit and an output unit with two translation units connected via a line system, where biasing elements are supported in opposite directions by a movable clamping component, maintaining constant pressures and allowing for symmetrical deflection paths, thus ensuring constant force and increased stroke.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the hydraulic fluid is preloaded to enable bidirectional movement, then the actuator can move in both forward and backward directions, but the preload varies with deflection causing pressure differences that limit maximum deflection and result in inconsistent force development

Engineering Contradiction:
Improvebidirectional movement capabilityVSAvoidforce consistency
Core Design Contradiction:
Adaptability or versatilityVSForce

Solution Approach 1:

The patent applies the counterweight principle by introducing a second translation unit with a prestressing element that acts in opposition to the first translation unit. The prestressing elements are arranged such that they compensate for each other's force variations, with one element's increasing preload counterbalanced by the other's decreasing preload, thereby maintaining constant total force output throughout the deflection range

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent merges two translation units with opposing prestressing elements into a single actuator system. The fluid chambers of both units are connected to the same hydraulic fluid supply, and their outputs are combined to produce a unified actuator response. This merging allows the system to achieve constant force by combining the complementary force characteristics of the two opposing elements

Inventive Principle:
Principle #5Merging (Combining)

2Adaptability or versatility

If the hydraulic fluid is preloaded for bidirectional movement, then the actuator can operate in both directions, but pressure differences arise that limit the maximum possible deflection

Engineering Contradiction:
Improvebidirectional movement capabilityVSAvoidmaximum deflection
Core Design Contradiction:
Adaptability or versatilityVSLength of moving object

Solution Approach 1:

The opposing prestressing elements function as counterweights that balance each other's force variations. As one element's preload increases with deflection, the other's preload decreases, creating a compensating effect that eliminates net force variation and removes the pressure difference limitation on maximum deflection

Inventive Principle:
Principle #8Anti-weight (Counterweight)

Solution Approach 2:

The patent changes the system parameters by using two translation units with opposing prestressing characteristics. By selecting prestressing elements with appropriate spring rates and preloads, the system parameters are configured to achieve constant total force and eliminate pressure differences, thereby enabling greater maximum deflection

Inventive Principle:
Principle #35Parameter changes

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 design maintains constant force and increases the maximum stroke by keeping fluid pressures consistent, allowing for symmetrical and efficient operation in both directions, simplifying assembly and enhancing the actuator's performance.

Implementation Method 1

The first translation unit and the second translation unit each have a biasing element. According to the invention, these prestressing elements are supported in opposite directions against a movably mounted common clamping.

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

In order to deflect the drives, a fluid can be exchanged between the first translation unit and the second translation unit by means of the drive unit. The first translation unit and the second translation unit each have a biasing element.

Methodology Applied
Scientific EffectHydraulic pressure transmission: Pascal's Law

Data Source

PatentEP2938885B1Actuator device
Publication Date: 2018.05.30 SIEMENS AG
  • EP2938885B1 patent drawingFigure 1
  • EP2938885B1 patent drawingFigure 2~4

AI summary

The invention relates to an actuator device (1) having a drive unit (3) and an output unit (19). The output unit (19) comprises a first translation unit (15) having a first output (7) and a second translation unit (16), connected in a fluid manner to the first translation unit (15) via a pipeline system, having a second output (8). The drive unit (3) is connected to the pipeline system (27) in a fluid manner. To deflect the outputs (7, 8), a fluid can be exchanged between the first translation unit (15) and the second translation unit (16) by means of the drive unit (3). The first translation unit (15) and the second translation unit (16) each have a pre-clamping element (12, 25). According to the invention, said pre-clamping elements (12, 25) are supported in the opposite direction against a movably mounted clamping (4).