Disc Brake Torque Reproduction for Spacecraft Valve Actuators

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Solution Overview

Problem

Existing systems face challenges in accurately reproducing the complex, nonlinear, and discontinuous dry friction loads experienced by rocket engine valve actuators, which are crucial for simulating real operating conditions but are difficult to replicate effectively.

Innovation Solution

A system utilizing a disc brake with a caliper and piezoelectric actuator to apply controlled resistive torque to a power transmission shaft, incorporating strain gauges for precise force measurement and closed-loop control to replicate dry friction torque, allowing for reliable and simple implementation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a motor is used to apply force simulating hydrodynamic loads, then the hydrodynamic loads are reproduced, but the dry and viscous friction loads become complex to reproduce due to their nonlinear discontinuous behavior

Engineering Contradiction:

Improvereproduction of hydrodynamic loadsVSAvoidcomplexity of reproducing dry and viscous friction loads

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The invention segments the friction reproduction task by separating the dry friction component (handled by the disc brake with plates) from the viscous friction component (handled by the viscous fluid in the cylindrical cavity). This segmentation allows each friction type to be reproduced by dedicated, simpler mechanisms rather than attempting to reproduce both simultaneously with a single complex system.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention introduces a viscous fluid as an intermediary substance within the cylindrical cavity to reproduce viscous friction effects. The fluid acts as a mediator between the rotating disc and the stationary housing, providing the necessary viscous resistance without requiring complex mechanical friction mechanisms. This intermediary approach simplifies the overall system by using fluid dynamics rather than mechanical contact for viscous friction reproduction.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If tests are carried out on the actuator taken in isolation, then the cost of tests is limited, but the entire range of the qualification field cannot be covered

Engineering Contradiction:

Improvecost of testsVSAvoidcoverage of qualification field

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The invention creates a simplified copy of the actual friction mechanisms (dry friction through the disc brake and viscous friction through the fluid) that can be applied to the isolated actuator. This copying approach allows the actuator to be tested in isolation while still experiencing representative friction loads, thereby maintaining test validity without requiring integration into the complete valve assembly.

Inventive Principle:

Principle #26Copying

3Measurement precision

If strain gauges are used to measure forces transmitted by the caliper, then direct measurement of braking force is achieved, but the measurement may be affected by dynamic phenomena related to the braking device

Engineering Contradiction:

Improvedirect measurement of braking forceVSAvoidaccuracy of force measurement under dynamic conditions

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The invention implements a feedback control system where the forces measured by strain gauges on the caliper are continuously monitored and used to adjust the braking force applied by the electric actuator. This feedback mechanism compensates for measurement errors and dynamic phenomena, ensuring accurate reproduction of the desired friction torque despite the challenging measurement environment.

Inventive Principle:

Principle #23Feedback

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 accurate and reliable reproduction of dry friction torque, independent of friction coefficients, improving simulation fidelity without requiring integration into a complete system, thus reducing testing costs and complexities.

Implementation Method 1

The electric actuator is for example a piezoelectric actuator. The electric actuator is typically configured so as to generate a displacement and/or a force proportional to a control voltage or current which is applied to it.

Methodology Applied

Scientific EffectPiezoelectric effect: Piezoelectric Effect

Implementation Method 2

a disc brake including a caliper mounted on a frame and plates adapted to be put into contact with the disc... generating a resisting torque on the power transmission shaft of the actuator

Methodology Applied

Scientific EffectFriction: Friction

Implementation Method 3

said device for measuring tangent forces includes strain gauges measuring the strains applied to the fixing of the caliper on the frame

Methodology Applied

Scientific EffectStrain measurement:

Data Source

PatentUS10151653B2System for reproducing a dry friction torque applied to an actuator of a valve located in a hydraulic line of an engine of a spacecraft including an electrical actuator controlling orthogonal forces of plates on a disc to apply resistive torque to a shaft of the actuator

Publication Date: 2018.12.11 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A system for reproducing a dry friction torque applied to an actuator on a valve of a hydraulic line including a disc coupled to a power transmission shaft; a disc brake including a caliper mounted on a frame and plates adapted to be put into contact with the disc; and an electric actuator configured to control the force of application of the plates onto the disc so as to apply a controlled resistive torque to the power transmission shaft, is provided.